Optimization for Production of a Plant Growth Promoting Agent from the Degradation of Chicken Feather Using Keratinase Producing Novel Isolate Bacillus pumilus JYL

Abstract

Feather is a good source of nitrogen but the highly rigid structure limits its utilization and leads to environmental pollution and resource wastage. Traditional feather degradation processes such as alkali hydrolysis and steam pressure cooking not only destroy the amino acids but also consume large amounts of energy. Therefore, searching for feather degrading bacteria to transform feather waste to nitrogen fertilizer to improve soil and plant growth is needed. And this also will solve the soil nitrogen deficiency problem in China. In this study, a bacteria that could degrade feather and promote plant growth was isolated from soil sample using dilution plate method. And the isolated bacteria was identified as Bacillus pumilus JYL according to its morphology, biochemical characteristics and 16S rRNA sequence. And the maximum keratinase activity (57.14 U/mL) was obtained under optimal conditions of 0.036% FeSO4, 0.025% MgSO4, 0.073% K2HPO4, 0.5% feather with 2% inoculant at pH 6.5 fermented for 36 h at 35 ℃ after optimization using (response surface methodology) RSM. The effect of hydrolyzate on wheat seed germination and growth was studied. The results showed that germination engergy and germination index with 3% feather hydrolyzate addition group was 94.22% and 87.52%, significantly higher than that of the control group (p < 0.05), respectively. The plant height, root length, fresh weight and dry weight in the T2 treatment (added 5 mL feather hydrolysate in 100 g soil) at 60th day were 1.10, 1.16, 1.77 and 1.73 times than that in the CK treatment (without addition of hydrolysate), respectively. And the soil enzyme activities in all treatment groups (T1, T2, T3) significantly increased compared with control group (CK) (p < 0.05). This result will provide a potential utilization method for feather valoration.