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353400.9576The Effects of Flavomycin and Colistin Sulfate Pre-Treatment on Ileal Bacterial Community Composition, the Response to Salmonella typhimurium and Host Gene Expression in Broiler Chickens. The composition of the bacterial community affects the intestinal health and growth performance of broiler chickens. The main purpose of this study was to explore the effects of flavomycin and colistin sulfate on the resistance to Salmonella typhimurium infection, ileal bacteria and intestinal health. In total, 396 1-day-old broiler chickens were randomly divided into six groups. Two groups were fed each one of the diets-the control diet (CON), the flavomycin at 10 mg/kg diet (AntiG+), and the colistin sulfate at 40 mg/kg diet (AntiG-), for 5 days. Then, one of each of the two groups was challenged with S. typhimurium on the 8th day; these were named CONS, AntiG+S and AntiG-S, respectively. The results showed that S. typhimurium significantly reduced the feed intake and body weight gain, and increased the feed conversion ratio (p < 0.05). It also increased the inflammatory expressions of NF-κB and MyD88 genes (p < 0.05); and reduced the expressions of claudin-1, occludin and mucin-2 (p < 0.05) tight junction genes in the intestines. S. typhimurium significantly reduced ileal bacterial diversity indexes of observed-species, chao1 and Shannon (p < 0.05). Compared with AntiG+S group, AntiG-S group increased the body weight gain of broiler chickens (p < 0.05), reduced the expression of inflammatory genes (p < 0.05) and intestinal permeability to fluorescein isothiocyanate (p < 0.05). AntiG-S group also improved the ileal bacterial diversity indexes of observed-species and Shannon (p < 0.05). There were many significant correlations between intestinal bacteria, intestinal gene expressions and intestinal morphology (p < 0.05). This study indicated that pre-constructed AntiG- bacteria could against a S. typhimurium infection by inhibiting the expressions of intestinal inflammation genes and increasing the diversity of intestinal bacteria.201931752202
601310.9565Multidrug resistance in hydrocarbon-tolerant Gram-positive and Gram-negative bacteria. New Gram-positive and Gram-negative bacteria were isolated from Poeni oily sludge, using enrichment procedures. The six Gram-positive strains belong to Bacillus, Lysinibacillus and Rhodococcus genera. The eight Gram-negative strains belong to Shewanella, Aeromonas, Pseudomonas and Klebsiella genera. Isolated bacterial strains were tolerant to saturated (i.e., n-hexane, n-heptane, n-decane, n-pentadecane, n-hexadecane, cyclohexane), monoaromatic (i.e., benzene, toluene, styrene, xylene isomers, ethylbenzene, propylbenzene) and polyaromatic (i.e., naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons, and also resistant to different antimicrobial agents (i.e., ampicillin, kanamycin, rhodamine 6G, crystal violet, malachite green, sodium dodecyl sulfate). The presence of hydrophilic antibiotics like ampicillin or kanamycin in liquid LB-Mg medium has no effects on Gram-positive and Gram-negative bacteria resistance to toxic compounds. The results indicated that Gram-negative bacteria are less sensitive to toxic compounds than Gram-positive bacteria, except one bacteria belonging to Lysinibacillus genus. There were observed cellular and molecular modifications induced by ampicillin or kanamycin to isolated bacterial strains. Gram-negative bacteria possessed between two and four catabolic genes (alkB, alkM, alkB/alkB1, todC1, xylM, PAH dioxygenase, catechol 2,3-dioxygenase), compared with Gram-positive bacteria (except one bacteria belonging to Bacillus genus) which possessed one catabolic gene (alkB/alkB1). Transporter genes (HAE1, acrAB) were detected only in Gram-negative bacteria.201121478643
605320.9562Probiotic properties of lactic acid bacteria isolated from water-buffalo mozzarella cheese. This study evaluated the probiotic properties (stability at different pH values and bile salt concentration, auto-aggregation and co-aggregation, survival in the presence of antibiotics and commercial drugs, study of β-galactosidase production, evaluation of the presence of genes encoding MapA and Mub adhesion proteins and EF-Tu elongation factor, and the presence of genes encoding virulence factor) of four LAB strains (Lactobacillus casei SJRP35, Leuconostoc citreum SJRP44, Lactobacillus delbrueckii subsp. bulgaricus SJRP57 and Leuconostoc mesenteroides subsp. mesenteroides SJRP58) which produced antimicrobial substances (antimicrobial peptides). The strains survived the simulated GIT modeled in MRS broth, whole and skim milk. In addition, auto-aggregation and the cell surface hydrophobicity of all strains were high, and various degrees of co-aggregation were observed with indicator strains. All strains presented low resistance to several antibiotics and survived in the presence of commercial drugs. Only the strain SJRP44 did not produce the β-galactosidase enzyme. Moreover, the strain SJRP57 did not show the presence of any genes encoding virulence factors; however, the strain SJRP35 presented vancomycin resistance and adhesion of collagen genes, the strain SJRP44 harbored the ornithine decarboxylase gene and the strain SJRP58 generated positive results for aggregation substance and histidine decarboxylase genes. In conclusion, the strain SJRP57 was considered the best candidate as probiotic cultures for further in vivo studies and functional food products development.201425117002
