van den Wijngaard A J, van der Kleij R G, Doornweerd R E, Janssen D B
Department of Biochemistry, University of Groningen, The Netherlands.
Appl Environ Microbiol. 1993 Oct;59(10):3400-5. doi: 10.1128/aem.59.10.3400-3405.1993.
The effects of organic nutrients and cocultures on substrate removal by and competitive behavior of 1,2-dichloroethane-degrading bacteria were investigated. Xanthobacter autotrophicus GJ10 needed biotin for optimal growth on 1,2-dichloroethane. In continuous culture, dilution of biotin to a concentration below 0.2 nM resulted in washout. Growth could be restored by inoculation with the 2-chloroethanol utilizer Pseudomonas sp. strain GJ1, leading to a new steady state in which about 1% of the mixed culture consisted of cells of strain GJ1. This indicates that strain GJ1 excreted biotin or a precursor for its synthesis. Inoculation of the mixed culture with Ancylobacter aquaticus AD25 did not result in washout of strain GJ10, although strain AD25 has a 10-fold-lower Ks for growth on 1,2-dichloroethane. Strain AD25 did not become dominant because of the lack of vitamins, which are necessary for its optimal growth. The results indicate that medium composition and the presence of other species strongly influence the effect of substrate limitation on the composition of a bacterial population that degrades a xenobiotic compound in a continuous culture.
研究了有机营养物和共培养物对1,2 - 二氯乙烷降解菌去除底物的效果及其竞争行为。自养黄色杆菌GJ10在以1,2 - 二氯乙烷为底物生长时需要生物素以实现最优生长。在连续培养中，将生物素稀释至浓度低于0.2 nM会导致菌液被冲出。接种利用2 - 氯乙醇的假单胞菌属菌株GJ1可恢复生长，从而达到一个新的稳定状态，此时混合培养物中约1%由菌株GJ1的细胞组成。这表明菌株GJ1分泌了生物素或其合成前体。用嗜水生柄杆菌AD25接种混合培养物，尽管菌株AD25在以1,2 - 二氯乙烷为底物生长时的Ks值低10倍，但并未导致菌株GJ10被冲出。由于缺乏对其最优生长所必需的维生素，菌株AD25并未成为优势菌。结果表明，培养基组成和其他物种的存在强烈影响底物限制对连续培养中降解外源化合物的细菌群体组成的作用。
