Viable State Research Articles

Two-Round Treatment With Propidium Monoazide Completely Inhibits the Detection of Dead Campylobacter spp. Cells by Quantitative PCR.

Campylobacter spp. are known as important foodborne gastroenteric pathogens worldwide. Campylobacter spp. can exist in a viable but non-culturable (VBNC) state under unsuitable environmental conditions, which is undetectable by conventional culture methods. Quantitative polymerase chain reaction (qPCR) can be used to detect VBNC Campylobacter spp.; however, both viable and dead bacteria are detected during qPCR and are indistinguishable. Propidium monoazide (PMA), which can only enter dead bacterial cells through a damaged cell wall/cell membrane, binds to DNA and inhibits qPCR. PMA treatment has been performed along with qPCR (PMA-qPCR) to detect viable bacteria. However, the efficacy of detection inhibition differed among studies, and PMA can potentially enter living cells after changes in cell membrane permeability. In this study, we optimized the PMA treatment method by conducting it before qPCR. Two-round PMA treatment completely inhibited the qPCR signals from dead cells, whereas single-round PMA treatment failed to facilitate this. An optimized PMA-qPCR method was developed using commercial chicken meat, and VBNC Campylobacter spp., which are undetectable using conventional culture-based methods, were successfully detected. In conclusion, this study presents a novel, efficient PMA treatment method for the detection of viable Campylobacter spp., including VBNC Campylobacter spp., in chicken meat. We believe that this method will aid the reliable risk assessment of commercial chicken meat.

PM 7/20 (3) Erwinia amylovora

PM 7/20 (3) <i>Erwinia amylovora</i>

Characterization of two predicted lipid metabolism genes (FTL_1569 and FTL_1570) in the intracellular pathogen, Francisella tularensis LVS

Many species of bacteria enter a viable but non-culturable (VBNC) state when exposed to stressful conditions. Since cells in the VBNC state can only be resuscitated under favorable conditions, this acts as an adaptive strategy that allows for long-term survival of bacteria in unfavorable environments. The ability to enter the VBNC state may be advantageous for bacteria, but it poses a risk to human health. Francisella tularensis,transitions rapidly and spontaneously to the VBNC state, giving it the potential to be an excellent model organism for the study of this phenomenon. Although dormant, these cells are still biologically active, and can stimulate cytokine production and interact with host cells. Microscopic observations reveal that changes in cell morphology are coincident with the VBNC state. To characterize these morphological changes, fluorescence microscopy using membrane lipid (acridine orange 10-nonyl bromide) staining has been used and these experiments suggest that lipid metabolism may be important for the transition into the VBNC state. To investigate further, genetic mutants have been constructed of two genes, FTL_1569 (phosphoglycolate phosphatase) and FTL_1570 (Phospholipase D family protein) which are predicted to be involved in lipid metabolism. Gentamicin protection assays with immune cells and red blood cells have been conducted to investigate the role of these genes in virulence of F. tularensis. Our preliminary results suggest that lipid metabolism may play roles in both persistence and in infection of F. tularensis. (This work was supported by NIH Grant P20GM103434 to the West Virginia IDeA Network for Biomedical Research Excellence).

Transcriptomic Responses of Salmonella enterica Serovars Enteritidis in Sodium Hypochlorite.