600530.9561Antimicrobial activity of Pediococcus pentosaceus strains against diarrheal pathogens isolated from pigs and effect on paracellular permeability of HT-29 cells. This study aimed to investigate lactic acid bacteria with antimicrobial activities against infectious diarrheal pathogens in pigs and their genetic characteristics. Acid-resistant lactic acid bacteria were examined for bile resistance, pancreatic enzyme resistance, gelatinase and urease activities, and antibiotic resistance. Subsequently, selected isolates were examined for antimicrobial activities against Campylobacter coli, Clostridium perfringens, Escherichia coli, and Salmonella Typhimurium, and their effects on paracellular permeability and the expression of tight junction protein-encoding genes in HT-29 cells were assessed. Whole genome sequencing was performed to identify the genes related to safety and antibacterial activity. Of the 51 isolates examined, 12 were resistant to bile and pancreatin and did not produce gelatinase and urease. Of these 12, isolates 19, 20, 30, 36, and 67 showed tetracycline resistance and isolates 15, 19, and 38W showed antimicrobial activity against infectious diarrheal bacteria. Treatment with isolate 38W significantly reduced the paracellular permeability induced by E. coli in HT-29 cells and alleviated the expression of tight junction protein-encoding genes (claudin-1, occludin, and ZO-1) induced by E. coli inoculation. Isolates 15, 19, and 38W were named as Pediococcus pentosaceus SMFM2016-NK1, SMFM2016-YK1, and SMFM2016-WK1, respectively. Bacteriocin-related genes were YheH, ytrF, BceA, BceB, and MccF in SMFM2016-NK1; YheH, ytrF, BceA, BceB, entK, lcnA, MccF, and skgD in SMFM2016-YK1; and YheH, ytrF, BceA, BceB, and MccF in SMFM2016-WK1. SMFM2016-YK1 harbored the tetM gene. These results indicate that P. pentosaceus SMFM2016-WK1 might control diarrheal pathogens isolated from pigs. However, a further study is necessary because the results were obtained only from in vitro experiment.202540873998
125940.9558Tetracycline resistance potential of heterotrophic bacteria isolated from freshwater fin-fish aquaculture system. AIMS: This study investigated the tetracycline resistance potential of heterotrophic bacteria isolated from twenty-four freshwater fin-fish culture ponds in Andhra Pradesh, India. METHODS AND RESULTS: A total of 261 tetracycline resistant bacteria (tetR) were recovered from pond water, pond sediment, fish gills, fish intestine, and fish feed. Bacteria with high tetracycline resistance (tetHR) (n = 30) that were resistant to tetracycline concentrations above 128  μg mL-1 were predominantly Lactococcus garvieae followed by Enterobacter spp., Lactococcus lactis, Enterobacter hormaechei, Staphylococcus arlettae, Streptococcus lutetiensis, Staphylococcus spp., Brevundimonas faecalis, Exiguobacterium profundum, Lysinibacillus spp., Stutzerimonas stutzeri, Enterobacter cloacae, and Lactococcus taiwanensis. Resistance to 1024 μg mL-1 of tetracycline was observed in L. garvieae, S. arlettae, Enterobacter spp., B. faecalis. Tet(A) (67%) was the predominant resistance gene in tetHR followed by tet(L), tet(S), tet(K), and tet(M). At similar concentrations of exposure, tetracycline procured at the farm level (69.5% potency) exhibited lower inhibition against tetHR bacteria compared to pure tetracycline (99% potency). The tetHR bacteria showed higher cross-resistance to furazolidone (100%) followed by co-trimoxazole (47.5%) and enrofloxacin (11%). CONCLUSIONS: The maximum threshold of tetracycline resistance at 1024 μg mL-1 was observed in S. arlettae, Enterobacter spp., B. faecalis, and L. garvieae and tet(A) was the major determinant found in this study.202336958862
