• Title/Summary/Keyword: Marine bacteria

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Diversity and Chemical Defense Role of Culturable Non-Actinobacterial Bacteria Isolated from the South China Sea Gorgonians

  • Jiang, Peng;Zhang, Xiaoyong;Xu, Xinya;He, Fei;Qi, Shuhua
    • Journal of Microbiology and Biotechnology
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    • v.23 no.4
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    • pp.437-443
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    • 2013
  • The diversity of culturable non-actinobacterial (NA) bacteria associated with four species of South China Sea gorgonians was investigated using culture-dependent methods followed by analysis of the bacterial 16S rDNA sequence. A total of 76 bacterial isolates were recovered and identified, which belonged to 21 species of 7 genera, and Bacillus was the most diverse genus. Fifty-one percent of the 76 isolates displayed antibacterial activities, and most of them belonged to the Bacillus genus. From the culture broth of gorgonian-associated Bacillus methylotrophicus SCSGAB0092 isolated from gorgonian Melitodes squamata, 11 antimicrobial lipopeptides including seven surfactins and four iturins were obtained. These results imply that Bacillus strains associated with gorgonians play roles in coral defense mechanisms through producing antimicrobial substances. This study, for the first time, compares the diversity of culturable NA bacterial communities among four species of South China Sea gorgonians and investigates the secondary metabolites of gorgonian-associated B. methylotrophicus SCSGAB0092.

Recycling Marine Fish Farm Effluent by Microorganisms (유용미생물을 이용한 육상수조식 양식장 배출물의 재활용)

  • 문상욱;이준백;이영돈;김세재;강봉조;고유봉
    • Journal of Aquaculture
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    • v.15 no.4
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    • pp.261-266
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    • 2002
  • The effluent sediment from the land-based seawater fish farms of Jeju consists of proteins, fats, ash and moisture. An evaluation of the effluent sediment as substrate for growth of phototrophic or lactic acid bacteria revealed that the sediment supported the growth of phototrophic bacteria but could support lactic acid bacteria only on supplementation with sugar. The possibility of using phototrophic bacteria for recycling the land-based seawater fish farm effluent is shown.

Survey of Antibiotic Resistant Bacteria in Ulleungdo, Korea (울릉도의 항생제 내성균 조사)

  • Jun Hyung Lee;Hye Won Hong;Dukki Han
    • Korean Journal of Environmental Agriculture
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    • v.41 no.4
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    • pp.344-354
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    • 2022
  • BACKGROUND: Although antibiotics have contributed to treatment of bacterial infection, the antibiotic abuse can lead to antibiotic resistant bacteria. Impact of human activities on distribution of antibiotic resistance has been intensively issued and occurrence of antibiotic resistant bacteria in contaminated environments would not be a surprise. Nonetheless, anthropogenic contamination with the dissemination of antibiotic resistance along uncontaminated environments has been less considered. The aim of this study is to investigate antibiotic resistant bacteria across Ulleungdo, known as antibiotic resistance free and anthropogenic pollution free environment in Rep. of Korea. METHODS AND RESULTS: Antibiotic resistant bacteria in coastal seawater of Ulleungdo were investigated in July 2021. Antibiotic susceptibility test using the disk diffusion method was applied with six drugs according to the Clinical and Laboratory Standards Institute (CLSI) guideline. Total 43 bacterial isolates were tested and 20 isolates among of them showed multidrug resistance. Particularly, the number and ratio of resistant bacteria were relatively high in a densely populated area of Ulleungdo. The bacterial communities were investigated using 16S rRNA gene metabarcoding approach in the coastal seawater and soils of Ulleungdo. In the bacterial communities, Firmicutes were selectively distributed only in seawater, suggesting the possibility of anthropogenic contamination in coastal seawater of Ulleungdo. CONCLUSION(S): We found antibiotic resistant bacteria in a populated area of Ulleungdo. The occurrence of antibiotic resistant bacteria in Ulleungdo seems to result from the recent anthropogenic impact. Consistent monitoring of antibiotic resistant bacteria in the uncontaminated environment needs to considered for future risk assessment of antibiotics.

The Stability of Carotenoids Extracted from Halophilic Bacteria (호염세균으로부터 추출한 카로테노이드 색소의 안정성)

  • 정영기;최병대
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.28 no.6
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    • pp.1405-1407
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    • 1999
  • A carotenoid pigment, which was a determinant for food quality, was extracted from a marine halophilic bacteria. The stability of the pigment extract was investigated for a food additive. The optimum temperature for stability was 20oC. The pigment degradation was significantly affected by solvent polarity, however, stable in salvent methanol and ethanol. The pigment degradation was highly sensitive to light and UV exposure.

