Acta Veterinaria et Zootechnica Sinica ›› 2020, Vol. 51 ›› Issue (5): 1126-1137.doi: 10.11843/j.issn.0366-6964.2020.05.024

• BASIC VETERINARY MEDICINE • Previous Articles     Next Articles

Response of Antibiotic Resistance Genes (ARGs) in Rumen of Yak to Three Exogenous Stimulating Factors

ZHAO Jiaqi1, WEN Yongli1*, AN Yajing1, LI Ziqian1, QI Peisen1, LI Qiang2, HOU Dingchao3   

  1. 1. Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu 610041, China;
    2. Sichuan Animal Husbandry Station, Chengdu 610041, China;
    3. Animal Husbandry and Veterinary Service Center of Jinchuan Country, Jinchuan 624100, China
  • Received:2019-09-16 Online:2020-05-25 Published:2020-05-16

Abstract: This study aimed to analyze the effects of three exogenous stimulating factors on the species, resistance types, and resistance mechanisms, etc. of antibiotic resistance genes (ARGs) by feeding yak with cefquinome (CEF), difloxacin (DIF), and aflatoxin B1 (AFB1), and sequence the rumen microorganisms by metagenomics. It is important to study the characteristics and resistance mechanisms of microbial antibiotic resistome or resistance reservoirs. Fifteen yaks were selected and randomly divided into 5 groups. According to the recommended dosage of the instructions, the Cef group and the Dif group were orally administered with CEF 1 mg·kg-1 and DIF 1 mL·kg-1, respectively. E1 groups and E2 groups were fed AFB1 20 and 60 μg·kg-1, respectively. Group C was the control group. The rumen fluid samples of yaks were collected 7 days after treatment and DNA was extracted. The DNA was sequenced by Illumina HiSeq. After standardizing the reads counts, the TPM was obtained. An analysis of variance was performed on the TPM. The results showed that 132 ARGs were obtained in the control group, belonging to 30 resistance types, among which the abundance of tetracycline tetQ and tetW genes was higher. The abundance of tetW gene in Cef group increased (P<0.05). The abundance of tetQ in Dif group increased (P<0.05). The abundance of tetracycline antibiotic and cephalosporin antibiotic resistance genes in Cef group increased (P<0.05). The abundance of tetracycline antibiotic and aminocoumarin antibiotic resistance genes in Dif group increased (P<0.05). The abundance of aminocoumarin antibiotic and penem antibiotic resistance genes in the E1 group increased (P<0.05). The abundances of 9 resistance genes such as penems antibiotic and cephalosporins antibiotic in E2 group increased (P<0.05). The abundance of Erm 23S ribosomal RNA methyltransferase in Dif group increased (P<0.05). The abundance of three resistance mechanisms such as ATP-binding cassette (ABC) antibiotic efflux pump in E2 group increased (P<0.05). All three treatments significantly increased the host species of tetracycline antibiotic resistance genes. In conclusion:The rumen is a rich library of ARGs, in which tetQ and tetW are dominant ARGs. Not only CEF, DIF increase the abundance of some ARGs species, resistance types and enzymes related to resistance mechanisms, thereby increasing rumen microbial resistance, but also AFB1 has a similar effect. Moreover, the high-dose AFB1 has a greater range of effects on antibiotic resistance than antibiotics. These three factors also increase types of host microorganisms carrying tetracycline antibiotic resistance gene, thereby enhancing the horizontal gene transfer, accelerating the spread of ARGs, and enhancing the resistance of microorganisms to tetracycline antibiotics.

Key words: rumen microorganisms, antibiotic resistance genes (ARGs), metagenome, difloxacin, cefquinome, aflatoxin B1, yak

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