Molecular identification of cellulose-degrading bio-control Bacillus strains and their stress-resistance and growth-promoting characteristics

Abstract:

[Objective] Bio-control Bacillus resource with cellulose-degrading research in special ecological environment of Qinghai-Tibetan Plateau was explored in this research. [Methods] Five Bacillus strains isolated from rhizosphere of birch in Huzhu Northern Mountain of Qinghai Province, were identified by molecular taxonomy methods including BOX-PCR fingerprints, as well as gyrB and 16S rRNA gene partial sequence analysis. Cellulose-degrading activity of these isolates were detected by CMC plate screening method, and antagonistic activity to pathogenic fungi and bacteria were checked by plate confrontation method. Furthermore, growth-promoting and stress-resistance activity of isolates including salt-resistance and low-temperature adaptability were tested. [Results] Five isolates were identified as Bacillus amyloliquefaciens and all of isolates presented distinguished cellulose-degrading activity and could form transparent zone (diameter ≥20 mm) of cellulose-degrading on CMC medium. Isolates presented distinct antagonistic activity and bio-control efficacy to Sclerotinia sclerotiorum, Fusarium oxysporum, Xanthomonas oryzae pv. oryzae and Erwinia amylovora. Strains could grow under the condition of 10 °C low-temperature as well as LB medium with 11% NaCl concentration, and bacterial cell suspension (concentration of 106 CFU/mL) of strains BS11 and BS12 could promote seed germination and seedling-growth of rice. [Conclusion] Five B. amyloliquefaciens strains own advantage with stress-resistance, cellulose-degrading and bio-control characteristic, thus possess application potential in ecological agriculture and animal husbandry field in Qinghai Province.