608050.9556Metagenomic Insights into the Taxonomic and Functional Features of Traditional Fermented Milk Products from Russia. Fermented milk products (FMPs) contain probiotics that are live bacteria considered to be beneficial to human health due to the production of various bioactive molecules. In this study, nine artisanal FMPs (kefir, ayran, khurunga, shubat, two cottage cheeses, bryndza, khuruud and suluguni-like cheese) from different regions of Russia were characterized using metagenomics. A metagenomic sequencing of ayran, khurunga, shubat, khuruud and suluguni-like cheese was performed for the first time. The taxonomic profiling of metagenomic reads revealed that Lactococcus species, such as Lc. lactis and Lc. cremoris prevailed in khuruud, bryndza, one sample of cottage cheese and khurunga. The latter one together with suluguni-like cheese microbiome was dominated by bacteria, affiliated to Lactobacillus helveticus (32-35%). In addition, a high proportion of sequences belonging to the genera Lactobacillus, Lactococcus and Streptococcus but not classified at the species level were found in the suluguni-like cheese. Lactobacillus delbrueckii, as well as Streptococcus thermophilus constituted the majority in another cottage cheese, kefir and ayran metagenomes. The microbiome of shubat, produced from camel's milk, was significantly distinctive, and Lentilactobacillus kefiri, Lactobacillus kefiranofaciens and Bifidobacterium mongoliense represented the dominant components (42, 7.4 and 5.6%, respectively). In total, 78 metagenome-assembled genomes with a completeness ≥ 50.2% and a contamination ≤ 8.5% were recovered: 61 genomes were assigned to the Enterococcaceae, Lactobacillaceae and Streptococcaceae families (the Lactobacillales order within Firmicutes), 4 to Bifidobacteriaceae (the Actinobacteriota phylum) and 2 to Acetobacteraceae (the Proteobacteria phylum). A metagenomic analysis revealed numerous genes, from 161 to 1301 in different products, encoding glycoside hydrolases and glycosyltransferases predicted to participate in lactose, alpha-glucans and peptidoglycan hydrolysis as well as exopolysaccharides synthesis. A large number of secondary metabolite biosynthetic gene clusters, such as lanthipeptides, unclassified bacteriocins, nonribosomal peptides and polyketide synthases were also detected. Finally, the genes involved in the synthesis of bioactive compounds like β-lactones, terpenes and furans, nontypical for fermented milk products, were also found. The metagenomes of kefir, ayran and shubat was shown to contain either no or a very low count of antibiotic resistance genes. Altogether, our results show that traditional indigenous fermented products are a promising source of novel probiotic bacteria with beneficial properties for medical and food industries.202338276185
604960.9552Probiotic Properties and Antioxidant Activity In Vitro of Lactic Acid Bacteria. The properties of probiotics such as lactic acid bacteria (LAB) have been widely studied over the last decades. In the present study, four different LAB species, namely Lactobacillus gasseri ATCC 33323, Lacticaseibacillus rhamnosus GG ATCC 53103, Levilactobacillus brevis ATCC 8287, and Lactiplantibacillus plantarum ATCC 14917, were investigated in order to determine their ability to survive in the human gut. They were evaluated based on their tolerance to acids, resistance to simulated gastrointestinal conditions, antibiotic resistance, and the identification of genes encoding bacteriocin production. All four tested strains demonstrated high resistance to simulated gastric juice after 3 h, and the viable counts revealed declines in cell concentrations of less than 1 log cycle. L. plantarum showed the highest level of survival in the human gut, with counts of 7.09 log CFU/mL. For the species L. rhamnosus and L. brevis, the values were 6.97 and 6.52, respectively. L. gasseri, after 12 h, showed a 3.96 log cycle drop in viable counts. None of the evaluated strains inhibited resistance to ampicillin, gentamicin, kanamycin, streptomycin, erythromycin, clindamycin, tetracycline, or chloramphenicol. With regard to bacteriocin genes, the Pediocin PA gene was identified in Lactiplantibacillus plantarum ATCC 14917, Lacticaseibacillus rhamnosus GG ATCC 53103, and Lactobacillus gasseri ATCC 33323. The PlnEF gene was detected in Lactiplantibacillus plantarum ATCC 14917 and Lacticaseibacillus rhamnosus GG ATCC 53103. The Brevicin 174A and PlnA genes were not detected in any bacteria. Moreover, the potential antioxidant activity of LAB's metabolites was evaluated. At the same time, the possible antioxidant activity of metabolites of LAB was first tested using the free radical DDPH(•) (a, a-Diphenyl-β-Picrylhydrazyl) and then evaluated with regard to their radical scavenging activity and inhibition against peroxyl radical induced DNA scission. All strains showed antioxidant activity; however, the best antioxidant activity was achieved by L. brevis (94.47%) and L. gasseri (91.29%) at 210 min. This study provides a comprehensive approach to the action of these LAB and their use in the food industry.202337317238
