Biofilm Genes Research Articles

Genotypic investigation of drugs resistance and biofilm genes among ciprofloxacin-resistant Pseudomonas aeruginosa isolated from burn patients

Burn patients are the serious targets of hospital-acquired infection occurred by Pseudomonas aeruginosa ( P. aeruginosa) , which is a main cause of burn patients morbidity and mortality, so this study aimed to molecular investigation of genes associated with antibiotic resistance among ciprofloxacin-resistant Pseudomonas aeruginosa. Current study involved 168 burn patients involved 107(63.69%) and 61 (36.3%) were females and male respectively, the results showed 132(78.57%) gram negative bacteria and 27(16.0%) gram positive bacteria while 9(5.3%) no bacterial growth. The results of Vitek-2 compact system recorded 75(44.64%) as P. aeruginosa isolates. Results of ciprofloxacin susceptibility showed 29(38.67%), while 34(45.33%) and 12(16%) of isolates were intermediate and sensitive respectively. Congo red agar assay was applied in current study for qualitative evaluation of pathogenic biofilm were 23/29 (79.31%), and 6/26(20.86%) as high, and moderate biofilm producer among isolates respectively. Result of Polymerase chain reaction (PCR) showed that gyrB was recorded among ciprofloxacin-resistant P. aeruginosa at rate 28/29 (96.55%). At same respect. results of efflux pump genes for oqxA and oqxB genes were detected among this pathogen at rate 26/29 (89.65%) and 29/29(100%) respectively. outer membrane genes, revealed that mexR gene was 27/29 (93.1%), while the spreading of the oprD gene was 26/29(89.65%). Results of molecular detection about colistin resistance genes revealed that the mcr-3 gene was 8/29 (27.58%), but genes of mcr-1 and mcr-2 were no detected in this work, Finally, results showed that 23/29 (79.31%) of ciprofloxacin-resistant P. aeruginosa were harbored pml gene.

The impact of quorum sensing and biofilm formation on antimicrobial resistance and virulence of XDR and MDR Pseudomonas aeruginosa in laying chickens.

Pseudomonas aeruginosa plays a major influence on poultry outbreaks. Several factors may contribute to its pathogenicity. This study aimed to investigate the prevalence of P. aeruginosa infection among layer chickens with phenotypic and genotypic characterization of the isolates. Samples (n=160) were collected from respiratory distressed layer chickens according to the lesion and bacteriologically examined for isolation of P. aeruginosa from Sharkia province, Egypt. The antimicrobial sensitivity was performed against 18 antimicrobial agents. A qualitative assessment of biofilm production was performed using the Tube method. The isolates were genetically examined for confirmation, detection of quorum sensing genes, virulence genes, and biofilm production genes by conventional PCR. P. aeruginosa was isolated from 25% of the samples. Moreover, 95% of the isolates were extensively drug-resistant (XDR) with multiple antibiotic resistance indices (MARI) of 0.67 to 0.83. A total of 38 isolates were able to produce biofilm with different degrees. PCR of 16S rRNA (P. aeruginosa) and oprL genes confirmed the existence of P. aeruginosa isolates. For quorum sensing genes, lasI and lasR were successfully amplified at 100% and 89.5%, respectively. For virulence genes, toxA and exoU were amplified by a percentage of 78.9%, while the higBA gene was in 100% of the isolates. pprA and pprB genes were amplified at 100% and 89.5%, respectively. For biofilm genes, pslA, fliC, and pelA were amplified in 100%, 84.2%, and 10.5%, respectively. A strong correlation between quorum sensing genes, biofilm genes, and virulence genes was detected. Further, biofilm production increases the resistance of the isolates to antimicrobial agents.

The stress response mechanisms and resistance change of chlorine-resistant microbial community at multi-phase interface under residual antibiotics in drinking water distribution system

The presence of multiple trace amounts of antibiotics in drinking water has recently drawn much attention. However, synergistic effects between disinfectants and antibiotics often occur in pipeline due to the presence of residual disinfectants. How this interaction affects the drinking water microbial community remains unknown. Herein, reactors with 2 h of hydraulic retention time (HRT) were constructed to simulate the drinking water distribution system (DWDS), and the antibiotics were continuously discharged to the reactor. Sulfamethoxazole (SMX) was used as a representative antibiotic, and treatment protocols with and without disinfectants were compared. High-throughput sequencing and metagenome were used to study the microbial community and function in polyethylene (PE) and ductile cast iron (DI) (protected by cement mortar lining) pipes. By measuring the enzyme activity and ATP content, we found that disinfectant exposure could not only increase the secretion of biofilm EPS, but also improve the bacterial activity to a certain extent. The synergistic effect of antibiotics and disinfectants could increase the activity of oxidative stress-related enzymes in microbial communities, and the main effect was antibiotic stress. This study not only provides insights into how to inhibit the transmission process of antibiotic resistance genes (ARGs) in biofilm in DWDS, but also provides enlightenment for the harm of ARGs in all carriers where biofilms may exist in water plants.

