Rhizosphere microbial populations in contaminated soils

• Published in: Water, air, and soil pollution air, and soil pollution, 1997-04, Vol.95 (1-4), p.165-178
• Main Authors: Nichols, T.D. (Arkansas Univ., Fayetteville, AR (USA). Dept. of Agronomy), Wolf, D.C, Rogers, H.B, Beyrouty, C.A, Reynolds, C.M
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Alfalfa; Animal, plant and microbial ecology; AROMATIC HYDROCARBONS; Bacteria; Benzene; Benzoic acid; BIODECONTAMINACION; Biological and medical sciences; BIOREMEDIATION; CHEMICALS; Contamination; Decalin; Decontamination; Environmental monitoring; Fundamental and applied biological sciences. Psychology; Fungi; Growth chambers; Hexadecane; HIDROCARBUROS AROMATICOS; HYDROCARBURE AROMATIQUE; MEDICAGO SATIVA; Microbial contamination; Microbial ecology; MICROORGANISME; MICROORGANISMOS; MICROORGANISMS; Mixtures; Organic chemicals; Organic chemistry; Organic soils; Phenanthrene; Plant roots; POA; Poa alpina; POLLUTION DU SOL; POLUCION DEL SUELO; Populations; PRODUCTOS QUIMICOS; PRODUIT CHIMIQUE; Q1; RHIZOSPHERE; RIZOSFERA; Soil; Soil and water pollution; Soil chemistry; Soil contamination; Soil mixtures; SOIL POLLUTION; Soil science; Soils
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/BF02406163

Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber study was conducted to evaluate rhizosphere microbial populations in contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane, (2,2-dimethylpropyl)benzene, cis-decahydronaphthalene (decalin), benzoic acid, phenanthrene, and pyrene was added at levels of 0 and 2000 mg/kg. Organic chemical degrader (OCD) populations were assessed by a Most-Probable-Number technique, and bacteria and fungi were enumerated by plate count methods. Different methods for expressing OCD rhizosphere populations were investigated to determine the effect it had on interpretation of the results. At 9 weeks, the OCD numbers were significantly higher in rhizosphere and contaminated soils than in bulk and non-contaminated soils, respectively. Alfalfa rhizosphere OCD levels were 4 × 107/g for contaminated and 6 × 106/g for non-contaminated soils. Bluegrass rhizosphere OCD levels were 1 × 107/g and 1 × 106/g in contaminated and non-contaminated soils, respectively. Selective enrichment of OCD populations was observed in contaminated rhizosphere soil. Higher numbers of OCD in contaminated rhizospheres suggest potential stimulation of bioremediation around plant roots.