80870.9552Exposure of Legionella pneumophila to low-shear modeled microgravity: impact on stress response, membrane lipid composition, pathogenicity to macrophages and interrelated genes expression. Here, we studied the effect of low-shear modeled microgravity (LSMMG) on cross stress resistance (heat, acid, and oxidative), fatty acid content, and pathogenicity along with alteration in expression of stress-/virulence-associated genes in Legionella pneumophila. The stress resistance analysis result indicated that bacteria cultivated under LSMMG environments showed higher resistance with elevated D-values at 55 °C and in 1 mM of hydrogen peroxide (H(2)O(2)) conditions compared to normal gravity (NG)-grown bacteria. On the other hand, there was no significant difference in tolerance (p < 0.05) toward simulated gastric fluid (pH-2.5) acid conditions. In fatty acid analysis, our result showed that a total amount of saturated and cyclic fatty acids was increased in LSMMG-grown cells; as a consequence, they might possess low membrane fluidity. An upregulated expression level was noticed for stress-related genes (hslV, htrA, grpE, groL, htpG, clpB, clpX, dnaJ, dnaK, rpoH, rpoE, rpoS, kaiB, kaiC, lpp1114, ahpC1, ahpC2, ahpD, grlA, and gst) under LSMMG conditions. The reduced virulence (less intracellular bacteria and less % of induce apoptosis in RAW 264.7 macrophages) of L. pneumophila under LSMMG conditions may be because of downregulation related genes (dotA, dotB, dotC, dotD, dotG, dotH, dotL, dotM, dotN, icmK, icmB, icmS, icmT, icmW, ladC, rtxA, letA, rpoN, fleQ, fleR, and fliA). In the LSMMG group, the expression of inflammation-related factors, such as IL-1α, TNF-α, IL-6, and IL-8, was observed to be reduced in infected macrophages. Also, scanning electron microscopy (SEM) analysis showed less number of LSMMG-cultivated bacteria attached to the host macrophages compared to NG. Thus, our study provides understandings about the changes in lipid composition and different genes expression due to LSMMG conditions, which apparently influence the alterations of L. pneumophila' stress/virulence response.202438305908
848180.9548Universal stress proteins contribute Edwardsiella piscicida adversity resistance and pathogenicity and promote blocking host immune response. Universal stress proteins (Usps) exist ubiquitously in bacteria and other organisms. Usps play an important role in adaptation of bacteria to a variety of environmental stresses. There is increasing evidence that Usps facilitate pathogens to adapt host environment and are involved in pathogenicity. Edwardsiella piscicida (formerly included in E. tarda) is a severe fish pathogen and infects various important economic fish including tilapia (Oreochromis niloticus). In E. piscicida, a number of systems and factors that are involved in stress resistance and pathogenesis were identified. However, the function of Usps in E. piscicida is totally unknown. In this study, we examined the expressions of 13 usp genes in E. piscicida and found that most of these usp genes were up-regulated expression under high temperature, oxidative stress, acid stress, and host serum stress. Particularly, among these usp genes, usp13, exhibited dramatically high expression level upon several stress conditions. To investigate the biological role of usp13, a markerless usp13 in-frame mutant strain, TX01Δusp13, was constructed. Compared to the wild type TX01, TX01Δusp13 exhibited markedly compromised tolerance to high temperature, hydrogen peroxide, and low pH. Deletion of usp13 significantly retarded bacterial biofilm growth and decreased resistance against serum killing. Pathogenicity analysis showed that the inactivation of usp13 significantly impaired the ability of E. piscicida to invade into host cell and infect host tissue. Introduction of a trans-expressed usp13 gene restored the lost virulence of TX01Δusp13. In support of these results, host immune response induced by TX01 and TX01Δusp13 was examined, and the results showed reactive oxygen species (ROS) levels in TX01Δusp13-infected macrophages were significantly higher than those in TX01-infected cells. The expression level of several cytokines (IL-6, IL-8, IL-10, TNF-α, and CC2) in TX01Δusp13-infected fish was significantly higher than that in TX01-infected fish. These results suggested that the deletion of usp13 attenuated the ability of bacteria to overcome the host immune response to pathogen infection. Taken together, our study indicated Usp13 of E. piscicida was not only important participant in adversity resistance, but also was essential for E. piscicida pathogenicity and contributed to block host immune response to pathogen infection.201931654767
