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472900.9984Newly isolated lactic acid bacteria from silage targeting biofilms of foodborne pathogens during milk fermentation. BACKGROUND: Raw milk, meat and plant materials are subjected to high risks of contamination by various pathogenic bacteria and thus their growth prevention is a great challenge in the food industry. Food fermentation by lactic acid bacteria (LAB) besides changing its organoleptic characteristics also helps to eliminate unfavorable microflora and represses growth of pathogens. To the date only few LABs has been reported to exhibit activity against bacteria embedded in the biofilms characterized by extreme resistance to antimicrobials, high exchange rate with resistance genes and represent high risk factor for foodborne disease development. RESULTS: Six novel LAB strains isolated from the clover silage exhibited pronounced antibacterial activity against biofilm embedded pathogens. We show explicitly that these strains demonstrate high acidification rate, completely repress the growth of E. coli, S. aureus and to a lesser extent P. aeruginosa as well as exhibit appropriate probiotic and milk-fermenting properties. Moreover, in contrast to the approved probiotic strain Lactobacillus plantarum 8PA3, the new isolates were able to efficiently eradicate preformed biofilms of these pathogens and prevent bacterial spreading originating from the biofilm. We suggest these strains as potential additives to the pre-cultures of conventional LAB strains as efficient tools targeting foodborne pathogens in order to prevent food contamination from either seeded raw material or biofilm-fouled equipment. CONCLUSIONS: The AG10 strain identified as L. plantarum demonstrate attractive probiotic and milk fermentation properties as well as high resistance to simulated gastric conditions thus appearing perspective as a starter culture for the prevention of bacterial contamination originating from fouled equipment during milk fermentation.201931703621
609410.9984Genomic characterization and computational phenotyping of nitrogen-fixing bacteria isolated from Colombian sugarcane fields. Previous studies have shown the sugarcane microbiome harbors diverse plant growth promoting microorganisms, including nitrogen-fixing bacteria (diazotrophs), which can serve as biofertilizers. The genomes of 22 diazotrophs from Colombian sugarcane fields were sequenced to investigate potential biofertilizers. A genome-enabled computational phenotyping approach was developed to prioritize sugarcane associated diazotrophs according to their potential as biofertilizers. This method selects isolates that have potential for nitrogen fixation and other plant growth promoting (PGP) phenotypes while showing low risk for virulence and antibiotic resistance. Intact nitrogenase (nif) genes and operons were found in 18 of the isolates. Isolates also encode phosphate solubilization and siderophore production operons, and other PGP genes. The majority of sugarcane isolates showed uniformly low predicted virulence and antibiotic resistance compared to clinical isolates. Six strains with the highest overall genotype scores were experimentally evaluated for nitrogen fixation, phosphate solubilization, and the production of siderophores, gibberellic acid, and indole acetic acid. Results from the biochemical assays were consistent and validated computational phenotype predictions. A genotypic and phenotypic threshold was observed that separated strains by their potential for PGP versus predicted pathogenicity. Our results indicate that computational phenotyping is a promising tool for the assessment of bacteria detected in agricultural ecosystems.202133911103
471420.9984Screening and genome analysis of heat-resistant and antioxidant lactic acid bacteria from Holstein cow milk. BACKGROUND: Heat stress significantly impacts dairy cows, primarily through oxidative stress, which undermines their health. The problem is exacerbated by the ongoing global warming trend. Lactic acid bacteria (LAB) are safe, economical, and readily accessible options for enhancing the host's antioxidant defenses and preventing oxidative damage. They have been proven effective in alleviating heat stress-related damage, making them an excellent choice for protecting dairy cows from the adverse effects of heat stress. METHOD: In this study, five strains of LAB from Holstein cow milk (Lactobacillus plantarum L5, L14, L17, L19, L20) were evaluated for their heat resistance and antioxidant capacity by evaluating the growth characteristics and tolerance of the strains under high-temperature conditions, as well as their H(2)O(2) tolerance, free radical scavenging ability (DPPH, OH(-), ABTS), reducing ability, and EPS production ability. Furthermore, we employed Caco-2 cells to assess the adhesion rate of the strain, thereby confirming its ability to successfully colonize the host's intestinal tract and ensuring the effective execution of its probiotic functions. The strain with excellent heat resistance and antioxidant