China Animal Husbandry & Veterinary Medicine ›› 2025, Vol. 52 ›› Issue (6): 2839-2850.doi: 10.16431/j.cnki.1671-7236.2025.06.036

• Basic Veterinary Medicine • Previous Articles     Next Articles

Isolation and Identification of a High-temperature Tolerant Bacillus thermoamylovorans and Optimization of Its Enzyme Production Conditions

YANG Qinhong1, YANG Jia1, DUAN Wenjie1, ZHANG Yongxian2, ZHU Youshuai2, YANG Shaohong3, HE Cheng4, YIN Hongbin2, LI Suhua1   

  1. 1. College of Biological Science and Food Engineering, Southwest Forestry University, Kunming 650224, China;
    2. Animal Disease Inspection and Supervision Institution of Yunnan Province, Kunming 650051, China;
    3. Shangri-La City Agricultural and Rural Affairs Bureau Animal Health Supervision Office, Shangri-La 674400, China;
    4. Nujiang Animal Disease Prevention and Control Center, Lushui 673200, China
  • Received:2024-10-14 Published:2025-05-27

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Abstract: 【Objective】 This study was conducted to isolate high-temperature protease-producing strains from the fermentation reactor of rendering by-product of animal carcass meat and bone residue,and study their protease activity,with the aim of providing a theoretical basis and research strategy for the degradation and utilization of proteins in meat and bone residues.【Method】 High-temperature culture conditions were established,and high-temperature tolerant protease-producing strain was assessed using casein plate hydrolysis and the Folin phenol method.Strains were identified through 16S rRNA sequencing.Thermal acclimation and UV mutation were employed to enhance the strain’s heat resistance and protease activity.Optimal enzyme production conditions were explored using single-factor and response surface methodology.【Result】 A high-temperature protease-producing strain,Bacillus thermoamylovorans R4.1,was isolated from rendering-processed meat and bone residues.UV mutation increased the protease activity by 40.92%.Thermal acclimation raised the optimal growth and enzyme production temperature of the strain from 50 to 65 ℃.Single-factor experiments indicated that the strain’s protease activity was significantly influenced by fermentation time,pH,NaCl concentration and Ca2+ concentration.Response surface optimization determined the optimal enzyme production conditions to be fermentation at 65 ℃ for 96.36 h,pH 8.02,NaCl concentration of 0.59%,Ca2+ concentration of 1.11%,and an inoculum size of 1%,under which the protease activity reached 55.08 U/mL.Compared to the original strain,the enzyme activity increased by 1.96 times.Additionally,the strain demonstrated a weight reduction rate of 12.30% in meat and bone meal after 120 h,with a crude protein content decrease of 11.06%.【Conclusion】 Bacillus thermoamylovorans R4.1 exhibited high protease activity at elevated temperatures and could effectively degrade proteins in meat and bone meal,indicating promising application potential.

Key words: Bacillus thermoamylovorans; high-temperature tolerant screening; isolation and identification; protease production conditions

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