365690.9545Surveillance of antimicrobial resistance in bacteria isolated from food animals to antimicrobial growth promoters and related therapeutic agents in Denmark. This study was conducted to describe the occurrence of acquired resistance to antimicrobials used for growth promotion among bacteria isolated from swine, cattle and poultry in Denmark. Resistance to structurally related therapeutic agents was also examined. Three categories of bacteria were tested: 1) indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium), 2) zoonotic bacteria (Campylobacter, Salmonella, Yersinia enterocolitica), and 3) animal pathogens (E. coli, Staphylococcus aureus, coagulase-negative staphylococci (CNS), Staphylococcus hyicus, Actinobacillus pleuropneumoniae). All antimicrobials used as growth promoters in Denmark and some structurally related therapeutic agents (in brackets) were included: Avilamycin, avoparcin (vancomycin), bacitracin, carbadox, flavomycin, monensin, olaquindox, salinomycin, spiramycin (erythromycin, lincomycin), tylosin (erythromycin, lincomycin), and virginiamycin (pristinamycin). Bacterial species intrinsically resistant to an antimicrobial were not tested towards that antimicrobial. Breakpoints for growth promoters were established by population distribution of the bacteria tested. A total of 2,372 bacterial isolates collected during October 1995 to September 1996 were included in the study. Acquired resistance to all currently used growth promoting antimicrobials was found. A frequent occurrence of resistance were observed to avilamycin, avoparcin, bacitracin, flavomycin, spiramycin, tylosin and virginiamycin, whereas resistance to carbadox, monensin, olaquindox and salinomycin was less frequent. The occurrence of resistance varied by animal origin and bacterial species. The highest levels of resistance was observed among enterococci, whereas less resistance was observed among zoonotic bacteria and bacteria pathogenic to animals. The association between the occurrence of resistance and the consumption of the antimicrobial is discussed. The results show the present level of resistance to growth promoters in bacteria from food animals in Denmark. They will form the baseline for comparison with future prospective studies, thereby enabling the determination of trends over time.19989725794
5390100.9542Presence of erythromycin and tetracycline resistance genes in lactic acid bacteria from fermented foods of Indian origin. Lactic acid bacteria (LAB) resistant to erythromycin were isolated from different food samples on selective media. The isolates were identified as Enterococcus durans, Enterococcus faecium, Enterococcus lactis, Enterococcus casseliflavus, Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus fermentum, Pediococcus pentosaceus and Leuconostoc mesenteroides. Of the total 60 isolates, 88 % harbored the ermB gene. The efflux gene msrA was identified in E. faecium, E. durans, E. lactis, E. casseliflavus, P. pentosaceus and L. fermentum. Further analysis of the msrA gene by sequencing suggested its homology to msrC. Resistance to tetracycline due to the genes tetM, tetW, tetO, tetK and tetL, alone or in combination, were identified in Lactobacillus species. The tetracycline efflux genes tetK and tetL occurred in P. pentosaceus and Enterococcus species. Since it appeared that LAB had acquired these genes, fermented foods may be a source of antibiotic resistance.201222644346
3608110.9540Natural antibiotic resistance of bacteria isolated from larvae of the oil fly, Helaeomyia petrolei. Helaeomyia petrolei (oil fly) larvae inhabit the asphalt seeps of Rancho La Brea in Los Angeles, Calif. The culturable microbial gut contents of larvae collected from the viscous oil were recently examined, and the majority (9 of 14) of the strains were identified as Providencia spp. Subsequently, 12 of the bacterial strains isolated were tested for their resistance or sensitivity to 23 commonly used antibiotics. All nine strains classified as Providencia rettgeri exhibited dramatic resistance to tetracycline, vancomycin, bacitracin, erythromycin, novobiocin, polymyxin, colistin, and nitrofurantoin. Eight of nine Providencia strains showed resistance to spectinomycin, six of nine showed resistance to chloramphenicol, and five of nine showed resistance to neomycin. All 12 isolates were sensitive to nalidixic acid, streptomycin, norfloxacin, aztreonam, cipericillin, pipericillin, and cefotaxime, and all but OF008 (Morganella morganii) were sensitive to ampicillin and cefoxitin. The oil fly bacteria were not resistant to multiple antibiotics due to an elevated mutation rate. For each bacterium, the number of resistant mutants per 10(8) cells was determined separately on rifampin, nalidixic acid, and spectinomycin. In each case, the average frequencies of resistant colonies were at least 50-fold lower than those established for known mutator strain ECOR 48. In addition, the oil fly bacteria do not appear to excrete antimicrobial agents. When tested, none of the oil fly bacteria produced detectable zones of inhibition on Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, or Candida albicans cultures. Furthermore, the