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Screening and Characterization of Psychrotrophic, Lipolytic Bacteria from Deep-Sea Sediments

  • Zeng, Xiang;Xiao, Xiang;Wang, Peng;Wang, Rengping
    • Journal of Microbiology and Biotechnology
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    • v.14 no.5
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    • pp.952-958
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    • 2004
  • Of 23 psychrotrophic bacteria isolated from the west Pacific deep-sea sediments, 19 were assigned to the $\gamma$-Proteobacteria, 3 to the <$\beta$-Proteobacteria, and 1 to the Gram-positive bacteria, as determined by their 16S rDNA sequences. Ten psychrotrophs, affiliated to the Psychrobacter, Pseudoalteromonas, and Pseudomonas genera in the $\gamma$-Proteobacteria group, were screened for lipolytic bacteria. The majority of the lipolytic isolates had growth temperatures between 4-$30^\circ{C}$, and all of them were neutrophilic, aerobic, or facultatively anaerobic, and some were able to produce multiple kinds of ectohydrolytic enzymes. The deep-sea strains Psychrobacter sp. wp37 and Pseudoalteromonas sp. wp27 were chosen for further lipase production analysis. Both strains had the highest lipase production when grown at 10 to $20^\circ{C}$; their highest lipase production occurred at the late-exponential growth stage; and the majority of the enzymes were excreted to the outside of the cells. Lipases from both strains had the same optimal reaction temperature and pH (20-$30^\circ{C}$, pH 7-8) and could retain about 60% of their highest activity at $4^\circ{C}$. Furthermore, SDS-PAGE and an in-gel activity test showed that they had the same high molecular mass of about 85 kDa.

Algicidal Activity of Substance Purified from Marine Bacteria Metabolites against Cochlodinium polykrikoides

  • Byun Hee-Guk;Jeong Seong-Youn;Park Young-Tae;Lee Won-Jae;Kim Se-Kwon
    • Fisheries and Aquatic Sciences
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    • v.5 no.3
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    • pp.150-155
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    • 2002
  • Marine bacteria producing algicidal substance against Cochlodinium polykrikoides was screened and isolated from seawater. Metabolite of marine bacteria Micrococcus sp. LG-5 showed strong algicidal activity against C. polykrikoides. C. polykrikoides was inhibited above $90\%$ at $5\%$ solution of the metabolite within 24 hrs. Algicidal substance from the metabolite was extracted with ethyl acetate, and then purified by PTLC and reversed-phase HPLC. Algicidal activity of purified compound against C. polykrikoides was above $90\%$ at 3.7, 11.0 and 33.0${\mu}g/mL$ concentration after 12, 9 and 3 hrs, respectively. Ninety percent inhibition of other red tides, Gymnodinium sanguineum and Gyrodinium impudicum was observed when treated with 3.7${\mu}g/mL$ of purified compound within a period of 12 hrs. The microscopic view of red tides treated with purified compound showed the deformations such as cell node cuts and swelling of cells.

Bacterial Communities from the Water Column and the Surface Sediments along a Transect in the East Sea

  • Lee, Jeong-Kyu;Choi, Keun-Hyung
    • Journal of Marine Life Science
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    • v.6 no.1
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    • pp.9-22
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    • 2021
  • We determined the composition of water and sediment bacterial assemblages from the East Sea using 16S rRNA gene sequencing. Total bacterial reads were greater in surface waters (<100 m) than in deep seawaters (>500 m) and sediments. However, total OTUs, bacterial diversity, and evenness were greater in deep seawaters than in surface waters with those in the sediment comparable to the deep sea waters. Proteobacteria was the most dominant bacterial phylum comprising 67.3% of the total sequence reads followed by Bacteriodetes (15.8%). Planctomycetes, Verrucomicrobia, and Actinobacteria followed all together consisting of only 8.1% of the total sequence. Candidatus Pelagibacter ubique considered oligotrophic bacteria, and Planctomycetes copiotrophic bacteria showed an opposite distribution in the surface waters, suggesting a potentially direct competition for available resources by these bacteria with different traits. The bacterial community in the warm surface waters were well separated from the other deep cold seawater and sediment samples. The bacteria exclusively associated with deep sea waters was Actinobacteriacea, known to be prevalent in the deep photic zone. The bacterial group Chromatiales and Lutibacter were those exclusively associated with the sediment samples. The overall bacterial community showed similarities in the horizontal rather than vertical direction in the East Sea.

