Amylolytic enzymes are currently investigated to improve industrial processes of starch degradation. Saccharomyces diastaticus 2047 isolated from cassava waste showed amylase and glucoamylase production, using starch ...Amylolytic enzymes are currently investigated to improve industrial processes of starch degradation. Saccharomyces diastaticus 2047 isolated from cassava waste showed amylase and glucoamylase production, using starch medium, and the highest rate was obtained in the initial growth phase, after incubation for 24 h at pH 5.5. Maximum amylase and glucoamylase activities （483.62 U mg^-1 protein and 290.85 U mg^-1 protein） were obtained at pH 5.5. The isolated enzymes exhibited thermostable properties as indicated by retention of 100% of residual activity at 55 ℃ for 45 min with total inhibition at 100 ℃. Extracellular enzyme from S diastaticus 2047 was partially purified by fractionated precipitation with ammonium sulphate. After 40% saturation produced 2,197.00 and 1,192.83 U/mg protein, and yield was 40% with purification 4.54 and 4.1 fold, respectively. This study presents feasibility on ethanol production from cassava pulps pretreated with diluted sulfuric acid by simultaneous saccharification and fermentation （SSF） with S. diastaticus 2047. The results indicated that the culture was able to produce ethanol with high yield without amylolytic enzyme adding by using cassava pulps pretreated with distilled water at 135 ℃ under pressure of 15 lb/inch^2 to produce ethanol yield as high as the cassava pulps pretreated with diluted sulfuric acid under the same condition. This suggests that S diastaticus with enzyme produced has potential for industrial applications.展开更多
A total of 500 thermotolerant fermenting yeast isolates (100 from palm-wine and 400 from spoilt fruits) were screened for ethanol production at high temperatures. The best isolate that produced up to 4% ethanol from 1...A total of 500 thermotolerant fermenting yeast isolates (100 from palm-wine and 400 from spoilt fruits) were screened for ethanol production at high temperatures. The best isolate that produced up to 4% ethanol from 10% glucose at 45°C was selected for further experiments. The optimum pH for ethanol production by the isolate was pH 6 at both 30°C and 42°C. The isolate was identified as Pichia kudriavzevii base on the 18s ribosomal DNA. Ethanol production from 200 g/L cassava pulp using Simultaneous Saccharification and Fermentation (SSF) method at 30°C and 42°C by the isolate was investigated. At 30°C, an ethanol concentration of 30 g/L was produced. This represents an ethanol yield of 0.15 g/g of cassava pulp and 58.8% of the theoretical yield. However at 42°C, the concentration of ethanol produced increased to 42 g/L representing an ethanol yield of 0.21 g/g of cassava pulp and 82.4% of the theoretical yield. The isolate produced slightly higher ethanol than the two typed strains NCYC 587 and NCYC 2791 at 42°C. This isolate has a good potential to be used for commercial bioethanol production since it can produce ethanol at 45°C without a significant drop in ethanol yield.展开更多
Carbon dots(CDs)have been attracted to nanocarbon materials for metal ion sensing,biological activity,and plant phytotoxicity due to their excellent photophysical properties,such as low cytotoxicity,high quantum yield...Carbon dots(CDs)have been attracted to nanocarbon materials for metal ion sensing,biological activity,and plant phytotoxicity due to their excellent photophysical properties,such as low cytotoxicity,high quantum yield,tunable fluorescence emission,and biocompatibility.Cassava pulp,which consists mainly of starch,has been identified as a low-cost biomass waste from the cassava starch industry.Therefore,this research developed CDs and nitrogen-doped CDs(NCDs)from cassava pulp using a one-step hydrothermal process in deionized water at 200℃.The effects of the synthesis conditions,including reaction time(6-24 h)and the nitrogen doping derivatives,were also investigated.CDs and ethylenediamine doped-NCDs exhibited tunable fluorescence emission,strong quantum yield,high photostability,and tolerance to photobleaching.Furthermore,the potential applications of CDs-12 h were demonstrated such as fluorescent sensors for metal ion sensing,antioxidant activity,and mercury detoxification in plants.Fluorescence quenching of the CDs-12 h via both static and dynamic quenching mechanisms was observed in the presence of several metal ions such as Hg^(2+),Cu^(2+),and Fe^(3+)with the detection limit in micromolar levels and further applied to real water samples with good recovery and acceptable relative standard derivation.The paper test strip coated with CDs-12 h could also detect these metal ions under UV light.CDs and NCDs-EDA also showed potential DPPH radical scavenging activity and alleviated mercury toxicity in the Chinese cabbage seedlings with the incubation of CDs-12 h and NCDs-EDA-12 h(30 mg/L).展开更多
