Biodegradation of herbicide diuron by streptomycetes isolated from soil

The diuron degrading activity of 17 streptomycete strains, obtained from agricultural and non-agricultural soils, was determined in the laboratory. All strains were identified as Streptomyces sp. by phenotypic characteristics and PCR-based assays. The strains were cultivated in liquid medium with diuron (4mgL(-1)) at 25 degrees C for 15 days. Biodegradation activity was deter-mined by high-performance liquid chromatography. The results indicated that all strains were able to degrade diuron, but to different amounts. Twelve strains degraded the herbicide by up to 50% and four of them by up to 70%. Strain A7-9, belonging to S. albidoflavus cluster, was the most efficient organism in the degradation of diuron, achieving 95% degradation after five days of incubation and no herbicide remained after 10 days. Overall, the strains isolated from agricultural soils exhibited higher degradation percentages and rates than those isolated from non-agricultural soils. Given the high degradation activity observed here, the streptomycete strains show a good potential for bioremediation of soils contaminated with diuron. (c) 2006 Elsevier Ltd. All rights reserved.Castillo López, MÁ.; Felis Reig, N.; Aragón Revuelta, P.; Cuesta Amat, G.; Sabater Marco, C. (2006). Biodegradation of herbicide diuron by streptomycetes isolated from soil. International Biodeterioration and Biodegradation. 58(3-4):196-202. doi:10.1016/j.ibiod.2006.06.020S196202583-

Bacterial populations associated with rice seed in the tropical environment

During the 1995 wet season, harvested rice seed was collected from farmers' fields at different locations in Iloilo, Philippines. Bacterial isolations from crushed seed yielded 428 isolates. The isolates were characterized by BOX-polymerase chain reaction fingerprinting of total genomic DNA and represented 151 fingerprint types (FPT). Most FPTs were found on a single occasion, although matching fingerprints for isolates from different samples also were found. Identifications were made by cellular fatty acid methyl ester analysis and additional use of Biolog GN/GP MicroPlates and API 20E/50CHE systems. The predominant bacteria were Enterobacteriaceae (25%), Bacillus spp. (22%), and Pseudomonas spp. (14%). Other bacteria regularly present were identified as Xanthomonas spp., Cellulomonas flavigena, and Clavibacter michiganense. Of the total number of isolated bacteria, 4% exhibited in vitro antifungal activity against Rhizoctonia solani or Pyricularia grisea. Two percent of isolates were pathogens identified as Burkholderia glumae and Burkholderia gladioli. Five percent of isolates induced sheath necrosis on only 50 to 90% of inoculated plants and were related to Bacillus pumilus, Paenibacillus spp., Pseudomonas spp., and Pantoea spp