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Microorganisms mainly exist in the form of biofilm in nature. Biofilm can contaminate food and drinking water system, as well as cause chronic wound infections, thereby posing a potential threat to public health safety. In the last two decades, researchers have made efforts to investigate the genetic contributors control different stages of biofilm development (adherence, initiation, maturation, and dispersal). As an opportunistic pathogen, C. albicans causes severe superficial or systemic infections with high morbidity and mortality under conditions of immune dysfunction. It has been reported that 80% of C. albicans infections are directly or indirectly associated with biofilm formation on host or abiotic surfaces including indwelling medical devices, resulting in high morbidity and mortality. Significantly, the outcome of C. albicans biofilm development includes enhanced invasion, exacerbated inflammatory responses and intrinsic resistance to antimicrobial chemotherapy. Thus, this review aimed at providing a comprehensive overview of the regulatory network controls microbial biofilm development, with C. albicans as a representative, served as reference for therapeutic targets.

The coordination of single or multiple microorganisms are required for the manufacture of traditional fermented foods, improving the flavour and nutrition of the food materials. However, both the additional economic benefits and safety concerns have been raised by microbiotas in fermented products. Among the fermented products, Lactobacillus and Saccharomyces cerevisiae are one of the stable microbiotas, suggesting their interaction is mediated by coexistence-relevant mechanisms and prevent to be excluded by other microbial species. Thus, aiming to guide the manufacture of fermented foods, this review will focus on interactions of coexistence-relevant mechanisms between Lactobacillus and S. cerevisiae, including metabolites communications, aggregation, and polymicrobial biofilm. Also, the molecular regulatory network of the coexistence-relevant mechanisms is discussed according to omics researches.

Antimicrobial resistance (AMR) has been a leading issue for human health globally threatening the achievement of several of the Sustainable Development Goals (SDGs). Originated from

Since antimicrobial resistance, especially β-lactam resistance genes were common in clinical

Antimicrobial resistance (AMR) has been a leading issue for human health globally threatening the achievement of several of the Sustainable Development Goals (SDGs). Originated from Bacillus cereus, carbapenemases phenotype has been considered to be a major concern in AMR. In this study, the AMR identification rate of P. aeruginosa isolates and infections in FAHJU showed an obvious upward trend from 2012 to 2016. All 88 carbapenem-resistant P. aeruginosa strains were screened for carbapenemase phenotype by modified Carbapenem Inactivation Method (mCIM), and these results of mCIM were compared with traditional PCR results. The isolates of P. aeruginosa and infected patients showed obvious upward trend from 2012 to 2016. The drug resistance to common clinical antibiotics was serious that the clinical rational use of antibiotics should be strengthened, which is in accordance with the Global Antimicrobial Resistance and Use Surveillance System (GLASS) report. In comparison, the results of mCIM showed that 18 out of 88 CRPA strains were carbapenemase positive, which were completely consistent with the results yielded by PCR method. Therefore, it is convinced that this mCIM methodology is a simple and quick method for detected carbapenemases producing P. aeruginosa and has a potential capability in carbapenemases phenotype of pathogen like B. cereus, which will undoubtedly aid in the AMR therapy.

Microorganisms mainly exist in the form of biofilm in nature. Biofilm can contaminate food and drinking water system, as well as cause chronic wound infections, thereby posing a potential threat to public health safety. In the last two decades, researchers have made efforts to investigate the genetic contributors control different stages of biofilm development (adherence, initiation, maturation, and dispersal). As an opportunistic pathogen, C. albicans causes severe superficial or systemic infections with high morbidity and mortality under conditions of immune dysfunction. It has been reported that 80% of C. albicans infections are directly or indirectly associated with biofilm formation on host or abiotic surfaces including indwelling medical devices, resulting in high morbidity and mortality. Significantly, the outcome of C. albicans biofilm development includes enhanced invasion, exacerbated inflammatory responses and intrinsic resistance to antimicrobial chemotherapy. Thus, this review aimed at providing a comprehensive overview of the regulatory network controls microbial biofilm development, with C. albicans as a representative, served as reference for therapeutic targets.