Prevalence and clonal lineages of biofilm-producing Staphylococcus aureus from clinical samples and healthcare workers at Ahmadu Bello University Teaching Hospital, Nigeria.

This study determined the frequency and molecular features of Staph y lo coccus aureus from 206 burn and wound patients (BWPs) as well as 94 healthcare workers (HCWs) at the Ahmadu Bello University Teaching Hospital, Zaria, Northern Nigeria. Nine (4.4%) and five (5.3%) samples from BWPs and HCWs were identified as S. aureus positive, respectively. Seven (50%) were mecA-positive (associated with SCCmec types IVa and V), while 35.7% presented a multidrug resistance (MDR) phenotype. The S. aureus isolates belonged to 11 diverse spa types, including three new (t4539, t6043, t11694) and one singleton (t779), which were assigned to four clonal complexes. Two tst and three luk-F/S-PV carrying strains were identified. All the S. aureus isolates were moderate biofilm producers with diverse combinations of the icaABCD biofilm and icaR regulatory genes. The detection of genetically diverse S. aureus lineages and toxigenic strains highlights the need for improved surveillance of resistant and pathogenic strains in healthcare facilities.

Apple cider vinegar exhibits promising antibiofilm activity against multidrug-resistant Bacillus cereus isolated from meat and their products.

Bacillus cereus (B. cereus) biofilm is grown not only on medical devices but also on different substrata and is considered a potential hazard in the food industry. Quorum sensing plays a serious role in the synthesis of biofilm with its surrounding extracellular matrix enabling irreversible connection of the bacteria. The goal of the current investigation was to ascertain the prevalence, patterns of antimicrobial resistance, and capacity for B. cereus biofilm formation in meat and meat products in Egypt. In all, 150 meat and meat product samples were used in this study. For additional bacteriological analysis, the samples were moved to the Bacteriology Laboratory. Thereafter, the antimicrobial, antiquorum sensing, and antibiofilm potential of apple cider vinegar (ACV) on B. cereus were evaluated. Out of 150 samples, 34 (22.67%) tested positive for B. cereus. According to tests for antimicrobial susceptibility, every B. cereus isolates tested positive for colistin and ampicillin but negative for ciprofloxacin and imipenem. The ability to form biofilms was present in all 12 multidrug-resistant B. cereus isolates (n = 12); of these, 6 (50%), 3 (25%), and 3 (25%) isolates were weak, moderate, and strong biofilm producers, respectively. It is noteworthy that the ACV demonstrated significant inhibitory effects on B. cereus isolates, with minimum inhibitory concentrations varying between 2 and 8 μg/ml. Furthermore, after exposing biofilm-producing B. cereus isolates to the minimum biofilm inhibitory concentrations 50 of 4 μg/ml, it demonstrated good antibiofilm activity (>50% reduction of biofilm formation). Strong biofilm producers had down-regulated biofilm genes (tasA and sipW) and their regulator (plcR) compared to the control group, according to reverse transcriptase quantitative polymerase chain reaction analysis. Our study is the first report, that spotlights the ACV activity against B. cereus biofilm and its consequence as a strong antibacterial and antibiofilm agent in the food industry and human health risk.

