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Kunoh T, Yamamoto T, Ono E, Sugimoto S, Takabe K, Takeda M, Utada AS, Nomura N. Identification of lthB, a Gene Encoding a Putative Glycosyltransferase Family 8 Protein Required for Leptothrix Sheath Formation. Appl Environ Microbiol 2023; 89:e0191922. [PMID: 36951572 PMCID: PMC10132092 DOI: 10.1128/aem.01919-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 02/20/2023] [Indexed: 03/24/2023] Open
Abstract
The bacterium Leptothrix cholodnii generates cell chains encased in sheaths that are composed of woven nanofibrils. The nanofibrils are mainly composed of glycoconjugate repeats, and several glycosyltransferases (GTs) are required for its biosynthesis. However, only one GT (LthA) has been identified to date. In this study, we screened spontaneous variants of L. cholodnii SP6 to find those that form smooth colonies, which is one of the characteristics of sheathless variants. Genomic DNA sequencing of an isolated variant revealed an insertion in the locus Lcho_0972, which encodes a putative GT family 8 protein. We thus designated this protein LthB and characterized it using deletion mutants and antibodies. LthB localized adjacent to the cell envelope. ΔlthB cell chains were nanofibril free and thus sheathless, indicating that LthB is involved in nanofibril biosynthesis. Unlike the ΔlthA mutant and the wild-type strain, which often generate planktonic cells, most ΔlthB organisms presented as long cell chains under static conditions, resulting in deficient pellicle formation, which requires motile planktonic cells. These results imply that sheaths are not required for elongation of cell chains. Finally, calcium depletion, which induces cell chain breakage due to sheath loss, abrogated the expression of LthA, but not LthB, suggesting that these GTs cooperatively participate in glycoconjugate biosynthesis under different signaling controls. IMPORTANCE In recent years, the regulation of cell chain elongation of filamentous bacteria via extracellular signals has attracted attention as a potential strategy to prevent clogging of water distribution systems and filamentous bulking of activated sludge in industrial settings. However, a fundamental understanding of the ecology of filamentous bacteria remains elusive. Since sheath formation is associated with cell chain elongation in most of these bacteria, the molecular mechanisms underlying nanofibril sheath formation, including the intracellular signaling cascade in response to extracellular stimuli, must be elucidated. Here, we isolated a sheathless variant of L. cholodnii SP6 and thus identified a novel glycosyltransferase, LthB. Although mutants with deletions of lthA, encoding another GT, and lthB were both defective for nanofibril formation, they exhibited different phenotypes of cell chain elongation and pellicle formation. Moreover, LthA expression, but not LthB expression, was influenced by extracellular calcium, which is known to affect nanofibril formation, indicating the functional diversities of LthA and LthB. Such molecular insights are critical for a better understanding of ecology of filamentous bacteria, which, in turn, can be used to improve strategies to control filamentous bacteria in industrial facilities.
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Affiliation(s)
- Tatsuki Kunoh
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Tatsuya Yamamoto
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Erika Ono
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shinya Sugimoto
- Department of Bacteriology, The Jikei University School of Medicine, Tokyo, Japan
- Jikei Center for Biofilm Science and Technology, The Jikei University School of Medicine, Tokyo, Japan
| | - Kyosuke Takabe
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Minoru Takeda
- Division of Materials Science and Chemical Engineering, Faculty of Engineering, Yokohama National University, Yokohama, Kanagawa, Japan
| | - Andrew S. Utada
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
- Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
- Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Ibaraki, Japan
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Benedek T, Táncsics A, Szabó I, Farkas M, Szoboszlay S, Fábián K, Maróti G, Kriszt B. Polyphasic analysis of an Azoarcus-Leptothrix-dominated bacterial biofilm developed on stainless steel surface in a gasoline-contaminated hypoxic groundwater. Environ Sci Pollut Res Int 2016; 23:9019-9035. [PMID: 26825521 DOI: 10.1007/s11356-016-6128-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 01/18/2016] [Indexed: 06/05/2023]
Abstract
Pump and treat systems are widely used for hydrocarbon-contaminated groundwater remediation. Although biofouling (formation of clogging biofilms on pump surfaces) is a common problem in these systems, scarce information is available regarding the phylogenetic and functional complexity of such biofilms. Extensive information about the taxa and species as well as metabolic potential of a bacterial biofilm developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater is presented. Results shed light on a complex network of interconnected hydrocarbon-degrading chemoorganotrophic and chemolitotrophic bacteria. It was found that besides the well-known hydrocarbon-degrading aerobic/facultative anaerobic biofilm-forming organisms (e.g., Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), representatives of Fe(2+)-and Mn(2+)-oxidizing (Thiobacillus, Sideroxydans, Gallionella, Rhodopseudomonas, etc.) as well as of Fe(3+)- and Mn(4+)-respiring (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) bacteria were present in the biofilm. The predominance of β-Proteobacteria within the biofilm bacterial community in phylogenetic and functional point of view was revealed. Investigation of meta-cleavage dioxygenase and benzylsuccinate synthase (bssA) genes indicated that within the biofilm, Azoarcus, Leptothrix, Zoogloea, and Thauera species are most probably involved in intrinsic biodegradation of aromatic hydrocarbons. Polyphasic analysis of the biofilm shed light on the fact that subsurface microbial accretions might be reservoirs of novel putatively hydrocarbon-degrading bacterial species. Moreover, clogging biofilms besides their detrimental effects might supplement the efficiency of pump and treat systems.
