Journal of Microbiology

Journal Articles

Secretions from Serratia marcescens Inhibit the Growth and Biofilm Formation of Candida spp. and Cryptococcus neoformans: Caiyan Xin , Fen Wang , Jinping Zhang , Quan Zhou , Fangyan Liu , Chunling Zhao , Zhangyong Song; J. Microbiol. 2023;61(2):221-232. Published online February 21, 2023; DOI: https://doi.org/10.1007/s12275-022-00007-3

Abstract: Candida spp. and Cryptococcus are conditional pathogenic fungi that commonly infect immunocompromised patients. Over the past few decades, the increase in antifungal resistance has prompted the development of new antifungal agents. In this study, we explored the potential antifungal effects of secretions from Serratia marcescens on Candida spp. and Cryptococcus neoformans. We confirmed that the supernatant of S. marcescens inhibited fungal growth, suppressed hyphal and biofilm formation, and downregulated the expression of hyphae-specific genes and virulence-related genes in Candida spp. and C. neoformans. Furthermore, the S. marcescens supernatant retained biological stability after heat, pH, and protease K treatment. The chemical profile of the S. marcescens supernatant was characterized by ultra-high-performance liquid chromatography–linear ion trap/orbitrap high resolution mass spectrometry analysis and a total of 61 compounds with an mzCloud best match of greater than 70 were identified. In vivo, treatment with the S. marcescens supernatant reduced the mortality of fungi-infected Galleria mellonella. Taken together, our results revealed that the stable antifungal substances in the supernatant of S. marcescens have promising potential applications in the development of new antifungal agents.

RNase G controls tpiA mRNA abundance in response to oxygen availability in Escherichia coli: Jaejin Lee , Dong-Ho Lee , Che Ok Jeon , Kangseok Lee; J. Microbiol. 2019;57(10):910-917. Published online September 30, 2019; DOI: https://doi.org/10.1007/s12275-019-9354-6

Abstract: Studies have shown that many enzymes involved in glycolysis are upregulated in Escherichia coli endoribonuclease G (rng) null mutants. However, the molecular mechanisms underlying the RNase G-associated regulation of glycolysis have not been characterized. Here, we show that RNase G cleaves the 5􍿁􀁇untranslated region of triosephosphate isomerase A (tpiA) mRNA, leading to destabilization of the mRNA in E. coli. Nucleotide substitutions within the RNase G cleavage site in the genome resulted in altered tpiA mRNA stability, indicating that RNase G activity influences tpiA mRNA abundance. In addition, we observed that tpiA expression was enhanced, whereas that of RNase G was decreased, in E. coli cells grown anaerobically. Our findings suggest that RNase G negatively regulates tpiA mRNA abundance in response to oxygen availability in E. coli.

Research Support, Non-U.S. Gov't

RNase G Participates in Processing of the 5′-end of 23S Ribosomal RNA: Woo-Seok Song , Minho Lee , Kangseok Lee; J. Microbiol. 2011;49(3):508-511. Published online June 30, 2011; DOI: https://doi.org/10.1007/s12275-011-1198-7

Abstract: In Escherichia coli, primary rRNA transcripts must be processed by a complex process in which several ribonucleases are involved in order to generate mature 16S, 23S, and 5S rRNA molecules. While it is known that RNase G, a single-stranded RNA-specific endoribonuclease encoded by the rng gene, plays an active role in the maturation of the 5′-end of 16S rRNA, its involvement in the maturation of the 5′-end of 23S rRNA remains unclear. Here we show that E. coli cells deleted for the rng gene accumulate the 23S rRNA precursor containing an extra 77 nucleotides at its mature 5′-end. In vitro cleavage assays show that RNase G cleaves synthetic RNA containing a sequence encompassing the 5′-end to 77 nucleotides upstream of mature 23S rRNA at two sites present in single-stranded regions. Our results suggest the involvement of RNase G in the processing of the 5′-region of 23S rRNA precursors.

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