Membrane biofouling by chlorine resistant <i>Bacillus</i> spp.: effect of feedwater chlorination on bacteria and membrane biofouling

Bhojani, Gopal; Kumar, Sweta Binod; Saha, Nirmal; Haldar, Soumya

doi:10.1080/08927014.2018.1461213

Cited by 17 publications

(9 citation statements)

References 30 publications

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“…Therefore, it is important to study the phenotypic and chemical characteristics of cultivable bacteria frequently detected in the RO system ( Belila et al, 2016 ; Nagaraj et al, 2017b ). Furthermore, Bacillus are chlorine resistant, which allows them to survive the pretreatment and deposit on the membrane, contributing to biofouling and flux decline ( Bhojani et al, 2018 ).…”

Section: Resultsmentioning

confidence: 99%

Physicochemical Properties of Extracellular Polymeric Substances Produced by Three Bacterial Isolates From Biofouled Reverse Osmosis Membranes

2021

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This work describes the chemical composition of extracellular polymeric substances (EPS) produced by three bacteria (RO1, RO2, and RO3) isolated from a biofouled reverse osmosis (RO) membrane. We isolated pure cultures of three bacterial strains from a 7-year-old biofouled RO module that was used in a full-scale seawater treatment plant. All the bacterial strains showed similar growth rates, biofilm formation, and produced similar quantities of proteins and polysaccharides. The gel permeation chromatography showed that the EPS produced by all the strains has a high molecular weight; however, the EPS produced by strains RO1 and RO3 showed the highest molecular weight. Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance (1H NMR), and Carbon NMR (13C NMR) were used for a detailed characterization of the EPS. These physicochemical analyses allowed us to identify features of EPS that are important for biofilm formation. FTIR analysis indicated the presence of α-1,4 glycosidic linkages (920 cm–1) and amide II (1,550 cm–1) in the EPS, the presence of which has been correlated with the fouling potential of bacteria. The presence of α-glycoside linkages was further confirmed by 13C NMR analysis. The 13C NMR analysis also showed that the EPS produced by these bacteria is chemically similar to foulants obtained from biofouled RO membranes in previous studies. Therefore, our results support the hypothesis that the majority of substances that cause fouling on RO membranes originate from bacteria. Investigation using 1H NMR showed that the EPS contained a high abundance of hydrophobic compounds, and these compounds can lead to flux decline in the membrane processes. Genome sequencing of the isolates showed that they represent novel species of bacteria belonging to the genus Bacillus. Examination of genomes showed that these bacteria carry carbohydrates-active enzymes that play a role in the production of polysaccharides. Further genomic studies allowed us to identify proteins involved in the biosynthesis of EPS and flagella involved in biofilm formation. These analyses provide a glimpse into the physicochemical properties of EPS found on the RO membrane. This knowledge can be useful in the rational design of biofilm control treatments for the RO membrane.

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Section: Resultsmentioning

confidence: 99%

Physicochemical Properties of Extracellular Polymeric Substances Produced by Three Bacterial Isolates From Biofouled Reverse Osmosis Membranes

2021

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“…Among the compounds degraded by chlorination, the degradation of extracellular genomic DNA consequently reduced the fluorometric signal of qPCR (Zhang et al, 2019). Spore‐forming Bacillus were known as bacteria that are chlorine resistant in drinking water and membrane processes (Bhojani et al, 2018a; Ridgway & Olson, 1982). Although the CFU counts declined below the limit of detection (Figure 2), bacterial cells measured by FCM and PMA‐qPCR displayed noticeable cell counts, suggesting that bacteria membrane remained intact (Nocker et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Assessment of physiological responses of bacteria to chlorine and UV disinfection using a plate count method, flow cytometry and viability PCR

