Surface modification of carrier materials with LDH can improve pesticides biodegradation by microbial inoculants
Improvement of bioaugmentation technology to treat pesticide contaminated soils was tested by focusing on microbial inoculum preparation. For this, three natural carrier materials, oyster shell, pozzolana and zeolite, were evaluated for supporting the growth, activity and biodiversity of a MCPA (2-methyl-4-chlorophenoxyacetic acid) degrading microbial consortium as biofilm. The added value of modifying carrier materials surface using Layered Double Hydroxides (as Ca/Fe-LDHs) was also tested. All carrier materials supported the growth of biofilms displaying MCPA dissipation and mineralization in liquid medium and soil, with pozzolana and zeolite leading to highest dissipation rates. Bacterial diversity varied according to the carrier material and was the most apart in terms of diversity and richness on oyster shell. LDH covering itself led to partial MCPA dissipation suggesting MCPA adsorption on LDH, but total MCPA removal only occurred in the presence of biofilm. The studied Ca/Fe-LDH formulation showed no toxicity towards biofilm and even increased biomass, MCPA degradation activity, richness and diversity on zeolite. Particularly on Z, it promoted (Pseudomonas, Hyphomicrobium, Pseudoxanthomonas) or disadvantaged (Azohydromonas, Sphingopyxis, Parvibaculum) some bacterial species. This work thus highlights the possibility to improve pesticides biodegradation and adsorption by choosing appropriate carrier material and LDH covering.
Improvement of bioaugmentation technology to treat pesticide contaminated soils was tested by focusing on microbial inoculum preparation. For this, three natural carrier materials, oyster shell, pozzolana and zeolite, were evaluated for supporting the growth, activity and biodiversity of a MCPA (2-methyl-4-chlorophenoxyacetic acid) degrading microbial consortium as biofilm. The added value of modifying carrier materials surface using Layered Double Hydroxides (as Ca/Fe-LDHs) was also tested. All carrier materials supported the growth of biofilms displaying MCPA dissipation and mineralization in liquid medium and soil, with pozzolana and zeolite leading to highest dissipation rates. Bacterial diversity varied according to the carrier material and was the most apart in terms of diversity and richness on oyster shell. LDH covering itself led to partial MCPA dissipation suggesting MCPA adsorption on LDH, but total MCPA removal only occurred in the presence of biofilm. The studied Ca/Fe-LDH formulation showed no toxicity towards biofilm and even increased biomass, MCPA degradation activity, richness and diversity on zeolite. Particularly on Z, it promoted (Pseudomonas, Hyphomicrobium, Pseudoxanthomonas) or disadvantaged (Azohydromonas, Sphingopyxis, Parvibaculum) some bacterial species. This work thus highlights the possibility to improve pesticides biodegradation and adsorption by choosing appropriate carrier material and LDH covering.
BRGM