AUTHOR=Peng Shuang , Dolfing Jan , Feng Youzhi , Wang Yiming , Lin Xiangui 

TITLE=Enrichment of the Antibiotic Resistance Gene tet(L) in an Alkaline Soil Fertilized With Plant Derived Organic Manure

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01140

DOI=10.3389/fmicb.2018.01140

ISSN=1664-302X

ABSTRACT=<p>Fifteen antibiotic resistance genes (ARGs) and <italic>intI1</italic>, a gene involved in horizontal gene transfer (HGT) of ARGs, were quantified in three different soil samples from a 22 year old field experiment that had received inorganic fertilizer (NPK), organic manure (OM; a mixture of wheat straw, soybean oil cake and cotton cake), and control fields that had received no fertilizer and manure (CK). <italic>Tet</italic>(L) was the most abundant ARG in OM, which also contained considerable levels of <italic>intI1</italic>. Molecular analysis of yearly collected archived soils over the past 22 years showed that <italic>tet</italic>(L) and <italic>intI1</italic> were higher in OM soils than in NPK soils. The relative abundance of <italic>tet</italic>(L) was essentially constant during these years, while the level of <italic>intI1</italic> in OM soils decreased over time. The main genotype of <italic>tet</italic>(L) was the same in archived and in fresh soil, OM, and irrigation water. Phylogenetic analysis of the 16S rRNA genes of tetracycline-resistant bacteria (TRB) isolates indicated that the <italic>Firmucutes</italic> carrying <italic>tet</italic>(L) in OM were similar to those in the OM soil, suggesting that OM transferred TRB into the OM soils where they survived. Almost all of the TRB isolated from OM carried <italic>tet</italic>(L) and belonged to the <italic>Firmicutes</italic>. Survival of bacteria from the organic manure that carried <italic>tet</italic>(L) may be the cause of the increased level of <italic>tet</italic>(L) in OM soil.</p>