Escherichia coli O157:H7 is an important food-borne pathogen and has ability to contaminate food, such as water, meat products, and milk. Moreover, E. coli O157:H7 is the main toxin-producing serotype which can produce Shiga toxin type 1 and type 2 and cause intestinal disease. The strong pathogenicity and lethality of Escherichia coli O157:H7 pose a serious threat to human. This study aims to develop a rapid and visual detection assay of E. coli for rfbE, stx1, and stx2 genes by crossing priming amplification (CPA). The limit of detection of CPA assay for rfbE, stx1, and stx2 genes was 3.20 fg/μl, 320 fg/μl, and 320 fg/μl in genomic DNA, while that of in artificially contaminated food samples was 103 cfu/ml, 105 cfu/ml, and 105 cfu/ml, respectively, which was distinctly higher than that of PCR methods. And the specificity of CPA assay was tested by 22 different bacterial strains and except for E. coli O157:H7 ATCC43895 and other E. coli O157:H7 isolated from eggs, milk, and beef, all strains showed negative results. The visible detection assay was conducted by the addition of calcein in the reaction solutions. The CPA assay showed a successful detection of E. coli O157:H7 (Shiga toxin–producing and non-Shiga toxin–producing) within 60 min under 63 °C with high sensitivity and specificity. These results indicated that the CPA assays with calcein can provide an advanced method to achieve the rapid and visual detection of food-borne E. coli O157:H7.

Objectives Pseudomonas aeruginosa is a medically important pathogen showing intrinsic low permeability to various antimicrobial agents and its potential to acquire multiple resistance mechanism. A longitudinal surveillance aimed to investigate the antimicrobial resistance and its determinants of Pseudomonas aeruginosa in Southern China. A total of 2163 P. aeruginosa isolates were obtained from patients in Southern China during 2004–2016. Methods The antimicrobial susceptibility of the isolates was performed by disk diffusion and Vitek 2 automated system and interpreted according to the Clinical and Laboratory Standard Institute (CLSI) 2015. Results A significant downtrend of resistant rate (>10.0%) was observed for tested antibiotic agents including ciprofloxacin (>30.0%), gentamicin (29.0%), tobramycin (24.2%) and ceftazidime (24.0%) except for aztreonam and amikacin. A total of 269 randomly selected isolates were further studied on the carriage of β-lactam resistance genes by using 7 groups of multiplex PCRs targeting on 20 genes. β-lactam resistance genes were rarely detected with a rate lower than 8%. Among all β-lactam resistance genes, blaSHV acquired the highest identification rate (18/269, 6.7%), followed by blaOXA-1-like (6/269, 2.2%) and blaPER (6/269, 2.2%). In addition, 8 different plasmid replicons were amplified using 8 groups of multiplex PCRs including 18 sets of primers. Only five plasmid replicons were identified in 5 different P. aeruginosa isolates. Insignificant clonal relatedness among the positive strains identified by regular PCR were further verified by randomly amplified polymorphic DNA (RAPD)-PCR. Conclusion This study has provided comprehensive knowledge on current antimicrobial resistance, β-lactam resistance genes and plasmid replicons carriage in a large scale of clinical P. aeruginosa isolates.

The coordination of single or multiple microorganisms are required for the manufacture of traditional fermented foods, improving the flavour and nutrition of the food materials. However, both the additional economic benefits and safety concerns have been raised by microbiotas in fermented products. Among the fermented products

Background Lactobacillus brevis is a major contaminant of spoiled beer. And it was able to enter VBNC state and cause false negative detection, which poses a major challenge to the brewing industry. Methods The genomic DNA of L. brevis BM-LB13908 was extracted and purified to form a sequencing library that meets the quality requirements and was sequenced. The sequencing results were then screened and assembled to obtain the entire genome sequence of L. brevis. Predicted genes were annotated by GO database, KEGG pathway database and COG functional classification system. Results The final assembly yielded 275 scaffolds of a total length of 2 840 080 bp with a G + C content of 53.35%. There were 2357, 701, 1519 predicted genes with corresponding GO functional, COG functional, and KEGG biological pathway annotations, respectively. The genome of L. brevis BM-LB13908 contains hop resistance gene horA and multiple genes related to the formation of VBNC state. Conclusions This report describes the draft genome sequence of L. brevis BM-LB13908, a spoilage strain isolated from finished beer sample. This study may support further study on L. brevis and other beer spoilage bacteria, and prevent and control beer spoilage caused by microorganisms.