Salmonella enterica serovars Enteritidis (S. Enteritidis) can survive extreme food processing environments including bactericidal sodium hypochlorite (NaClO) treatments generally recognized as safe. In order to reveal the molecular regulatory mechanisms underlying the phenotypes, the overall regulation of genes at the transcription level in S. Enteritidis after NaClO stimulation were investigated by RNA-sequencing. We identified 1399 differentially expressed genes (DEG) of S. Enteritidis strain CVCC 1806 following treatment in liquid culture with 100 mg/L NaClO for 20 min (915 upregulated and 484 downregulated). NaClO stress affects the transcription of genes related to a range of important biomolecular processes such as membrane damage, membrane transport function, energy metabolism, oxidative stress, DNA repair, and other important processes in Salmonella enterica. First, NaClO affects the structural stability of cell membranes, which induces the expression of a range of outer and inner membrane proteins. This may lead to changes in cell membrane permeability, accelerating the frequency of DNA conversion and contributing to the production of drug-resistant bacteria. In addition, the expression of exocytosis pump genes (emrB, yceE, ydhE, and ydhC) was able to expel NaClO from the cell, thereby increasing bacterial tolerance to NaClO. Secondly, downregulation of genes related to the Kdp-ATPase transporter system (kdpABC) and the amino acid transporter system (aroP, brnQ and livF) may to some extent reduce active transport by bacterial cells, thereby reducing their own metabolism and the entry of disinfectants. Downregulation of genes related to the tricarboxylic acid (TCA) cycle may drive bacterial cells into a viable but non-culturable (VBNC) state, resisting NaClO attack by reducing energy metabolism. In addition, significant upregulation of genes related to oxidative stress could mitigate damage caused by disinfectants by eliminating alkyl hydroperoxides, while upregulation of genes related to DNA repair could repair damage to bacterial cells caused by oxidative stress. Therefore, this study indicated that S. Enteritidis has genomic mechanisms to adapt to NaClO stress.

Variations in the Adaptive Response of &lt;i&gt;Burkholderia pseudomallei&lt;/i&gt; to Cold Stress

The aim of the study was to analyze differential gene expression in Burkholderia pseudomallei strains with different survival rates under cold stress conditions.Materials and methods. Three strains of B. pseudomallei (sequence types ST 46, ST 70, and ST 85) were used as model strains. The RNA was isolated using the membrane columns method and stabilized through dehydration. The cDNA was sequenced on the Illumina MiSeq platform. Gene functions were classified using the KEGG PATHWAY database.Results and discussion. Based on the analysis of transcriptomes of B. pseudomallei strains after prolonged exposure to cold stress, the molecular mechanisms of B. pseudomallei adaptation to low temperatures have been described for the first time ever. It was shown that adaptation of B. pseudomallei to cold stress is associated with regulatory processes leading to a significant decrease in the total transcriptional activity. Two strategies of adaptation to low temperatures have been found: 1) modulation of regulatory processes leading to suppression of gene expression of the main metabolic pathways to the minimum level that ensures cell viability and activation of the minimum required set of stress response genes, and 2) less noticeable suppression of general metabolism in combination with activation of expression of an extended range of genes for cold and heat shock, general, osmotic, and universal stresses. Both mechanisms provide the causative agent of melioidosis with survival under conditions of prolonged cold stress at low positive temperatures. The first strategy showed greater efficiency at negative temperatures. The transition of B. pseudomallei to a viable but uncultivated state occurs in the long term (at least 2 years). While with the second strategy, this happens within 2 months. Assessment of the potential and molecular mechanisms of adaptation of this bacterium to cold stress is necessary to understand the degree of risk in case of a possible introduction of B. pseudomallei into regions with a temperate climate and to develop effective measures to ensure the biosafety of the environment.

A modified flower pollen-based photothermocatalytic process for enhanced solar water disinfection: Photoelectric effect and bactericidal mechanisms

Solar disinfection (SODIS) is regarded as an affordable and effective point-of-use (POU) water disinfection treatment urgently needed in rural developing world. This work developed an enhanced SODIS scheme that utilized a novel flower pollen-based catalyst (Te-TRP). The bench-scale experiments demonstrated 100% photothermocatalytic inactivation of approximately 7-log E. coli K-12, Spingopyxis sp. BM1-1, or S. aureus bacterium by Te-TRP within 40–60 min. Moving toward practical device design, we constructed a flow-through reactor and demonstrated the outstanding water disinfection performance of Te-TRP. The in-depth mechanistic study revealed the synergetic effect between photocatalysis and photothermal conversion and identified the bacterial inactivation pathway. 1O2 and ·O2¯ were verified to be the dominant reactive oxygen species involved in the bacterial inactivation. The damage to bacterial cells caused by photothermocatalytic reactions was systematically investigated, demonstrating the cell membrane destruction, the loss of enzyme activity, the increased cell membrane permeability, and the complete inactivation of bacteria without the viable but nonculturable state cells. This work not only affords a facile approach to preparing biomaterial-based catalysts capable of efficient photothermocatalytic bacterial inactivation, but also proposes a prototype of POU water treatment, opening up an avenue for sustainable environmental remediation.

