Journal of Microbiology

Reviews

Denitrifying Woodchip Bioreactors: A Microbial Solution for Nitrate in Agricultural Wastewater—A Review: Sua Lee , Min Cho , Michael J. Sadowsky , Jeonghwan Jang; J. Microbiol. 2023;61(9):791-805. Published online August 18, 2023; DOI: https://doi.org/10.1007/s12275-023-00067-z

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Nitrate ( NO3 −) is highly water-soluble and considered to be the main nitrogen pollutants leached from agricultural soils. Its presence in aquatic ecosystems is reported to cause various environmental and public health problems. Bioreactors containing microbes capable of transforming NO3 − have been proposed as a means to remediate contaminated waters. Woodchip bioreactors (WBRs) are continuous flow, reactor systems located below or above ground. Below ground systems are comprised of a trench filled with woodchips, or other support matrices. The nitrate present in agricultural drainage wastewater passing through the bioreactor is converted to harmless dinitrogen gas ( N2) via the action of several bacteria species. The WBR has been suggested as one of the most cost-effective NO3 −-removing strategy among several edge-of-field practices, and has been shown to successfully remove NO3 − in several field studies. NO3 − removal in the WBR primarily occurs via the activity of denitrifying microorganisms via enzymatic reactions sequentially reducing NO3 − to N2. While previous woodchip bioreactor studies have focused extensively on its engineering and hydrological aspects, relatively fewer studies have dealt with the microorganisms playing key roles in the technology. This review discusses NO3 − pollution cases originating from intensive farming practices and N-cycling microbial metabolisms which is one biological solution to remove NO3 − from agricultural wastewater. Moreover, here we review the current knowledge on the physicochemical and operational factors affecting microbial metabolisms resulting in removal of NO3 − in WBR, and perspectives to enhance WBR performance in the future.

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Complete genome sequence of Neobacillus sp. strain OS1-2, a denitrifying bacterium isolated from apple orchard soil
Jinwoo Ahn, Jeonghwan Jang, Elinne Becket
Microbiology Resource Announcements.2025;[Epub] CrossRef
Dissimilatory nitrate reductions in soil Neobacillus and Bacillus strains under aerobic condition
Seohyun Ahn, Min Cho, Michael J. Sadowsky, Jeonghwan Jang
Journal of Microbiology.2025; 63(2): e2411019. CrossRef
Mn-oxidizing microalgae and woodchip-denitrifying bioreactor system for recovering manganese and removing nitrogen from electrolytic manganese metal industrial tailwater
Xinyue Gong, Qin Peng, Ruixin Jiang, Na Yang, Cijun Xing, Rui Wang
Journal of Hazardous Materials.2025; 488: 137383. CrossRef

Apoptotic Factors, CaNma111 and CaYbh3, Function in Candida albicans Filamentation by Regulating the Hyphal Suppressors, Nrg1 and Tup1: Suyoung Kim , Se Hyeon Kim , Eunjoong Kweon , Jinmi Kim; J. Microbiol. 2023;61(4):403-409. Published online March 27, 2023; DOI: https://doi.org/10.1007/s12275-023-00034-8

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Abstract: The morphological switch from the yeast to hyphal form is a key virulence attribute of the opportunistic fungal pathogen, Candida albicans. Our recent report showed that deletion of the newly identified apoptotic factor, CaNma111 or CaYbh3, leads to hyperfilamentation and increased virulence in a mouse infection model. CaNma111 and CaYbh3 are homologs of the pro-apoptotic protease, HtrA2/Omi, and BH3-only protein, respectively. In this study, we examined the effects of CaNMA111 and CaYBH3 deletion mutations on the expression levels of the hypha-specific transcr!ption factors, Cph1 (a hyphal activator), Nrg1 (a hyphal repressor), and Tup1 (a hyphal repressor). The protein levels of Nrg1 were decreased in Caybh3/Caybh3 cells while those of Tup1 were decreased in both Canma111/Canma111 and Caybh3/Caybh3 cells. These effects on Nrg1 and Tup1 proteins were retained during serum-induced filamentation and appear to explain the hyperfilamentation phenotypes of the CaNMA111 and CaYBH3 deletion mutants. Treatment with the apoptosis-inducing dose of farnesol decreased the Nrg1 protein levels in the wild-type strain and more evidently in Canma111/Canma111 and Caybh3/Caybh3 mutant strains. Together, our results suggest that CaNma111 and CaYbh3 are key regulators of Nrg1 and Tup1 protein levels in C. albicans.

Journal Article

Characterization of a Spontaneous Avirulent Mutant of Legionella pneumophila Serogroup 6: Evidence of DotA and Flagellin Involvement in the Loss of Virulence: Maria Scaturro , Stefania Meschini , Giuseppe Arancia , Fontana Stefano , Maria Luisa Ricci; J. Microbiol. 2009;47(6):768-773. Published online February 4, 2010; DOI: https://doi.org/10.1007/s12275-009-0103-0

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Abstract

The pathogenesis of Legionella pneumophila mainly resides in its ability to inhibit the phagosome-lysosome fusion, which normally prevents the killing of the host cells. In order to characterize the molecular alterations that occurred in a spontaneous avirulent mutant of Legionella pneumophila serogroup 6, named Vir-, we investigated the ability of the mutant to adhere to and multiply in the WI26VA4 alveolar epithelial cell line and in human macrophages, when compared to its parental strain, Vir+. We also determined the co- localization of bacteria with LAMP-1 to gain an insight into the phagosome-lysosome fusion process. Additionally, we determined the flagellin expression and dotA nucleotide sequencing. We observed a lack of expression of flagellin and an in-frame mutation in the dotA gene. The data obtained strongly suggest the loss of virulence of the mutant could probably be due to the absence of flagellin and the dysfunctional type IV secretion system, resulting from the DotA protein being severely compromised.

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Identification and characterization of genes, encoding the 3‐hydroxybutyrate dehydrogenase and a putative lipase, in an avirulent spontaneous Legionella pneumophila serogroup 6 mutant
Maria Scaturro, Cristina Barello, Melania De Giusti, Stefano Fontana, Federica Pinci, Maria Gabriella Giuffrida, Maria Luisa Ricci
APMIS.2015; 123(4): 330. CrossRef
Evidence of the Presence of a Functional Dot/Icm Type IV-B Secretion System in the Fish Bacterial Pathogen Piscirickettsia salmonis
Fernando A. Gómez, Jaime A. Tobar, Vitalia Henríquez, Mariel Sola, Claudia Altamirano, Sergio H. Marshall, Riccardo Manganelli
PLoS ONE.2013; 8(1): e54934. CrossRef

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