Spoilage bacteria had been shown to form viable but nonculturable (VBNC) state maintaining food spoilage capability. In this study, a novel procedure was used to confirm a beer spoilage case caused by a Pediococcus damnosus strain in the VBNC state. Firstly, flow cytometry, routine culturing and PMA-PCR methods were used to identify approximately 103 cells/ml VBNC cells in the spoiled beer sample based on the difference between CFU and viable cell numbers. Secondly, genomic sequencing showed all acquired scaffolds were identical to the genome of P. damnosus with no existence of other species or isolates. In addition, VBNC cells were obtained in both simulation conditions, including beer low temperature storage and subculturing. MRS agar supplemented with catalase was found to resuscitate VBNC cells. Normal, VBNC and resuscitated cells showed similar level of beer spoilage capability. As concluded, a novel procedure, in combination of genomic sequencing, flow cytometry and routine culturing was used to confirm VBNC cells in spoiled beer sample, providing direct evidence on the beer spoilage caused by VBNC P. damnosus cells, and will aid in further study on VBNC state in food industry so that more evidence on food safety problem caused by VBNC microbes will be shown.

Nowadays, food quality and safety issues caused by foodborne pathogens and spoilage bacteria have attracted widespread attention. This study examined effectiveness of intense pulsed light (IPL) treatment on the inactivation of seven foodborne gram-positive bacteria, including Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Enterococcus faecium, Bacillus thuringiensis, Lactobacillus brevis, and Pediococcus acidilactici. The bacteria of three survival states, including planktonic, early (8 h) and mature biofilm (48 h), and in two biofilm models, including 96 well cell culture plate and polycarbonate membrane were cultivated, which were treated by IPL with three fluences (0.0407, 0.0319 and 0.0150 J*cm−2) under different number of pulses at 25 °C and 4 °C. Results showed that high level inactivation under different conditions were achieved and the inactivation rate improved with the increasing of fluence and pulse number. Moreover, mature biofilm had the strongest resistance ability to IPL, followed by early biofilm, while both of them were far more resistant than planktonic state. IPL may provide a means of surface decontamination, thereby reducing the contamination of microorganisms on the food surface.

Cronobacter sakazakii is an emerging opportunistic foodborne pathogen causing rare but severe infections in neonates. Furthermore, the formation of biofilm allows C. sakazakii to persist in different environments. We have demonstrated that the mutator phenotype ascribed to deficiency of the pmrA gene results in more biomass in the first 24 h but less during the post maturation stage (7–14 d) compared with BAA 894. The present study aimed to investigate the regulatory mechanism modulating biofilm formation due to pmrA mutation. The transcriptomic analyses of BAA 894 and s-3 were performed by RNA-sequencing on planktonic and biofilm cells collected at different time points. According to the results, when comparing biofilm to planktonic cells, expression of genes encoding outer membrane proteins, lysozyme, etc. were up-regulated, with LysR family transcriptional regulators, periplasmic proteins, etc. down-regulated. During biofilm formation, cellulose synthase operon genes, flagella-related genes, etc. played essential roles in different stages. Remarkably, pmrA varies the expression of a number of genes related to motility, biofilm formation, and antimicrobial resistance, including srfB, virK, mviM encoding virulence factor, flgF, fliN, etc. encoding flagellar assembly, and marA, ramA, etc. encoding AraC family transcriptional regulators in C. sakazakii. This study provides valuable insights into transcriptional regulation of C. sakazakii pmrA mutant during biofilm formation.

Lactic acid bacteria (LAB) have caused many microbiological incidents in the brewing industry, resulting in severe economic loss. Meanwhile, traditional culturing method for detecting LAB are time-consuming for brewers. The present review introduces LAB as spoilage microbes in daily life, with focus on LAB in the brewing industry, targeting at the spoilage mechanism of LAB in brewing industry including the special metabolisms, the exist of the viable but nonculturable (VBNC) state and the hop resistance. At the same time, this review compares the traditional and novel rapid detection methods for these microorganisms which may provide innovative control and detection strategies for preventing alcoholic beverage spoilage, such as improvement of microbiological quality control using advanced culture media or different isothermal amplification methods.