Current Perspectives on Viable but Non-culturable Bacteria in Food Safety and Public Health

The viable but non-culturable (VBNC) state is defined as an adaptive mechanism for microorganisms adjusting to stressful conditions. Although VBNC bacteria are alive and metabolically active, they are unable to grow on routine culture media. Nevertheless, the potential capacity of VBNC pathogens to retain virulence activity and further resuscitate into the culturable state in favorable conditions constitutes a major hazard to food safety and public health. Food processing, transformation, and storage, as well as non-thermal techniques, can provoke pathogens toward VBNC induction. The distinct characteristic of VBNC bacteria led to the emergence of novel culture-independent techniques to prevent the misinterpretation of food safety. To deepen our knowledge of the molecular aspect of the VBNC state, several mechanism-oriented studies investigated the metabolic activity of VBNC bacteria and their correlation with different stressful conditions. This review aims to discuss the molecular mechanisms and genomic factors underlying the induction and resuscitation of the VBNC state. The study will further highlight innovative detection methods to provide a comprehensive perspective for future studies in the emerging fields of research concerning VBNC state, food safety, and public health.

Role of temperature, nutrition, oxygen, osmolality, and bacterial strain in inducing a viable but non-culturable state in Campylobacter jejuni

Campylobacter jejuni is a globally important foodborne pathogen that can exist environmentally in a viable but non-culturable (VBNC) state, leading to missed detection of VBNC cells in food and false results in epidemiological surveillance. To establish a method for its resuscitation from the VBNC state and enable better detection, the mechanisms by which C. jejuni are induced into the VBNC state should be understood in detail. However, experimental induction of the VBNC state can be rather time consuming. Therefore, in this study, we investigated the effects of temperature, nutrition, oxygen, and osmolality, in an attempt to achieve a shorter induction time for VBNC state in C. jejuni. Culture at 4 °C under aerobic conditions in nutrient-rich Mueller–Hinton broth was the most effective condition for inducing the VBNC state in the C. jejuni strain JCM 2013. However, in C. jejuni strains 81–176 and B17, this condition induced the VBNC state slower than in the JCM 2013 strain, suggesting that the bacterial strain characteristics also affected the induction of VBNC state. These findings provide novel insights into the effects of various conditions on inducing the VBNC state in C. jejuni.

The Viable But Non-Culturable State of Listeria monocytogenes in the One-Health Continuum.

Many bacterial species, including several pathogens, can enter a so-called “viable but non-culturable” (VBNC) state when subjected to stress. Bacteria in the VBNC state are metabolically active but have lost their ability to grow on standard culture media, which compromises their detection by conventional techniques based on bacterial division. Under certain conditions, VBNC bacteria can regain their growth capacity and, for pathogens, their virulence potential, through a process called resuscitation. Here, we review the current state of knowledge of the VBNC state of Listeria monocytogenes (Lm), a Gram-positive pathogenic bacterium responsible for listeriosis, one of the most dangerous foodborne zoonosis. After a brief summary of characteristics of VBNC bacteria, we highlight work on VBNC Lm in the environment and in agricultural and food industry settings, with particular emphasis on the impact of antimicrobial treatments. We subsequently discuss recent data suggesting that Lm can enter the VBNC state in the host, raising the possibility that VBNC forms contribute to the asymptomatic carriage of this pathogen in wildlife, livestock and even humans. We also consider the resuscitation and virulence potential of VBNC Lm and the danger posed by these bacteria to at-risk individuals, particularly pregnant women. Overall, we put forth the hypothesis that VBNC forms contribute to adaptation, persistence, and transmission of Lm between different ecological niches in the One-Health continuum, and suggest that screening for healthy carriers, using alternative techniques to culture-based enrichment methods, should better prevent listeriosis risks.

