# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 7985 | 0 | 0.9855 | Differential response of nonadapted ammonia-oxidising archaea and bacteria to drying-rewetting stress. Climate change is expected to increase the frequency of severe drought events followed by heavy rainfall, which will influence growth and activity of soil microorganisms, through osmotic stress and changes in nutrient concentration. There is evidence of rapid recovery of processes and adaptation of communities in soils regularly experiencing drying/rewetting and lower resistance and resilience in nonadapted soils. A microcosm-based study of ammonia-oxidising archaea (AOA) and bacteria (AOB), employing a grassland soil that rarely experiences drought, was used to test this hypothesis and also whether AOB were more resistant and resilient, through greater tolerance of high ammonia concentrations produced during drought and rewetting. Treated soils were dried, incubated for 3 weeks, rewetted, incubated for a further 3 weeks and compared to untreated soils, maintained at a constant moisture content. Nitrate accumulation and AOA and AOB abundance (abundance of respective amoA genes) and community composition (DGGE analysis of AOA amoA and AOB 16S rRNA genes) were poorly adapted to drying-rewetting. AOA abundance and community composition were less resistant than AOB during drought and less resilient after rewetting, at times when ammonium concentration was higher. Data provide evidence for poor adaptation of microbial communities and processes to drying-rewetting in soils with no history of drought and indicate niche differentiation of AOA and AOB associated with high ammonia concentration. | 2014 | 25070168 |
| 6018 | 1 | 0.9848 | Effect of Trehalose and Lactose Treatments on the Freeze-Drying Resistance of Lactic Acid Bacteria in High-Density Culture. Freeze-drying is a commonly used method in commercial preparations of lactic acid bacteria. However, some bacteria are killed during the freeze-drying process. To overcome this, trehalose and lactose are often used as protective agents. Moreover, high-density culture is an efficient way to grow bacterial strains but creates a hypertonic growth environment. We evaluated the effects of trehalose and lactose, as a primary carbon source or as an additive in fermentation, on the freeze-drying survival of Lactobacillus fermentum FXJCJ6-1, Lactobacillus brevis 173-1-2, and Lactobacillus reuteri CCFM1040. Our results showed that L. fermentum FXJCJ6-1 accumulated but did not use intracellular trehalose in a hypertonic environment, which enhanced its freeze-drying resistance. Furthermore, genes that could transport trehalose were identified in this bacterium. In addition, both the lactose addition and lactose culture improved the freeze-drying survival of the bacterium. Further studies revealed that the added lactose might exert its protective effect by attaching to the cell surface, whereas lactose culture acted by reducing extracellular polysaccharide production and promoting the binding of the protectant to the cell membrane. The different mechanisms of lactose and trehalose in enhancing the freeze-drying resistance of bacteria identified in this study will help to elucidate the anti-freeze-drying mechanisms of other sugars in subsequent investigations. | 2022 | 36677339 |
| 6017 | 2 | 0.9848 | Selection of lactic acid bacteria to promote an efficient silage fermentation capable of inhibiting the activity of Aspergillus parasiticus and Fusarium gramineraum and mycotoxin production. AIMS: To select lactic acid bacteria with potential silage inoculant properties. The bio-control activity against mycotoxicogenic fungi and the presence of antibiotics resistance gene were also evaluated. METHODS AND RESULTS: Lactobacillus rhamnosus RC007 and Lactobacillus plantarum RC009 were selected on the basis of growth rate and efficacy in reducing the pH of maize extract medium; therefore, they were evaluated for their bio-control ability against Fusarium graminearum and Aspergillus parasiticus. Studies on lag phase, growth rate and aflatoxin B1 (AFB1) and zearalenone (ZEA) production were carried out in vitro under different regimes of aw (0·95 and 0·99); pH (4 and 6); temperature (25 and 37°C); and oxygen availability (normal and reduced). Lactobacillus rhamnosus RC007 was able to completely inhibit the F. graminearum growth at all assayed conditions, while Lact. plantarum RC009 only did it at pH 4. Both Lactobacillus strains were able to significantly reduce the A. parasiticus growth rate mainly at 0·99 aw . A decrease in ZEA production was observed as result of Lactobacillus strains -F. graminearum interaction; however, the A. parasiticus- Lact. plantarum interaction resulted in an increased AFB1 production. Lactobacillus rhamnosus RC007 proved to have no genes for resistance to the tested antibiotics. CONCLUSIONS: The ability of Lact. rhamnosus RC007 to rapidly drop the pH and to inhibit fungal growth and mycotoxin production and the absence of antibiotic resistance genes shows the potential of its application as inoculant and bio-control agent in animal feed. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the importance of selecting bacteria for silage inoculants not only for the improvement of silage fermentation but also for their effects on mycotoxicogenic fungi and the resulting mycotoxin production due to the risk that they may involve. | 2013 | 23437822 |