capacity was then subjected to genomic analysis to gain insight into the molecular mechanisms behind their heat resistance, antioxidant capacity, and safety. RESULTS: Among the two strains, Lactobacillus plantarum L19 emerges as a highly promising candidate. The strain exhibits robust growth even at high temperatures at 40°C and maintains a survival rate of 16.42% at the extreme temperature of 65°C. Furthermore, it demonstrates superior tolerance to hydrogen peroxide (27.3%), and possesses a notably higher free radical scavenging capacity with a high adhesion rate to Caco-2 cell (22.19%) compared to the other four strains tested. Genomic analysis revealed its' genome has 17 genes related to antioxidants and three genes related to heat resistance. Importantly, L19 lacks any resistance genes, ensuring its safety as a probiotic. CONCLUSION: The results imply that Lactobacillus plantarum L19 has the potential to serve as an effective food additive in mitigating damages associated with heat stress. This research offers a valuable reference for the prevention and management of heat stress in dairy cows, while also expanding the scope of applications for LAB derived from cow milk.202439611093
607430.9984Beneficial properties of lactic acid bacteria naturally present in dairy production. BACKGROUND: Consumers are increasingly demanding for natural and beneficial foods, in order to improve their health and well-being. Probiotics play an important role in such demand, and dairy foods are commonly used as vehicles for such bacteria, represented predominantly by lactic acid bacteria. Due to consumers demand, food industry is constantly looking for novel bacterial strains, leading to studies that aims the isolation and characterization of their beneficial features. This study aimed to characterize the naturally occurring lactic acid bacteria obtained from a dairy environment, in order to assess their potential use as probiotics. RESULTS: Preliminary screening and PCR analysis, based on 16S rRNA sequencing, were applied to select and identify 15 LAB strains from the genera Lactobacillus (n = 11), Pediococcus (n = 2) and Weissella (n = 2). All strains showed resistance to low pH and the evaluated bile salt concentrations in vitro. The API ZYM test characterized the enzymatic activity of the strains, and a high β-galactosidase activity was observed in 13 strains. All strains presented resistance to simulated gastric (3 h) and intestinal (4 h) conditions in vitro, the ability to auto- and co-aggregate with indicator microorganisms and a high cell surface hydrophobicity. Most of the strains were positive for map and EFTu beneficial genes. All strains exhibited strong deconjugation of bile salts in vitro and all assimilated lactose. CONCLUSIONS: The phenotypes exhibited in vitro and the presence of beneficial genes revealed the beneficial potential of the studied strains, demanding further analyses in a food matrix and in vivo to allow the development of a functional product, with health-related properties.201830567551
607140.9984Functional properties of novel protective lactic acid bacteria and application in raw chicken meat against Listeria monocytogenes and Salmonella enteritidis. In this study 635 lactic acid bacteria of food origin were evaluated for their potential application as protective cultures in foods. A stepwise selection method was used to obtain the most appropriate strains for application as protective cultures in chicken meat. Specifically, all strains were examined for antimicrobial activity against various Gram positive and Gram negative pathogenic and spoilage bacteria. Strains exhibiting anti-bacterial activity were subsequently examined for survival in simulated food processing and gastrointestinal tract conditions, such as high temperatures, low pH, starvation and the presence of NaCl and bile salts. Selected strains where then examined for basic safety properties such as antibiotic resistance and haemolytic potential, while their antimicrobial activity was further investigated by PCR screening for possession of known bacteriocin genes. Two chosen strains were then applied on raw chicken meat to evaluate their protective ability against two common food pathogens, Listeria monocytogenes and Salmonella enteritidis, but also to identify potential spoilage effects by the application of the protective cultures on the food matrix. Antimicrobial activity in vitro was evident against Gram positive indicators, mainly Listeria and Brochothrix spp., while no antibacterial activity was obtained against any of the Gram negative bacteria tested. The antimicrobial activity was of a proteinaceous nature while strains with anti-listerial activity were found to possess one or more bacteriocin genes, mainly enterocins. Strains generally exhibited sensitivity to pH 2.0, but good survival at 45 degrees C, in the presence of bile salts and NaCl as well as during starvation, while variable survival rates were obtained at 55 degrees C. None of the strains was found to be haemolytic while variable antibiotic resistance profiles were obtained. Finally, when the selected strains Enterococcus faecium PCD71 and Lactobacillus fermentum ACA-DC179 were applied as protective cultures in chicken meat against L. monocytogenes and S. enteritidis respectively, a significantly reduced growth of these pathogenic bacteria was observed. In addition, these two strains did not appear to have any detrimental effect on biochemical parameters related to spoilage of the chicken meat.200919249112