The healing effect of Pseudomonas Quinolone Signal (PQS) with co-infection of Staphylococcus aureus and Pseudomonas aeruginosa: A preclinical animal co-infection model

BackgroundBecause of the rise in antibiotic resistance and the control of pathogenicity, polymicrobial bacterial biofilms exacerbate wound infections. Since bacterial quorum sensing (QS) signals can dysregulate biofilm development, they are interesting therapeutic treatments. In this study, Pseudomonas Quinolone Signal (PQS) was used to treat an animal model of a wound that had both Staphylococcus aureus and Pseudomonas aeruginosa co-infection. MethodsS. aureus and P. aeruginosa mono- and co-infection models were developed in vitro on the L-929 cell line and in an animal model of wound infection. Moreover, PQS was extracted and purified using liquid chromatography. Then, the mono- and co-infection models were treated by PQS in vitro and in vivo. RT-PCR analysis was used to look into changes in biofilm, QS, tissue regeneration, and apoptosis genes after the treatment. ResultsPQS significantly disrupted established biofilm up to 90% in both in vitro and in vivo models. Moreover, a 93% reduction in the viability of S. aureus and P. aeruginosa was detected during the 10 days of treatment in comparison to control groups. In addition, the biofilm-encoding and QS-regulating genes were down-regulated to 75% in both microorganisms. Also, fewer epithelial cells died when treated with PQS compared to control groups in both mono- and co-infection groups. ConclusionAccording to this study, PQS may facilitate wound healing by stimulating the immune system and reducing apoptosis. It seems to be a potential medication to use in conjunction with antibiotics to treat infections that are difficult to treat.

Enhancing column bioleaching of chalcocite by isolated iron metabolism partners Leptospirillum ferriphilum/Acidiphilium sp. coupling with systematically utilizing cellulosic waste

The iron metabolism partners Leptospirillum ferriphilum and Acidiphilium sp. were screened from industrial bioheap site. An integrated multi-stage strategy was proposed to improve chalcolite column bioleaching coupling with synergistical utilization of cellulosic waste such as acid hydrolysate of aquatic plants. L. ferriphilum was used to accelerate the initial iron metabolism, and Acidithiobacillus caldus maintained a lower pH in the middle stage, while Acidiphilium sp. greatly inhibited jarosite passivation in the later stage. Meanwhile, L. ferriphilum (38.3 %) and Acidiphilium sp. (37.0 %) dominated the middle stage, while the abundance of Acidiphilium sp. reached 63.5 % in the later stage. The ferrous, sulfate ion and biomass were improved and the transcriptional levels of some biofilm and morphology related genes were significantly up-regulated. The final Cu2+ concentration reached 325.5 mg·L-1, improved by 43.8 %. Moreover, Canonical Correlation Analysis (CCA) analysis between bioleaching performance, iron/sulfur metabolism and community verified the important role of iron metabolism partners.

Antibiofilm activity of biosynthesized silver and copper nanoparticles using Streptomyces S29

Microbial resistance and biofilm formation have been considered as the main problems associated with microbial resistance. Several antimicrobial agents cannot penetrate biofilm layers and cannot eradicate microbial infection. Therefore, the aim of this study is the biological synthesis of silver and copper nanoparticles to assess their activities on bacterial attachment and on the viability of dormant cells within the biofilm matrix. Ag-NPs and Cu-NPs were biosynthesized using Streptomyces isolate S29. The biologically synthesized Ag-NPs and Cu-NPs exhibited brown and blue colors and were detected by UV/Vis spectrophotometry at 476 and 594 nm, respectively. The Ag-NPs showed an average size of 10–20 nm as indicated by TEM, and 25–35 nm for Cu-NPs. Both Ag-NPs and Cu-NPs were monodispersed with a polydispersity index of 0.1–0.546 and zeta potential were − 29.7, and − 33.7 mv, respectively. The biologically synthesized Ag-NPs and Cu-NPs significantly eliminated bacterial attachment and decreased the viable cells in the biofilm matrix as detected by using crystal violet and tri-phenyl tetrazolium chloride assays. Furthermore, Ag-NPs and Cu-NPs significantly eradicated mature biofilms developed by various Gram-negative pathogens, including A. baumannii, K. pneumoniae and P. aeruginosa standard strains and clinical isolates. Data were also confirmed at the molecular level with prominent elimination of biofilm gene expression carO, bssS and pelA in A. baumannii, K. pneumoniae and P. aeruginosa, respectively compared to untreated cells under the same conditions. As indicated, Ag-NPs and Cu-NPs could be used as adjuvant therapy in eradication of antibiotic resistance and biofilm matrix associated with Gram-negative bacterial infection.Graphical

Impacts of substrate properties and aquatic nutrient concentrations on the relative abundance of nitrifying/denitrifying genes and the associated microbes in epilithic biofilms.