Organic Matter Cycle by Biogeochemical Indicator in Tidal Mud Flat, West Coast of Korea (생지화학적 지표를 이용한 서해안 갯벌 퇴적층에서의 유기물 순환에 관한 연구)

  • Lee, Dong-Hun;Lee, Jun-Ho;Jeong, Kap-Sik;Woo, Han Jun;Kang, Jeongwon;Shin, Kyung-Hoon;Ha, Sun-Yong
    • Ocean and Polar Research
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    • v.36 no.1
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    • pp.25-37
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    • 2014
  • To understand the degradation processes of organic matter related to sulfate reduction by Sulfate Reduction Bacteria (SRB) in the tidal flat sediments of Hwang-do and Sogeun-ri, Tae-an Peninsula in Chungnam-do, biogeochemical characteristics were analyzed and highlighted using specific microbial biomarkers. The organic geochemical parameters (TOC, ${\delta}^{13}C_{org}$, C/N ratio, long-chain-n-alkane) indicate that most of the organic matter has been derived from marine phytoplankton and bacteria in the fine-grained sediment of Sogeun-ri, although terrestrial plant components have occasionally been incorporated to a significant degree in the coarse-grained sediment of Hwang-do. The concentration of sulfate in pore water is a constant tendency with regard to depth profile, while methane concentration appears to be slightly different with regard to depth profile at the two sites. Especially, the sum of bacteria fatty acid (a-C15:0 + i-C15:0 + C16:1w5) confirms that the these concentrations in Sogeun-ri are related to the degradation of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) compounds from the crude oil retained in the sediments as a result of the Hebei Spirit oil-spill accident in 2007. The methane-related microbial communities as shown by lipid biomarkers (crocetane, PMI) are larger in some sedimentary sections of Hwang-do than in the Sogeunri tidal flat. These findings suggest that methane production by microbiological processes is clearly governed by SRB activity along the vertical succession in organic-enriched tidal flats.

Isolation and identification of protease-producing bacteria from the intertidal zone in Jeju Island, Korea (제주 조간대로부터 단백질 가수분해효소를 생산하는 세균의 분리 및 동정)

  • Moon, Young-Gun;Dharaneedharan, Subramanian;Kim, Dong-Hwi;Park, So-Hyun;Heo, Moon Soo
    • Korean Journal of Microbiology
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    • v.51 no.4
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    • pp.382-388
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    • 2015
  • Eleven protease-producing bacteria were isolated from the organisms' external shells and the inorganic materials collected from intertidal zone of Jeju Island, Republic of Korea. The samples were diluted serially, inoculated on Zobell agar plates with 1% skim milk and incubated at $20^{\circ}C$. Clear zone forming colonies were selected as protease-producing bacteria and each strain was identified based on the phylogenetic analysis with their 16S rDNA sequences. Strains JJM125, JJM129, YG47 and YG49 belong to the marine bacterial genus Pseudoalteromonas; strain JJM122 belong to the genus Microbulbifer; strains YG51, YG52, YG62 and YG63 belong to the genus Vibrio; and strain YG65 belong to genus Bacillus. Hence, the present study suggests that these protease producing bacteria could be further used to develop new varieties of protease with various biotechnological applications.

Antimicrobial effect of chitosan oligosaccharides, prepared under ultrafiltration membrane bioreactor, against pathogenic bacteria causing flounder fish diseases in aquacultural farm

  • Heo, Moon-Soo;Jeon, You-Jin;Lee, Ki-Wan;Song, Choon-Bok;Lee, Jehee;Yeo, In-Kyo;Yang, Byung-Gyoo;Kim, Se-Kwon
    • Proceedings of the Korean Society of Fisheries Technology Conference
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    • 2001.10a
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    • pp.145-146
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    • 2001
  • Despite a variety of development in fish farming during the last decades, fish diseases by bacteria, virus, and parasites are still major problems in aquaculture. Aquaculture of Hounder fish is widely performed around Korea as well as Jeju island, due to relatively stable seed production, short farming period, and a higher value in market. However, intensive feeding and environmental pollution in aquacutural farm act as a great limiting factor in economic aspect. (omitted)

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