resistance properties of oil fly bacteria extended to organic solvents as well as antibiotics. When pre-exposed to 20 microg of tetracycline per ml, seven of nine oil fly bacteria tolerated overlays of 100% cyclohexane, six of nine tolerated 10% xylene, benzene, or toluene (10:90 in cyclohexane), and three of nine (OF007, OF010, and OF011) tolerated overlays of 50% xylene-50% cyclohexane. The observed correlation between antibiotic resistance and organic solvent tolerance is likely explained by an active efflux pump that is maintained in oil fly bacteria by the constant selective pressure of La Brea's solvent-rich environment. We suggest that the oil fly bacteria and their genes for solvent tolerance may provide a microbial reservoir of antibiotic resistance genes.200011055901
6087120.9540Draft genome of Raoultella planticola, a high lead resistance bacterium from industrial wastewater. Isolation of heavy metals-resistant bacteria from their original habitat is a crucial step in bioremediation. Six lead (Pb) resistant bacterial strains were isolated and identified utilizing 16S rRNA to be Enterobacter ludwigii FACU 4, Shigella flexneri FACU, Microbacterium paraoxydans FACU, Klebsiella pneumoniae subsp. pneumonia FACU, Raoultella planticola FACU 3 and Staphylococcus xylosus FACU. It was determined that all these strains had their Minimum inhibitory concentration (MIC) to be 2500 ppm except R. planticola FACU 3 has a higher maximum tolerance concentration (MTC) up to 2700 ppm. We evaluated the survival of all six strains on lead stress, the efficiency of biosorption and lead uptake. It was found that R. planticola FACU 3 is the highest MTC and S. xylosus FACU was the lowest MTC in this evaluation. Therefore, transmission electron microscopy (TEM) confirmed the difference between the morphological responses of these two strains to lead stress. These findings led to explore more about the genome of R. planticola FACU 3 using illumine Miseq technology. Draft genome sequence analysis revealed the genome size of 5,648,460 bp and G + C content 55.8% and identified 5526 CDS, 75 tRNA and 4 rRNA. Sequencing technology facilitated the identification of about 47 genes related to resistance to many heavy metals including lead, arsenic, zinc, mercury, nickel, silver and chromium of R. planticola FACU 3 strain. Moreover, genome sequencing identified plant growth-promoting genes (PGPGs) including indole acetic acid (IAA) production, phosphate solubilization, phenazine production, trehalose metabolism and 4-hydroxybenzoate production genes and a lot of antibiotic-resistant genes.202336715862
3627130.9539Effect of in-feed paromomycin supplementation on antimicrobial resistance of enteric bacteria in turkeys. Histomoniasis in turkeys can be prevented by administering paromomycin sulfate, an aminoglycoside antimicrobial agent, in feed. The aim of this study was to evaluate the impact of in-feed paromomycin sulfate supplementation on the antimicrobial resistance of intestinal bacteria in turkeys. Twelve flocks of breeder turkeys were administered 100 ppm paromomycin sulfate from hatching to day 120; 12 flocks not supplemented with paromomycin were used as controls. Faecal samples were collected monthly from days 0 to 180. The resistance of Escherichia coli, Enterococcus faecium and Staphylococcus aureus to paramomycin and other antimicrobial agents was compared in paromomycin supplemented (PS) and unsupplemented (PNS) flocks. E. coli from PS birds had a significantly higher frequency of resistance to paromomycin, neomycin and kanamycin until 1 month after the end of supplementation compared to PNS birds. Resistance to amoxicillin or trimethoprim-sulfamethoxazole was also more frequent in PS turkeys. Resistance was mainly due to the presence of aph genes, which could be transmitted by conjugation, sometimes with streptomycin, tetracycline, amoxicillin, trimethoprim or sulfonamide resistance genes. Resistance to kanamycin and streptomycin in E. faecium was significantly different in PS and PNS breeders on days 60 and 90. Significantly higher frequencies of resistance to paromomycin, kanamycin, neomycin and tobramycin were observed in S. aureus isolates from PS birds. Paromomycin supplementation resulted in resistance to aminoglycosides in bacteria of PS turkeys. Co-selection for resistance to other antimicrobial agents was observed in E. coli isolates.201323800604