Substrates like sand or gravels and aquatic nutrient concentrations of rivers are highly heterogeneous, influencing the abundance of functional genes in epilithic biofilms where nitrification-denitrification processes take place. To analyze how the relative abundance of nitrifying/denitrifying genes and the associated microbes changes with the physical properties of substrates and aquatic concentrations of nutrients, this paper utilized metagenomics to comprehensively characterize these functional genes (i.e., amoA, hao, and nxrB involved in nitrification, and napA, narG, nirS, norB, and nosZ associated with denitrification) from epilithic biofilms collected along the Shitingjiang River in Southwest China and further obtained the relative abundance of major nitrifiers and denitrifiers. The results show that substrate size most significantly affects the relative abundance of hao and norB by altering the hydrodynamic conditions. In sampling sites with high heterogeneity in substrate size distribution, the relative abundance of most denitrifying genes is also higher. The carbon-nitrogen ratio negatively correlates with the relative abundance of all the nitrifying genes, while ammonium, total inorganic carbon, and total organic carbon concentrations positively affect the relative abundance of amoA and nxrB. As to the relative abundance of nitrifiers and denitrifiers, mainly belonging to phyla Proteobacteria and Actinobacteria, substrate heterogeneity and the aquatic concentrations of nutrients have greater influences than substrate size. Also, the substrate heterogeneity exerted positive influence on functional species of Pseudogemmobacter bohemicus and Paracoccus zhejiangensis. Considering the genes' functions and the dominant species linked to denitrification, nitrous oxide is more likely to occur in rivers with higher heterogeneity and larger substrates.

Global transcriptional analysis of Geobacter sulfurreducens gsu1771 mutant biofilm grown on two different support structures.

Electroactive biofilms formation by the metal-reducing bacterium Geobacter sulfurreducens is a step crucial for bioelectricity generation and bioremediation. The transcriptional regulator GSU1771 controls the expression of essential genes involved in electron transfer and biofilm formation in G. sulfurreducens, with GSU1771-deficient producing thicker and more electroactive biofilms. Here, RNA-seq analyses were conducted to compare the global gene expression patterns of wild-type and Δgsu1771 mutant biofilms grown on non-conductive (glass) and conductive (graphite electrode) materials. The Δgsu1771 biofilm grown on the glass surface exhibited 467 differentially expressed (DE) genes (167 upregulated and 300 downregulated) versus the wild-type biofilm. In contrast, the Δgsu1771 biofilm grown on the graphite electrode exhibited 119 DE genes (79 upregulated and 40 downregulated) versus the wild-type biofilm. Among these DE genes, 67 were also differentially expressed in the Δgsu1771 biofilm grown on glass (56 with the same regulation and 11 exhibiting counter-regulation). Among the upregulated genes in the Δgsu1771 biofilms, we identified potential target genes involved in exopolysaccharide synthesis (gsu1961-63, gsu1959, gsu1972-73, gsu1976-77). RT-qPCR analyses were then conducted to confirm the differential expression of a selection of genes of interest. DNA-protein binding assays demonstrated the direct binding of the GSU1771 regulator to the promoter region of pgcA, pulF, relA, and gsu3356. Furthermore, heme-staining and western blotting revealed an increase in c-type cytochromes including OmcS and OmcZ in Δgsu1771 biofilms. Collectively, our findings demonstrated that GSU1771 is a global regulator that controls extracellular electron transfer and exopolysaccharide synthesis in G. sulfurreducens, which is crucial for electroconductive biofilm development.

Seasonal variations of biofilm C, N and S cycling genes in a pilot-scale chlorinated drinking water distribution system

