[Bioactivity survey of natural microbial consortium from mangrove]

Microbial natural products have been mainly acquired by pure culture. While in nature, different microorganisms in one habitat may work together as a whole to produce special secondary metabolites to adapt to their environments. "Quorum-sensing" is a way that they would use. A microbial consortium is like a multi-cellular individual that different microorganisms interact with each other to fulfill a special function. A marine fungus only produce antibiotics when a bacterium co-cultured (Cueto et al, 2001); and some traditional Chinese fermentation food are produced by mixed culture. These inspired us that directly using natural microbial consortium instead of isolate the individual microorganism may be a worth to risk in search for bioactive products. In this research, One hundred and eighty one samples were collected from three mangrove areas of Hainan, Guangxi and Guangdong, in China, which were fermented directly and evaluated for their anti-bacteria, anti-fungi and anti-cancer cell activities. Fifteen samples with high activities were further studied. Microorganisms were isolated from these 15 high bioactive samples and re-detected for their bioactivity, among which, microorganisms isolated from 5 samples that numbered 1106, 1122, 1116, 1214 and 1305 didn' t show any activity although the un-isolated samples themselves showed high bioactivity. Four strains were isolated from one sample of number 1146. Among these strains, one strain showed the same bioactivity targets as the sample itself , but lower activity of anti-fungi than the sample itself. The other three strains didn't show any bioactivity. Microorganisms isolated from three samples that numbered 1161, 1123 and 1111, changed their initial bioactivity targets. These results suggested that natural microbial consortium culture have the potential to produce bioactive metabolites. It is supposed that some uncultured microorganisms or the community action may be the reason for their activity. This is an initial step on using microbial consortium to produce bioactive metabolites.