Novel resources of chitinolytic bacteria isolated from Yok Don National Park, Vietnam.

Abstract

This study focused on the isolation and characterization of chitinolytic bacteria from Yok Don National Park, Vietnam for future studies regarding biofertilizers and biocontrol agents. Chitinolytic bacteria were isolated from soils and chitin flakes soaked in river water at the National Park. On the basis of the halo zones caused by colloidal chitin degradation and colony morphologies, 12 chitinolytic strains were chosen from 15 700 isolates for various examinations. Findings from 16S rDNA analysis indicated that among these strains, 10 could be identified as different species, and the remaining 2 showed less identity to known species and genera. The 12 bacteria possess numerous properties concerning plant growth promotion and/or phytopathogenic biocontrol. Paenibacillus chitinolyticus YSY-3.1, which exhibited the highest chitinase activity and remarkable properties for plant growth, was chosen for sequencing and draft genome analysis. The results showed that the genome is 6571 781bp in length with 6194 coding sequences, 52.2% G+C, and 96.53% ANI value. It harbors the chitinolytic system comprising 22 enzymes. Among these enzymes, PcChiQ has a loop structure different from that of known family 19 chitinases, PcChiA contains two GH18 catalytic domains rarely found in microorganisms, and PcChiF contains three GH18 catalytic domains that have never been reported. The 12 identified chitinolytic bacteria exhibit great potential for further studies on plant growth-promoting and/or biocontrol properties. Among these bacteria, two strains might be good candidates for next examinations concerning novel species and/or genera, and strain YSY-3.1 could possess a novel chitinolytic system.