Biofilms in drinking water distribution systems (DWDS) host diverse microorganisms. However, the functional attributes of DWDS biofilms and their associations with seasonality remain unclear. This study aims to characterize variations in the microbial metabolic traits of DWDS biofilms collected during different seasons, using a pilot-scale DWDS in dark under plug-flow conditions during one-year operation period. Network analysis was used to predict the functional gene hosts. The overall functional attributes determined by shotgun metagenomics exhibited significant differences among seasons. Genes associated with aromatic metabolism, fatty acid biosynthesis and degradation, and capsular extracellular polymeric substance (EPS) were significantly upregulated in summer owing to the higher temperatures and chlorine in the influent of the DWDS. Moreover, the pathways associated with nitrogen, sulfur, glycolysis, and tricarboxylic acid (TCA) cycling, as well as carbon fixation were reconstructed and displayed according to the sampling season. Nitrogen reduction pathways [dissimilatory nitrate reduction to ammonium (DNRA) 73 %, assimilatory nitrate reduction to ammonium (ANRA) 21 %] were identified in DWDS biofilms, but nitrogen oxidation pathways were not. Sulfur cycling were involved in diverse pathways and genes. Glycolysis and TCA cycling offered electron donors and energy sources for nitrogen and sulfur reduction in biofilms. Carbon fixation was observed in DWDS biofilms, with the predominant pathway for fixing carbon dioxide being the reductive citrate cycle (38 %). Constructed functional gene networks composed of carbon, nitrogen, and sulfur cycling-related genes demonstrated synergistic effects (Positive proportion: 63.52−71.09 %). In addition, from spring to autumn, the network complexity decreased and network modularity increased. The assembly mechanism of carbon, nitrogen and sulfur cycling-related genes was driven by stochastic processes for all samples. These results highlight the diverse functional genes in DWDS biofilms, their synergetic interrelationships, and the seasonality effect on functional attributes.

Investigation of genetic relatedness, antimicrobial resistance, biofilm formation, biofilm-related virulence genes and integron-related genes of Stenotrophomonas maltophilia isolates obtained from bovine milk samples with mastitis

Treatment of infections caused by opportunistic pathogenic Stenotrophomonas maltophilia is complicated by the bacterium's ability to produce biofilms and high antibiotic resistance. This study aimed to investigate the prevalence of genetic relatedness, antimicrobial resistance, biofilm formation, biofilm genes associated with virulence and integron genes among isolates of S. maltophilia recovered from bovine milk with subclinical mastitis. In this study, bacterial identification was performed using conventional methods. While using the smeT gene-based Polymerase Chain Reaction (PCR) to confirm the species-level identification of isolates; PCR was also used to detect virulence and integron genes, too. The quantitative Microplate Test (MP) method was used to determine the phenotypic biofilm production capacity of the isolates. The resistance patterns of the isolates against 9 antibiotics belonging to 9 antimicrobial families were examined using the disk diffusion method. Isolates resistant to at least three drug classes from various antimicrobial drug classes were defined as multi-drug resistant (MDR). The genetic linkage of S. maltophilia isolates was investigated by Enterobacterial Repetitive Intragenic Consensus (ERIC) PCR. The Chi-Square (χ2) test was used to compare the relationship between the biofilm-forming capacity of the isolates with the prevalence of biofilm-associated virulence genes and integron genes with MDR. In the study, a total of 312 milk samples with subclinical mastitis were taken from 27 farms. Ten isolates from five farms were phenotypically and genotypically identified as S. maltophilia. All isolates were resistant to cefepime and imipenem. While 70% of the isolates were MDR; 80% carried one of the integron genes. By the MP test, the phenotypically biofilm-forming capacity identified in isolates was detected at 80%. The prevalence of the studied virulence genes was rpfF 60%, rmlA 70%, spgM and smf1 80%. There was no significant relationship between the biofilm-forming capacity of the isolates with the prevalence of biofilm-associated virulence genes and MDR with integron genes. S. maltophilia isolates were detected simply and quickly, using PCR based on the smeT gene, from bovine milk samples for the first time in Turkey. In the UPGMA analysis performed in the PyElph 1.4 program, a total of 5 genotypes were found, 2 single and 3 multiple according to 18% similarity coefficient. ERIC-PCR can be useful in identifying S. maltophilia isolates with epidemic potential.

INVESTIGATING THE RELATIONSHIP BETWEEN SOME VIRULENCE AND ANTIBIOTICS RESISTANCE GENES OF SOME LOCAL PATHOGENIC BACTERIA IN IRAQ

