ABSTRACT

At the spring, goat and sheep herds are transferred to planted forests, in a semi-arid region in the northern Negev Desert, Israel, to reduce herbaceous biomass and, fire risk. The herds are held overnight in corrals for about 4 months, enriching the soil with organic matter and nitrogen. This research examined the effect of these enrichments on soil bacterial community structure (BCS) and the abundance of tetracycline resistance genes (TRGs) in active and abandoned corrals (1–10-years-old). Based on 16S rRNA gene sequences, the Proteobacteria and Actinobacteria phyla dominated the soil of all corrals. The Actinobacteria were less abundant in the active and 1-year-old corrals (23–26%) than in the other corrals and the control (33–38%). A principal component analysis showed that, the BCS in the active and the 1-year-old abandoned corrals was significantly different from that in the older corrals and the control. The Firmicutes phylum constituted 28% of the BCS in the active corrals, 12.5% in the 1-year-old corrals and 2% in the older corrals and the control. In contrast, the Acidobacteria phylum was hardly detected in the active and 1-year-old abandoned corrals and constituted 10% of the BCS in the older corrals. Genes conferring resistance to tetracycline were detected in high numbers. The tetG and tetW genes were detected in the active and abandoned corrals (1–10 years). The tetQ gene was detected only in the active and 1-year-old abandoned corrals. None of the genes were detected in the control soil. The three genes were detected outside an active corral, in the downstream section of an ephemeral tributary. The results prove that abandoned and unobserved periodic animal corrals are an environmental reservoir for TRGs.

中文翻译：

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半干旱人工林动物畜栏土壤中四环素抗性基因的持久性和传播及微生物群落变异

摘要

在春天，山羊和绵羊群被转移到以色列内盖夫沙漠北部半干旱地区的人工林中，以减少草本生物量和火灾风险。牛群在畜栏里过夜约 4 个月，用有机物质和氮丰富土壤。这项研究检查了这些富集对土壤细菌群落结构 (BCS) 和活跃和废弃畜栏（1-10 年）中四环素抗性基因 (TRG) 丰度的影响。根据 16S rRNA 基因序列，变形菌门和放线菌门在所有畜栏的土壤中占主导地位。该放线菌与其他畜栏和对照（33-38%）相比，活跃和 1 岁的畜栏（23-26%）中的含量较少。主成分分析表明，活动和1岁废弃畜栏的BCS与旧畜栏和对照的BCS显着不同。的厚壁菌门构成在活性畜栏的BCS的28％，在1岁畜栏12.5％和在旧畜栏和控制2％。相比之下，在活跃的和 1 年的废弃畜栏中几乎没有检测到酸杆菌门，占旧畜栏 BCS 的 10%。大量检测到赋予四环素抗性的基因。该tetG和tetW在活跃和废弃的畜栏（1-10 年）中检测到基因。该tetQ检测仅在激活和1岁被遗弃的畜栏基因。在对照土壤中没有检测到基因。这三个基因是在一个活跃的畜栏外被检测到的，在一个短暂的支流的下游部分。结果证明，被遗弃和未被观察到的周期性动物畜栏是 TRG 的环境储存库。