Bioremediation mechanism of Monensin contaminated chicken manure by a combination of housefly larvae and Stenotrophomonas sp. DM-2

Abstract

There is an urgent need to find efficient methods to remediate polluted manure by ionophore antibiotics (IPAs). In the present study, we tried a novel bioremediation strategy for monensin (MON, one of IPAs) contaminated chicken manure through a combined bioaugmentation-vermicomposting approach with housefly larvae and MON-degrading bacteria. Under aerobic conditions, 31.37% of MON was degraded over 12 days through bioaugmentation using only Stenotrophomonas sp. DM-2, while the degradation rate of MON was 88.15% under the combined action of the larvae and Stenotrophomonas sp. DM-2. It was found that housefly larvae activity could change the pH and temperature of chicken manure and then reshaped the microbial community structure of chicken manure substrates. This activity of larvae enhanced the abundance of MON-degrading bacterial genera ( Stenotrophomonas and Alcaligenes ), making the genera Pseudogracilibacillus, Pseudomonas, Oligella, and Stenotrophomonas dominant after a 12-day bioremediation period, which contributed to the marked reduction of MON in manure. A novel potential degradation pathway of MON in chicken manure was also speculated based on the identification and characterization from LC-QToF/MS spectral data of two new MON metabolic intermediates. The present study provided a novel efficient method to remediate IPAs contaminated manure and provide new insights into the microbial molecular ecological mechanisms for bioremediation of MON contaminated chicken manure. • Bioaugmentation with DM-2 can effectively improve MON biodegradation in manure. • Housefly larvae and DM-2 have a combined effect on bioremediation of MON. • MON degradation produced two intermediates that were analyzed by LC-QToFMS. • Housefly larvae and DM-2 can change the composition of major bacterial groups. • Bioremediation makes MON-degrading bacterial genera dominant in manure.