471850.9984Formic acid, an organic acid food preservative, induces viable-but-non-culturable state, and triggers new Antimicrobial Resistance traits in Acinetobacter baumannii and Klebsiella pneumoniae. Numerous human pathogens, especially Gram-negative bacteria, are able to enter the viable-but-non-culturable (VBNC) state when they are exposed to environmental stressors and pose the risk of being resuscitated and causing infection after the removal of the trigger. Widely used food preservatives like weak organic acids are potential VBNC inducers in food processing and packaging facilities but have only been reported for food-borne pathogens. In the present study, it is demonstrated for the first time that one such agent, formic acid (FA), can induce a VBNC state at food processing, storage, and distribution temperatures (4, 25, and 37(°)C) with a varied time of treatment (days 4-10) in pathogenic Gram-negative bacteria Acinetobacter baumannii and Klebsiella pneumoniae. The use of hospital-associated pathogens is critical based on the earlier reports that demonstrated the presence of these bacteria in hospital kitchens and commonly consumed foods. VBNC induction was validated by multiple parameters, e.g., non-culturability, metabolic activity as energy production, respiratory markers, and membrane integrity. Furthermore, it was demonstrated that the removal of FA was able to resuscitate VBNC with an increased expression of multiple virulence and Antimicrobial Resistance (AMR) genes in both pathogens. Since food additives/preservatives are significantly used in most food manufacturing facilities supplying to hospitals, contamination of these packaged foods with pathogenic bacteria and the consequence of exposure to food additives emerge as pertinent issues for infection control, and control of antimicrobial resistance in the hospital setting.202236504816
895460.9984Effect of biofilm formation by antimicrobial-resistant gram-negative bacteria in cold storage on survival in dairy processing lines. Antimicrobial-resistant gram-negative bacteria in dairy products can transfer antimicrobial resistance to gut microbiota in humans and can adversely impact the product quality. In this study, we aimed to investigate their distribution in dairy processing lines and evaluate biofilm formation and heat tolerance under dairy processing line-like conditions. Additionally, we compared the relative expression of general and heat stress-related genes as well as spoilage-related gene between biofilm and planktonic cells under consecutive stresses, similar to those in dairy processing lines. Most species of gram-negative bacteria isolated from five different dairy processing plants were resistant to one or more antimicrobials. Biofilm formation by the bacteria at 5 °C increased with the increase in exposure time. Moreover, cells in biofilms remained viable under heat treatment, whereas all planktonic cells of the selected strains died. The expression of heat-shock-related genes significantly increased with heat treatment in the biofilms but mostly decreased in the planktonic cells. Thus, biofilm formation under raw milk storage conditions may improve the tolerance of antimicrobial-resistant gram-negative bacteria to pasteurization, thereby increasing their persistence in dairy processing lines and products. Furthermore, the difference in response to heat stress between biofilm and planktonic cells may be attributed to the differential expression of heat stress-related genes. Therefore, this study contributes to the understanding of how gram-negative bacteria persist under consecutive stresses in dairy processing procedures and the potential mechanism underlying heat tolerance in biofilms.202336436412
471570.9984Genomic and stress resistance characterization of Lactiplantibacillus plantarum GX17, a potential probiotic for animal feed applications. Lactobacilli, recognized as beneficial bacteria within the human body, are celebrated for their multifaceted probiotic functions, including the regulation of intestinal flora, enhancement of body immunity, and promotion of nutrient absorption. This study comprehensively analyzed the genotypic and phenotypic characteristics of Lactiplantibacillus plantarum (L. plantarum) strains isolated from the intestines of healthy chicks and assessed their potential as probiotics. The assembled genome consists of 29,521,986 bp, and a total of 1,771 coding sequences (CDSs) were predicted. Based on the entire genome sequence analysis, 50 stress resistance genes and seven virulence factors were identified. The results of the