Development of Resistance in Escherichia coli Against Repeated Water Disinfection

Pathogen resistance against common disinfectants in drinking water treatment could have serious public health implications, particularly in potable water reuse. Frequent disinfection in potable water reuse has a potential to facilitate resistance development. This study investigated resistance development in Escherichia coli against repeated monochloramine and ferrate disinfection. E. coli cultures repeatedly treated with monochloramine developed resistance after 12 + treatment rounds, whereas repeated ferrate disinfection did not lead to resistance development. Monochloramine induced cells into the viable but nonculturable (VBNC) state in initial disinfection rounds; however, repeated monochloramine treatment caused increases in culturability, which corresponded to decreases in the fraction of VBNC cells post-disinfection. The cumulative number of disinfection episodes (∼12 times) rather than treatment frequency (e.g., every 48, 96, or 144 h) played a critical role in resistance development against monochloramine. In addition to preventing resistance, ferrate effectively inactivated (&amp;gt;3-log10) the evolved monochloramine-stressed cultures, suggesting that the evolutionary adaptations against monochloramine were ineffective against ferrate. The lack of resistance against ferrate renders it a promising disinfection agent that deserves further assessment. This work’s findings demonstrate that repeated disinfection coupled with the type of applied disinfectant can influence bacterial resistance development. Therefore, current and future water disinfection schemes, especially within potable water reuse, need regular monitoring to evaluate the resistance profile of pathogenic bacteria.

Photoelectrocatalytic inactivation mechanism of E. coli DH5α (TET) and synergistic degradation of corresponding antibiotics in water

The occurrence and proliferation of antibiotic-resistance genes (ARGs) / antibiotic-resistant bacteria (ARB) have been currently aggravating due to the increase of antibiotic residues in the aquatic environment. The interaction of ARB/ARGs with antibiotics inevitably occurred during water purification, yet their synergistic purification mechanism remains unclear. Herein, a systematic approach was developed to understand, in-depth, the synergistic mechanism in the coexisted E. coli DH5α (TET) inactivation and tetracycline hydrochloride (TET) degradation using photoelectrocatalysis (PEC) as a model technology. Results showed that low dosage (0 – 40 ppm) of TET exerted a negative influence on ARB inactivation with prolonged bactericidal time from 60 to 160 min. Addition of TET in environmental concentration (5 – 60 ppm) resulted in sub-lethal damage and prolonged PEC treatment time (100 – 160 min), accounting for inhibition effects on ARB inactivation. The major reactive species (RSs) involved in ARB inactivation and TET degradation were evidenced as photogenerated hole, •OH and O2•−, whereas hole and O2•− were demonstrated to be the major disinfectants for ARB/ARG inactivation. The bacterial defense system displayed increased antioxidative activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to protect ARB cells against oxidative stress. Exposure to 60 ppm TET was a threshold where certain ARB cells were induced into viable but nonculturable bacterial cell (VBNC) state, as evidenced by plate counting and ATP activity analysis, together with the integral cell membranes observed by flow cytometry (FCM) and scanning electron microscope (SEM). These findings appeal for appropriate technical adjustments for water and wastewater treatment to ensure safety of water.

