Influence of oxytetracycline on the structure and activity of microbialcommunity in wheat rhizosphere soil
YANG Qingxiang , ZHANG Jing , ZHU Kongfang , ZHANG Hao
DOI:
Received August 29, 2008,Revised November 10, 2008, Accepted , Available online
Volume 21,2009,Pages 954-959
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The microbial community composition in wheat rhizosphere was analyzed by detecting colony forming units (CFUs) in agar plates.
The total CFUs in rhizosphere were 1.04 109/g soil with 9.0 108/g bacteria, 1.37 108/g actinomyces and 3.6 106/g fungi. The 10
dominant bacteria were isolated from wheat rhizosphere and were grouped into genus Bacillus according to their full length 16S rRNA
gene sequences. Although belonging to the same genus, the isolated strains exhibited di erent sensitivities to oxytetracycline. When
a series of the rhizosphere soil was exposed under various concentrations of oxytetracycline, the microbial community structure was
highly a ected with significant decline of CFUs of bacteria and actinomyces (22.2% and 31.7% at 10 mg/kg antibiotic, respectively).
This inhibition was clearly enhanced with the increase exposure dosage of antibiotic and could not be eliminated during 30 d incubation.
There was no obvious influence of this treatment on fungi population. Among the four soil enzymes (alkaline phosphatase, acidic
phosphatase, dehydrogenase and urease), only alkaline phosphatase was sensitive to oxytetracycline exposure with 41.3% decline of
the enzyme activity at 10 mg/kg antibiotic and further decrease of 64.3%–80.8% when the dosage over 30 mg/kg.