phenotypic experiments showed that the strain had good resistance to high temperature, low temperature, acid, alkali, salt, artificial gastrointestinal fluid, and strong antioxidant capacity. Additionally, transcriptomic analysis confirmed that under stress conditions, the expression levels of key genes were significantly upregulated. Therefore, the phenotypic characteristics of L. plantarum GX17 align well with its genotypic features, demonstrating promising probiotic properties. This strain holds great potential as a probiotic candidate, and further investigation into its beneficial effects on human health is warranted. IMPORTANCE: In humans, Lactiplantibacillus plantarum may synergize with host microbiota to ameliorate dysbiosis-related pathologies, enhance immunomodulation, and facilitate micronutrient bioavailability. For livestock, its application could improve feed conversion ratios, suppress enteric pathogens through competitive exclusion, and mitigate antibiotic overuse, "a critical strategy in One Health frameworks." Further investigations into strain-specific mechanisms (e.g., postbiotic metabolites, quorum sensing regulation) are warranted to translate these genomic-phenotypic advantages into sustainable health solutions across species.202540919934
604480.9984Phenotypic and Genetic Characterization and Production Abilities of Lacticaseibacillus rhamnosus Strain 484-A New Probiotic Strain Isolated From Human Breast Milk. Recent studies suggest that human breast milk (HBM) is a promising source of probiotic bacteria with potential applications in both medicine and the food industry. Probiotic bacteria, particularly species of the genus Lactobacillus, are classified as lactic acid bacteria (LAB). However, probiotic properties are strain-specific, as not all Lactobacillus strains exhibit health benefits or inhibit pathogens. This study evaluated the probiotic potential of a newly isolated strain, Lacticaseibacillus rhamnosus strain 484, derived from human milk. Phenotypic and genomic analyses were performed, with L. rhamnosus 1.0320 serving as a reference genome. We focused on strain safety for human use and potential health benefits. Strain 484 underwent probiotic characterization and demonstrated strong auto- and co-aggregation abilities, contributing to effective pathogenic bacteria inhibition. The strain also showed bile tolerance, antibiotic sensitivity, and lacked hemolytic and catalase activity, indicating safety and suitability profiles for oral administration. Its resistance to low pH and bile salts indicated survival during gastrointestinal transit and intestinal colonization. Notably, cell surface hydrophobicity (CSH) exceeded that of the well-known L. rhamnosus GG strain, potentially enhancing adhesion to intestinal epithelial cells. Genomic analysis confirmed no antibiotic resistance genes (ARGs) and plasmids, suggesting genetic stability. Overall, L. rhamnosus 484 appears to be a safe and promising probiotic candidate with potential applications in both medical and food-related fields, particularly for oral use in preventing and controlling common pathogens.202541019172
477590.9984Safety assessment of dairy microorganisms: the Lactobacillus genus. Lactobacilli are Gram positive rods belonging to the Lactic Acid Bacteria (LAB) group. Their phenotypic traits, such as each species' obligate/facultative, homo/heterofermentation abilities play a crucial role in souring raw milk and in the production of fermented dairy products such as cheese, yoghurt and fermented milk (including probiotics). An up to date safety analysis of these lactobacilli is needed to ensure consumer safety. Lactobacillus genus is a heterogeneous microbial group containing some 135 species and 27 subspecies, whose classification is constantly being reshuffled. With the recent use of advanced molecular methods it has been suggested that the extreme diversity of the Lactobacillus genomes would justify recognition of new subgeneric divisions. A combination of genotypic and phenotypic tests, for example DNA-based techniques and conventional carbohydrate tests, is required to determine species. Pulsed-Field gel Electrophoresis (PFGE) has been successfully applied to strains of dairy origin and is the most discriminatory and reproducible method for differentiating Lactobacillus strains. The bibliographical data support the hypothesis that the ingestion of Lactobacillus is not at all hazardous since lactobacillemia induced by food, particularly fermented dairy products, is extremely rare and only occurs in predisposed patients. Some metabolic features such as the possible production of biogenic amines in fermented products could generate undesirable adverse effects. A minority of starter and adjunct cultures and probiotic Lactobacillus strains may exceptionally show transferable antibiotic resistance. However, this may be underestimated as transferability studies are not systematic. We consider that transferable antibiotic resistance is the only relevant cause for caution and justifies performing antibiotic-susceptibility assays as these strains have the potential to serve as hosts of antibiotic-resistance genes, with the risk of transferring these genes to other bacteria. However, as a general rule, lactobacilli have a high natural resistance to many antibiotics, especially vancomycin, that is not transferable. Safety assessment requirements for Lactobacillus strains of technological interest should be limited to an antibiotic profile and a study to determine whether any antibiotic resistance(s) of medical interest detected is (or are) transferable. This agrees with the recent EFSA proposal suggesting attribution of a QPS status for 32 selected species of lactobacilli.200817889388
