To obtain a kind of biodegradable polymer material with satisfactory properties, a new biodegradable copolyester poly（lactic acid-co-glycol terephthalate） （PETA）, was synthesized from three monomers of lactic acid...To obtain a kind of biodegradable polymer material with satisfactory properties, a new biodegradable copolyester poly（lactic acid-co-glycol terephthalate） （PETA）, was synthesized from three monomers of lactic acid, glycol and terephthalic acid. The resulting copolyesters, PETA, were characterized by FT-IR, ^1H-NMR, DSC, TGA and by the ways of weight loss rate to characterize their biodegradability. The findings in this work indicated that, the Tins and Tas of copolyesters PETA increased with increasing contents of the terephthalic acid units. From the biodegradation tests in natural soil, boiling water, acid buffer solution and alkali buffer solution, it was shown that the biodegradability of copolyesters PETA decreased with increasing contents of the terephthalic acid units.展开更多
Nitrogen is one of the most needed elements by coffee plants. Utilization of biological nitrogen fixation by non symbiotic bacteria offers alternative to reduce the N fertilizer usage. This study was focused to obtain...Nitrogen is one of the most needed elements by coffee plants. Utilization of biological nitrogen fixation by non symbiotic bacteria offers alternative to reduce the N fertilizer usage. This study was focused to obtain aerobic non symbiotic nitrogen-fixing bacteria from coffee rhizosphere. The application of those bacteria was expected to enhance coffee seedling growth. Sixty four aerobic nitrogen-fixing bacterial isolates were isolated from coffee plants rhizosphere from Jember, East Java using several nitrogen free medium, such as Ashby, malate acid, and fahreus agar. The nitrogen fixation ability of the isolates was determined by measuring their ability in pellicle formation on semi solid medium and ammonium excretion on growth medium. Ab Kws.l, Asm E6s.3.a, Asm Bsl.1, and Asm E6s were the isolates which showed the best performance on nitrogen fixation with excreted ammonium concentration ranged from 129.6 up to 239.8 pM/mg dry weight cell. Acetylene reduction assay was used to detect nitrogenase activity. Ab Kws.1 was the isolate which had the highest nitrogenase activity （7.4 mmol N2 fixed/gram dry weight cell/hour）. Inoculation of the four best isolates onto Robusta coffee seedling positively enhanced the seedling growth in this green house experiment. Based on the results of Becton Dickinson＇s （BD） PhoenixTM Automated Microbiology System biochemical tests, Asm Bls.l isolates has similarities with Achromobacter sp., Asm E6s.l and Asm E6s.3.a had similarities with Stenotrophomonas maltophilia, while Ab Kws. 1 had similarities with Leifsonia aquatica.展开更多
文摘To obtain a kind of biodegradable polymer material with satisfactory properties, a new biodegradable copolyester poly（lactic acid-co-glycol terephthalate） （PETA）, was synthesized from three monomers of lactic acid, glycol and terephthalic acid. The resulting copolyesters, PETA, were characterized by FT-IR, ^1H-NMR, DSC, TGA and by the ways of weight loss rate to characterize their biodegradability. The findings in this work indicated that, the Tins and Tas of copolyesters PETA increased with increasing contents of the terephthalic acid units. From the biodegradation tests in natural soil, boiling water, acid buffer solution and alkali buffer solution, it was shown that the biodegradability of copolyesters PETA decreased with increasing contents of the terephthalic acid units.
文摘Nitrogen is one of the most needed elements by coffee plants. Utilization of biological nitrogen fixation by non symbiotic bacteria offers alternative to reduce the N fertilizer usage. This study was focused to obtain aerobic non symbiotic nitrogen-fixing bacteria from coffee rhizosphere. The application of those bacteria was expected to enhance coffee seedling growth. Sixty four aerobic nitrogen-fixing bacterial isolates were isolated from coffee plants rhizosphere from Jember, East Java using several nitrogen free medium, such as Ashby, malate acid, and fahreus agar. The nitrogen fixation ability of the isolates was determined by measuring their ability in pellicle formation on semi solid medium and ammonium excretion on growth medium. Ab Kws.l, Asm E6s.3.a, Asm Bsl.1, and Asm E6s were the isolates which showed the best performance on nitrogen fixation with excreted ammonium concentration ranged from 129.6 up to 239.8 pM/mg dry weight cell. Acetylene reduction assay was used to detect nitrogenase activity. Ab Kws.1 was the isolate which had the highest nitrogenase activity （7.4 mmol N2 fixed/gram dry weight cell/hour）. Inoculation of the four best isolates onto Robusta coffee seedling positively enhanced the seedling growth in this green house experiment. Based on the results of Becton Dickinson＇s （BD） PhoenixTM Automated Microbiology System biochemical tests, Asm Bls.l isolates has similarities with Achromobacter sp., Asm E6s.l and Asm E6s.3.a had similarities with Stenotrophomonas maltophilia, while Ab Kws. 1 had similarities with Leifsonia aquatica.
