Biofilm Formation Pathways Research Articles

Transcriptomic Analyses to Unravel Cronobacter sakazakii Resistance Pathways.

The proliferation of antibiotic usage has precipitated the emergence of drug-resistant variants of bacteria, thereby augmenting their capacity to withstand pharmaceutical interventions. Among these variants, Cronobacter sakazakii (C. sakazakii), prevalent in powdered infant formula (PIF), poses a grave threat to the well-being of infants. Presently, global contamination by C. sakazakii is being observed. Consequently, research endeavors have been initiated to explore the strain's drug resistance capabilities, alterations in virulence levels, and resistance mechanisms. The primary objective of this study is to investigate the resistance mechanisms and virulence levels of C. sakazakii induced by five distinct antibiotics, while concurrently conducting transcriptomic analyses. Compared to the susceptible strains prior to induction, the drug-resistant strains exhibited differential gene expression, resulting in modifications in the activity of relevant enzymes and biofilm secretion. Transcriptomic studies have shown that the expression of glutathione S-transferase and other genes were significantly upregulated after induction, leading to a notable enhancement in biofilm formation ability, alongside the existence of antibiotic resistance mechanisms associated with efflux pumps, cationic antimicrobial peptides, and biofilm formation pathways. These alterations significantly influence the strain's resistance profile.

Fitness and transcriptomic analysis of pathogenic Vibrio parahaemolyticus in seawater at different shellfish harvesting temperatures

ABSTRACT To better characterize the population dynamics of Vibrio parahaemolyticus ( Vp ) containing different virulence genes, two Vp strains were inoculated into seawater separately and incubated at temperatures (10°C and 30°C) mimicking winter and summer pre-harvest shellfish rearing seasons. The cellular responses of two Vp strains, one containing the thermostable direct hemolysin ( tdh +) gene and the other one containing tdh -related hemolysin ( trh +) gene, were studied at the transcriptomic level. Results showed that, at 30°C, tdh + and trh + strains reached 6.77 ± 0.20 and 6.14 ± 0.07 log CFU/mL, respectively, after 5 days. During this time, a higher growth rate was observed in the tdh + strain than in the trh + strain. When being kept at 10°C, both Vp strains persisted at ca. 3.0 log CFU/mL in seawater with no difference observed between them. Survival and growth models were then established based on the Baranyi equation. The goodness-of-fit scores ranged from 0.674 to 0.950. RNA sequencing results showed that downregulated central energy metabolism and weakened degradation of branched-chain amino acid were observed only in the trh + strain not in the tdh + strain at 30°C. This might be one reason for the lower growth rates of the trh + strain at 30°C. Histidine metabolism and biofilm formation pathways were significantly downregulated in both strains at 10°C. No significant difference was observed for virulence-associated gene expression between 10°C and 30°C, regardless of the strains. IMPORTANCE Given the involvement of Vibrio parahaemolyticus ( Vp ) in a wide range of seafood outbreaks, a systematical characterization of Vp fitness and transcriptomic changes at temperatures of critical importance for seafood production and storage is needed. In this study, one of each virulent Vp strain ( tdh + and trh +) was tested. While no difference in survival behavior of the two virulent strains was observed at 10°C, the tdh + strain had a faster growth rate than the trh + strain at 30°C. Transcriptomic analysis showed that a significantly higher number of genes were upregulated at 30°C than at 10°C. The majority of differentially expressed genes of Vp at 30°C were annotated to functional categories supporting cellular growth. At 10°C, the downregulation of the biofilm formation and histidine metabolism indicates that the current practice of storing seafood at low temperatures not only protects seafood quality but also ensures seafood safety.

Whole-transcriptome analysis after the acquisition of antibiotic resistance of Cronobacter sakazakii: Mechanisms of antibiotic resistance and virulence changes

The emergence of antibiotic-resistant bacteria led to the misuse of antibiotics, resulting in the emergence of more resistant bacteria and continuous improvement in their resistance ability. Cronobacter sakazakii (C. sakazakii) has been considered a pathogen that harms infants. Incidents of C. sakazakii contamination have continued globally, several studies have indicated that C. sakazakii is increasingly resistant to antibiotics. A few studies have explored the mechanism of antibiotic resistance in C. sakazakii, and some have examined the antibiotic resistance and changes in virulence levels. We aimed to investigate the antibiotic resistance mechanism and virulence differences in C. sakazakii. The level of virulence factors of C. sakazakii was modified after induction by antibiotics compared with the antibiotic-sensitive strains, and the XS001-Ofl group had the strongest capacity to produce enterotoxin (85.18 pg/mL) and hemolysin (1.47 ng/mL). The biofilm formation capacity after induction significantly improved. The number of bases and mapped reads in all groups accounted for more than 55 % and 70 %, as detected by transcriptomic analysis. The resistance mechanism of different antibiotics was more common in efflux pumps, cationic antimicrobial peptides, and biofilm formation pathways. The level of antibiotic resistance mainly affected the expression of virulence genes associated with flagella assembly and synthesis.