| 8110 | 3 | 0.9848 | Removal of chlortetracycline and antibiotic resistance genes in soil by earthworms (epigeic Eisenia fetida and endogeic Metaphire guillelmi). The impacts of two ecological earthworms on the removal of chlortetracycline (CTC, 0.5 and 15 mg kg(-1)) and antibiotic resistance genes (ARGs) in soil were explored through the soil column experiments. The findings showed that earthworm could significantly accelerate the degradation of CTC and its metabolites (ECTC) in soil (P < 0.05), with epigeic Eisenia fetida promoting degradation rapidly and endogeic Metaphire guillelmi exhibiting a slightly better elimination effect. Earthworms alleviated the abundances of tetR, tetD, tetPB, tetG, tetA, sul1, TnpA, ttgB and intI1 in soil, with the total relative abundances of ARGs decreasing by 35.0-44.2% in earthworm treatments at the 28th day of cultivation. High throughput sequencing results displayed that the structure of soil bacteria community was modified apparently with earthworm added, and some possible CTC degraders, Aeromonas, Flavobacterium and Luteolibacter, were promoted by two kinds of earthworms. Redundancy analysis demonstrated that the reduction of CTC residues, Actinobacteria, Acidobacteria and Gemmatimonadetes owing to earthworm stimulation was responsible for the removal of ARGs and intI1 in soil. Additionally, intI1 declined obviously in earthworm treatments, which could weaken the risk of horizontal transmission of ARGs. Therefore, earthworm could restore the CTC-contaminated soil via enhancing the removal of CTC, its metabolites and ARGs. | 2021 | 33798888 |
| 7987 | 4 | 0.9844 | Assessing the effect of composted cyclosporin A fermentation residue as organic fertilizer: Focus on soil fertility and antibiotic resistance. Cyclosporin A fermentation residue (CFR) is a type of organic waste generated during the production of cyclosporin A, which are abundant in nutrients including organic matter, phosphorus, nitrogen and potassium. Inappropriate handling of CFR not only waste valuable bioresources, but may also lead to the cyclosporin A and associated resistance genes into the natural environment, posing a significant threat to ecological system and human health. Land application was an effective way to resource recovery of CFR after aerobic composting (CAC). This study investigated the impact of CAC on soil fertility and environmental safety. The results indicated that CAC could improve soil nutrient contents and enhance enzyme activities. CAC altered the diversity and community composition of soil bacteria, resulting in an increase in the abundance of relevant bacteria beneficial for organic matter decomposition and cyclosporin A degradation. The introduced cyclosporin A (71.69 µg/kg) completely degraded within 20 days due to soil biodegradation. The significantly increased abundance of intIl, mdr3, pgp, TSR and pmra in the soil cultivation early stage were restored to the soil background level within 90 days, indicating a reduced risk of antimicrobial resistance. The results demonstrated that reasonable land application of CAC could improve soil fertility without antimicrobial resistance risk, which is helpful for evaluating the resource utilization value and environmental risks of antibiotic fermentation residue after aerobic composting. | 2025 | 40602925 |
| 7969 | 5 | 0.9841 | Metagenomic insights into the influence of pH on antibiotic removal and antibiotic resistance during nitritation: Regulations on functional genus and genes. The changes in pH and the resulting presence of free nitrous acid (FNA) or free ammonia (FA) often inhibit antibiotic biodegradation during nitritation. However, the specific mechanisms through which pH, FNA and FA influence antibiotic removal and the fate of antibiotic resistance genes (ARGs) are not yet fully understood. In this study, the effects of pH, FNA, and FA on the removal of cefalexin and amoxicillin during nitritation were investigated. The results revealed that the decreased antibiotic removal under both acidic condition (pH 4.5) and alkaline condition (pH 9.5) was due to the inhibition of the expression of amoA in ammonia-oxidizing bacteria and functional genes (hydrolase-encoding genes, transferase-encoding genes, lyase-encoding genes, and oxidoreductase-encoding genes) in heterotrophs. Furthermore, acidity was the primary inhibitor of antibiotic removal at pH 4.5, followed by FNA. Antibiotic removal was primarily inhibited by alkalinity at pH 9.5, followed by FA. The proliferation of ARGs mediated by mobile genetic element was promoted under both acidic and alkaline conditions, attributed to the promotion of FNA and FA, respectively. Overall, this study highlights the inhibitory effects of acidity and alkalinity on antibiotic removal during nitritation. | 2024 | 39068965 |
| 7059 | 6 | 0.9841 | Composting reduces the risks of antibiotic resistance genes in maize seeds posed by gentamicin fermentation waste. Using high-throughput quantitative PCR and next generation sequencing, the impact of land application of raw and composted gentamicin fermentation waste (GFW) on antibiotic resistance genes (ARGs) in maize seeds was studied in a three-year field trial. The raw and composted GFW changed both the bacterial community composition and the ARGs diversity in the maize seeds compared to non-amended controls and chemical fertilizer. The abundance of ARGs after raw GFW amendment was significantly higher than other treatments because of a high abundance of aadA1, qacEdeltal and aph(2')-Id-02; probably induced by gentamicin selection pressure in maize tissues. Meanwhile, the potential host of these three ARGs, pathogenic bacteria Tenacibaculum, also increased significantly in maize seeds after the application of raw GFW. But our result proved that composting could weaken the risk posed by GFW. We further reveal that the key biotic driver for shaping the ARG profiles in maize seeds is bacterial community followed by heavy metal resistance genes, and ARGs are more likely located on bacterial chromosomes. Our findings provide new insight into ARGs dispersal mechanism in maize seeds after long-term GFW application, demonstrate the potential benefits of composting the GFW to reduce risks as well as the potential efficient management method to GFW. | 2023 | 36736399 |
| 8767 | 7 | 0.9840 | Poly-γ-glutamic acid enhanced the drought resistance of maize by improving photosynthesis and affecting the rhizosphere microbial community. BACKGROUND: Compared with other abiotic stresses, drought stress causes serious crop yield reductions. Poly-γ-glutamic acid (γ-PGA), as an environmentally friendly biomacromolecule, plays an important role in plant growth and regulation. RESULTS: In this project, the effect of exogenous application of γ-PGA on drought tolerance of maize (Zea mays. L) and its mechanism were studied. Drought dramatically inhibited the growth and development of maize, but the exogenous application of γ-PGA significantly increased the dry weight of maize, the contents of ABA, soluble sugar, proline, and chlorophyll, and the photosynthetic rate under severe drought stress. RNA-seq data showed that γ-PGA may enhance drought resistance in maize by affecting the expression of ABA biosynthesis, signal transduction, and photosynthesis-related genes and other stress-responsive genes, which was also confirmed by RT-PCR and promoter motif analysis. In addition, diversity and structure analysis of the rhizosphere soil bacterial community demonstrated that γ-PGA enriched plant growth promoting bacteria such as Actinobacteria, Chloroflexi, Firmicutes, Alphaproteobacteria and Deltaproteobacteria. Moreover, γ-PGA significantly improved root development, urease activity and the ABA contents of maize rhizospheric soil under drought stress. This study emphasized the possibility of using γ-PGA to improve crop drought resistance and the soil environment under drought conditions and revealed its preliminary mechanism. CONCLUSIONS: Exogenous application of poly-γ-glutamic acid could significantly enhance the drought resistance of maize by improving photosynthesis, and root development and affecting the rhizosphere microbial community. | 2022 | 34979944 |