5168100.9984Bacteriophage Resistance Affects Flavobacterium columnare Virulence Partly via Mutations in Genes Related to Gliding Motility and the Type IX Secretion System. Increasing problems with antibiotic resistance have directed interest toward phage therapy in the aquaculture industry. However, phage resistance evolving in target bacteria is considered a challenge. To investigate how phage resistance influences the fish pathogen Flavobacterium columnare, two wild-type bacterial isolates, FCO-F2 and FCO-F9, were exposed to phages (FCO-F2 to FCOV-F2, FCOV-F5, and FCOV-F25, and FCO-F9 to FCL-2, FCOV-F13, and FCOV-F45), and resulting phenotypic and genetic changes in bacteria were analyzed. Bacterial viability first decreased in the exposure cultures but started to increase after 1 to 2 days, along with a change in colony morphology from original rhizoid to rough, leading to 98% prevalence of the rough morphotype. Twenty-four isolates (including four isolates from no-phage treatments) were further characterized for phage resistance, antibiotic susceptibility, motility, adhesion, and biofilm formation, protease activity, whole-genome sequencing, and virulence in rainbow trout fry. The rough isolates arising in phage exposure were phage resistant with low virulence, whereas rhizoid isolates maintained phage susceptibility and high virulence. Gliding motility and protease activity were also related to the phage susceptibility. Observed mutations in phage-resistant isolates were mostly located in genes encoding the type IX secretion system, a component of the Bacteroidetes gliding motility machinery. However, not all phage-resistant isolates had mutations, indicating that phage resistance in F. columnare is a multifactorial process, including both genetic mutations and changes in gene expression. Phage resistance may not, however, be a challenge for development of phage therapy against F. columnare infections since phage resistance is associated with decreases in bacterial virulence. IMPORTANCE Phage resistance of infectious bacteria is a common phenomenon posing challenges for the development of phage therapy. Along with a growing world population and the need for increased food production, constantly intensifying animal farming has to face increasing problems of infectious diseases. Columnaris disease, caused by Flavobacterium columnare, is a worldwide threat for salmonid fry and juvenile farming. Without antibiotic treatments, infections can lead to 100% mortality in a fish stock. Phage therapy of columnaris disease would reduce the development of antibiotic-resistant bacteria and antibiotic loads by the aquaculture industry, but phage-resistant bacterial isolates may become a risk. However, phenotypic and genetic characterization of phage-resistant F. columnare isolates in this study revealed that they are less virulent than phage-susceptible isolates and thus not a challenge for phage therapy against columnaris disease. This is valuable information for the fish farming industry globally when considering phage-based prevention and curing methods for F. columnare infections.202134106011
3917110.9983Antibiotic resistance of lactic acid bacteria isolated from dry-fermented sausages. Dry-fermented sausages are meat products highly valued by many consumers. Manufacturing process involves fermentation driven by natural microbiota or intentionally added starter cultures and further drying. The most relevant fermentative microbiota is lactic acid bacteria (LAB) such as Lactobacillus, Pediococcus and Enterococcus, producing mainly lactate and contributing to product preservation. The great diversity of LAB in dry-fermented sausages is linked to manufacturing practices. Indigenous starters development is considered to be a very promising field, because it allows for high sanitary and sensorial quality of sausage production. LAB have a long history of safe use in fermented food, however, since they are present in human gastrointestinal tract, and are also intentionally added to the diet, concerns have been raised about the antimicrobial resistance in these beneficial bacteria. In fact, the food chain has been recognized as one of the key routes of antimicrobial resistance transmission from animal to human bacterial populations. The World Health Organization 2014 report on global surveillance of antimicrobial resistance reveals that this issue is no longer a future prediction, since evidences establish a link between the antimicrobial drugs use in food-producing animals and the emergence of resistance among common pathogens. This poses a risk to the treatment of nosocomial and community-acquired infections. This review describes the possible sources and transmission routes of antibiotic resistant LAB of dry-fermented sausages, presenting LAB antibiotic resistance profile and related genetic determinants. Whenever LAB are used as starters in dry-fermented sausages processing, safety concerns regarding antimicrobial resistance should be addressed since antibiotic resistant genes could be mobilized and transferred to other bacteria.201526002560