Enhancing the bioavailability of sulfur for denitrification in integrated floating-film and activated sludge (IFFAS) system filled with modified carriers under mixotrophic and autotrophic conditions

Sulfur autotrophic denitrification (SAD) holds application prospect in carbon-limited wastewater due to no additional carbon source, less sludge yield, and lower costs. However, the poor bioavailability of sulfur (S0) and the slow development of sulfur oxidizing bacteria (SOB) limit its wide application. Tween 80 is a nonionic surfactant with low toxicity and can regulate interface action between S0 and microorganisms. In this study, integrated floating-film and activated sludge (IFFAS) filled with graphene oxide (GO)-modified carriers was adopted and Tween 80 was introduced to enhance bioavailability of S0. When the influent C/N was below 0.7 and nitrogen loading was 0.24 Kg/(m3∙d), the total nitrogen removal efficiencies in reactors filled with GO-modified carriers and Tween 80 were above 90% while that of reactors filled with high density polyethylene (HDPE) carriers and 0.5 wt% GO-modified carriers was74.08 ± 12.8% and 81.87 ± 11.51%. Microbial analysis revealed that Tween 80 could enhance autotrophic denitrification bacteria relative abundance in biofilm at C/N ratios of < 0.7, such as Sulfurisoma (21.21%), Dechloromonas (8.42%) and Ignavibacterium (14.68%). Furthermore, predicted microbial functions analysis by PICRUSt showed that denitrification, sulfide oxidation, electron transfer and biofilm formation pathways were enhanced in reactors added Tween 80. This study demonstrated Tween 80 was able to improve the bioavailability of S0 and enhance the efficiency of SAD.

Complete Genome Sequence of Industrial Biocontrol Strain Paenibacillus polymyxa HY96-2 and Further Analysis of Its Biocontrol Mechanism.

Paenibacillus polymyxa (formerly known as Bacillus polymyxa) has been extensively studied for agricultural applications as a plant-growth-promoting rhizobacterium and is also an important biocontrol agent. Our team has developed the P. polymyxa strain HY96-2 from the tomato rhizosphere as the first microbial biopesticide based on P. polymyxa for controlling plant diseases around the world, leading to the commercialization of this microbial biopesticide in China. However, further research is essential for understanding its precise biocontrol mechanisms. In this paper, we report the complete genome sequence of HY96-2 and the results of a comparative genomic analysis between different P. polymyxa strains. The complete genome size of HY96-2 was found to be 5.75 Mb and 5207 coding sequences were predicted. HY96-2 was compared with seven other P. polymyxa strains for which complete genome sequences have been published, using phylogenetic tree, pan-genome, and nucleic acid co-linearity analysis. In addition, the genes and gene clusters involved in biofilm formation, antibiotic synthesis, and systemic resistance inducer production were compared between strain HY96-2 and two other strains, namely, SC2 and E681. The results revealed that all three of the P. polymyxa strains have the ability to control plant diseases via the mechanisms of colonization (biofilm formation), antagonism (antibiotic production), and induced resistance (systemic resistance inducer production). However, the variation of the corresponding genes or gene clusters between the three strains may lead to different antimicrobial spectra and biocontrol efficacies. Two possible pathways of biofilm formation in P. polymyxa were reported for the first time after searching the KEGG database. This study provides a scientific basis for the further optimization of the field applications and quality standards of industrial microbial biopesticides based on HY96-2. It may also serve as a reference for studying the differences in antimicrobial spectra and biocontrol capability between different biocontrol agents.

Targeting Multiple Biofilm Pathways

Cegelski et al. (2009) demonstrate the importance of amyloid production for biofilm formation and host colonization using several mutant strains of pathogenic E. coli and small molecule inhibitors. This work reveals a path forward for studying the role of bacterial amyloids in vivo and suggests the potential for small molecules to target multiple biofilm formation pathways.