Fate of 14C-labeled microbial products derived from nitrifying bacteria in autotrophic nitrifying biofilms
Fate of 14C-labeled microbial products derived from nitrifying bacteria in autotrophic nitrifying biofilms
复制标题
DOI：
10.1128/aem.71.7.3987-3994.2005
复制
发表时间：
2005-07-01
影响因子：
4.4
通讯作者：
Ito, T
中科院分区：
文献类型：
--
作者：
Okabe, S;Kindaichi, T;Ito, T
采用显微放射自显影与荧光原位杂交相结合的方法，定量分析了C-14标记硝化细菌产生的微生物产物与自养硝化生物膜中共存的异养菌的交叉摄食。只用[C-14]碳酸氢盐标记硝化细菌后，将生物膜样品在NH4+作为唯一能源和不作为唯一能源的情况下培养10天。利用MAR-FISH对硝化细菌细胞中的C-14向异养细菌的转移进行了时间监测。MAR-FISH分析表明，除β-变形杆菌外，大多数异养菌的系统发育类群都显示出对C-14标记微生物产品的显著摄取。尤其是在无NH4+添加的培养条件下，Chloroflei的MAR呈强阳性，硝化细菌容易腐烂。这表明，绿藻的成员优先利用主要来自生物量腐烂的微生物产物。另一方面，在硝化细菌生长的NH4+添加培养中，Cytophaga-黄杆菌群的成员逐渐利用C-14标记的产物。这一结果表明，这些细菌优先利用硝化细菌的底物利用相关产物和/或C-14标记的结构细胞成分的次生代谢物。我们的结果清楚地表明，共存的异养菌有效地降解和利用了硝化细菌的死亡生物量和代谢产物，从而防止了有机废物在生物膜中的积累。
The cross-feeding of microbial products derived from C-14-labeled nitrifying bacteria to heterotrophic bacteria coexisting in an autotrophic nitrifying biofilm was quantitatively analyzed by using microautoradiography combined with fluorescence in situ hybridization (MAR-FISH). After only nitrifying bacteria were labeled with [C-14] bicarbonate, biofilm samples were incubated with and without NH4+ as a sole energy source for 10 days. The transfer of C-14 originally incorporated into nitrifying bacterial cells to heterotrophic bacteria was monitored with time by using MAR-FISH. The MAR-FISH analysis revealed that most phylogenetic groups of heterotrophic bacteria except the beta-Proteobacteria showed significant uptake of C-14-labeled microbial products. In particular, the members of the Chloroflexi were strongly MAR positive in the culture without NH4+ addition, in which nitrifying bacteria tended to decay. This indicated that the members of the Chloroflexi preferentially utilized microbial products derived from mainly biomass decay. On the other hand, the members of the Cytophaga-Flavobacterium cluster gradually utilized C-14-labeled products in the culture with NH4+ addition in which nitrifying bacteria grew. This result suggested that these bacteria preferentially utilized substrate utilization-associated products of nitrifying bacteria and/or secondary metabolites of C-14-labeled structural cell components. Our results clearly demonstrated that the coexisting heterotrophic bacteria efficiently degraded and utilized dead biomass and metabolites of nitrifying bacteria, which consequently prevented accumulation of organic waste products in the biofilm.