Rhizosphere activity of cattail (Typha latifolia) and spike rush (Eleocharis tuberculosa) inhabiting an oil spill

The esterase activity and populations of soil microorganisms inhabiting cat tail (Typha latifolia) and spike rush (Eleocharis tuberculosa) stands growi ng in a crude oil and brine spill within the Roy E. Larsen Sandyland Sanctu ary, Silsbee, Texas were investigated. Rhizosphere and non-rhizosphere soil samples were analyzed for populations of total bacteria, gram-negative bac teria, fungi and actinomycetes, and soil esterase: activity. No significant differences among population numbers were found within the microorganism c ategories. Esterase activity was significantly higher in soils collected ou tside the contaminated site than within. Twenty-four potential crude oil de graders ware isolated from the soil samples and screened for growth on dies el, pentane and anthracene and tolerance to NaCl. Twelve and five isolates utilized diesel and pentane, respectively, as sole carbon sources while non e utilized anthracene. All, 23, 17 and 10 of the isolates were found to be tolerant of 0.85, 5, 10 and 15% salt, respectively. Although microbial popu lations were not affected by the spill, microbial activity was significantl y reduced within the impacted site. This may hinder the ability of hydrocar bon degraders indigenous to the spill site to decompose the oil contaminant s.