Chiang

Lee

Medriano

et al. 2022

Journal of Applied Microbiology

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Aims This study aimed to investigate the physiological responses of two gram‐negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two gram‐positive bacteria (Enterococcus faecalis and Bacillus sphaericus) to ultraviolet (UV) and chlorine disinfection. Methods and Results Bacterial inactivation by UV and chlorine disinfection were evaluated with a plate count method for culturability, FCM and PMA‐qPCR for membrane integrity and DyeTox13‐qPCR for enzymatic activity, respectively. Both UV and chorine disinfection caused complete loss of culturability while membrane integrity remained intact after UV disinfection. Both DyeTox13‐qPCR and PMA‐qPCR showed high ΔCt values up to 8.9 after chlorine disinfection, indicating that both methods were able to distinguish non‐treated from chlorine‐treated cells. Although PMA‐qPCR could not differentiate membrane integrity of cells on UV exposure, DyeTox13‐qPCR showed significant differences in ΔCt values of 5.05 and 10.4 for gram‐negative (E. coli) and gram‐positive (Enterococcus) bacteria, respectively. However, DyeTox13‐qPCR for gram‐negative bacteria displayed relatively small differences in ΔCt values compared with gram‐positive bacteria. Conclusion UV and chlorine disinfection led to changes in physiological state of gram‐negative and gram‐positive bacteria. Particularly, UV disinfection could induce active but non‐culturable (ABNC) for gram‐negative bacteria and dormant cell for gram‐positive bacteria where intact cells no longer showed the enzymatic activity. Significance and Impact of the Study UV and chlorine are commonly used to disinfect water, food and fomites to inactivate pathogenic bacteria. However, a viable but non‐culturable (VBNC) state of bacteria induced by disinfection may underestimate the health risks because of the potential resuscitation of VBNC cells. This study highlighted that bacteria could undergo different physiological (ABNC or dormant) states during UV and chlorine disinfection. In addition, viability PCR techniques could provide insight into the changes in physiological states during disinfection processes.

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“…In particular, Salmonella possesses a high level of regeneration capacity in reclaimed water after chlorine disinfection (Li et al, 2013). Recent studies have focused on chlorine tolerance of bacteria in water while few studies addressed contamination on the processed poultry products (Roy and Ghosh, 2017;Bhojani et al, 2018;Wang et al, 2019;Luo et al, 2020). In China, 50-100 mg/L of sodium hypochlorite (NaClO) is commonly used in poultry processing and environmental disinfection while the inactivation of Salmonella was limited (< 1 Log) and could be due to chlorine tolerance (Jun et al, 2013;Lee et al, 2014;Xiao et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Chlorine Tolerance and Cross-Resistance to Antibiotics in Poultry-Associated Salmonella Isolates in China

Xiao

Bai²,

Wang³

et al. 2022

Front. Microbiol.

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Chlorine disinfectants have been widely used in the poultry supply chain but this exposure can also result in the development of bacterial tolerance to chlorine and this is often linked to antibiotic cross-resistance. The objectives of this study were to investigate sodium hypochlorite (NaClO) tolerance of Salmonella isolated from poultry supply chains and evaluate cross-resistance. We collected 172 Salmonella isolates from poultry farms, slaughter houses and retail markets in China during 2019–2020. We found that S. Enteritidis, S. Kentucky, and S. Typhimurium constituted > 80% of our Salmonella isolates. Overall, 68% of Salmonella isolates were resistant to > 3 antibiotics and S. Kentucky displayed a significantly (p > 0.05) higher frequency (93.2%) of multidrug resistance than the other serovars. Tolerance to chlorine at MIC > 256 mg/L was detected in 93.6% of isolates (161/172) and tolerant isolates displayed higher decimal reduction times (D value) and less ultrastructural damage than did the suspectable strains under chlorine stress. Spearman analysis indicated significant positive correlations between chlorine tolerance (evaluated by the OD method) and antibiotic resistance (p < 0.05) to ceftiofur, tetracycline, ciprofloxacin and florfenicol and this was most likely due to efflux pump over-expression. The most frequently detected chlorine resistance gene was qacEΔ1 (83.1%, n = 143) and we found a positive correlation between its presence and MIC levels (r = 0.66, p < 0.0001). Besides, we found weak correlations between chlorine-tolerance and antibiotic resistance genes. Our study indicated that chlorine disinfectants most likely played an important role in the emergence of chlorine tolerance and spread of antibiotic resistance and therefore does not completely control the risk of food-borne disease. The issue of disinfectant resistance should be examined in more detail at the level of the poultry production chain.

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Membrane biofouling by chlorine resistant Bacillus spp.: effect of feedwater chlorination on bacteria and membrane biofouling

Cited by 17 publications

References 30 publications

Physicochemical Properties of Extracellular Polymeric Substances Produced by Three Bacterial Isolates From Biofouled Reverse Osmosis Membranes

Physicochemical Properties of Extracellular Polymeric Substances Produced by Three Bacterial Isolates From Biofouled Reverse Osmosis Membranes

Assessment of physiological responses of bacteria to chlorine and UV disinfection using a plate count method, flow cytometry and viability PCR

Chlorine Tolerance and Cross-Resistance to Antibiotics in Poultry-Associated Salmonella Isolates in China

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