Effect of Thermophilic Microbial Agents on Antibiotic Resistance Genes and Microbial Communities during Co-Composting of Pig Manure and Tea Stalks

Abstract

Antibiotic resistance caused by antibiotic resistance genes (ARGs) threatens human health. ARGs in animal manure can be degraded by composting. This study explored the changes in ARGs and microbial communities during co-composting of pig manure and tea stalks with (T) thermophilic microbial agents, including Geobacillus toebii ZF1 and Geobacillus sp. ZF2 for 15 days in a 4 L vacuum flask. Composting without thermophilic microbial agents served as control (CK). The results showed that the compost temperature of group T peaked at 72.1 °C and maintained above 70 °C for 4 days. The maximum temperature of group CK was 64.0 °C. The seed germination index showed that group T had reached maturity on day 9, while group CK reached maturity on day 15. The dominant bacteria in group CK were Bacillus. In group T, the dominant bacteria changed from Bacillus and Corynebacterium to Geobacillus. Compared with that of group CK, group T increased the removal of cmx, baeS and TaeA by 24.6%, 18.6% and 12.1%, respectively. Group T promoted and inhibited the removal of arlR and novA, respectively (p < 0.05), while group CK showed the opposite effect. Network analysis suggested that group T effectively inactivated Dietzia, Clostridium and Corynebacterium (p < 0.05) and promoted the removal of cmx and baeS. These results showed that thermophilic microbial agents could accelerate the maturation of pig manure and tea stalks, change microbial communities and promote the removal of ARGs. It is of great significance to reduce the spread of ARGs and, in turn, human health risks.

Effect of Thermophilic Microbial Agents on Crude Fiber Content, Carbohydrate-Active Enzyme Genes, and Microbial Communities during Chinese Medicine Residue Composting

“…Origin 2021 was used to plot data. The specific parameter settings were consistent with those in previous studies …”

“…Similarly, the method for gene prediction was consistent with that in previous studies, but the removed host DNA sequences needed to be changed to the following sequences:…”

“…Based on identical dry weights, three groups of parallel samples from each experiment were evenly mixed and sent to Majorbio Bio-Pharm Technology Co., Ltd. (Shanghai, China) for metagenomic sequencing. We used Illumina HiSeq sequencing during metagenomic sequencing, and the reagents and methods were consistent with those in previous studies . The original data obtained after sequencing are stored at NCBI () under accession number SRP364545.…”

“…Each collected sample was divided into two parts: one part was stored at 4 °C for the determination of Temperature, water content, pH, electrical conductivity (EC), seed germination index (GI), total organic carbon (TOC), total nitrogen (TN), and the ratio of TOC to TN (C/ N) were determined in accordance with methods reported in our previous study. 21 In addition, the method for cellulose, hemicellulose, and lignin determination was as follows: a filter paper bag was dried, weighed, and denoted m0 (unit: mg). A sample was dried to a constant weight, 1000 mg of dry matter from the sample was placed in the filter paper bag, and then, the filter paper bag was placed in a Soxhlet extractor and extracted with pure water for 6 h. At the end of the extraction, the filter paper bags were dried to a constant weight and then extracted with absolute ethanol for 6 h. At the end of the extraction, the filter paper bag was dried to a constant weight and weighed.…”

“…We used Illumina HiSeq sequencing during metagenomic sequencing, and the reagents and methods were consistent with those in previous studies. 21 The original data obtained after sequencing are stored at NCBI (https:// www.ncbi.nlm.nih.gov/) under accession number SRP364545.…”