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Zhang X, Ding Z, Usman S, Zhang J, Chen M, Guo X. Metagenomics insights into the effects of lactic acid bacteria inoculation on the biological reduction of antibiotic resistance genes in alfalfa silage. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130329. [PMID: 36444055 DOI: 10.1016/j.jhazmat.2022.130329] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/01/2022] [Accepted: 11/03/2022] [Indexed: 06/16/2023]
Abstract
Antibiotic resistance genes (ARGs) are a new type of pollutant and pose major threats to public health. However, the distribution and transmission risk of ARGs in alfalfa silage as the main forage for ruminants have not been studied. This study first deciphered the effects of Lactobacillus plantarum MTD/1 or Lactobacillus buchneri 40788 inoculations on distribution and transmission mechanism of ARGs in alfalfa silage by metagenomics. Results showed that multidrug and bacitracin resistance genes were the dominant ARGs in ensiled alfalfa. The natural ensiling process increased the abundances of bacitracin, beta_lactam, and aminoglycoside in alfalfa silage with 30% DM, and vancomycin in alfalfa silage with 40% DM. Meanwhile, prolonged wilting increased ARG enrichment in fresh alfalfa. Interestingly, alfalfa silage inoculated with L. plantarum MTD/1 or L. buchneri 40788 reduced the abundances of total ARG, and multidrug, MLS, vancomycin, aminoglycoside, tetracycline, and fosmidomycin resistance genes by reductions of the host bacteria and the enrichment of ARGs located in the plasmid. The hosts of ARG in alfalfa silage were mainly derived from harmful bacteria or pathogens, and some of the clinical ARGs were observed in alfalfa silage. Basically, the combined effect of microbes, MGEs, and fermentation quality was the major driver of ARG transfer and dissemination in microecosystem of ensiling, where the microbes appeared to be the crucial factor. In summary, inoculation with the present lactic acid bacteria could reduce ARG abundance in ensiled alfalfa, and a better effect was observed in L. plantarum-treated silage than in L. buchneri treated silage.
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Affiliation(s)
- Xia Zhang
- State Key Laboratory of Grassland and Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China
| | - Zitong Ding
- State Key Laboratory of Grassland and Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China
| | - Samaila Usman
- State Key Laboratory of Grassland and Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, PR China
| | - Jiayao Zhang
- State Key Laboratory of Grassland and Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China
| | - Mengyan Chen
- State Key Laboratory of Grassland and Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China
| | - Xusheng Guo
- State Key Laboratory of Grassland and Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China.
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Effect of Homo-Fermentative Lactic Acid Bacteria Inoculants on Fermentation Characteristics and Bacterial and Fungal Communities in Alfalfa Silage. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8110621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We evaluated the effects of a homo-fermentative lactic acid bacteria (homo-LAB) inoculant on the fermentation and microbial communities of alfalfa ensiled at two dry matter (DM) contents of 38 and 46% DM. At both DMs, alfalfa was treated or not with an inoculant containing Pediococcus acidilactici, Enterococcus faecium and Lactobacillus plantarum at a targeted application rate of 165,000 cfu/g of fresh weight and stored for 3, 30 and 60 days. Treatment with the inoculant resulted in a lower drop in pH and, in general, higher lactic acid and lower acetic acid when applied to medium DM silage. For the four most abundant microbial genera, increased abundances of Bacteroides and Lactobacillus (p < 0.05), as well as decreased abundances of Muribaculaceae were observed in high DM and inoculated silages. The abundance of Prevotellaceae-UCG-001 was lower in medium DM control silages than in high DM control silages. Inoculation and DM affected abundances of Vishniacozyma (p < 0.05). Increased abundances of Vishniacozyma, as well as decreased abundances of Leucosporidium were observed in medium DM-inoculated silages. Changes in the relative abundance (RA) of the main populations of bacteria and yeasts did explain the fermentation and nutrition differences among treatments.
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