PI-129:

Random Mutation Enhances Degradation of Benzaldehyde by Rhodococcus jostii RHA1

Benzaldehyde is aromatic compound and found in nature such as plant. Benzaldehyde is used mainly as a precursor to other organic compounds, ranging from pesticide agents to plastic additives. Benzaldehyde contaminated water and soil, which lead to great pollution and result in health problem. Therefore, microorganism with biodegradation ability was gradually noticed by environmental restoration. The actinomycete Rhodococcus jostii RHA1 was isolated from lindane-contaminated soil and it was belong to a mycolic acid-containing suborder of actinobacteria. Rhodococcus jostii RHA1 is notable for its ability to degrade a wide range of aromatic compounds. We screened benzaldehyde degradation gene from Tn 917ac1 mutant library was constructed by Dr. Hao-Ping Chen. Interestingly, we found transposon mutant 1-3(BA1~BA3) with the ability to degrade 10 mM benzaldehyde but not wild type. Wild type can degrade 2 mM benzaldehyde only. We want to find the regulatory pathway of benzaldehyde degradation gene. First of all, we cloned benzaldehyde degradation gene by arbitrary PCR, inverse PCR and check the result by sequencing. The genome of RHA1 contains ro02797 and ro02986 * were annotated benzaldehyde dehydrogenase. RT-qPCR was employed to evaluate the expression of *ro02797 and ro02986 during growth of wild type and transposon mutant on 2 mM and 10 mM benzaldehyde. Expression of ro02797 and ro02986 in wild type were higher than mutant BA3 growth on 2 mM and 10 mM benzaldehyde. HPLC was employed to evaluate degradation of benzaldehyde between WT and mutant. Degradation of 2 mM and 10 mM benzaldehyde in BA3 mutant strains were more than WT strains. Together, these results provide new insights into the possible regulator pathway of benzaldehyde in *Rhodococcus jostii * RHA1.

keywords:*Rhodococcus jostii* RHA1,Benzaldehyde,Tn*917ac1*,RT-qPCR,HPLC