| 8725 | 8 | 0.9840 | CuO nanoparticles facilitate soybean suppression of Fusarium root rot by regulating antioxidant enzymes, isoflavone genes, and rhizosphere microbiome. BACKGROUND: Fusarium root rot is a widespread soil-borne disease severely impacting soybean yield and quality. Compared to traditional fertilizers' biological and environmental toxicity, CuO nanoparticles (NPs) hold promise for disease control in a low dose and high efficiency manner. METHODS: We conducted both greenhouse and field experiments, employing enzymatic assays, elemental analysis, qRT-PCR, and microbial sequencing (16S rRNA, ITS) to explore the potential of CuO NPs for sustainable controlling Fusarium-induced soybean disease. RESULTS: Greenhouse experiments showed that foliar spraying of CuO NPs (10, 100, and 500 mg L(-1)) promoted soybean growth more effectively than EDTA-CuNa(2) at the same dose, though 500 CuO NPs caused mild phytotoxicity. CuO NPs effectively controlled root rot, while EDTA-CuNa(2) worsened the disease severity by 0.85-34.04 %. CuO NPs exhibited more substantial antimicrobial effects, inhibiting F. oxysporum mycelial growth and spore germination by 5.04-17.55 % and 10.24-14.41 %, respectively. 100 mg L(-1) CuO NPs was the optimal concentration for balancing soybean growth and disease resistance. Additionally, CuO NPs boosted antioxidant enzyme activity (CAT, POD, and SOD) in leaves and roots, aiding in ROS clearance during pathogen invasion. Compared to the pathogen control, 100 mg L(-1) CuO NPs upregulated the relative expression of seven isoflavone-related genes (Gm4CL, GmCHS8, GmCHR, GmCHI1a, GmIFS1, GmUGT1, and GmMYB176) by 1.18-4.51 fold, thereby enhancing soybean disease resistance in place of progesterone-receptor (PR) genes. Field trials revealed that CuO NPs' high leaf-to-root translocation modulated soybean rhizosphere microecology. Compared to the pathogen control, 100 mg L(-1) CuO NPs increased nitrogen-fixing bacteria (Rhizobium, Azospirillum, Azotobacter) and restored disease-resistant bacteria (Pseudomonas, Burkholderia) and fungi (Trichoderma, Penicillium) to healthy levels. Furthermore, 100 mg L(-1) CuO NPs increased beneficial bacteria (Pedosphaeraceae, Xanthobacteraceae, SCI84, etc.) and fungi (Trichoderma, Curvularia, Hypocreales, etc.), which negatively correlated with F. oxysporum, while recruiting functional microbes to enhance soybean yield. CONCLUSION: 100 mg L(-1) CuO NPs effectively promoting soybean growth and providing strong resistance against root rot disease by improving antioxidant enzyme activity, regulating the relative expression of isoflavone-related genes, increasing beneficial bacteria and fungi and restoring disease-resistant. Our findings suggest that CuO NPs offer an environmentally sustainable strategy for managing soybean disease, with great potential for green production. | 2025 | 40096759 |
| 7536 | 9 | 0.9840 | The effects of tetracycline concentrations on tetracycline resistance genes and their bacterial hosts in the gut passages of earthworms (Eisenia fetida) feeding on domestic sludge. Vermi-composting is considered to be a feasible method for reducing tetracycline resistance genes (TRGs) in the sludge. Nevertheless, the way different gut passages of earthworm might affect the fates of TRGs and whether this process is affected by tetracycline (TC) concentrations need to be further investigated. In this study, we examined the effects of TC concentrations on changes in TRGs and bacterial communities in gut passages of earthworm were determined by using quantitative PCR and Illumina high-throughput sequencing. TRGs and intI1 were mainly reduced in the hindgut under the TC concentrations ranging from 0 to 25 mg/kg, while they were enriched under higher TC stress exposure. Consequently, we suggest the TC limitation of 25 mg/kg in the domestic sludge (DS) for vermi-composting. Although the predominant genera were TC sensitive under TC stress, many bacterial hosts harboring multiple TRGs (especially those in the hindgut) should be paid further attention to. In the foregut, five genera with abundant tetracycline-resistant bacteria (TRB) were specialized taxa. Among these genera, Unclassified_Solirubrobacterales and Pirellulaceae were probably related to the digestion processes. Other unclassified taxa related to the TRGs were probably derived from the DS. Five genera with abundant TRB were shared in the gut passages, and three specialized genera in the hindgut. These genera could spread TRGs and intI1 to the environment. These results suggest that vermi-composting is a feasible approach for TRG control in the DS containing TC concentration that does not exceed 25 mg/kg. Fates of TRGs and intI1 widely differ in the gut passages, showing inevitable connections with bacterial communities. | 2019 | 31637618 |
