Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan.
Department of Microbiology, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan.
World J Microbiol Biotechnol. 2023 Feb 9;39(4):94. doi: 10.1007/s11274-023-03532-4.
Natural pristine environments including cold habitats are thought to be the potent reservoirs of antibiotic-resistant genes and have been recurrently reported in polar glaciers' native bacteria, nevertheless, their abundance among the non-polar glaciers' inhabitant bacteria is mostly uncharted. Herein we evaluated antibiotic resistance profile, abundance of antibiotic-resistant genes plus class 1, 2, and 3 integron integrases in 65 culturable bacterial isolates retrieved from a non-polar glacier. The 16S rRNA gene sequencing analysis identified predominantly Gram-negative 43 (66.15%) and Gram-positive 22 (33.84%) isolates. Among the Gram-negative bacteria, Gammaproteobacteria were dominant (62.79%), followed by Betaproteobacteria (18.60%) and Alphaproteobacteria (9.30%), whereas Phyla Actinobacteria (50%) and Firmicutes (40.90%) were predominant among Gram-positive. The Kirby Bauer disc diffusion method evaluated significant antibiotic resistance among the isolates. PCR amplification revealed phylum Proteobacteria predominantly carrying 21 disparate antibiotic-resistant genes like; AmpC 6 (100%), VIM-1, SHV and DHA 5 (100%) each, OXA-1 1 (100%), CMY-4 4 (100%), followed by Actinobacteria 14, Firmicutes 13 and Bacteroidetes 11. Tested isolates were negative for KPC, qnrA, vanA, ermA, ermB, intl2, and intl3. Predominant Gram-negative isolates had higher MAR index values, compared to Gram-positive. Alignment of protein homology sequences of antibiotic-resistant genes with references revealed amino acid variations in NDM-1, OXA-1, SHV, mecA, aac(6)-Ib3, tetA, tetB, sul2, qnrB, gyrA, and intI1. Promising antibiotic-resistant bacteria, harbored with numerous antibiotic-resistant genes and class 1 integron integrase with some amino acid variations detected, accentuating the mandatory focus to evaluate the intricate transcriptome analysis of glaciated bacteria conferring antibiotic resistance.
自然原始环境，包括寒冷栖息地，被认为是抗生素耐药基因的强大储存库，并且已经在极地冰川的本地细菌中反复报道，然而，它们在非极地冰川栖息细菌中的丰度大多是未知的。在此，我们评估了从非极地冰川中分离的 65 个可培养细菌分离物的抗生素耐药谱、抗生素耐药基因的丰度以及 1 类、2 类和 3 类整合子整合酶。16S rRNA 基因测序分析鉴定出主要为革兰氏阴性菌 43 株（66.15%）和革兰氏阳性菌 22 株（33.84%）。在革兰氏阴性菌中，γ-变形菌门占主导地位（62.79%），其次是β-变形菌门（18.60%）和α-变形菌门（9.30%），而革兰氏阳性菌中优势菌门为放线菌门（50%）和厚壁菌门（40.90%）。Kirby Bauer 圆盘扩散法评估了分离物的显著抗生素耐药性。PCR 扩增显示，变形菌门主要携带 21 种不同的抗生素耐药基因，如 AmpC-6（100%）、VIM-1、SHV 和 DHA-5（100%）各、OXA-1-1（100%）、CMY-4-4（100%），其次是放线菌 14 株、厚壁菌 13 株和拟杆菌 11 株。测试的分离物均为阴性 KPC、qnrA、vanA、ermA、ermB、intl2 和 intl3。主要革兰氏阴性菌的 MAR 指数值高于革兰氏阳性菌。与参考序列比对抗生素耐药基因的蛋白质同源性序列表明，NDM-1、OXA-1、SHV、mecA、aac(6)-Ib3、tetA、tetB、sul2、qnrB、gyrA 和 intI1 中的氨基酸发生了变异。存在大量抗生素耐药基因和 1 类整合子整合酶的有前途的抗生素耐药细菌，并且检测到一些氨基酸变异，强调了必须关注评估冰川细菌的复杂转录组分析，这些细菌赋予了抗生素耐药性。
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