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Shindoh S, Obayashi Y, Suzuki S. Induction of Extracellular Aminopeptidase Production by Peptides in Some Marine Bacterial Species. Microbes Environ 2021; 36:ME20150. [PMID: 33716237 PMCID: PMC7966946 DOI: 10.1264/jsme2.me20150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/16/2021] [Indexed: 11/26/2022] Open
Abstract
Bacterial extracellular aminopeptidases are key enzymes in protein processing in oligotrophic seawater. To the best of our knowledge, the regulation of aminopeptidase production in microbes inhabiting seawater has not yet been reported. The present study attempted to experimentally clarify which organic materials affect bacterial extracellular aminopeptidase production by nutrient-rich and starved cells growing in artificial seawater using Photobacterium, Alteromonas, Ruegeria, and Sulfitobacter. In all four species, we found that peptides induced bacterial extracellular aminopeptidase production. Amino acids led to cell growth with markedly lower aminopeptidase production by Photobacterium and Sulfitobacter, but not by Alteromonas and Ruegeria. These results suggest that the extracellular aminopeptidases of marine bacteria are primarily produced on demand in response to the presence of relevant substrates (peptides) in seawater. Peptidyl substances may be regulatory nutrients for marine bacterial growth in aquatic environments.
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Affiliation(s)
- Suzune Shindoh
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Ehime 790–8577 Japan
| | - Yumiko Obayashi
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Ehime 790–8577 Japan
| | - Satoru Suzuki
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Ehime 790–8577 Japan
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Isolation and identification of herbivorous ciliates from contaminated microalgal cultures. Eur J Protistol 2020; 76:125743. [PMID: 33166874 DOI: 10.1016/j.ejop.2020.125743] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/15/2020] [Accepted: 10/07/2020] [Indexed: 11/23/2022]
Abstract
Ciliates are a common but understudied group of grazers that can invade microalgal cultures. To estimate the potential impact of ciliates on microalgal culture productivity, the identification of species that can invade these cultures is essential. Furthermore, isolation of these herbivorous ciliates allows to use them in experiments that investigate the impact of ciliate grazing on the productivity of microalgal cultures. The main aims of this study were to isolate and identify ciliates that invade cultures of the freshwater microalgae Chlorella and Chlamydomonas, and to establish a live collection of these ciliates for usage in future experiments. To this end, we optimized a method for isolating ciliates from contaminated microalgal cultures and we developed a new PCR primer set for amplifying the partial 18S rDNA of ciliates belonging to the classes Spirotrichea, Oligohymenophorea and Colpodea. As a result, we isolated 11 ciliates from microalgal enrichment cultures inoculated with non-sterile dust and various freshwater sources. Of these 11 species, 7 were found to be feeding on Chlamydomonas. Ciliate species that fed on Chlorella could not be isolated in this study. Ciliate species feeding on Chlamydomonas were identified based on a combination of morphological observations and molecular analyses of partial 18S rDNA sequences.
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Shintre NA, Tamhane VA, Baig UI, Pund AS, Patwardhan RB, Deshpande NM. Diversity of Culturable Actinobacteria Producing Protease Inhibitors Isolated from the Intertidal Zones of Maharashtra, India. Curr Microbiol 2020; 77:3555-3564. [PMID: 32902705 DOI: 10.1007/s00284-020-02174-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 08/21/2020] [Indexed: 11/26/2022]
Abstract
Phylogenetic diversity of culturable actinobacteria isolated from the intertidal regions of west coast of Maharashtra, India was studied using 16S rRNA gene sequencing. Total of 140 actinobacterial isolates were obtained, which belonged to 14 genera, 10 families and 65 putative species with Streptomyces being the most dominant (63%) genus followed by Nocardiopsis and Micromonospora. Isolates were screened for production of extracellular protease inhibitors (PI) against three pure proteases viz. chymotrypsin, trypsin, subtilisin and a crude extracellular protease from Pseudomonas aeruginosa. Eighty percent of the isolates showed PI activity against at least one of the four proteases, majority of these belonged to genus Streptomyces. Actinobacterial diversity from two sites Ade (17° 52' N, 73° 04' E) and Harnai (17° 48' N, 73° 05' E) with varying anthropological pressure showed that more putative species diversity was obtained from site with lower human intervention i.e. Ade (Shannon's H 3.45) than from Harnai (Shannon's H 2.83), a site with more human intervention. However, in Ade, percentage of isolates not showing PI activity against any of the proteases was close to 21% and that in Harnai was close to 9%. In other words, percentage of PI producers was lower at a site with lesser human intervention.