| 8037 | 10 | 0.9840 | Dosage effects of lincomycin mycelial residues on lincomycin resistance genes and soil microbial communities. Lincomycin mycelial residues (LMRs) are one kind of byproduct of the pharmaceutical industry. Hydrothermal treatment has been used to dispose of them and land application is an attractive way to reuse the treated LMRs. However, the safe dose for soil amendment remains unclear. In this study, a lab-scale incubation experiment was conducted to investigate the influence of the amendment dosage on lincomycin resistance genes and soil bacterial communities via quantitative PCR and 16S rRNA sequencing. The results showed that introduced lincomycin degraded quickly in soil and became undetectable after 50 days. Degradation rate of the high amendment amount (100 mg kg(-1)) was almost 4 times faster than that of low amendment amount (10 mg kg(-1)). Moreover, the introduced LMRs induced the increase of lincomycin resistance genes after incubation for 8 days, and two genes (lmrA and lnuB) showed a dosage-related increase. For example, the abundance of gene lmrA was 17.78, 74.13 and 128.82 copies g(-1) soil for lincomycin concentration of 10, 50 and 100 mg kg(-1), respectively. However, the abundance of lincomycin resistance genes recovered to the control level as the incubation period extended to 50 days, indicating a low persistence in soil. In addition, LMRs application markedly shifted the bacterial composition and significant difference was found between control soil, 10 mg kg(-1) and 50 mg kg(-1) lincomycin amended soil. Actually, several genera bacteria were significantly related to the elevation of lincomycin resistance genes. These results provided a comprehensive understanding of the effects of lincomycin dosage on the fate of resistance genes and microbial communities in LMRs applied soil. | 2020 | 31662263 |
| 7995 | 11 | 0.9840 | Risk of penicillin fermentation dreg: Increase of antibiotic resistance genes after soil discharge. Penicillin fermentation dreg (PFD) is a solid waste discharged by pharmaceutical enterprises in the fermentation production process. Due to the residual antibiotic of PFD, the risk of antibiotic resistance bacteria (ARB) generation should be considered in the disposal process. High-throughput quantitative PCR (HT-qPCR) and 16S rRNA gene sequencing were performed to investigate the effect of PFD on the dynamics of antibiotic resistance genes (ARGs) and bacterial community during a lab-scale soil experiment. After the application of PFD, the bacterial number and diversity showed an obvious decrease in the initial days. The abundances of Streptomyces and Bacillus, which are the most widespread predicted source phyla of ARGs, increased remarkably from 4.42% to 2.59%-22.97% and 21.35%. The increase of ARGs was observed during the PFD application and the ARGs carried by PFD itself contributed to the initiation of soil ARGs. The results of redundancy analysis (RDA) show that the shift in bacterial community induced by variation of penicillin content is the primary driver shaping ARGs compositions. | 2020 | 32023801 |
| 8641 | 12 | 0.9839 | Uncovering acid resistance genes in lactic acid bacteria and impact of non-viable bacteria on bacterial community during Chinese strong-flavor baijiu fermentation. Chinese strong-flavor baijiu (CSFB) brewing is a spontaneously solid-state fermentation process for approximately 60 days. Numerous microorganisms grow, die, and spark a series of metabolic reactions during fermentation. In this study, the microbial community and structure between total and viable bacteria in zaopei from the 5- and 20-year pits of CSFB are revealed by amplicon sequencing. Metagenome sequencing was applied to investigate acid resistance genes in Lactobacillus and predict carbohydrate active enzyme in zaopei. Besides, SourceTracker was conducted to expose bacterial sources. Results revealed that there was no significant difference in the bacterial community and structure between the total and viable bacteria; Lactobacillus was the most dominant bacterium in zaopei of two types of pits. Meanwhile, acid resistance genes argR, aspA, ilvE, gshA, DnaK, and cfa were genes that sustained Lactobacillus survival in the late stages of fermentation with high contents of acid and ethanol, and glycosyltransferases were identified as the predominated enzymes during the CSFB fermentation which catalyzed the process of lactic acid generation via Embden-Meyerhof-Parnas pathway and Hexose Monophosphate Pathway. Moreover, the environment contributed most bacteria to zaopei of the 5- and 20-year pits. These findings will provide a deeper understanding of the microbial community structure of viable and total bacteria and the reason for the dominance of Lactobacillus in the later stages of CSFB fermentation. | 2023 | 37087286 |
