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In order to find culturable bacteria resources and antibacterial activity strain in the rhizosphere soil of mangrove plants from the Maowei Sea, the rhizosphere soil of five mangrove plants (Rhizophora stylosa, Talipariti tiliaceum, Sonneratia apetala, Aegiceras corniculatum, and Pluchea indica) was cultured by enrichment media and then isolated the culturable bacteria. The culturable bacteria were purified by six different isolation media. The diversity of culturable bacteria was analyzed by the 16S rRNA gene sequence information. Antimicrobial activities (Staphylococcus epidermidis, methicillin-resistant S. aureus, and Pseudomonas aeruginosa) of the culturable bacteria were analyzed by disk diffusion method. The results were as follows: (1) A total of 120 strains were isolated from seven rhizosphere soil samples of mangrove plants which could be classified into 35 families and 47 genera, among which five potential new species were obtained. The dominant genus was Streptomyces sp. (14.2%). (2) It was found that the crude extracts of nine strains had antibacterial activity against at least one pathogen. The results indicate that there are abundant culturable bacteria and potential new antibiotics resources in the mangrove rhizosphere soils from the Maowei Sea. [ABSTRACT FROM AUTHOR]

This study aims to explore potential new bacterial species and bioactive substances in true mangrove plants, which can enrich the diversity of mangrove microorganisms and provide strain resources for the development of new active products. A total of 22 samples were collected from three true mangrove plants of Kandelia candel, Bruguiera gymnorrhiza, Rhizophora stylosa, and their habitats, in Guangxi coastal area. Then 22 samples were divided according to different parts such as roots, stems, leaves, flowers, fruits and soils. Eight different culture media were used to isolate culturable bacteria, and 16 S rRNA gene sequences were used to identify bacteria and analyze diversity. For cultured bacteria, the antibacterial and enzyme activities of fermented crude extracts were screened with Kirby-Bauer method and spot planting method, respectively. The results were as follows:（1）Based on sequencing results of 16 S rRNA gene, a total of 35 strains of culturable bacteria were isolated, belonging to 28 genera and 23 families. Bacillus accounted for 14.3% of the total bacteria, which was the dominant bacteria. Meanwhile, 11 potential new bacterial species were found.（2）Four strains of bacteria showed antibacterial activities, 16 strains had enzyme activities, and Bacillus was the dominant strain in enzyme activities. The above results show that Guangxi true mangrove plants are rich in bacterial diversity, and some bacteria show antibacterial activities and enzyme activities. The new bacterial species and active strains had certain development potential in the new antibiotics and enzymes application. [ABSTRACT FROM AUTHOR]

Four true mangrove rhizosphere soils in the intertidal zone of the west coast of Hainan were studied to analyze the species diversity composition and metabolite activity of mangrove rhizosphere actinomycetes, in order to accumulate abundant actinomycetes for better exploitation and utilization of marine microbial resources. In this study, seven samples of true mangrove rhizosphere soil were selected as research objects and nine different media were used as the isolation media. Pure culture method and three-zone scribing method were used to isolate and purify the strains. The species diversity composition was analyzed by combinating with the morphological characteristics of actinomycetes and the 16S rRNA gene sequence results. The actinomycete fermentation broth was extracted with ethyl acetate, and its anti-aging activity was tested using Caenorhabditis elegans model. The results were as follows:(1)A total of 22 strains of actinomycetes were isolated, belonging to four orders, seven families and nine genera consist of Amycolatopsis, Curtobacterium, Demequina, Isoptericola, Lysinimicrobium, Microbacterium, Rhodococcus, Sinomonas, Streptomyces, and Streptomyces was the dominant flora of this study with eleven strains isolated, and five strains of IMDGX 6012, IMDGX 6028, IMDGX 6118, IMDGX 6326, IMDGX 6119 were identified as potential new species actinobacteria. The highest similarities among the strains and the effective published strains Amycolatopsis lexingtonensis, A. niigatensis, Curtobacterium albidum, C. cit-reum, Demequina salsinemoris were 97.75%, 98.15%, 98.32%, 98.44%, 98.45%, respectively. The above five rhizosphere actinobacteria belong to rare actinobacteria and were preliminarily identified as potential new species.(2)The results of anti-aging of fermentation products showed that the metabolites of eight strains of actinobacteria could signifi-cantly prolong the lifespan of nematodes(P<0.05), including one strains of Curtobacterium, one strains of Demequina, one strain of Sinomonas and five of which were from Streptomyces, indicating that Streptomyces had potential to produce anti-aging active substances. IMDGX 6028 and IMDGX 6118, as potential new species of Amycolatopsis and Curtobacte-rium, had extremely significant anti-aging activity(P<0.01). When the crude metabolite concentration was 500 μg·mL-1, the survival time of C. elegans was increased by 22.2% and 26.6%, respectively, compared with the blank group. The results indicate that there are abundant resources of culturable actinobacteria and the potential to discover new species and anti-aging activity strains in the true mangrove rhizosphere soils in the west coast of Hainan. [ABSTRACT FROM AUTHOR]