Evaluation of optimal reference genes for the normalization by qPCR in viable but nonculturable state in Xanthomonas campestris pv. campestris

AbstractXanthomonas campestris pv. campestris (Xcc), the pathogen of black rot of crucifers, could be induced into the viable but nonculturable (VBNC) state under stress, such as being induced by low concentration of Cu2+ and acid condition induction. The main objective of current study was to select the optimal reference genes for data normalization by qPCR in the VBNC state of Xcc. In this study, Xcc was induced into VBNC state by Cu2+ with an initial concentration of OD600 = 0.18 and OD600 = 0.45, and all viable bacterial cells lost the culturability and entered into the VBNC state at 24 h and 48 h respectively. The concentration of VBNC cells was 3.3 × 107 cells/ml and 1.5 × 107 cells/ml respectively. Eight candidate reference genes (gyrB, pbpA, gapA, rpoB, tufA, 16S rRNA, ugpC and recA) were selected to assess the expression stability in the VBNC state of Xcc by four algorithms (geNorm, NormFinder, delta‐Ct and BestKeeper), while RefFinder was used to integrate the output from the four algorithms in fine. According to the algorithm analysis and validation of clpX expression analysis, the most suitable reference gene this study identified was the combination of ugpC and pbpA, and the least suitable gene was 16S rRNA in the Xcc VBNC state. In this study, we identified the most stable internal controls under Cu2+‐inducing conditions for calibration qRT‐PCR analyses of Xanthomonas campestris pv. campestris and will be helpful to explore the stress resistance mechanism in this bacterium.

Characterization of persistent organic pollutants and culturable and non-culturable bacterial communities in pulp and paper sludge after secondary treatment

Due to the presence of various organic contaminants, improper disposal of pulp-paper wastewater poses harm to the environment and human health. In this work, pulp-paper sludge (PPS) after secondary treatment were collected from M/s Century Pulp-paper Mills in India, the chemical nature of the organic pollutants was determined after solvent extraction. All the isolates were able to produce lipase (6.34–3.93 U ml−1) which could account for the different fatty acids detected in the PPS. The dominant strains were in the classes of α and γ Proteobacteria followed by Firmicutes. The Shannon-Weiner diversity indexes for phylotype richness for the culturable and non-culturable bacterial community were 2.01 and 3.01, respectively, indicating the non-culturable bacterial strains has higher species richness and diversity compared to the culturable bacterial strains. However, the culturable strains had higher species evenness (0.94 vs 0.90). Results suggested only a few isolated strains were resistant to the POPs in the PPS, where as non-cultural bacteria survived by entering viable but non-cultural state. The isolated strains (Brevundimonas diminuta, Aeromonas punctata, Enterobacter hormaechei, Citrobacter braakii, Bacillus pumilus and Brevundimonas terrae) are known for their multidrug resistance but their tolerance to POPs have not previously been reported and deserved further investigation. The findings of this research established the presence of POPs which influence the microbial population. Tertiary treatment is recommended prior to the safe disposal of pulp paper mill waste into the environment.

Metabolism differences of biofilm and planktonic Pseudomonas aeruginosa in viable but nonculturable state induced by chlorine stress

More than 95% of the bacteria in environment are viable but nonculturable (VBNC). However, it is difficult to elucidate directly the metabolic characteristics of these VBNC bacteria and the differences between biofilm-VBNC bacteria and planktonic-VBNC bacteria. In this study, VBNC P. aeruginosa induced by chlorine was used to clarify the metabolism characteristics and mechanism of differential metabolism between biofilm-VBNC bacteria and planktonic-VBNC bacteria. Results showed that P. aeruginosa in biofilm state was more likely to enter VBNC state. The mechanisms of differential metabolism were involved in the difference of reactive oxygen species production owing to the protection of extracellular polymers. 15N and 2H labeled single-cell Raman spectra directly proved that VBNC state bacteria still maintained low material and energy metabolism, and the metabolic activity of biofilm-VBNC P. aeruginosa was lower than that of planktonic-VBNC P. aeruginosa. GC–MS/MS analysis showed 51 metabolites with significant differences. KEGG analysis showed that the types and contents of extracellular metabolites from P. aeruginosa in VBNC states were significantly lower than those in the culturable state (p < 0.05), mainly involving in citrate cycle, glutathione metabolism, phenylalanine metabolism, tyrosine metabolism and fatty acid degradation. Also, the contents of most extracellular metabolites from P. aeruginosa in biofilm-VBNC state were lower than those in VBNC planktonic state. The significant differences (p < 0.05) were mainly involved in alanine, aspartate and glutamate metabolism, glycolysis/gluconeogenesis, D-Alanine metabolism and glycerophospholipid metabolism. The result of this research was favorable to the accurate identification of VBNC bacteria, the health risk assessment and scientific control of harmful VBNC bacteria.

