Phylogenetic Analysis of Polygalacturonase-Producing Bacillus and Pseudomonas Isolated From Plant Waste Material

BACKGROUND Keeping in mind the commercial application of polygalacturonase (PG) in juice and beverages industry, bacterial strains were isolated from rotten fruits and vegetables to screen for competent producers of PG. OBJECTIVES In this study, the plate method was used for preliminary screening of polygalacturonase-producing bacteria, while the Dinitrosalicylic Acid (DNS) method was used for quantifications of PG. MATERIALS AND METHODS Biochemically-identified polygalacturonase-producing Bacillus and Pseudomonas species were further characterized by molecular markers. The genetic diversity among these selected strains was analyzed by investigating microsatellite distribution in their genome. Out of 110 strains, 17 competent strains of Bacillus and eight strains of Pseudomonas were selected, identified and confirmed biochemically. Selected strains were characterized by 16S rRNA sequencing and data was submitted to the national center for biotechnology information (NCBI) website for accession numbers. RESULTS Among the Bacillus, Bacillus vallismortis (JQ990307) isolated from mango was the most competent producer of PG; producing up to 4.4 U/µL. Amongst Pseudomonas, Pseudomonas aeruginosa (JQ990314) isolated from oranges was the most competent PG producer equivalent to B. vallismortis (JQ990307). To determine genetic diversity of different strains of Pseudomonas and Bacillus varying in PG production, fingerprinting was done on the basis of Simple Sequence Repeats (SSR) or microsatellites. The data was analyzed and a phylogenetic tree was constructed using the Minitab 3 software for comparison of bacterial isolates producing different concentrations of PG. Fingerprinting showed that presence or absence of certain microsatellites correlated with the ability of PG production. CONCLUSIONS Bacteria from biological waste were competent producers of PG and must be used on an industrial scale to cope with the demand of PG in the food industry.