The bacteria were isolated and purified from 46 tissues of 14 true mangrove plants used nine kinds of isolation media by dilution coating method. The bacteria were isolated from strains, and the species and genus diversities were analyzed by bacteria morphological characteristics and 16S rRNA gene sequences. The anti-aging activities of the bacteria were tested by Caenorhabditis elegans screening models. The results were as follows:(1)The 32 marine bacteria were obtained from 46 tissues of true mangrove plants without repeatitions. The 32 bacteria to comparison of 16S rRNA gene sequences which could be classified into 12 families and 17 genera. The dominant genus were Bacillus. It was discovered that a novel strain of suspected genus Aurantimonas, which 16S rRNA gene sequence similarities were less than 97%;(2)The three cultured marine bacteria could significantly delay Caenorhabditis elegans developing and had dominant anti-aging activities(P<0.05). All the above results indicate that the true mangrove plants collected from the west coast of Hainan have high species diversity and part strains are rich in anti-aging activity. [ABSTRACT FROM AUTHOR]

In order to find endophytie bacteria resources and search for new microbial insecticides from mangrove plants, the bacteria were isolated from sixteen samples of seven mangrove plants which collected from Beibu Gulf coast at Xuwen with designed ten kinds of isolation media. The 16S rRNA molecular biology method, dilution coating method and Caenorhabditis elegans screening model were used to explore the diversity and nematicidal activity of endophytic bacteria isolated from mangrove plants. The results were as follows:(1)A total of 33 endophytic bacteria were isolated by 16 organs and tissues which could be classified into 19 families and 23 genera and the dominant genus were Bacillus, and ten potential new species or genera were obtained.(2)Through the nematicidal activity test, two kinds of bacteria with nematicidal activity were obtained. Two endophytic bacteria IMDGX 4725 and IMDGX 4744 had the extremely significant nematicidal activities and the lethal concentrations of 50% were 61.58 and 100.89 mg·mL-1, respectively. The research confirm that mangrove plants collected from Xuwen are rich in endophytic bacteria. At the same time, parts of the bacteria have strong nematicidal activity, which could be a potential source for the discovery of the new microbial insecticides. [ABSTRACT FROM AUTHOR]

In order to find endophytic actinomycetes resources and research on new marine drugs, we studied the diversity and anti-aging activity of endophytic actinobacteria from ture mangrove plants of the west coast of Hainan. In this study, roots, stems, leaves, flowers and hypocotyl of 14 species of true mangrove plants from the west coast of Hainan were selected as research objects. Twenty-four strains of actinobacteria were obtained, from 46 plant tissues of ture mangrove plants, by using improved Gause's medium(AGG), trehalose-asparagine medium(M4), trehalose-proline medium(M5), improved ISP5 medium(M7), arginine-asparagine medium(M9), improved starch-hydrolyzed casein medium(M10), tyrosine-asparagine medium(P7), oat medium(P3), cottonseed sugar-histidine medium(M11)of nine kinds of different media, through dilution coating method and the third line marking method. The diversity of marine actinobacteria was analyzed by molecular biological identification methods such as 16S rRNA gene sequence information. The anti-aging activities of endophtic actinobacteria were analyzed by using Caenorhabditis elegans screening models. The results were as follows:(1)A total of 24 strains of actinobacteria were isolated from 46 plant tissues of true mangrove plants and distributed in eleven genera, seven families. Nine strains belonged to Streptomyces. Moreover, IMDGX 6270, IMDGX 6137 and IMDGX 6173 were three suspected potential new strains. The number of strains isolated from each sample varied greatly. Among them, the leaves had the largest number of strains and the richest diversity(18 strains). Next, eight strains were obtained from the stem. The number of roots was four, which may be related to the large number of stem and leaf tissue samples, and the number and diversity of strains isolated from M5 medium were the highest, while the number and diversity of strains isolated from M11 medium were the lowest. The results showed that the isolation medium with different nutrients had a great influence on the growth of microorganisms.(2)In addition, four strains of actinobacteria were screened by Caenorhabditis elegans model and showed anti-aging activity, and the survival time was increased by 17.16%, 28.11%, 29.05% and 27.10%, respectively, compared with the blank group. This indicates that there may be abundant actinobacteria resources in the mangrove plants in the west coast of Hainan, which can provide a new source for the research and development of anti-aging drugs. [ABSTRACT FROM AUTHOR]

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