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Affiliation(s)
- Tibor Benedek
- Regional University Center of Excellence in Environmental Industry, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary
| | - András Táncsics
- Regional University Center of Excellence in Environmental Industry, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary.
| | - István Szabó
- Department of Environmental Safety and Ecotoxicology, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary
| | - Milán Farkas
- Department of Environmental Safety and Ecotoxicology, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary
| | - Sándor Szoboszlay
- Department of Environmental Safety and Ecotoxicology, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary
| | - Krisztina Fábián
- Department of Environmental Safety and Ecotoxicology, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary
| | - Gergely Maróti
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62., Szeged, 6726, Hungary
| | - Balázs Kriszt
- Department of Environmental Safety and Ecotoxicology, Szent István University, Páter K. u. 1, Gödöllő, 2100, Hungary
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Babauta JT, Nguyen HD, Istanbullu O, Beyenal H. Microscale gradients of oxygen, hydrogen peroxide, and pH in freshwater cathodic biofilms. ChemSusChem 2013; 6:1252-61. [PMID: 23766295 PMCID: PMC4247834 DOI: 10.1002/cssc.201300019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/21/2013] [Indexed: 05/05/2023]
Abstract
Cathodic reactions in biofilms employed in sediment microbial fuel cells is generally studied in the bulk phase. However, the cathodic biofilms affected by these reactions exist in microscale conditions in the biofilm and near the electrode surface that differ from the bulk phase. Understanding these microscale conditions and relating them to cathodic biofilm performance is critical for better-performing cathodes. The goal of this research was to quantify the variation in oxygen, hydrogen peroxide, and the pH value near polarized surfaces in river water to simulate cathodic biofilms. We used laboratory river-water biofilms and pure culture biofilms of Leptothrix discophora SP-6 as two types of cathodic biofilms. Microelectrodes were used to quantify oxygen concentration, hydrogen peroxide concentration, and the pH value near the cathodes. We observed the correlation between cathodic current generation, oxygen consumption, and hydrogen peroxide accumulation. We found that the 2 e(-) pathway for oxygen reduction is the dominant pathway as opposed to the previously accepted 4 e(-) pathway quantified from bulk-phase data. Biofouling of initially non-polarized cathodes by oxygen scavengers reduced cathode performance. Continuously polarized cathodes could sustain a higher cathodic current longer despite contamination. The surface pH reached a value of 8.8 when a current of only -30 μA was passed through a polarized cathode, demonstrating that the pH value could also contribute to preventing biofouling. Over time, oxygen-producing cathodic biofilms (Leptothrix discophora SP-6) colonized on polarized cathodes, which decreased the overpotential for oxygen reduction and resulted in a large cathodic current attributed to manganese reduction. However, the cathodic current was not sustainable.
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Affiliation(s)
| | | | | | - Haluk Beyenal
- The Gene & Linda Voiland School of Chemical Engineering and Bioengineering, PO Box 642710, Washington State University, Pullman, WA 99164-2710 (USA), Fax: (+ 1) 509-335-4806
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Katsoyiannis IA, Zouboulis AI. Biological treatment of Mn(II) and Fe(II) containing groundwater: kinetic considerations and product characterization. Water Res 2004; 38:1922-1932. [PMID: 15026247 DOI: 10.1016/j.watres.2004.01.014] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 11/06/2003] [Accepted: 01/05/2004] [Indexed: 05/24/2023]
Abstract
In the present article, the treatment of groundwater containing Mn(II) and Fe(II) has been investigated. The biological oxidation of Mn(II) and Fe(II) in upflow filtration units comprised the applied experimental technique. The oxidation processes were mediated by specific bacteria, namely the Leptothrix ochracea and Gallionella ferruginea, which belong to the general category of manganese and iron oxidizing bacteria. This work was focused on the characterization of the products of biological oxidation and to the examination of the kinetics of Mn(II) removal as compared with Fe(II) removal from groundwaters. The products of biological oxidation were characterized using the spectroscopic techniques XRD, XPS and SEM-EDS and comprised a mixture of biogenic hydrous manganese and iron oxides. The oxidation state of manganese in the precipitates was found to be between 3 and 4. Iron oxides were mainly in the form of amorphous ferrihydrite. The kinetic results indicated that the rates of manganese and iron oxidation were several orders of magnitude greater than the respective for abiotic oxidation. The bacterially mediated oxidation of iron was faster than manganese oxidation, presenting half-lives of reaction 0.9 and 3.98 min, respectively.
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Affiliation(s)
- Ioannis A Katsoyiannis
- Department of Chemistry, Aristotle University of Thessaloniki, PO Box 116, Thessaloniki GR-54124, Greece
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