Spirodela polyrhiza stimulates the growth of its endophytes but differentially increases their fenpropathrin-degradation capabilities

In situ remediation of organic contaminants via physical, chemical, and biological approaches is a practical technique for cleansing contaminated water and soil. In the present study, we showed that the three bacterial strains Pseudomonas sp. E1, Klebsiella terrigena E42, and Pseudomonas sp. E46, which can infect and colonize the aquatic plant Spirodela polyrhiza, utilize fenpropathrin as the sole carbon source for growth. S. polyrhiza helped enhance fenpropathrin degradation by E46 by 17.5%, only slightly improved fenpropathrin degradation by E42, and had no effect on strain E1. The application of plant exudates and extracts from fenpropathrin-unexposed/induced plants stimulated bacterial growth of the three strains, but resulted in differential fenpropathrin degradation, suggesting that not all plants and their endophytic bacteria are suitable for coupling phytoremediation and microbial-remediation. Moreover, addition of soil sediments to a microcosm not only stimulated the growth of strain E46 but also increased the rate of fenpropathrin degradation.