Since the potential link between virulence genes and bacterial antibiotic resistance is of great importance in medical aspects, the properties of such a link were thoroughly investigated in this work. Sixty bacterial isolates were collected from patients with urinary tract infection (UTI) who visited the medical lab at the College of Science/the University of Al-Kufa. Preservation and sub-culture of these isolates were performed according to the guidelines of microorganism's care and the Research Committee of Al-Qasim Green University. Several phenotypic tests were performed involving hemolysis, haemagglutination, serum resistance, and biofilm formation. Genotypic analysis of virulence genes (biofilm and Iss) and antibiotics resistance genes (blaAmpC, blaTEM, blaSHV-5, and blaCTX-M) were measured using the polymerase chain reaction (PCR) technique. All isolates of P. mirabillis were extracted as positive for the serum resistance test with 100%, while a percentage of than less 14% was observed with isolates of Pseudomonas aeruginosa. From the acquired results of the biofilm formation test, it was revealed that all bacterial isolates exhibited negative results except in isolates of E. coli, Proteus mirabillis, and Enterococcus faecalis. As far as the genetic study is concerned, the biofilm gene was abundant and was also found in 95% of bacterial isolates followed by an increase in the serum survival (Iss) gene by 86.66%. Interestingly, the genotype study of antibiotic resistance genes showed that both blaAmpC and blaTEM had significantly greater prevalence in all isolates compared to blaSHV-5 and blaCTX-M at P≤ 0.05. In addition, the percentages of the prevalence of blaAmpC and blaTEM were significantly higher (93.33 and 71.66), respectively, compared to the respective values found in blaSHV-5 and blaCTX-M (20%, 46.66%). From the correlation findings, a significant constructive association between virulence and resistance to antibiotic profile was found (r=0.957, P=0.000). In conclusion, our work provides valuable insights for better understanding the potential link between genotypic (virulence genes) and phenotypic traits (antibiotic resistance). Future research holds the potential to deepen our comprehension of the intricate relationship between virulence genes and antibiotic resistance, thereby making substantial contributions to the development of more efficacious approaches for the management of bacterial infections. This recommendation extends to fellow researchers in the field.

Role of type VI secretion system protein TssJ-3 in virulence and intracellular survival of Burkholderia pseudomallei

TssJ-3 is an outer-membrane lipoprotein and is one of the key components of the type VI secretion system in Burkholderia pseudomallei. TssJ translocates effector proteins to target cells to induce innate immune response in the host. However, the tssJ gene has not been identified in B. pseudomallei and its function in this bacterium has not yet been characterized. tssJ-3 knockout and tssJ-3-complemented B. pseudomallei strains were constructed to determine the effects of tssJ-3 on bacterial growth, biofilm formation, flagellum synthesis, motility, host cell infection, and gene expression in B. pseudomallei. We found that the ΔtssJ-3 mutant strain of B. pseudomallei showed significantly suppressed biofilm formation, flagellum synthesis, bacterial growth, motility, and bacterial invasion into host cells (A549 cells). Furthermore, the ΔtssJ-3 mutation downregulated multiple key genes, including biofilm and flagellum-related genes in B. pseudomallei and induced interleukin-8 gene expression in host cells. These results suggest that tssJ-3, an important gene controlling TssJ-3 protein expression, has regulatory effects on biofilm formation and flagellum synthesis in B. pseudomallei. In addition, B. pseudomallei-derived tssJ-3 contributes to cell infiltration and intracellular replication. This study provides a molecular basis of tssJ-3 for developing therapeutic strategies against B. pseudomallei infections.

Effect of ZnO nanoparticles on biofilm formation and gene expression of the toxin-antitoxin system in clinical isolates of Pseudomonas aeruginosa

BackgroundBiofilm formation by Pseudomonas aeruginosa (P. aeruginosa) is known to be characteristic of this organism. This bacterium is considered one of the most life-threatening bacteria and has been identified as a priority pathogen for research by WHO. Biofilm-producing P. aeruginosa is a concern in many parts of the world due to antibiotic resistance. Alginate also plays an important role in the biofilm formation of P. aeruginosa as well as the emergence of antibiotic resistance in biofilms. In addition, the systems of toxin-antitoxin( TA) play an important role in biofilm formation. Metal nanoparticle(NP) such as zinc oxide (ZnO) also have extensive biological properties, especially anti-biofilm properties. Therefore, this study was conducted in relation to the importance of zinc oxide nanoparticles (ZnO NPs) in biofilm formation and also the correlation of gene expression of TA systems in clinical isolates of P. aeruginosa.MethodsA total of 52 P. aeruginosa isolates were collected from burns (n = 15), UTI (n = 31), and trachea (n = 6) in hospitals in Ilam between May 2020 and October 2020. Biofilm formation was assessed using a microtiter plate assay. MIC and sub-MIC concentrations of ZnO NPs (10–30 nm with purity greater than 99.8%) in P. aeruginosa were determined. Subsequently, biofilm formation was investigated using sub-MIC concentrations of ZnO NPs. Finally, total RNA was extracted and RT- qPCR was used to determine the expression levels of genes of mazEF, mqsRA, and higBA of TA systems.ResultsSix isolates of P. aeruginosa were found to form strong biofilms. The results showed that ZnO NPs were able to inhibit biofilm formation. In our experiments, we found that the sub-MIC concentration of ZnO NPs increased the gene expression of antitoxins mazE and mqsA and toxin higB of TA systems treated with ZnO NPs.ConclusionsIn the present study, ZnO NPs were shown to effectively inhibit biofilm formation in P. aeruginosa. Our results support the relationship between TA systems and ZnO NPs in biofilm formation in P. aeruginosa. Importantly, the expression of antitoxins mazE and mqsA was high after treatment with ZnO NPs, but not that of antitoxin higA.

