Characterization of a novel beta-cypermethrin-degrading strain of Lactobacillus pentosus 3-27 and its effects on bioremediation and the bacterial community of contaminated alfalfa silage.

In this study, a novel beta-cypermethrin (beta-cyp)-degrading strain Lactobacillus pentosus 3-27 (LP3-27) was screened from beta-cyp-contaminated silage. The strain could degrade 96% of beta-cyp (50 mg/L) in MSM medium after 4 d of culture, while the strain lost its degradation ability when the beta-cyp concentration reached 250 mg/L. The effects of LP 3-27 on fermentation, bacterial community, and bioremediation of contaminated alfalfa silage at two dry matter (DM) contents were studied. The results showed that inoculation with LP3-27 not only degraded beta-cyp, but also improved the fermentation quality of alfalfa silage after 60 d of ensiling. Meanwhile, L. pentosus dominated the bacterial community during ensiling in LP3-27 inoculated silages, whereas Pediococcus acidilactici was the dominant species in the control silage. LP3-27 inoculation also simplified the bacterial interaction networks of ensiled alfalfa. Beta-cyp degradation was positively correlated with L. pentosus in LP- inoculated silages, which confirmed the function of beta-cyp degradation by L. pentosus. In addition, higher beta-cyp degradation was observed in silage with 35% versus 43% DM. In summary, strain LP3-27 could be used as a candidate inoculum for bioremediation of beta-cyp-contaminated silage and to produce safe silage for animal production.