The inhibition of microbial biofilms is a significant concern in food safety. In the present study, the inhibitory effect of sodium citrate and cinnamic aldehyde on biofilm formation at minimum inhibitory concentrations (MICs) and sub‐MICs was investigated for Escherichia coli O157:H7 and Staphylococcus aureus. The biofilm inhibition rate was measured to evaluate the effect of sodium citrate on S. aureus biofilms at 24, 48, 72, and 96 hr. According to the results, an antibiofilm effect was shown by both food additives, with 10 mg/ml of sodium citrate exhibiting the greatest inhibition of S. aureus biofilms at 24 hr (inhibition rate as high as 77.51%). These findings strongly suggest that sodium citrate exhibits a pronounced inhibitory effect on biofilm formation with great potential in the extension of food preservation and storage.

The objective of this study was to evaluate the ability of a polyphenolic extract from longan seeds as a wound-healing material for deep second-degree burn wounds. The total phenol content of the extract reached 45.28 ± 1.22 mg GAE per g DW when 70% ethanol was used as the extraction solvent, and then AB-8 resin was used for purification. Results from the antioxidant assay in vitro (DPPH˙ and hydroxyl radical scavenging activity) and antimicrobial activity assay (ZOI, MIC and MBC) showed that the fractions eluted by 30% ethanol tend to have greater antioxidant ability, as well as higher bactericidal and antibacterial activities, than the other elution fractions. Low-, middle-, and high-doses of the polyphenolic extract were applied for wound-healing of mice, and were compared with 30% ethanol solution (negative control) and ‘Jing Wan Hong®’ (positive control). The results showed that on the 11th day, the wound-healing rate and levels of hydroxyproline and protein indicated that wound healing in the high-dose polyphenolic group was similar to that of the positive control, which was higher than that in the other groups (p < 0.01). The histological results indicated that high-dose polyphenolic extracts are capable of leading to the formation of new blood vessels and capillaries, regenerating new dermal tissue and remodeling the newly formed tissue during the proliferative period. Our results provided first-hand information on the would-healing potential of the polyphenolic extract from longan seeds.

This study aimed to evaluate the Staphylococcus aureus biofilm formation and Nε-carboxymethyl-lysine generation ability under food heat processing conditions including pH (5.0–9.0), temperature (25 °C, 31 °C, 37 °C, 42 °C and 65 °C), NaCl concentration (10%, 15% and 20%, w/v) and glucose concentration (0.5%, 1%, 2%, 3%, 5%, 10%, w/v). S. aureus biofilm genetic character was obtained by PCR detecting atl, ica operon, sasG and agr. Biofilm biomass and metabolic activity were quantified with crystal violet and methyl thiazolyl tetrazolium staining methods. S. aureus biofilm was sensitive to food heat processing conditions with 37 °C, pH 7.0, 2% glucose concentration (w/v) and 10% NaCl concentration (w/v) were favorable conditions. Besides, free and bound Nε-carboxymethyl-lysine level in weak, moderate and strong biofilm were detected by optimized high performance liquid chromatography tandem mass spectrometry. Nε-carboxymethyl-lysine level in S. aureus biofilm possessed a significant gap between strong, moderate and weak biofilm strains. This investigation revealed the biological and chemical hazard of Staphylococcus aureus biofilm to food processing environment.

This study aimed to characterize the antimicrobial susceptibility and genetic features of a heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) strain Guangzhou-SauVS2 recovered from a female patient in Guangzhou, representative of southern China. The genome of Guangzhou-SauVS2 was sequenced using Illumina HiSeq 2500 platform and assembled de novo using Velvet v1.2.08. Annotations and bioinformatics analysis were further performed. Results showed that Guangzhou-SauVS2 was susceptible and resistant to 7 and 11 antibiotic drugs, respectively, and exhibited hVISA with a minimum inhibitory concentration of vancomycin as 4 μg/mL. Its genome is 2,883,941 bp in length and contains 2934 predicted genes with an average G + C content of 32.9%. Besides, a total of 38 virulence factors and 4 antibiotic-resistant genes were identified. These results can be employed to further study the pathogenic and antimicrobial mechanisms of hVISA

