Screening and identification of IAA-capable and cellulose-degrading bacteria with the potential for plant growth-promoting traits

Strains with both straw degradation and plant growth promotion ability were selected from the cultivated soil in Bac Kan, Vietnam to solve the problems of poor soil microbial diversity status, weak corrosion promotion effect, and poor crop growth caused by fungal rot diseases. Among seventeen bacteria isolated, strain NR1 presented the highest value for cellulase enzyme activity (Hydrolysis index = 24.8 mm), and IAA production (20.15 mg l-1), and was identified as Bacillus amyloliquefaciens Priest et al., 1987. Inoculation with NR1 significantly increased the rot promotion rate of straw under liquid fermentation by 54.71 % compared with the control and increased the root length and average diameter, and SPAD value of maize under soil culture by 18.3 %, 22.0 %, and 5.24 % respectively (p < 0.05). In addition, fertilizing 8 or 9 tons of NR1-degraded compost fertilizer per hectare had the best effect on the growth, development, and productivity of the L14 peanut variety. These results suggest strain NR1 could be used to produce multi-functional humus, accelerate the decomposition of straw in the cultivated soil, and promote crop growth.