4740120.9983Resensitization of Multi Drug-Resistant Aeromonas caviae with Exogenous Hydrogen Sulfide Potentiated Antibiotics. Antimicrobial resistance (AMR) is a growing public health threat caused by the widespread overuse of antibiotics. Bacteria with antibiotic resistance may acquire resistance genes from soil or water. Endogenous hydrogen sulfide (H(2)S) production in bacteria confers antibiotic tolerance in many, suggesting a universal defense mechanism against antibiotics. In this study, we isolated and identified soil-based antibiotic-resistant bacteria collected from contaminated areas. An antibiotic-resistant bacterium was identified as non-endogenous-H(2)S-producing, allowing us to examine the effect of exogenous H(2)S on its resistance mechanism. Therefore, we demonstrated that different classes of antibiotic resistance can be reverted by employing H(2)S with antibiotics like ampicillin and gentamicin. Methods like Kirby-Bauer Disk-Diffusion, Scanning Electron Microscopy, and Flow Cytometer analysis were performed to assess the antibacterial activity of H(2)S with ampicillin and gentamicin. The antioxidative efficiency of H(2)S was evaluated using the DCFH-DA (ROS) test, as well as lipid peroxidation, and LDH activity. These were further confirmed with enzymatic and non-enzymatic (SOD, CAT, GST, and GSH) antioxidant studies. These findings support H(2)S as an antibiotic-potentiator, causing bacterial membrane damage, oxidative stress, and disrupting DNA and proteins. Thus, supplying exogenous H(2)S can be a good agent for the reversal of Antibiotic resistance.202439579197
8467130.9983The Impacts of Lactiplantibacillus plantarum on the Functional Properties of Fermented Foods: A Review of Current Knowledge. One of the most varied species of lactic acid bacteria is Lactiplantibacillus plantarum (Lb. plantarum), formerly known as Lactobacillus plantarum. It is one of the most common species of bacteria found in foods, probiotics, dairy products, and beverages. Studies related to genomic mapping and gene locations of Lb. plantarum have shown the novel findings of its new strains along with their non-pathogenic or non-antibiotic resistance genes. Safe strains obtained with new technologies are a pioneer in the development of new probiotics and starter cultures for the food industry. However, the safety of Lb. plantarum strains and their bacteriocins should also be confirmed with in vivo studies before being employed as food additives. Many of the Lb. plantarum strains and their bacteriocins are generally safe in terms of antibiotic resistance genes. Thus, they provide a great opportunity for improving the nutritional composition, shelf life, antioxidant activity, flavour properties and antimicrobial activities in the food industry. Moreover, since some Lb. plantarum strains have the ability to reduce undesirable compounds such as aflatoxins, they have potential use in maintaining food safety and preventing food spoilage. This review emphasizes the impacts of Lb. plantarum strains on fermented foods, along with novel approaches to their genomic mapping and safety aspects.202235456875
4713140.9983Characterization and Preliminary Safety Evaluation of Akkermansia muciniphila PROBIO. In addition to providing certain health advantages to the host, a bacterial strain must possess a clearly defined safety profile to be regarded as a probiotic. In this study, we present a thorough and methodical assessment of the safety of a novel strain of bacteria, Akkermansia muciniphila PROBIO, which was isolated from human feces. Firstly, we examined the strain's overall features, such as its gastrointestinal tolerance and its physiological and biochemical traits. Next, we verified its genotoxic properties through bacterial reverse mutation and in vitro mammalian cell micronucleus assays. The drug sensitivity of A. muciniphila PROBIO was subsequently examined through an analysis of its antibiotic resistance genes. Additionally, the toxicological impact was verified through acute and sub-chronic toxicity studies. A genome-based safety assessment was conducted to gain further insights into gene function, including potential virulence factors and pathogenic properties. Finally, we assessed whether moxifloxacin resistance in A. muciniphila PROBIO is transferred using in vitro conjugation experiments. A. muciniphila