Streptococcus agalactiae is considered as a leading case of bacterial infection among neonates. Although relative protection strategies have been performed in many high-income countries, resulting in a massive reduction in the occurrences of early-onset GBS disease, the late-onset disease has not affected. Here, the whole genome of S. agalactiae Guangzhou-SAG036 was sequenced by the Pacific Biosciences Sequel using the P4–C2 chemistry and the continuous long reads were used for de novo assembly using HGAP. Besides, genes prediction and multiply annotation were performed by comparing it with diverse databases. The whole genome has a length of 2,206,504 bp and contains 2162 predicted genes with an average G + C content of 35.85%. Based on the whole genome sequence, 2 large prophages, 20 virulence factors genes, and 8 antibiotic resistant genes were identified. MLST analysis revealed S. agalactiae Guangzhou-SAG036 was identified as ST-17. The virulence factors genes were identified with different functions including adherence, antiphagocytosis, spreading factor, immune evasion, invasion, toxin. Besides, the antibiotic-resistant genes may provide S. agalactiae with resistance to multi-drugs including erythromycin, streptomycin, azithromycin, spiramycin, ampicillin, kanamycin, cationic peptides, and tetracycline. Therefore, the infection of S. agalactiae Guangzhou-SAG036 ST-17 strain maybe caused by the complex virulence factors and multi-drugs resistance. These results contribute to further understand GBS epidemiology and surveillance targets.

Staphylococcus aureus is one of the representative foodborne pathogens which forms biofilm. Antibiotics are widely applied in livestock husbandry to maintain animal health and productivity, thus contribute to the dissemination of antimicrobial resistant livestock and human pathogens, and pose a significant public health threat. Effect of antibiotic pressure on S. aureus biofilm formation, as well as the mechanism, remains unclear. In this study, the regulatory mechanism of low concentration of ampicillin on S. aureus biofilm formation was elucidated. The viability and biomass of biofilm with and without 1/4 MIC ampicillin treatment for 8 h were determined by XTT and crystal violet straining assays, respectively. Transcriptomics analysis on ampicillin-induced and non-ampicillin-induced biofilms were performed by RNA-sequencing, differentially expressed genes identification and annotation, GO functional and KEGG pathway enrichment. The viability and biomass of ampicillin-induced biofilm showed dramatical increase compared to the non-ampicillin-induced biofilm. A total of 530 differentially expressed genes (DEGs) with 167 and 363 genes showing up- and down-regulation, respectively, were obtained. Upon GO functional enrichment, 183, 252, and 21 specific GO terms in biological process, molecular function and cellular component were identified, respectively. Eight KEGG pathways including “Microbial metabolism in diverse environments”, “S. aureus infection”, and “Monobactam biosynthesis” were significantly enriched. In addition, “beta-lactam resistance” pathway was also highly enriched. In ampicillin-induced biofilm, the significant up-regulation of genes encoding multidrug resistance efflux pump AbcA, penicillin binding proteins PBP1, PBP1a/2, and PBP3, and antimicrobial resistance proteins VraF, VraG, Dlt, and Aur indicated the positive response of S. aureus to ampicillin. The up-regulation of genes encoding surface proteins ClfB, IsdA, and SasG and genes (cap5B and cap5C) which promote the adhesion of S. aureus in ampicillin induced biofilm might explain the enhanced biofilm viability and biomass.

Bacillus cereus is one of the most common opportunistic pathogens responsible for various foodborn diseases. To investigate the regulatory mechanism of B. cereus under high osmotic pressure, two B. cereus strains B25 and B26 were isolated from the industrial soy sauce residue containing high-salt concentration. Resequencing was performed by Illumina/Solexa platform and 13,646 SNPs and 434 InDels were identified as common variants between B25 and B26 against reference genome, followed by COG, GO, and KEGG enrichment analysis. Furthermore, 49 key genes involving in Na+/H+,K+ transporter, dipeptide or tripeptide transporter, stress response were selected and classified into 27 groups. Further validation was performed by qRT-PCR, and 4 candidate genes were found most associated with osmotic response. Gene expression of the 4 candidate genes was then analyzed accordingly, and down regulation was obtained for gene BC0669 and BC0754 associated with K+ transport system. However, dramatic up regulation was detected for gene BC2114 involving in glutathione peroxidase, indicating the activation of antioxidant responses by osmotic stress via genetic regulation. As concluded, bioinformatic analysis and gene expression profile represented the basis of further investigation on the genetic and regulatory mechanism of bacterial salt tolerance.