Removal of malodorant skatole by two enriched microbial consortia: Performance, dynamic, function prediction and bacteria isolation

Malodor emission has become one of the major challenges in animal husbandry. Skatole, one of the most offensive odorous compounds, can cause several diseases to organisms and is resistant to biodegradation. However, the microbial community information for skatole degradation has yet to be reported. In this study, the aerobic sequencing batch reactors with two different inocula were constructed. Both Group N (sample from cattle house) and Group E (sample from goose house) could efficiently degrade skatole after 70 days operation under conditions of pH 7.0-9.0 and temperature 20-40 degrees C. High-throughput sequencing results showed that the alpha-diversity in Group N was higher than that in Group E, while neither of them changed during the whole operation process. Bacterial community structures in both groups shifted. Generally, Lactococcus, Pseudomonas and Flavobacterium remarkably reduced, while Arthrobacter became the dominant population. Function prediction results indicated that the xenobiotics biodegradation and metabolism category was significantly up-regulated in Group E but remained unchanged in Group N. On the other hand, culture-dependent technique was applied and ten bacteria were obtained from the sludges. Two strains belonged to Rhodococcus, a minor genus in the communities, were firstly proven to harbor excellent skatole-degrading capacity. This study proved that skatole could be effectively removed by activated sludges, and the non-core bacteria Rhodococcus would be functionally important in the degradation process. These findings provide new insights into our understanding of skatole biotransformation process, and offer valuable bacterial resources for bioremediation application.