Potential of Recombinant Raw Starch‐Degrading Enzyme from Escherichia coli for Sugar Syrup and Bioethanol Productions Using Broken Rice Powder as Substrate

Raw starch degrading alkaline α-amylase from Geobacillus kaustophilus TSCCA02: Production, characterization, and its potential for application as a detergent additive

Geobacillus kaustophilus TSCCA02, a newly isolated strain from cassava (Manihot esculenta L.) rhizosphere soil in Thailand, showed maximum raw starch degrading enzyme (RSDE) activity at 252.3 ± 9.32 U/mL with cassava starch and peptone at 5.0 and 3.0 g/L, respectively. 16 S ribosomal RNA (rRNA) sequencing and phylogenetic tree analyses indicated that the TSCCA02 strain was closely related to G. kaustophilus. The crude RSDE had optimal activity at 60°C and pH 9.0. This enzyme degraded various kinds of starch including potato starch, cassava starch, rice flour, corn starch, glutinous rice flour, and wheat flour to produce sugar syrup at 60°C, as confirmed by scanning electron microscopy (SEM), thin-layer chromatography (TLC), and Fourier-transform infrared spectroscopy (FTIR). The major end products of starch hydrolysis were maltose and maltotriose with a small amount of glucose, confirming this enzyme as an α-amylase. The enzyme improved the washing efficiency of cotton fabric with commercial detergent. Results indicated the potential of alkaline α-amylase produced from a new isolate of G. kaustophilus TSCCA02 for application as a detergent additive on an industrial scale.

Conversion of golden oyster mushroom, Pleurotus citrinopileatus to sugar syrup using enzymatic hydrolysis as a substrate for novel bacterial cellulose (Nata) fermentation

Enzymatic hydrolysis of the golden oyster mushroom (Pleurotus citrinopileatus) generated a new bacterial cellulose (BC). The sugar syrup obtained from the hydrolysis of mushroom powder by commercial enzymes gave maximum total soluble solids (TSS) content at 8.83 ± 0.29°Brix, while 8.82 ± 0.06 mg GAE/g substrate of total phenolic content (TPC) was obtained when using initial substrate and enzyme concentrations at 125 g/L and 5.0%, respectively. Glutamic acid, aspartic acid, alanine and valine were determined as the main amino acids found in P. citrinopileatus hydrolysis at 524.74 ± 0.03, 247.09 ± 0.04, 176.82 ± 0.07 and 174.57 ± 0.01 mg/100 g sample, respectively. Thin-layer chromatography revealed that the obtained sugar syrup was glucose. The hydrolyzed mushroom fermented with Komagataeibacter xylinus AGR 60 at 30 ± 2 °C for 9 days produced optimal conditions at 4.0°Brix of the initial mushroom syrup and 12.0% (v/v) of the starter culture. Maximum BC thickness was 0.88 ± 0.03 cm with 7.90 ± 0.07 g dry weight, equivalent to 39.50 ± 0.35 g/L and 4.39 ± 0.04 g/L/day for BC production (P) and BC production rate (R p), respectively. The obtained BC was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, small-angle X-ray scattering and wide-angle X-ray diffraction. These showed the structure and functional properties as a natural source of fiber from the fermentation of a novel substrate.