Diversity and anti-aging activity of the coepiphytic bacteria of three species of sea cucumbers from Weizhou Island in Guangxi

【Objective】In order to reveal the bacterial diversity and screen out the coepiphytic bacteria for new antiaging compounds of sea cucumbers from Weizhou Island, Guangxi.【Method】Nine kinds of media were used to cultivate and separate associated bacteria from 10 samples come from 3 species of sea cucumbers(Havelockia versicolor, Holothuria leucospilota, and Colochirus quadrangularis). 16S rRNA sequencing was applied to analyze the community diversity. C. elegans models were used to estimate the anti-aging activities of the coepiphytic bacteria metabolites.【Result】A total of 63 species bacteria were isolated and identified, which belonging to 3 phyla, 4 classes, 15 orders, 25 families and 35 genera. The dominant microflora was Actinobacteria(31 strians, 49%), and 2 of them(GXIMD LM0085 and GXIMD LM0159) were identified to be putatively novel bacterial species, whose similarities to the published Kocuria assamensis and K. salsicia were 97.38% and 97.00%, respectively. Differences were found in the number of coepiphytic bacteria isolated from different media at genus level. The M9 medium had the largest number of strains and the richest diversity(19 genera, 28 strains). However, the P7 medium had the least number(6 genera, 6 strains). Among the identified 35 genera, only Cobetia and Halomonas were distributed in all 9 growth media, another 13 genus could grow in single medium. The number of symbiotic bacteria isolated from different sea cucumbers was in the order to sort as follows:1# H. versicolor>C. quadrangularis>2# H. versicolor>H. leucospilota. For these sea cucumbers except H. leucospilota, the relative abundance of symbiotic actinomycetes in vivo were greatly higher than those on their surface. In the anti-aging research, the lifetime of C. elegans was significantly prolonged(P<0.05) by the crude extracts of GXIMD LM0037(Stenotrophomonas), GXIMD LM0005(Streptomyces), GXIMD LM0071(Paracoccus), GXIMD LM0114(Stenotrophomonas), GXIMD LM0099 (Promicromonospora), and GXIMD LM0032(Brachybacterium).【Conclusion】There are abundant marine coepiphytic bacteria and potential opportunity to discover new species in the sea cucumbers from Weizhou Island. Some bacteria show anti-aging activity, which provides huge potential in the research and development of anti-aging active substances and new anti-aging drugs.