Mycobacterium aviumGenes Associated with the Ability To Form a Biofilm

Mycobacterium aviumis widely distributed in the environment, and it is chiefly found in water and soil.M. avium, as well asMycobacterium smegmatis, has been recognized to produce a biofilm or biofilm-like structure. We screened anM. aviumgreen fluorescent protein (GFP) promoter library inM. smegmatisfor genes involved in biofilm formation on polyvinyl chloride (PVC) plates. Clones associated with increased GFP expression ≥2.0-fold over the baseline were sequenced. Seventeen genes, most encoding proteins of the tricarboxylic acid (TCA) cycle and GDP-mannose and fatty acid biosynthesis, were identified. Their regulation inM. aviumwas confirmed by examining the expression of a set of genes by real-time PCR after incubation on PVC plates. In addition, screening of 2,000 clones of a transposon mutant bank constructed usingM. aviumstrain A5, a mycobacterial strain with the ability to produce large amounts of biofilm, revealed four mutants with an impaired ability to form biofilm. Genes interrupted by transposons were homologues ofM. tuberculosis6-oxodehydrogenase (sucA), enzymes of the TCA cycle, protein synthetase (pstB), enzymes of glycopeptidolipid (GPL) synthesis, and Rv1565c (a hypothetical membrane protein). In conclusion, it appears that GPL biosynthesis, including the GDP-mannose biosynthesis pathway, is the most important pathway involved in the production ofM. aviumbiofilm.