PROBIO exhibited superior gastrointestinal tolerance, with no observed hematological or histopathological abnormalities. Moreover, the outcomes pertaining to mutagenic, clastogenic, or toxic impacts were found to be negative, even at exceedingly high dosages. Moreover, no adverse effects associated with the test substance were observed during the examination of acute and sub-chronic toxicity. Consequently, it was plausible to estimate the no-observed-adverse-effect level (NOAEL) to be 6.4 × 10(11) viable bacteria for an average individual weighing 70 kg. Additionally, only three potential drug resistance genes and one virulence factor gene were annotated. A. muciniphila PROBIO is naturally resistant to moxifloxacin, and resistance does not transfer. Collectively, the data presented herein substantiate the presumed safety of A. muciniphila PROBIO for its application in food.202438338577
3919150.9983Detection of antibiotic resistance in probiotics of dietary supplements. BACKGROUND: Probiotics are live microorganisms that confer nutrition- and health-promoting benefits if consumed in adequate amounts. Concomitant with the demand for natural approaches to maintaining health is an increase in inclusion of probiotics in food and health products. Since probiotic bacteria act as reservoir for antibiotic resistant determinants, the transfer of these genes to pathogens sharing the same intestinal habitat is thus conceivable considering the fact that dietary supplements contain high amounts of often heterogeneous populations of probiotics. Such events can confer pathogens protection against commonly-used drugs. Despite numerous reports of antibiotic resistant probiotics in food and biological sources, the antibiogram of probiotics from dietary supplements remained elusive. FINDINGS: Here, we screened five commercially available dietary supplements for resistance towards antibiotics of different classes. Probiotics of all batches of products were resistant towards vancomycin while batch-dependent resistance towards streptomycin, aztreonam, gentamycin and/or ciprofloxacin antibiotics was detected for probiotics of brands Bi and Bn, Bg, and L. Isolates of brand Cn was also resistant towards gentamycin, streptomycin and ciprofloxacin antibiotics. Additionally, we also report a discrepancy between the enumerated viable bacteria amounts and the claims of the manufacturers. CONCLUSIONS: This short report has highlighted the present of antibiotic resistance in probiotic bacteria from dietary supplements and therefore serves as a platform for further screenings and for in-depth characterization of the resistant determinants and the molecular machinery that confers the resistance.201526370532
6043160.9983Histamine and cholesterol lowering abilities of lactic acid bacteria isolated from artisanal Pico cheese. AIMS: This study was designed to select lactic acid bacteria with histamine- and cholesterol-reducing abilities to be used as potential probiotics. METHODS AND RESULTS: Thirty strains of lactic acid bacteria isolated from an artisanal raw milk cheese were screened for their abilities to degrade histamine, reduce cholesterol and hydrolyse bile salts. Strains were also screened for safety and probiotic traits, such as resistance to gastrointestinal conditions, adhesion to Caco-2 cells, resistance to antibiotics and presence of virulence genes. Two Lactobacillus paracasei strains presented high cholesterol- and histamine-lowering abilities, tested negative for the presence of virulence genes and showed susceptibility to most important antibiotics. These strains were also shown to possess desirable in vitro probiotic properties, revealed by tolerance to gastrointestinal conditions and high adhesion to intestinal cells. CONCLUSIONS: Among the screened strains, Lb. paracasei L3C21M6 revealed the best cholesterol and histamine reducing abilities together with desirable probiotic and safety features to be used in food applications. SIGNIFICANCE AND IMPACT OF THE STUDY: The strain L3C21M6 is a good candidate for use as a probiotic with histamine-degrading activity and cholesterol lowering effect. In addition, this strain could be use in dairy foods to prevent histamine food poisoning.202032500572
8838170.9983Dual RNA-seq analysis reveals the interaction between multidrug-resistant Klebsiella pneumoniae and host in a mouse model of pneumonia. BACKGROUND: Multidrug-resistant Klebsiella pneumoniae (MDR-KP) poses a significant global health threat, associated with high morbidity and mortality rates among hospitalized patients. The interaction between MDR-KP and its host is highly complex, and few studies have investigated these interactions from both the pathogen and host perspectives. Here, we explored these interactions in a mouse model of pneumonia using dual RNA-seq analysis. METHODS: PCR identification and antimicrobial susceptibility test were employed to screen for MDR-KP strains. A mouse model of pneumonia was established through aerosolized intratracheal inoculation with high-dose or low-dose bacteria. Bacterial