Inoculation of thermophilic bacteria from giant panda feces into cattle manure reduces gas emissions and decreases resistance gene prevalence in short-term composting

Jingxia Fu; Shujuan Chen; Yulan Tan; Keyi Zou; Xiumei Yu; Lin Ji; Jianmin Zhang; Xingning Xiao; Wen Wang; Ke Zhao; Likou Zou

doi:10.1016/j.jenvman.2024.123601

Inoculation of thermophilic bacteria from giant panda feces into cattle manure reduces gas emissions and decreases resistance gene prevalence in short-term composting

J Environ Manage. 2024 Dec 5:373:123601. doi: 10.1016/j.jenvman.2024.123601. Online ahead of print.

Authors

Jingxia Fu¹, Shujuan Chen², Yulan Tan³, Keyi Zou⁴, Xiumei Yu⁴, Lin Ji⁴, Jianmin Zhang⁵, Xingning Xiao⁶, Wen Wang⁷, Ke Zhao⁸, Likou Zou⁹

Affiliations

¹ College of Environmental Science, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China; College of Resources, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
² College of Food Science, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
³ College of Resources, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China; School of Life Sciences, Guizhou Normal University, Guiyang, 550025, Guizhou, China.
⁴ College of Resources, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
⁵ College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, Guangdong, China.
⁶ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, MOA Laboratory of Quality & Safety Risk Assessment for Agro-products (Hangzhou), Institute of Agro-product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
⁷ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, MOA Laboratory of Quality & Safety Risk Assessment for Agro-products (Hangzhou), Institute of Agro-product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China. Electronic address: ww_hi1018@163.com.
⁸ College of Resources, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China. Electronic address: zkfish@163.com.
⁹ College of Resources, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China. Electronic address: zoulikou@sicau.edu.cn.

PMID: 39642832
DOI: 10.1016/j.jenvman.2024.123601

Abstract

Here, thermophilic bacteria (TB) with cellulose degradation functions were screened from composting panda feces and applied to cattle manure composting. TB (Aeribacillus pallidus G5 and Parageobacillus toebii G12) inoculation led to remarkable improvement of the compost temperature, prolonging of the thermophilic stage and shortening of the composting process, resulting in increased manure harmlessness (GI ≥ 70%), compost humification, and greenhouse gas emission reduction (14.19%-22.57%), compared with the control compost, within 15 days of composting. In particular, G5 inoculation reduced NH₃ emissions by 41.97% relative to control composts over 15 days. G5 was capable of rapidly colonizing in the composts, and its inoculation immediately enriched the genera of Firmicutes, and simultaneously decreased the genera of Proteobacteria, contributing to the elimination of harmful microorganisms. Notably, this strain lacked antibiotic resistance genes, and the absolute abundances of resistance genes and mobile genetic genes (MGEs) decreased the most (by 80.84%). Metagenomic analysis revealed that enzymes capable of producing CO₂, N₂O, and NH₃ were generally inhibited, while CO₂ fixation and N₂O and NH₃ reduction enzymes were enriched in the G5 compost, since metagenome-assembled genomes of Proteobacteria harbored more key genes and enzymes in complete pathways for producing N₂O, NH₃, and CO₂. Moreover, Proteobacteria, such as Pseudomonas and Halopseudomonas, were the main host of resistance genes and MGEs. Overall, the gas emission could be reduced, and more efficient control of resistance genes could be achieved by inhibited the abundance of Proteobacteria during composting. This study provides a safe and effective microbial agent (A. pallidus) for manure treatment.

Keywords: Aerobic composting; Greenhouse gas; Resistance genes; Thermophilic bacteria.