Mechanism and potential risk of antibiotic resistant bacteria carrying last resort antibiotic resistance genes under electrochemical treatment

The significant rise in the number of antibiotic resistance genes (ARGs) that resulted from our abuse of antibiotics could do severe harm to public health as well as to the environment. We investigated removal efficiency and removal mechanism of electrochemical (EC) treatment based on 6 different bacteria isolated from hospital wastewater carrying 3 last resort ARGs including NDM-1, mcr-1 and tetX respectively. We found that the removal efficiency of ARGs increased with the increase of both voltage and electrolysis time while the maximum removal efficiency can reach 90%. The optimal treatment voltage and treatment time were 3 V and 120 min, respectively. Temperature, pH and other factors had little influence on the EC treatment process. The mechanism of EC treatment was explored from the macroscopic and microscopic levels by scanning electron microscopy (SEM) and flow cytometry. Our results showed that EC treatment significantly changed the permeability of cell membrane and caused cells successively experience early cell apoptosis, late cell apoptosis and cell necrosis. Moreover, compared with traditional disinfection methods, EC treatment had less potential risks. The conjugative transfer frequencies of cells were significantly reduced after treatment. Less than 1% of bacteria entered the viable but nonculturable (VBNC) state and less than 5% of intracellular ARGs (iARGs) turned into extracellular ARGs (eARGs). Our findings provide new insights into as well as important reference for future electrochemical treatment in removing ARB from hospital wastewater.

Phase Variation of LPS and Capsule Is Responsible for Stochastic Biofilm Formation in Francisella tularensis.

Biofilms have been established as an important lifestyle for bacteria in nature as these structured communities often enable survivability and persistence in a multitude of environments. Francisella tularensis is a facultative intracellular Gram-negative bacterium found throughout much of the northern hemisphere. However, biofilm formation remains understudied and poorly understood in F. tularensis as non-substantial biofilms are typically observed in vitro by the clinically relevant subspecies F. tularensis subsp. tularensis and F. tularensis subsp. holarctica (Type A and B, respectively). Herein, we report conditions under which robust biofilm development was observed in a stochastic, but reproducible manner in Type A and B isolates. The frequency at which biofilm was observed increased temporally and appeared switch-like as progeny from the initial biofilm quickly formed biofilm in a predictable manner regardless of time or propagation with fresh media. The Type B isolates used for this study were found to more readily switch on biofilm formation than Type A isolates. Additionally, pH was found to function as an environmental checkpoint for biofilm initiation independently of the heritable cellular switch. Multiple colony morphologies were observed in biofilm positive cultures leading to the identification of a particular subset of grey variants that constitutively produce biofilm. Further, we found that constitutive biofilm forming isolates delay the onset of a viable non-culturable state. In this study, we demonstrate that a robust biofilm can be developed by clinically relevant F. tularensis isolates, provide a mechanism for biofilm initiation and examine the potential role of biofilm formation.

Campylobacter hepaticus, the cause of Spotty Liver Disease in chickens, can enter a viable but nonculturable state

Campylobacter hepaticus causes Spotty Liver Disease (SLD) in layer hens, resulting in mortality and productivity losses. Like other Campylobacter species, C. hepaticus is a fastidious organism that requires microaerobic conditions to grow and efficiently replicate. Despite its apparent vulnerability to environmental conditions, it is suspected that there are environmental sources of C. hepaticus that cause infections in chickens newly placed in production houses. Although C. hepaticus DNA has been detected in insects, rodent and wild bird droppings, and in environmental samples such as water and soil, it has not been possible to culture C. hepaticus from these sources. Therefore, it is unclear whether these environments harbor viable bacteria or the remnants of dead bacteria. Determining the viability of C. hepaticus in challenging conditions has implications for understanding the potential relevance of environmental reservoirs and routes of transmission. Other Campylobacters are known to enter viable but nonculturable (VBNC) states that result in prolonged survival in hostile environmental conditions. This study has demonstrated that C. hepaticus can also enter a VBNC state when stored in water or a simple salt solution (Ringer’s solution). Cells in the VBNC state could not be recovered on media normally used for primary isolation, but media modifications were tested, and a ‘resuscitation’ media was developed. VBNC cells could be recovered from Ringer’s solution stored at 4 °C for up to 112 days. VBNC cells are postulated to play an important role in the epidemiology of SLD.