loads, pathological changes, inflammatory cytokine expression, and immune cell infiltration were assessed post-challenge. Dual RNA-seq analysis was conducted on lung tissues following infection. RESULTS: NY13307 was identified as an MDR-KP strain with minimal virulence factor genes and broad-spectrum drug resistance. High-dose bacteria induced more severe pulmonary pathological changes, a significant increase in bacterial load, and notably elevated secretion of inflammatory cytokines compared to low-dose bacteria. Alveolar macrophages and resident interstitial macrophages were identified as the primary sources of these cytokines. Further RNA-seq analysis revealed that, compared to the low-dose group, the high-dose group significantly upregulated hypoxia and pro-inflammatory cytokine-related genes in the host, and siderophore-related genes in the bacteria. Correlation analysis demonstrated a significant association between siderophore-related genes and clusters of genes related to pro-inflammatory cytokines and hypoxia. CONCLUSIONS: In this mouse model of bacterial pneumonia, excessive siderophore expression may trigger the activation of hypoxia signaling pathways and the release of pro-inflammatory cytokines, ultimately reducing survival rates.202540702458
6020180.9983Safety evaluation of Lactococcus lactis IDCC 2301 isolated from homemade cheese. For applications of microorganisms as probiotics in the food industry, safety evaluation has increasingly become important to ensure the health of consumers. Although people have been using various lactic acid bacteria for different purposes, some studies have reported that certain lactic acid bacteria exhibit properties of virulence and produce toxic compounds. Thus, it is necessary to examine the characteristics associated with lactic acid bacteria that are safe for use as probiotics. This research aimed to assess the safety of Lactococcus lactis IDCC 2301 isolated from homemade cheese using in vitro and in vivo assays, including antibiotic resistance, hemolytic activity, toxin production, infectivity, and metabolic activity in immune-compromised animal species. The results demonstrated that the strain was susceptible to nine antibiotics suggested by the European Food Safety Authority (EFSA). Whole-genome analysis revealed that L. lactis IDCC 2301 neither has toxigenic genes nor harbors antibiotic resistance. Moreover, L. lactis IDCC 2301 showed neither hemolytic nor β-glucuronidase activity. Furthermore, none of the D-lactate and biogenic amines were produced by L. lactis IDCC 2301. Finally, it was demonstrated that there was no toxicity and mortality using single-dose oral toxicity tests in rats. These results indicate that L. lactis IDCC 2301 can be safely used as probiotics for human consumption.202235035910
4574190.9983Antibiotic resistance and microbial composition along the manufacturing process of Mozzarella di Bufala Campana. The use of antibiotics as growth promoters in livestock, banned in all EU member states in January 2006, has led to selection of antibiotic resistant strains within environmental bacteria, including gram-positive, non pathogenic bacteria that colonize the GI tract of humans and animals. In Italy and in other Mediterranean countries, fermented foods employing environmental bacteria pre-existing in the raw substrates, rather than industrial starters of defined genotype, represent a significant proportion of cheese and meat products carrying the official PDO designation (Protected Designation of Origin). Our study focused on the microbiological and molecular analysis of lactobacilli and of other lactic acid bacteria (LABs) isolated from the Italian PDO product water buffalo Mozzarella cheese, with the aim of identifying genes responsible for tetracycline, erythromycin and kanamycin resistance. We isolated over 500 LAB colonies from retail products, as well as from raw milk and natural whey starters employed in their production. Microbiological analysis showed that about 50% of these isolates were represented by lactobacilli, which were further characterized in terms of species and strain composition, as well as by determining phenotypic and genotypic antibiotic resistance. To overcome the limits of culture-dependent approaches that select only cultivable species, we have also extracted total DNA from the whole microbiome present in the cheese and investigated the presence of specific antibiotic resistance genes with molecular approaches. Genetic determinants of antibiotic resistance were identified almost exclusively in bacteria isolated from the raw, unprocessed substrates, while the final, marketed products did not contain phenotypically resistant lactobacilli, i.e. displaying MIC values above the microbiological breakpoint. Overall, our results suggest that the traditional procedures necessary for manufacturing of this typical cheese, such as high temperature treatments, lead to a final product with low bacterial counts, lower biodiversity and lack of significant presence of antibiotic resistant lactobacilli.200818990462