| 6092 | 13 | 0.9839 | Colony-forming analysis of bacterial community succession in deglaciated soils indicates pioneer stress-tolerant opportunists. We investigated the response of bacterial communities inhabiting two deglaciated soils (10 and 100 years post-deglaciation) to two stimuli: (i) physical disruption (mixing), and (ii) disruption plus nutrient addition. PCR/DGGE analysis of 16S rRNA genes extracted from soil during a 168-h incubation period following the stimuli revealed that more bacterial phylotypes were stimulated in the 10-y soil than in the 100-y soil. In addition to 10-y and 100-y soils, two additional soils (46 and 70 y) were further differentiated using colony-forming curve (CFC) analysis during a 168-h incubation period, which revealed that younger soils contained a higher proportion of rapidly colonizing bacteria than successively older soils. "Eco-collections" of CFC isolates that represented colonies that formed "fast" (during the first 24 h) and "slow" (final 36 h) were harvested from 10-y and 100-y soils and differentiated according to response to three stress parameters: (i) tolerance to nutrient limitation, (ii) tolerance to temperature change, and (iii) resistance to antibiotics. The tested parameters distinguished "fast" from "slow" bacteria regardless of the age of the soil from which they were isolated. Specifically, eco-collections of "fast" bacteria exhibited greater nutrient- and temperature-stress tolerance as well as more frequent antibiotic resistance than "slow" bacteria. Further DGGE analysis showed that several eco-collection phylotype bands matched (electrophoretically) those of soil phylotypes enriched by mixing and nutrient stimulus. Overall, the results of this study indicated that the succession of colony-forming bacteria was differentiated by bacterial opportunism and temporal response to stimuli. Furthermore, although stress tolerance strategies are associated with opportunistic bacteria regardless of successional age, it appears that the proportion of opportunistic bacteria distinguishes early vs late succession forefield bacterial populations. | 2004 | 15692851 |
| 3548 | 14 | 0.9839 | From flagellar assembly to DNA replication: CJSe's role in mitigating microbial antibiotic resistance genes. The emergence of Antibiotic Resistance Genes (ARGs) in Campylobacter jejuni (CJ) poses a severe threat to food safety and human health. However, the specific impact of CJ and its variants on ARGs and other related factors remains to be further elucidated. Herein, integrated metagenomic sequencing and co-occurrence network analysis approach were employed to investigate the impact of CJ and CJ incorporated with biogenic selenium (CJSe) on ARGs, flagellar assembly pathways, microbial communities, and DNA replication pathways in chicken manure. Compared to the Control (CON) and CJ groups, the CJSe group exhibited 2.4-fold increase selenium levels (P < 0.01) in chicken manure. Notable differences were also observed between the CJ and CJSe groups, with sequence results showing a CJ > CJSe > CON trend in total ARG copy numbers. Furthermore, the CJSe group showed 31.6 % fewer flagellar assembly genes compared to the CJ group. Additionally, compared to the CJ group, CJSe inhibited pathways such as basal body/hook (e.g., FliH, FliO, FliQ reduced by 25-52 %) and stator (MotB downregulated by 42.3 %), suppressing flagellar assembly. We also found that both CJ and CJSe influenced bacterial DNA replication pathways, with the former increasing ARG-carrying bacteria and the latter, under selenium-induced selective pressure, reducing ARG-carrying bacteria. Moreover, compared to the CJ group, the CJSe group showed a significantly lower 9.72 % copy number of total archaeal DNA replication genes. Furthermore, through intricate co-occurrence network analysis, we discovered the complex interplay between changes in ARGs and bacterial and archaeal DNA replication dynamics within the microbial community. These findings indicate that CJSe mitigates the threat posed by CJ and reduces ARG prevalence, while its dual functionality enables applications in biofortified crop production and soil remediation in selenium-deficient regions, thereby advancing circular economy systems. While the current study demonstrates CJSe's dual functionality under controlled conditions, future work will implement a dedicated ecological risk assessment framework encompassing Se speciation/leaching tests and non-target organism assays to confirm environmental safety under field-relevant scenarios. This approach aligns with sustainable strategies for food security and public health safeguarding. | 2025 | 41108960 |