Oxidative dehalogenation and mineralization of polychlorinated biphenyls by a resuscitated strain Streptococcus sp. SPC0

Most functional microorganisms cannot be cultivated due to entering a viable but non-culturable (VBNC) state, which limits the characterization and application of polychlorinated biphenyl (PCB)-degrading strains. Resuscitating VBNC bacteria could provide huge candidates for obtaining high-efficient PCB degraders. However, limited studies have focused on the ability of resuscitated strains for PCBs degradation. In the present study, whole-genome analysis of a resuscitated strain SPC0, and its performances in degradation of three prevalent PCB congeners (PCBs 18, 52 and 77) were investigated. The results indicate that the strain SPC0 belonged to the genus Streptococcus, possessed the degradation potential for aromatic xenobiotics. The SPC0 could effectively degrade PCBs 18 and 52, but exhibited lower degradation efficiency of PCB 77. Degradation of PCBs 18 and 52 could be fitted well by zero-order model, whereas the fittest model for PCB 77 degradation was pseudo second-order kinetics. The bph genes expression, chloride ions release and degradation metabolites identification, suggest that SPC0 possessed the capability of oxidative dehalogenation and mineralization of PCBs. Interestingly, SPC0 can degrade PCBs via the bph-encoded biphenyl pathway, and further mineralize metabolite dichlorobenzoate via protocatechuate pathway. This study is the first to show that a strain belonging to genus Streptococcus possessed PCB-degrading capability, which uncovered the powerful potential of resuscitated strains for bioremediation of PCB-contaminated sites.

Mitigation of marine toxins by interactions with bacteria: The case of okadaic acid and tetrodotoxin

Harmful algal bloom and marine toxins are actual and overgrowing problems. Okadaic acid (OA) is the main toxin responsible for diarrheic shellfish poisoning in humans, while Tetrodotoxin (TTX) is a tremendously strong neurotoxin. Given their high toxicity, strategies to obtain a mitigation of these toxins are every day more fundamental, in the optic of preserve consumer health, and in giving supports to shellfisheries in selling their products. In this context, the ability of lactic acid bacteria (LAB) and Paracoccus spp. to reduce OA and TTX in vitro was evaluated using HPLC/MS-MS technique. Different mechanisms of interaction were observed. Some species of LAB were able to reduce significantly the amount of toxin while in viable state ( Lacticaseibacillus rhamnosus 1473 = 30% OA reduction), but also a binding effect of the toxins was observed. Contrarily, Paracoccus spp. was able to reduce significantly the amount of toxin while in a cell-free extract form, in particular Paracoccus aerius 5038 could reduce the presence of TTX of about 24%. This study provided a sound line of evidence for the possible future use of either specific bacteria or selected bacterial components to reduce the level of harmful marine toxins in aquaculture and food production. • Bonding effect of lactic acid bacteria with marine toxins was observed. • Metabolically active lactic acid bacteria significantly reduced the amount of toxins. • Cell-free extracts of Paracoccus strains reduced toxins' concentration.

Glyoxylate Cycle Maintains the Metabolic Homeostasis of Pseudomonas Aeruginosa in Viable But Nonculturable State Induced by Chlorine Disinfection

Glyoxylate Cycle Maintains the Metabolic Homeostasis of Pseudomonas Aeruginosa in Viable But Nonculturable State Induced by Chlorine Disinfection