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- Application of fast expectation-maximization microbial source tracking to discern fecal contamination in rivers exposed to low fecal inputs
- Youfen Xu , Ganghua Han , Hongxun Zhang , Zhisheng Yu , Ruyin Liu
- J. Microbiol. 2022;60(6):594-601. Published online April 18, 2022
- DOI: https://doi.org/10.1007/s12275-022-1651-9
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- 5 Citations
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Abstract
- Community-based microbial source tracking (MST) can be used to determine fecal contamination from multiple sources in the aquatic environment. However, there is little scientific information on its application potential in water environmental management. Here, we compared SourceTracker and Fast Expectation-maximization Microbial Source Tracking (FEAST) performances on environmental water bodies exposed to low fecal pollution and evaluated treatment effects of fecal pollution in the watershed utilizing community-based MST. Our results showed that FEAST overall outperformed SourceTracker in sensitivity and stability, and was able to discern multi-source fecal contamination (mainly chicken feces) in ambient water bodies exposed to low fecal inputs. Consistent with our previous PCR/qPCR-based MST assays, FEAST analysis indicates that fecal pollution has been significantly mitigated through comprehensive environmental treatment by the local government. This study suggests that FEAST can be a powerful tool for accurately evaluating the contribution of multi-source fecal contamination in environmental water, facilitating environmental management.
- Regulator of ribonuclease activity modulates the pathogenicity of Vibrio vulnificus
- Jaejin Lee , Eunkyoung Shin , Jaeyeong Park , Minho Lee , Kangseok Lee
- J. Microbiol. 2021;59(12):1133-1141. Published online November 9, 2021
- DOI: https://doi.org/10.1007/s12275-021-1518-5
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- 4 Citations
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Abstract
- RraA, a protein regulator of RNase E activity, plays a unique role in modulating the mRNA abundance in Escherichia coli. The marine pathogenic bacterium Vibrio vulnificus also possesses homologs of RNase E (VvRNase E) and RraA (VvRraA1 and VvRraA2). However, their physiological roles have not yet been investigated. In this study, we demonstrated that VvRraA1 expression levels affect the pathogenicity of V. vulnificus. Compared to the wild-type strain, the VvrraA1-deleted strain (ΔVvrraA1) showed decreased motility, invasiveness, biofilm formation ability as well as virulence in mice; these phenotypic changes of ΔVvrraA1 were restored by the exogenous expression of VvrraA1. Transcriptomic analysis indicated that VvRraA1 expression levels affect the abundance of a large number of mRNA species. Among them, the halflives of mRNA species encoding virulence factors (e.g., smcR and htpG) that have been previously shown to affect VvrraA1 expression-dependent phenotypes were positively correlated with VvrraA1 expression levels. These findings suggest that VvRraA1 modulates the pathogenicity of V. vulnificus by regulating the abundance of a subset of mRNA species.
- iTRAQ-facilitated proteomic analysis of Bacillus cereus via degradation of malachite green
- Bobo Wang , Jing Lu , Junfang Zheng , Zhisheng Yu
- J. Microbiol. 2021;59(2):142-150. Published online February 1, 2021
- DOI: https://doi.org/10.1007/s12275-021-0441-0
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- 2 Citations
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Abstract
- The wide use of malachite green (MG) as a dye has caused substantial concern owing to its toxicity. Bacillus cereus can against the toxic effect of MG and efficiently decolourise it. However, detailed information regarding its underlying adaptation and degradation mechanisms based on proteomic data is scarce. In this study, the isobaric tags for relative and absolute quantitation (iTRAQ)-facilitated quantitative method was applied to analyse the molecular mechanisms by which B. cereus degrades MG. Based on this analysis, 209 upregulated proteins and 198 downregulated proteins were identified with a false discovery rate of 1% or less during MG biodegradation. Gene ontology and KEGG analysis determined that the differentially expressed proteins were enriched in metabolic processes, catalytic activity, antioxidant activity, and responses to stimuli. Furthermore, real-time qPCR was utilised to further confirm the regulated proteins involved in benzoate degradation. The proteins BCE_4076 (Acetyl-CoA acetyltransferase), BCE_5143 (Acetyl-CoA acetyltransferase), BCE_5144 (3-hydroxyacyl-CoA dehydrogenase), BCE_4651 (Enoyl-CoA hydratase), and BCE_5474 (3-hydroxyacyl-CoA dehydrogenase) involved in the benzoate degradation pathway may play an important role in the biodegradation of MG by B. cereus. The results of this study not only provide a comprehensive view of proteomic changes in B. cereus upon MG loading but also shed light on the mechanism underlying MG biodegradation by B. cereus.
- The putative polysaccharide synthase AfCps1 regulates Aspergillus fumigatus morphogenesis and conidia immune response in mouse bone marrow-derived macrophages
- Sha Wang , Anjie Yuan , Liping Zeng , Sikai Hou , Meng Wang , Lei Li , Zhendong Cai , Guowei Zhong
- J. Microbiol. 2021;59(1):64-75. Published online November 17, 2020
- DOI: https://doi.org/10.1007/s12275-021-0347-x
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- 2 Citations
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Abstract
- Aspergillus fumigatus is a well-known opportunistic pathogen that causes invasive aspergillosis (IA) infections with high mortality in immunosuppressed individuals. Morphogenesis, including hyphal growth, conidiation, and cell wall biosynthesis is crucial in A. fumigatus pathogenesis. Based on a previous random insertional mutagenesis library, we identified the putative polysaccharide synthase gene Afcps1 and its paralog Afcps2. Homologs of the cps gene are commonly found in the genomes of most fungal and some bacterial pathogens. Afcps1/cpsA is important in sporulation, cell wall composition, and virulence. However, the precise regulation patterns of cell wall integrity by Afcps1/cpsA and further effects on the immune response are poorly understood. Specifically, our in-depth study revealed that Afcps1 affects cell-wall stability, showing an increased resistance of ΔAfcps1 to the chitinmicrofibril destabilizing compound calcofluor white (CFW) and susceptibility of ΔAfcps1 to the β-(1,3)-glucan synthase inhibitor echinocandin caspofungin (CS). Additionally, deletion of Afcps2 had a normal sporulation phenotype but caused hypersensitivity to Na+ stress, CFW, and Congo red (CR). Specifically, quantitative analysis of cell wall composition using high-performance anion exchange chromatography- pulsed amperometric detector (HPAEC-PAD) analysis revealed that depletion of Afcps1 reduced cell wall glucan and chitin contents, which was consistent with the downregulation of expression of the corresponding biosynthesis genes. Moreover, an elevated immune response stimulated by conidia of the ΔAfcps1 mutant in marrow-derived macrophages (BMMs) during phagocytosis was observed. Thus, our study provided new insights into the function of polysaccharide synthase Cps1, which is necessary for the maintenance of cell wall stability and the adaptation of conidia to the immune response of macrophages in A. fumigatus.
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