文摘Amylolytic enzymes are currently investigated to improve industrial processes of starch degradation. Saccharomyces diastaticus 2047 isolated from cassava waste showed amylase and glucoamylase production, using starch medium, and the highest rate was obtained in the initial growth phase, after incubation for 24 h at pH 5.5. Maximum amylase and glucoamylase activities （483.62 U mg^-1 protein and 290.85 U mg^-1 protein） were obtained at pH 5.5. The isolated enzymes exhibited thermostable properties as indicated by retention of 100% of residual activity at 55 ℃ for 45 min with total inhibition at 100 ℃. Extracellular enzyme from S diastaticus 2047 was partially purified by fractionated precipitation with ammonium sulphate. After 40% saturation produced 2,197.00 and 1,192.83 U/mg protein, and yield was 40% with purification 4.54 and 4.1 fold, respectively. This study presents feasibility on ethanol production from cassava pulps pretreated with diluted sulfuric acid by simultaneous saccharification and fermentation （SSF） with S. diastaticus 2047. The results indicated that the culture was able to produce ethanol with high yield without amylolytic enzyme adding by using cassava pulps pretreated with distilled water at 135 ℃ under pressure of 15 lb/inch^2 to produce ethanol yield as high as the cassava pulps pretreated with diluted sulfuric acid under the same condition. This suggests that S diastaticus with enzyme produced has potential for industrial applications.
文摘A total of 500 thermotolerant fermenting yeast isolates (100 from palm-wine and 400 from spoilt fruits) were screened for ethanol production at high temperatures. The best isolate that produced up to 4% ethanol from 10% glucose at 45°C was selected for further experiments. The optimum pH for ethanol production by the isolate was pH 6 at both 30°C and 42°C. The isolate was identified as Pichia kudriavzevii base on the 18s ribosomal DNA. Ethanol production from 200 g/L cassava pulp using Simultaneous Saccharification and Fermentation (SSF) method at 30°C and 42°C by the isolate was investigated. At 30°C, an ethanol concentration of 30 g/L was produced. This represents an ethanol yield of 0.15 g/g of cassava pulp and 58.8% of the theoretical yield. However at 42°C, the concentration of ethanol produced increased to 42 g/L representing an ethanol yield of 0.21 g/g of cassava pulp and 82.4% of the theoretical yield. The isolate produced slightly higher ethanol than the two typed strains NCYC 587 and NCYC 2791 at 42°C. This isolate has a good potential to be used for commercial bioethanol production since it can produce ethanol at 45°C without a significant drop in ethanol yield.
基金supported by The Thailand Science Research and Innovation(TSRI),Fundamental Fund 2022(Grant no FRB650070/0168)This research block grants was managed under Rajamangala University of Technology Thanyaburi(FRB65E0614).
文摘Carbon dots(CDs)have been attracted to nanocarbon materials for metal ion sensing,biological activity,and plant phytotoxicity due to their excellent photophysical properties,such as low cytotoxicity,high quantum yield,tunable fluorescence emission,and biocompatibility.Cassava pulp,which consists mainly of starch,has been identified as a low-cost biomass waste from the cassava starch industry.Therefore,this research developed CDs and nitrogen-doped CDs(NCDs)from cassava pulp using a one-step hydrothermal process in deionized water at 200℃.The effects of the synthesis conditions,including reaction time(6-24 h)and the nitrogen doping derivatives,were also investigated.CDs and ethylenediamine doped-NCDs exhibited tunable fluorescence emission,strong quantum yield,high photostability,and tolerance to photobleaching.Furthermore,the potential applications of CDs-12 h were demonstrated such as fluorescent sensors for metal ion sensing,antioxidant activity,and mercury detoxification in plants.Fluorescence quenching of the CDs-12 h via both static and dynamic quenching mechanisms was observed in the presence of several metal ions such as Hg^(2+),Cu^(2+),and Fe^(3+)with the detection limit in micromolar levels and further applied to real water samples with good recovery and acceptable relative standard derivation.The paper test strip coated with CDs-12 h could also detect these metal ions under UV light.CDs and NCDs-EDA also showed potential DPPH radical scavenging activity and alleviated mercury toxicity in the Chinese cabbage seedlings with the incubation of CDs-12 h and NCDs-EDA-12 h(30 mg/L).