| 7639 | 15 | 0.9838 | Structural and Functional Changes of Groundwater Bacterial Community During Temperature and pH Disturbances. In this study, we report the characteristics of a microbial community in sampled groundwater and elucidate the effects of temperature and pH disturbances on bacterial structure and nitrogen-cycling functions. The predominant phyla of candidate OD1, candidate OP3, and Proteobacteria represented more than half of the total bacteria, which clearly manifested as a "low nucleic acid content (LNA) bacteria majority" type via flow cytometric fingerprint. The results showed that LNA bacteria were more tolerant to rapid changes in temperature and pH, compared to high nucleic acid content (HNA) bacteria. A continuous temperature increase test demonstrated that the LNA bacterial group was less competitive than the HNA bacterial group in terms of maintaining their cell intactness and growth potential. In contrast, the percentage of intact LNA bacteria was maintained at nearly 70% with pH decrease, despite a 50% decrease in total intact cells. Next-generation sequencing results revealed strong resistance and growth potential of phylum Proteobacteria when the temperature increased or the pH decreased in groundwater, especially for subclasses α-, β-, and γ-Proteobacteria. In addition, relative abundance of nitrogen-related functional genes by qPCR showed no difference in nitrifiers or denitrifiers within 0.45 μm-captured and 0.45 μm-filterable bacteria due to phylogenetic diversity. One exception was the monophyletic anammox bacteria that belong to the phylum Planctomycetes, which were mostly captured on a 0.45-μm filter. Furthermore, we showed that both temperature increase and pH decrease could enhance the denitrification potential, whereas the nitrification and anammox potentials were weakened. | 2019 | 30706112 |
| 8033 | 16 | 0.9838 | Fate of pirlimycin and antibiotic resistance genes in dairy manure slurries in response to temperature and pH adjustment. Quantifying the fate of antibiotics and antibiotic resistance genes (ARGs) in response to physicochemical factors during storage of manure slurries will aid in efforts to reduce the spread of resistance when manure is land-applied. The objectives of this study were to determine the effects of temperature (10, 35, and 55 °C) and initial pH (5, 7, 9, and 12) on the removal of pirlimycin and prevalence of ARGs during storage of dairy manure slurries. We collected and homogenized feces and urine from five lactating dairy cows treated with pirlimycin and prepared slurries by mixing manure and sterile water. Aliquots (200 mL) of slurry were transferred and incubated in 400 mL glass beakers under different temperatures (10, 35, and 55 °C) or initial pH (5, 7, 9, and 12). Pirlimycin concentration and abundances of 16S rRNA, mefA, tet(W), and cfxA as indicators of total bacteria and ARGs corresponding to macrolide, tetracycline, and β-lactam resistance, respectively, were analyzed during manure incubation. The thermophilic environment (55 °C) increased the deconjugation and removal of pirlimycin, while the acidic shock at pH 5 increased deconjugation but inhibited removal of pirlimycin, suggesting that the chemical stability of pirlimycin could be affected by temperature and pH. The thermophilic environment decreased mefA relative abundance on day 7 and 28 (P = 0.02 and 0.04), which indicates that the bacteria that encoded mefA gene were not thermotolerant. Although mefA relative abundance was greater at the pH 9 shock than the rest of pH treatments on day 7 (P = 0.04), no significant pH effect was observed on day 28. The tet(W) abundance under initial pH 12 shock was less than other pH shocks on day 28 (P = 0.01), while no temperature effect was observed on day 28. There was no significant temperature and initial pH effect on cfxA abundance at any time point during incubation, implying that the bacteria that carrying cfxA gene are relatively insensitive to these environmental factors. Overall, directly raising temperature and pH can facilitate pirlimycin removal and decrease mefA and tet(W) relative abundances during storage of manure slurries. | 2020 | 32050366 |
| 3535 | 17 | 0.9837 | Bacillus licheniformis-fermented products and enramycin differentially modulate microbiota and antibiotic resistome in the cecal digesta of broilers. Since antibiotic resistance is a global health issues, the use of antibiotics in animal feed for growth promotion has been restricted in many countries. Bacillus licheniformis probiotic is a potential alternative to antibiotics for increasing poultry performance. Through metagenomic sequencing, this study investigated the effects of B. licheniformis-fermented products (BLFPs) and enramycin on the microbial community composition and antibiotic resistance gene (ARG) distribution in the cecal digesta of broilers at the age of 35 d. In total, 144 one-day-old male broiler chicks (Ross 308) were randomly assigned to 4 dietary treatments as follows: basal diet (control [C] group), basal diet plus 10 mg/kg enramycin (E group), basal diet plus 1 g/kg BLFPs (L group), and basal diet plus 3 g/kg BLFPs (H group), with 6 replicate cages per treatment group and 6 birds per cage. The results