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Affiliation(s)
- Neha A Shintre
- Department of Microbiology, M.E.S. Abasaheb Garware College, Karve Road, Pune, Maharashtra, 411004, India
| | - Vaijayanti A Tamhane
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University, Pune, Maharashtra, 411007, India
| | - Ulfat I Baig
- Indian Institute of Science Education and Research, Pune (IISER-P), Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra, 411008, India
| | - Anagha S Pund
- Indian Institute of Science Education and Research, Pune (IISER-P), Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra, 411008, India
| | - Rajashree B Patwardhan
- Department of Microbiology, Haribhai V. Desai College of Commerce, Arts and Science, Pune, Maharashtra, 411002, India
| | - Neelima M Deshpande
- Department of Microbiology, M.E.S. Abasaheb Garware College, Karve Road, Pune, Maharashtra, 411004, India.
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Bien TLT, Thao NV, Kitamura SI, Obayashi Y, Suzuki S. Release and Constancy of an Antibiotic Resistance Gene in Seawater under Grazing Stress by Ciliates and Heterotrophic Nanoflagellates. Microbes Environ 2017; 32:174-179. [PMID: 28592722 PMCID: PMC5478541 DOI: 10.1264/jsme2.me17042] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Extracellular DNA (exDNA) is released from bacterial cells through various processes. The antibiotic resistance genes (ARGs) coded on exDNA may be horizontally transferred among bacterial communities by natural transformation. We quantitated the released/leaked tetracycline resistance gene, tet(M) over time under grazing stress by ciliates and heterotrophic nanoflagellates (HNFs), and found that extracellular tet(M) (ex-tetM) increased with bacterial grazing. Separate microcosms containing tet(M)-possessing bacteria with ciliates or HNFs were prepared. The copy number of ex-tetM in seawater in the ciliate microcosm rapidly increased until 3 d after the incubation, whereas that in the HNF microcosm showed a slower increase until 20 d. The copy number of ex-tetM was stable in both cases throughout the incubation period, suggesting that extracellular ARGs are preserved in the environment, even in the presence of grazers. Additionally, ARGs in bacterial cells were constant in the presence of grazers. These results suggest that ARGs are not rapidly extinguished in a marine environment under grazing stress.
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Affiliation(s)
- Thi Lan Thanh Bien
- Center for Marine Environmental Studies, Ehime University.,The United Graduate School of Agricultural Sciences, Ehime University.,Department of Biotechnology, Nong Lam University
| | - Ngo Vy Thao
- Center for Marine Environmental Studies, Ehime University.,Faculty of Environment and Resources, Nong Lam University
| | | | | | - Satoru Suzuki
- Center for Marine Environmental Studies, Ehime University
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Tada Y, Suzuki K. Changes in the community structure of free-living heterotrophic bacteria in the open tropical Pacific Ocean in response to microalgal lysate-derived dissolved organic matter. FEMS Microbiol Ecol 2016; 92:fiw099. [PMID: 27162185 DOI: 10.1093/femsec/fiw099] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2016] [Indexed: 11/14/2022] Open
Abstract
Dissolved organic matter derived from phytoplankton (DOMP) can affect the bacterial biomass and community structure in aquatic ecosystems. Here, we examined the community response of free-living heterotrophic bacteria, with respect to cellular nucleic acid levels, to the DOMP lysates derived from three phytoplankton strains in the open tropical Pacific. The free amino acid (FAA) composition of each DOMP lysate differed among the microalgal strains. Terminal restriction fragment-length polymorphism analyses with 16S rRNA genes revealed that the community shifts of high nucleic acid (HNA) and low nucleic acid (LNA) bacteria varied significantly with the different DOMP lysate treatments. Furthermore, the FAA composition in DOMP lysates significantly affected the bacterial community shifts in HNA and LNA. Similarity percentage analysis using 16S rRNA gene deep-sequencing revealed that the DOMP lysates from the pelagophyte Pelagomonas calceolata caused relatively large community shifts with Alcaligenes predominating in the HNA fraction. In contrast, the DOMP lysate from the diatom Thalassiosira oceanica induced a community shift in the LNA fraction with a predominance of uncultured Actinobacteria Thus, the data indicate that the DOMP lysates from different microalgae constitute a primary factor altering the dominant bacterial groups in the open ocean.
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Affiliation(s)
- Yuya Tada
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Koji Suzuki
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
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