6115140.9539Role of Plasmid in Pesticide Degradation and Metal Tolerance in Two Plant Growth-Promoting Rhizobacteria Bacillus cereus (NCIM 5557) and Bacillus safensis (NCIM 5558). Disha A (Bacillus cereus) and Disha B (Bacillus safensis) were isolated from pesticide-infested agricultural field and showed tolerance against pesticides, heavy metals, and antibiotics. The isolates exhibited PGPR activities in vitro as well as in field conditions in lentil (Lens culinaris) and cow pea (Vigna unguiculata). Both the Bacillus species could not be grown in mineral salt medium but efficiently grown in the media supplemented with pesticide (imidacloprid/carbendazim) demonstrating the utilization of pesticide as carbon/nitrogen source. The HPLC studies exhibited the pesticide (imidacloprid/carbendazim) degradation by both the bacteria. B. safensis showed better degradation of carbendazim (88.93%) and imidacloprid (82.48%) than that of B. cereus 78.07% and 49.12%, respectively. The bacterial isolates showed high concentration of heavy metal tolerance viz. lead, molybdenum, cadmium, copper, cobalt, and zinc, except mercury. Both the bacteria possessed single plasmid. The plasmid-cured isolates of B. cereus did not tolerate any pesticide, whereas that of B. safensis tolerated all the pesticides, like wild strains. The plasmid curing experiments did not affect the heavy metal tolerance ability of both the bacteria indicating the genomic nature of heavy metal tolerance genes, whereas pesticide resistance genes are plasmid-dependent in B. cereus but genomic in B. safensis.202235157142
5389150.9539Identification and characterization of potential probiotic lactic acid bacteria isolated from pig feces at various production stages. Lactic acid bacteria (LAB) were isolated, identified, and characterized from pig feces at various growth stages and feed rations in order to be used as probiotic feed additives. Lactic acid bacteria numbers ranged from 7.10 ± 1.50 to 9.40 log CFUs/g for growing and lactating pigs, respectively. Isolates (n = 230) were identified by (GTG)5-polymerase chain reaction and partial sequence analysis of 16S rRNA. Major LAB populations were Limosilactobacillus reuteri (49.2%), Pediococcus pentosaceus (20%), Lactobacillus amylovorus (11.4%), and L. johnsonii (8.7%). In-vitro assays were performed, including surface characterization and tolerance to acid and bile salts. Several lactobacilli exhibited hydrophobic and aggregative characteristics and were able to withstand gastrointestinal tract conditions. In addition, lactobacilli showed starch- and phytate-degrading ability, as well as antagonistic activity against Gram-negative pathogens and the production of bacteriocin-like inhibitory substances. When resistance or susceptibility to antibiotics was evaluated, high phenotypic resistance to ampicillin, gentamicin, kanamycin, streptomycin, and tetracycline and susceptibility towards clindamycin and chloramphenicol was observed in the assayed LAB. Genotypic characterization showed that 5 out of 15 resistance genes were identified in lactobacilli; their presence did not correlate with phenotypic traits. Genes erm(B), strA, strB, and aadE conferring resistance to erythromycin and streptomycin were reported among all lactobacilli, whereas tet(M) gene was harbored by L. reuteri and L. amylovorus strains. Based on these results, 6 probiotic LAB strains (L. reuteri F207R/G9R/B66R, L. amylovorus G636T/S244T, and L. johnsonii S92R) can be selected to explore their potential as direct feed additives to promote swine health and replace antibiotics.202337020571
8736160.9539Effects of intracanal irrigant MTAD Combined with nisin at sub-minimum inhibitory concentration levels on Enterococcus faecalis growth and the expression of pathogenic genes. Exposure to antibiotics is considered to be the major driver in the selection of antibiotic-resistant bacteria and may induce diverse biological responses in bacteria. MTAD is a common intracanal irrigant, but its bactericidal activity remains to be improved. Previous studies have indicated that the antimicrobial peptide nisin can significantly improve the bactericidal activity of MTAD against Enterococcus faecalis. However, the effects of MTAD and its modification at sub-minimum inhibitory concentration (sub-MIC) levels on Enterococcus faecalis growth and the expression of pathogenic genes still need to be explored. In this study, the results of post-antibiotic effects (PAE) and post-antibiotic sub-MIC effects (PASME) showed that MTADN (nisin in combination with MTAD) had the best post-antibiotic effect. E. faecalis after challenge with MTAD was less sensitive to alkaline solutions compared with MTAN (nisin in place of doxycycline in MTAD) and MTADN. E. faecalis induced with sub-MIC of MTAD generated resistance to the higher concentration, but induction of E. faecalis with MTAN did not cause resistance to higher concentrations. Furthermore, real-time polymerase chain reaction (RT-PCR) showed that the stress caused by sub-MIC exposure to MTAD, MTAN, or MTADN resulted in up- or down-regulation of nine stress genes and four virulence-associated genes in E. faecalis and resulted in different stress states. These findings suggested that nisin improved the post-antibacterial effect of MTAD at sub-MIC levels and has considerable potential for use as a modification of MTAD.201424603760