Understanding the transcriptomic response of Lactiplantibacillus pentosus LPG1 during Spanish-style green table olive fermentations.

Lactiplantibacillus pentosus (Lbp. pentosus) is a species of lactic acid bacteria with a great relevance during the table olive fermentation process, with ability to form non-pathogenic biofilms on olive epidermis. The objective of this work is to deepen into the genetic mechanisms of adaptation of Lpb. pentosus LPG1 during Spanish-style green table olive fermentations, as well as to obtain a better understanding of the mechanisms of adherence of this species to the fruit surface. For this purpose, we have carried out a transcriptomic analysis of the differential gene expression of this bacterium during 60 days of fermentation in both brine and biofilms ecosystems. In brines, it was noticed that a total of 235 genes from Lpb. pentosus LPG1 were differentially expressed during course of fermentation and grouped into 9 clusters according to time-course analysis. Transport and metabolism of carbohydrates and amino acids, energy production, lactic acid and exopolysaccharide synthesis genes increased their expression in the planktonic cells during course of fermentation. On the other hand, expression of genes associated to stress response, bacteriocin synthesis and membrane protein decreased. A total of 127 genes showed significant differential expression between Lpb. pentosus LPG1 planktonic (brine) and sessile (biofilms) cells at the end of fermentation process (60 days). Among the 64 upregulated genes in biofilms, we found genes involved in adhesion (strA), exopolysaccharide production (ywqD, ywqE, and wbnH), cell shape and elongation (MreB), and well as prophage excision. Deeping into the genetic bases of beneficial biofilm formation by Lpb. pentosus strains with probiotic potential will help to turn this fermented vegetable into a carrier of beneficial microorganisms to the final consumers.

Vanadium nitride decorated carbon cloth anode promotes aniline degradation and electricity generation of MFCs by efficiently enriching electroactive bacteria and promoting extracellular electron transfer

To increase the colonization of electroactive bacteria and accelerate the rate of extracellular electron transfer, a simple coated anode of microbial fuel cell was designed. Here, we took advantage of vanadium nitride (VN) particles to modify the carbon cloth (VN@CC). Compared with bare carbon cloth, the designed VN@CC bioanodes exhibited a larger electrochemically active area, better biocompatibility, and smaller charge transfer impedance. The MFC with VN@CC bioanodes achieved the maximum power density of 3.89 W m−2 and chemical oxygen demand removal rate of 84% when 1000 mg L−1 aniline was degraded, which were about 1.88 and 2.8 times that of CC. The morphology of biofilm and 16s rRNA gene sequence analysis proved that the VN@CC bioanodes facilitated the enrichment of electroactive bacteria (99.02%) and increased the ratio of fast electron transfer in the extracellular electron transfer, thus enhancing the MFC performance of aniline degradation and power output. This work disclosed that it was feasible to increase the overall performance of MFC by enhancing the EET efficiency and presented valuable insights for future work.

Prevalence, drug resistance, molecular typing and comparative genomics analysis of MRSA strains from a tertiary A hospital in Shanxi Province, China.

