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.

Wickerhamiella nakhonpathomensis f.a. sp. nov., a novel ascomycetous yeast species isolated from a mushroom and a flower in Thailand.

Strains SU22T (TBRC 14875T) and FLA11.5, representing a novel anamorphic yeast species, were respectively isolated from a fruiting body of a Coprinus species and an inflorescence of a Coffea species collected in Thailand. Analysis of the sequences of the D1/D2 domains of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) regions showed that the two strains differed by two nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and were identical in the ITS regions. Wickerhamiella drosophilae CBS 8459T was the most closely related species, but with 24-26 nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and 24 nucleotide substitutions in the ITS regions. A phylogenetic analysis, based on the sequences of the D1/D2 domains, indicated that the two strains represented a species in the genus Wickerhamiella which was distinct from other recognized species of the genus. Therefore, the two strains were assigned as a novel species, for which we propose the name Wickerhamiella nakhonpathomensis f.a. sp. nov. The holotype is TBRC 14875T (isotype PYCC 8914T). The MycoBank number of the novel species is MB 840833.

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.

Production of poly (l-lactide)-degrading enzyme by Actinomadura keratinilytica strain T16-1 under solid state fermentation using agricultural wastes as substrate.

Poly (l-lactide) (PLLA) is an aliphatic polyester that can be obtained from renewable resources and degraded by various microorganisms. In previous reports, Actinomadura keratinilytica strain T16-1 demonstrated high ability to degrade PLLA under various conditions. PLLA-degrading enzyme production under solid state fermentation has been sparsely studied. PLLA-degrading enzyme production by A. keratinilytica strain T16-1 was investigated using agricultural wastes as substrate under solid state fermentation (SSF). Three agricultural wastes as soybean meal, cassava chips and duckweed were tested as substrates for PLLA-degrading enzyme production by statistical methods using mixture design. Results revealed that using duckweed as the substrate gave the highest enzyme production (138.66 ± 13.57 U/g dry substrate). Maximum enzyme activity of 391.24 ± 15.57 U/g dry substrate was obtained under 10 g duckweed, 10% inoculum size, 7 days of cultivation time, pH 7.0, 2.8% PLLA powder, and 60% moisture content at 45 °C. It can be concluded that duckweed is an inexpensive substrate, which reduces the costs of PLLA-degrading enzyme production, as an alternative to effective water weed management.

Application of raw starch degrading enzyme from Laceyella sacchari LP175 for development of bacterial cellulose fermentation using colored rice as substrate.

Brown and black rice substrates were applied for sugar syrup production by the hydrolysis of raw starch degrading enzyme (RSDE) from Laceyella sacchari LP175 (300 U/mL) and commercial glucoamylase (GA, 2.0 U/mL) at 50 °C for 12 h using a simplex centroid mixture design. Results indicated that 300 g/L of substrates, consisting of 255 g/L Leum Pua glutinous rice and 45 g/L Black Jasmine rice, gave the highest sugar syrup production at 124.6 ± 2.52 g/L with 2.00 ± 0.05 mg GAE/mL of total phenolic content (TPC), equivalent to 0.42 ± 0.01 g/g rice sample and 6.67 ± 0.15 mg GAE/g rice sample, respectively. The obtained sugar syrup was used as the substrate for production of bacterial cellulose (Nata) by Komagataeibacter xylinus AGR 60 in a plastic tray at room temperature for 9 days. The fermentation medium containing 200 mL of rice syrup (25 g/L), 2.0 g of ammonium sulfate [(NH4)2SO4] and 0.4 mL glacial acetic acid yielded 1.1 ± 0.08 cm thickness with 8.15 ± 0.12 g of dry weight. The obtained bacterial cellulose from colored rice was characterized compared with bacterial cellulose from the conventional coconut juice by scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) which demonstrated that the sugar syrup from colored rice could use as substrate for a novel bacterial cellulose as a healthy product in the future through microbial enzyme technological process. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02673-3.

Production and development of vinegar fermentation from broken Riceberry rice using raw starch-degrading enzyme hydrolysis.

Broken Riceberry rice was used as a substrate for sugar syrup production by the hydrolysis of raw starch-degrading enzyme as a low-temperature amylase (iKnowZyme® LTAA, Thailand). Response surface methodology (RSM) with a central composite design (CCD) showed that an optimized substrate concentration of 250 g/L yielded 13°Brix of total soluble solid (TSS) content when incubated at 50 °C for 12 h. The major product from the broken Riceberry rice hydrolysis was glucose with lesser amounts of maltose and maltotriose. Maximum alcohol content (16% w/v) for broken Riceberry rice wine was obtained after fermentation with two mixed strains of Saccharomyces cerevisiae for 10 days. Scanning electron micrographs showed that yeast strains could grow on the solid residue of broken Riceberry rice that supported yeast cell survival under stress conditions. Broken Riceberry rice wine was used as the substrate for vinegar fermentation by Acetobacter aceti TISTR 354. Maximum acetic acid concentration was achieved at 5.4% when incubated at room temperature for 6 days, containing 10.92 mg/L and 965.53 ± 7.74 mL sample/g DPPH of anthocyanin content and antioxidant assay, respectively. Our finding revealed the feasibility of broken Riceberry rice substrate for sugar syrup, wine and vinegar production by raw starch-degrading enzyme hydrolysis which increased the value of low-cost agricultural crops through biotechnological processes.