Biodegradation of benzoate by protoplast fusant via intergeneric protoplast fusion between Pseudomonas putida and Bacillus subtili

Intergeneric protoplast fusion was performed between Pseudomonas putida, a strain with moderate benzoate tolerance and degradation ability (<2000 mg l−1) while slow growth rate (specific growth rate μ = 4.5 × 10−3 h−1) and Bacillus subtilis, a strain with fast growth rate while intolerance to benzoate. A stable fusant (F29) with enhanced benzoate tolerance (as high as 10 000 mg l−1) and degradation ability (μ = 30.9 × 10−3 h−1) was obtained. The fusant is similar to P. putida in terms of amplified 16S ribosomal DNA restriction analysis (16S-ARDRA) and 16S rDNA clone sequencing analysis while alike to B. subtilis according to Gram staining. Possible biodegradation pathway of benzoate by F29 is benzene ring cleavage between two hydroxyl groups (ortho cleavage) with catechol being intermediate metabolite. However, the verification of benzoate biodegradation mechanism by this fusant requires further investigation.