Genomic insights into the antibiotic resistance pattern of the tetracycline-degrading bacterium, Arthrobacter nicotianae OTC-16

Although many bacteria have the potential to remove antibiotic residues from environmental niches, the benefits of using antibiotic-degrading bacteria to manage antibiotic pollution should be assessed against the risk of the potential expansion of antimicrobial resistance. This study investigated the antibiotic resistance pattern of the bacterium Arthrobacter nicotianae OTC-16, which shows substantial biodegradation of oxytetracycline (OTC)/tetracycline. The results showed that this strain could be resistant to at least seven categories of 15 antibiotics, based on antimicrobial susceptibility testing. The genome of A. nicotianae OTC-16 contains one chromosome (3,643,989 bp) and two plasmids (plasmid1, 123,894 bp and plasmid2, 29,841 bp). Of the 3,561 genes isolated, eight were related to antibiotic resistance. During OTC degradation by the strain OTC-16, the expression of ant2ia, sul1, tet33, and cml_e8 in the plasmid, and one gene (tetV) in the chromosome were tracked using real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Only the plasmid-derived resistance genes were up-regulated in the presence of OTC. The presence of OTC increased the tolerance of strain OTC-16 to streptomycin sulphate. The findings of this study can help deepen our understanding of the behavioural characteristics of resistance genes and adaptive evolution of drug-resistant bacteria.

Genomic Insights Into Antibiotic Resistance Pattern of Tetracycline Degrading Bacterium Arthrobacter Nicotianae OTC-16

Although many bacteria have the potential to remove antibiotic residues from environmental niches, the benefits of using antibiotic degrading bacteria to manage antibiotic pollution should be assessed against the risk of the potential expansion of antimicrobial resistance. This study investigated the antibiotic resistance pattern of the bacterium Arthrobacter nicotianae OTC 16, which shows substantial biodegradation of oxytetracycline/tetracycline. The results showed that this strain could be resistant to at least seven categories, 15 antibiotics, based on antimicrobial susceptibility testing. The genome of A. nicotianae OTC 16 contains one chromosome(3,643,989 bp) and two plasmids (plasmid1,123,894 bp and plasmid2, 29,841bp). Of the 3,561 genes isolated, eight were related to antibiotic resistance. During oxytetracycline (OTC) degradation by the strain OTC 16, the expression of ant2ia, sul1, tet33, and cml_e8 in the plasmid, and one gene(tetV) in the chromosome were tracked by real time quantitative reverse transcription polymerase chain reaction(qRT PCR). Only the plasmid derived resistance genes were up regulated under the pressure of OTC. The presence of OTC increased the tolerance of strain OTC 16 to streptomycin sulphate. This work deepens our understanding of the behavioural characteristics of resistance genes and adaptive evolution of resistant drug bacteria under the pressure of antibiotics.

Characteristics of Heterotrophic Nitrifying and Aerobic Denitrifying Arthrobacter nicotianae D51 Strain in the Presence of Copper

A heterotrophic nitrification and aerobic denitrification bacterium, strain D51, was identified as Arthrobacter nicotianae based on morphological, phospholipid fatty acids (PLFAs), and 16S rRNA gene sequence analyses. Further tests demonstrated that strain D51 had the capability to use nitrite, nitrate, or ammonium as the sole nitrogen source in the presence of Cu2+. The maximum removal efficiencies of nitrite, nitrate and ammonium were 68.97%, 78.32%, and 98.70%, respectively. Additionally, the maximum growth rate and denitrification capacity of this strain occurred in the presence of 0.05 mg·L−1 of Cu2+.However, the growth and aerobic denitrification capacity were intensively inhibited by Cu2+ at ≥0.1 mg·L−1. Moreover, gas chromatography indicated that a portion of the nitrogen was transformed into N2O when the nitrite, nitrate, and ammonium were separately used as the sole nitrogen source. This is the first study of the nitrification and denitrification ability of Arthrobacter nicotianae under aerobic conditions, and the first experiment to investigate the impact of Cu2+ concentration on the growth and denitrification ability of this bacteria. The results presented herein extend the known varieties of heterotrophic nitrifying–aerobic denitrifying bacteria and provide useful information regarding the specific bacteria for nitrogen bioremediation of industrial wastewater containing Cu2+.