Abstract: A bacterial strain with high efficiency of degrading petroleum was scr eened from Liaohe oil field, and identified as Bacillus licheniformis. Oligo nucleotide probe was specifically designed for the 16S rRNA of B. licheniformi s, and fluorescence in situ hybridization (FISH) technique was applied for the microbial detection in bioslurry. The optimal FISH test conditions for the B. licheniformis in bioslurry were fixation time 17 h, hybridization temperature 46 ℃, formamide concentration in hybridization buffer 35%, and NaCl concentrat ion in washing buffer 88 mmol·L-1. The quantitative changes of B. licheniformis in bioslurry reactor were monitored by FISH on different sa mpling days, and the changes of oil concentration in bioslurry were measured on the same sampling days. The two test results represented good consistency with t he trend of petroleum biodegradation, suggesting the feasibility of using FISH t echnique for monitoring the changes of microorganisms in oil-containing sludge.

Key words: Runoff plot, Transport parameters, Spatial variability