7951170.9537Proliferation of antibiotic resistance genes in microbial consortia of sequencing batch reactors (SBRs) upon exposure to trace erythromycin or erythromycin-H2O. A variety of antibiotics and their metabolites at sub-inhibitory level concentrations are suspected to expand resistance genes in the environment. However, knowledge is limited on the causal correlation of trace antibiotics or their metabolites with resistance proliferation. In this study, erythromycin (ERY) resistance genes were screened on microbial consortia of sequencing batch reactors (SBRs) after one year acclimation to ERY (100 μg/L) or dehydrated erythromycin (ERY-H(2)O, 50 μg/L). The identified esterase gene ereA explains that ERY could be degraded to six products by microbes acclimated to ERY (100 μg/L). However, ERY could not be degraded by microbes acclimated to ERY-H(2)O (50 μg/L), which may be due to the less proliferated ereA gene. Biodegradation of ERY required the presence of exogenous carbon source (e.g., glucose) and nutrients (e.g., nitrogen, phosphorus) for assimilation, but overdosed ammonium-N (>40 mg/L) inhibited degradation of ERY. Zoogloea, a kind of biofilm formation bacteria, became predominant in the ERY degradation consortia, suggesting that the input of ERY could induce biofilm resistance to antibiotics. Our study highlights that lower μg/L level of ERY or ERY-H(2)O in the environment encourages expansion of resistance genes in microbes.201121482429
6238180.9537A novel glutamate-dependent acid resistance among strains belonging to the Proteeae tribe of Enterobacteriaceae. Morganella, Providencia and Proteus strains were capable of surviving pH 2.0 for 1 h if glutamate was present. These strains did not have glutamic acid decarboxylase activity and the gadAB genes were not detected in any of these bacteria. When exposed to pH 2.0 acid shocks, the survival rate of these bacteria was significantly increased with glutamate concentrations as low as 0.3 mM in the acid media. Escherichia coli cells incubated at pH 3.4 consumed four times more glutamate and produced at least 7-fold more gamma-amino butyric acid than Morganella, Providencia and Proteus strains. These results indicate that strains belonging to the Proteeae tribe might have novel glutamate dependent acid-resistance mechanisms.200415321677
6019190.9537Effects of Lactobacillus pentosus combined with Arthrospira platensis on the growth performance, immune response, and intestinal microbiota of Litopenaeus vannamei. Litopenaeus vannamei is one of the most productive shrimp species in the world. However, shrimp farming is suffering from adverse environmental conditions and disease outbreaks. Typically, Lactobacillus pentosus and Arthrospira platensis are used as substitutes for some antibiotics. In the present study, we assessed the effects of dietary supplements along with living bacteria or cell-free extracts of L. pentosus combined with A. platensis on the growth performance, immune response, intestinal microbiota, and disease resistance of L. vannamei against Vibrio alginolyticus. Shrimp fed L. pentosus live bacteria combined with A. platensis showed the best growth performance and lowest feed conversion rate. The supplementation diet with L. pentosus live bacteria and A. platensis could significantly enhance the trypsin activity in shrimp after the feeding trial. Given the lowest feed conversion rate in shrimp fed L. pentosus live bacteria combined with A. platensis, we reasonably speculated that the decrease in feed conversion rate may be related to the increase in trypsin activity. In addition, dietary cell-free extracts of L. pentosus combined with A. platensis enhanced the expression of immune-related genes after the feeding trial or challenge test. Moreover, results of the bacterial challenge test indicated that the shrimp fed cell-free extracts of L. pentosus combined with A. platensis diet resulted in the highest survival rate, which suggested that cell-free extracts of L. pentosus and A. platensis could improve the disease resistance against V. alginolyticus by up-regulating the expressions of immune-related genes. Dietary L.pentosus or A. platensis, or their combination, reduced the abundance of harmful bacteria, including Proteobacteria in shrimp intestine, which suggested that L. pentosus and A. platensis could improve the growth performance and health of shrimp by regulating the structure of the intestinal microbiota. The findings of this study demonstrated that L. pentosus live bacteria and A. platensis exerted synergistic effects on the growth performance and digestion in shrimp, while cell-free extracts of L. pentosus and A. platensis showed synergistic effects on the immune response and disease resistance of shrimp against V. alginolyticus.202234883257