This study aimed to enhance the production of D-mannose and bioethanol from spent coffee grounds (SCGs) through pretreatment, enzymatic hydrolysis, and selective fermentation. Combined pretreatment with alkali, bleaching, and NaOH−hydrogen peroxide (NH) significantly increased glucose and mannose yield 5.44 and 3.49 times, respectively. After enzymatic hydrolysis using cellulase and mannanase, the pretreated SCGs produced high glucose and mannose yields of 15.3 and 10.6 mg/mL, respectively. Additionally, the mutant Pichia stipitis MH05 strain selectively consumed glucose during fermentation, resulting in a significant amount of mannose (79.9%) remaining after 48 h. In conclusion, SCGs demonstrate potential usefulness in D-mannose and bioethanol production, and combining enzymatic hydrolysis with selective fermentation offers an effective approach for achieving environmental sustainability and economic benefits.
Here, we report an increase in biomass yield and saccharification in transgenic tobacco plants (Nicotiana tabacumL.) overexpressing thermostable β-glucosidase from Thermotoga maritima, BglB, targeted to the chloroplasts and vacuoles. The transgenic tobacco plants showed phenotypic characteristics that were significantly different from those of the wild-type plants. The biomass yield and life cycle (from germination to flowering and harvest) of the transgenic tobacco plants overexpressing BglB were 52% higher and 36% shorter than those of the wild-type tobacco plants, respectively, indicating a change in the genome transcription levels in the transgenic tobacco plants. Saccharification in biomass samples from the transgenic tobacco plants was 92% higher than that in biomass samples from the wild-type tobacco plants. The transgenic tobacco plants required a total investment (US$/year) corresponding to 52.9% of that required for the wild-type tobacco plants, but the total biomass yield (kg/year) of the transgenic tobacco plants was 43% higher than that of the wild-type tobacco plants. This approach could be applied to other plants to increase biomass yields and overproduce β-glucosidase for lignocellulose conversion.
Three cystein-tagged cellulases co-immobilized on AuNP and Au-MSNP for the hydrolytic degradation of cellulose. The biochemical properties, stabilities, activities and reusability of these co-immobilized systems were compared to those of mixtures of free cellulases.
The integrated approach of biocatalytic conversion coupled with purification using selective enzyme was developed for achieving continuous trehalose production. The activity of trehalose synthase (TS) derived from three different bacteria—Deinococcus radiodurans, Pseudomonas stutzeri, and Thermus thermophillus—immobilized with chitin-binding domain (CBD-DrTS, CBD-PsTS, and CBD-TtTS, respectively) was compared in the production of trehalose from maltose syrup. The production yield of CBD-PsTS was 2.4 and 1.7-fold higher than those of CBD-DrTS and CBD-TtTS, respectively, after 24 h at 30°C and pH 7.0. In the integrated approach, a continuous bioconversion system was developed for trehalose production using CBD-PsTS in a fixed-bed bioreactor, resulting in an approximate yield of 72%, and a productivity of 4 g/L/h at pH 7.0 and 30 °C. Additionally, residual maltose was converted into glucose using glucoamylase, and the 37% of bioethanol was produced. The integrated approach demonstrated remarkable biocatalytic performance, biocatalyst reusability, and high product yield.
In this research, novel biorefinery processes for obtaining value-added chemicals such as biosugar and hesperidin from mandarin peel waste (MPW) are described. Herein, three different treatment methods were comparatively evaluated to obtain high yields of biosugar and hesperidin from MPW. Each method was determined by changes in the order of three processing steps, i.e., oil removal, hesperidin extraction, and enzymatic hydrolysis. The order of the three steps was found to have a significant influence on the production yields. Biosugar and hesperidin production yields were highest with method II, where the processing steps were performed in the following order: oil removal, enzymatic hydrolysis, and hesperidin extraction. The maximum yields obtained with method II were 34.46 g of biosugar and 6.48 g of hesperidin per initial 100 g of dry MPW. Therefore, the methods shown herein are useful for the production of hesperidin and biosugar from MPW. Furthermore, the utilization of MPWs as sources of valuable materials may be of considerable economic benefits and has become increasingly attractive.
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