Staphylococcus aureus (S. aureus) is an important zoonotic pathogen that causes a high incidence rate and mortality worldwide. This study investigated the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains in a tertiary A hospital in Shanxi Province, China, in order to determine the major epidemic clones as well as their antibiotic resistance and virulence characteristics. A total of 212 S. aureus strains were collected in this hospital, and were subjected to antimicrobial susceptibility testing, detection of virulence genes, resistance genes, and efflux pump genes. Among them, 38 MRSA strains were further subjected to detection of biofilm genes, assessment of biofilm formation ability, MLST, spa typing, SCCmec typing, and phylogenetic analysis. The majority of S. aureus strains came from the neonatology department, with secretions and purulent fluid being the main source of samples. The strains showed high resistance to penicillin (98.11%), erythromycin (64.62%) and clindamycin (59.91%), while being sensitive to vancomycin and linezolid. The detection rates of efflux pump genes and resistance genes were high, and there was a significant correlation between resistance gene types and phenotypes, with mecA showing a close correlation with oxacillin. The detection rates of virulence genes and the toxin gene profiles of MSSA and MRSA strains showed significant differences. And the detection rate of biofilm genes in MRSA strains was relatively high, with 13.16% of MRSA strains showing strong biofilm formation ability. The most common epidemic clone of MRSA was ST59-SCCmecIV-t437, followed by ST59-SCCmecV-t437. The former had a higher detection rate of resistance genes and a stronger biofilm formation ability, while the latter had a higher positive rate for pvl gene and stronger pathogenicity, making it more likely to cause systemic infections. Phylogenetic analysis showed that all MRSA strains in this study clustered into three major branches, with distinct differences in antibiotic resistance and virulence characteristics among the branches. ST59-MRSA strains from different species showed consistency and inter-species transmission, but there were differences among ST59-MRSA strains from different geographical locations. In general, most MSSA and MRSA strains exhibited multidrug resistance and carried multiple resistance genes, virulence genes, and biofilm formation genes, warranting further research to elucidate the mechanisms of drug resistance and pathogenesis.

Insights into the membrane fouling aggravation under polyethylene terephthalate microplastics contamination: From a biochemical point of view

This study evaluated the potential effects of polyethylene terephthalate microplastics (PET-MPs) on a membrane bioreactor. The results showed that 10–30 mg/L PET-MPs exposure showed a minor effect on reactor performances, while 50 mg/L PET-MPs significantly decreased the chemical oxygen demand and NH4+-N removal efficiencies. Long-term PET-MPs exposure resulted in sludge foaming, and significantly increased extracellular polymeric substances (EPS) contents from 463.08 ± 62.42 to 952.54 ± 23.67 mg/m2, which was the main factor in triggering severe membrane fouling. Excitation emission matrix and Fourier transform infrared spectroscopic analysis revealed significant changes in fluorescence properties and functional groups of EPS. Particularly, protein secondary structure analysis indicated that high abundant β-sheet facilitated the exposure of inner hydrophobic groups of bacterial cells and EPS, and consequently enhanced the interfacial interactions of foulants-foulants and membrane-foulants. Long-term PET-MPs exposure significantly shifted the microbial community structures. In particular, the abundances of foam-forming filamentous bacteria and quorum-sensing (QS) bacteria, such as Thiothrix, Kouleothrix and Aeromonas, were constantly increasing with the increasing PET-MPs concentration. Furthermore, PET-MPs exposure significantly up-regulated the abundances of genes encoding QS signaling molecules and exopolysaccharides, such as lasI, lsrA and algZ. Collectively, these findings suggested that PET-MPs exposure stimulated the excessive growth of fouling-causing bacteria, which contained more biofilm formation related genes, that consequently accelerated membrane fouling.

Antibacterial and antibiofilm effects of green synthesized selenium nanoparticles on clinical Klebsiella pneumoniae isolates.

Nanotechnology covers many disciplines, including the biological sciences. In this study, selenium nanoparticles (Se-NPs) were synthesized using Artemisia annua extract and investigated against clinical strains of klebsiella pneumoniae (K. pneumoniae) for their anti-biofilm effects. In this experimental study, from May 1998 to September 1998, 50 clinical samples of blood, urine, and sputum were collected, and K. pneumoniae strains were isolated using microbiological methods. Subsequently, the antibacterial effects of Se-NPs at concentrations of 12-25-50-100/5-6/3-25/125 μg/mL were studied. Finally, biofilm-producing strains were isolated, and the expression of mrkA biofilm gene was studied in real-time strains treated with Se-NPs using real-time polymerase chain reaction (PCR). Out of 50 clinical samples, 20 strains of K. pneumoniae were isolated. Minimum inhibitory concentration (MIC) results of Se-NPs showed that Se-NPs were capable of significant cell killing. Real-time PCR results also showed that mrkA gene expression was significantly reduced in strains treated with Se-NPs. According to this study, Se-NPs could reduce bacterial growth and biofilm formation, therefore, could be considered a candidate drug in the medical application for infections caused by K. pneumoniae.