Effects of carbohydrate addition on dynamics of bacterial community structures on the biofilms of artificial substrates

To evaluate the effects of carbohydrate addition on the artificial substrate biofilm, we studied dynamics of bacterial community structures on the biofilms of artificial substrates(bolting-silk nets) in six Litopenaeus vannamei aquaculture ponds by using methods of bacterial plate coating and terminal restriction fragment length polymorphism (T-RFLP).The results of bacterial plate coating showed that, during the 30 days' experiment, the heterotrophic bacteria on the biofilm of the two groups maintain relatively stable when the biofilm matured.The quantity of Vibrio in carbon regulation group was decreased significantly by 91.85% compared with control group (p0.01), the number ratio between Vibrio and heterotrophic bacteria was 96.98% lower than that of control group (p0.01).The T-RFLP profiles showed that the relative abundance of T-RF of 126、432、434、436、485、487、488 bp was significantly changed.Further analysis indicated that the bacterial abundance and diversity increased 100% and 33.9%, respectively, on the biofilms of carbon regulation groups, compared with those of the control groups.The moving window analysis showed that the community change rates in carbon regulation groups and control groups were 12.4%0.3% and 23.2%26.38%, respectively.The results obtained in the present study demonstrated that carbon regulation might not only increase the number of heterotrophic bacteria which inhibited the proliferation of Vibrio cholera by competition, but also improve the stability of bacterial community structure on the biofilms of artificial substrates in aquaculture ponds.