indicated that the cecal alpha diversity (richness and evenness) of bacterial species was higher in the H group than in the C group. Principal coordinate analysis of microbiota and the ARG composition indicated clear differences among the cecal samples of the groups. In the cecal digesta, the abundance of active bacteria associated with probiotic properties, such as Lactobacillus crispatus and Akkermansia muciniphila, was higher in the H group than in the other groups. Enramycin treatment promoted the expression of peptide (bcrA), glycopeptide (vanRI), and lincosamide (lsaE) resistance genes but inhibited the expression of aminocoumarin (parY) and pleuromutilin (TaeA) resistance genes. BLFP (1 and 3 g/kg) treatment suppressed the expression of aminoglycoside (ANT(6)-Ib), streptogramin (vatB), and peptide (ugd) resistance genes but enhanced the expression of macrolide (efrA) and aminocoumarin (novA) resistance genes. The abundance of peptide resistance genes in Bacteroides spp. was lower in the H group than in the C group. The abundance of lincosamide resistance genes in Lactobacillus spp. was higher in the E group than in the other groups. These results demonstrated that differential changes in the structure of 3 g/kg BLFPs and enramycin-induced cecal microbial communities accompany changes in the abundance of bacterial hosts carrying specific ARGs in the cecal microbiota of broilers. | 2022 | 35841645 |
| 6928 | 18 | 0.9837 | Assessing the effects of tylosin fermentation dregs as soil amendment on macrolide antibiotic resistance genes and microbial communities: Incubation study. Tylosin fermentation dregs (TFDs) are biosolid waste of antibiotics tylosin production process which contain nutritious components and may be recycled as soil amendments. However, the specific ecological safety of TFDs from the perspective of bacterial resistance in soil microenvironment is not fully explored. In the present study, a series of replicated lab-scale work were performed using the simulated fertilization to gain insight into the potential environmental effects and risks of macrolide antibiotic resistance genes (ARGs) and the soil microbial communities composition via quantitative PCR and 16S rRNA sequencing following the TFDs land application as the soil amendments. The results showed that bio-processes might play an important role in the decomposition of tylosin which degraded above 90% after 20 days in soil. The application of TFDs might induce the development of antibiotic-resistant bacteria, change soil environment and reduce the microbial diversity. Though the abundances of macrolide ARGs exhibited a decreasing trend following the tylosin degradation, other components in TFDs may have a lasting impact on both macrolide ARGs abundance and soil bacterial communities. Thus, this study pointed out the fate of TFDs on soil ecological environment when directly applying into soil, and provide valuable scientific basis for TFDs management. | 2020 | 32648501 |
| 7210 | 19 | 0.9837 | Managing Beef Backgrounding Residual Soil Contaminants by Alum and Biochar Amendments. Heavy manure-derived contamination of soils can make animal congregating areas nonpoint sources for environmental pollution. In situ soil stabilization is a cost-effective management strategy with a focus on lowering contaminant availability and limiting release to the environment. Soil stabilizing amendments can help mitigate the negative environmental impacts of contaminated soils. In this 2-yr study, we examined the effects of adding no amendment (control) or treating with alum [Al (SO)⋅18HO] or biochar as soil amendments on Mehlich-3 extractable soil P, Cu, and Zn contents, antimicrobial monensin concentrations, total bacteria (16S ribosomal RNA [rRNA] gene), antibiotic resistance genes (1 and B), and Class 1 integrons (1) in an abandoned beef backgrounding setting. The alum reduced soil P (1374 to 1060 mg kg), Cu (7.7 to 3.2 mg kg), and Zn (52.4 to 19.6 mg kg) contents. Both alum and biochar reduced monesin concentrations (1.8 to 0.7 and 2.1 to 1.1 ng g, respectively). All the treatments harbored consistent 16 rRNA concentrations (10 copies g) throughout. The B gene concentration (10 copies g) was lower than either the 1 or the 1 genes (10 copies g), regardless of treatments. However, concentrations of all genes in the soils of animal congregation areas were higher than those in background soils with the least animal impact. In contrast with the effect on other contaminants, the effect of soil amendments on bacteria with antibiotic resistance genes was not biologically significant. Future research should be directed toward evaluating effective alternative methods to mitigate these bacterial populations. | 2018 | 30272780 |