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1.  Contribution of soil esterase to biodegradation of aliphatic polyester agricultural mulch film in cultivated soils 
AMB Express  2015;5:10.
The relationship between degradation speed of soil-buried biodegradable polyester film in a farmland and the characteristics of the predominant polyester-degrading soil microorganisms and enzymes were investigated to determine the BP-degrading ability of cultivated soils through characterization of the basal microbial activities and their transition in soils during BP film degradation. Degradation of poly(butylene succinate-co-adipate) (PBSA) film was evaluated in soil samples from different cultivated fields in Japan for 4 weeks. Both the degradation speed of the PBSA film and the esterase activity were found to be correlated with the ratio of colonies that produced clear zone on fungal minimum medium-agarose plate with emulsified PBSA to the total number colonies counted. Time-dependent change in viable counts of the PBSA-degrading fungi and esterase activities were monitored in soils where buried films showed the most and the least degree of degradation. During the degradation of PBSA film, the viable counts of the PBSA-degrading fungi and the esterase activities in soils, which adhered to the PBSA film, increased with time. The soil, where the film was degraded the fastest, recorded large PBSA-degrading fungal population and showed high esterase activity compared with the other soil samples throughout the incubation period. Meanwhile, esterase activity and viable counts of PBSA-degrading fungi were found to be stable in soils without PBSA film. These results suggest that the higher the distribution ratio of native PBSA-degrading fungi in the soil, the faster the film degradation is. This could be due to the rapid accumulation of secreted esterases in these soils.
doi:10.1186/s13568-014-0088-x
PMCID: PMC4384995  PMID: 25852987
Aliphatic polyester; Biodegradable plastics; Esterase; PBSA
2.  Degradation of biodegradable plastic mulch films in soil environment by phylloplane fungi isolated from gramineous plants 
AMB Express  2012;2:40.
To improve the biodegradation of biodegradable plastic (BP) mulch films, 1227 fungal strains were isolated from plant surface (phylloplane) and evaluated for BP-degrading ability. Among them, B47-9 a strain isolated from the leaf surface of barley showed the strongest ability to degrade poly-(butylene succinate-co-butylene adipate) (PBSA) and poly-(butylene succinate) (PBS) films. The strain grew on the surface of soil-mounted BP films, produced breaks along the direction of hyphal growth indicated that it secreted a BP-degrading enzyme, and has directly contributing to accelerating the degradation of film. Treatment with the culture filtrate decomposed 91.2 wt%, 23.7 wt%, and 14.6 wt% of PBSA, PBS, and commercially available BP polymer blended mulch film, respectively, on unsterlized soil within 6 days. The PCR-DGGE analysis of the transition of soil microbial community during film degradation revealed that the process was accompanied with drastic changes in the population of soil fungi and Acantamoeba spp., as well as the growth of inoculated strain B47-9. It has a potential for application in the development of an effective method for accelerating degradation of used plastics under actual field conditions.
doi:10.1186/2191-0855-2-40
PMCID: PMC3444367  PMID: 22856640
Biodegradable plastic; Leaf surface; Phylloplane fungi; Mulch film; PCR-DGGE
3.  Nocardioides sp. strain WSN05-2, isolated from a wheat field, degrades deoxynivalenol, producing the novel intermediate 3-epi-deoxynivalenol 
The mycotoxin deoxynivalenol (DON) causes serious problems worldwide in the production of crops such as wheat and barley because of its toxicity toward humans and livestock. A bacterial culture capable of degrading DON was obtained from soil samples collected in wheat fields using an enrichment culture procedure. The isolated bacterium, designated strain WSN05-2, completely removed 1,000 μg/mL of DON from the culture medium after incubation for 10 days. On the basis of phylogenetic studies, WSN05-2 was classified as a bacterium belonging to the genus Nocardioides. WSN05-2 showed significant growth in culture medium with DON as the sole carbon source. High-performance liquid chromatography analysis indicated the presence of a major initial metabolite of DON in the culture supernatant. The metabolite was identified as 3-epi-deoxynivalenol (3-epi-DON) by mass spectrometry and 1H and 13C nuclear magnetic resonance analysis. The amount of DON on wheat grain was reduced by about 90% at 7 days after inoculation with WSN05-2. This is the first report of a Nocardioides sp. strain able to degrade DON and of the yet unknown 3-epi-DON as an intermediate in the degradation of DON by a microorganism.
doi:10.1007/s00253-010-2857-z
PMCID: PMC3291841  PMID: 20857291
Fusarium graminearum; Trichothecenes; Deoxynivalenol; Mycotoxin degradation; Nocardioides
4.  Root mucilage enhances aluminum accumulation in Melastoma malabathricum, an aluminum accumulator 
Plant Signaling & Behavior  2008;3(8):603-605.
Root mucilage is gelatinous polysaccharide-containing material exuded from the outer layers of the root cap. Although mucilage has been suggested to play several roles in plant growth, its role in mineral uptake has not been well understood. Melastoma malabathricum L. is an aluminum (Al) accumulator growing in tropical acid soils. This species accumulates more than 10 mg Al g−1 DW in leaves and roots. Root mucilage is generally known to immobilize metal cations such as Al in the rhizosphere. However, we found that roots of M. malabathricum exuded large amounts of mucilage. Using the Zea mays L. mucilage as a control, we have recently shown that mucilage of M. malabathricum has unique physical and chemical characteristics, and facilitates Al uptake in this species. Since M. malabathricum cannot grow well in Al-deficient soil (nonacid soils), this species might have developed a mechanism for Al acquisition. We have also discussed the reason for this species' requirement of Al, a nonessential element.
PMCID: PMC2634511  PMID: 19704812
aluminum accumulator; cation adsorption; Melastoma malabathricum L.; polysaccharide; root mucilage; uronic acid

Results 1-4 (4)