Statistical optimization of production conditions of β-glucosidase from Bacillus stratosphericus strain SG9

Microencapsulated granaticins from Streptomyces vilmorinianum YP1: Optimization, physiochemical characterization and storage stability

Granaticins are natural pigments derived from microorganisms with promising bioactivity. However, their practical applications have been restricted due to inherent instability. To improve the stability of granaticins from the novel strain Streptomyces vilmorinianum YP1, microcapsules were prepared using gum Arabic (GA) by a freeze-drying method. The optimal parameters for microencapsulation were determined using response surface methodology. Under the optimal conditions (GA 9.2% (v/v), a wall/-core ratio 4.8 (w/w), encapsulating temperature 29 °C), the maximum encapsulation efficiency achieved was 93.64%. The microcapsules were irregular single crystals with an average particle size of 206.37 ± 2.51 nm. Stability testing indicated improved stability of the microencapsulated granaticins. Notably, granaticnic B retention increased by 17.0% and 6.6% after exposure to sunlight and storage at 4 °C, respectively. These finding suggest that GA as a well material significantly enhances the stability of granaticins from S. vilmorinianum YP1, facilitating their potential applications.

A Thermotolerant Yeast Cyberlindnera rhodanensis DK Isolated from Laphet-so Capable of Extracellular Thermostable β-Glucosidase Production

This study aims to utilize the microbial resources found within Laphet-so, a traditional fermented tea in Myanmar. A total of 18 isolates of thermotolerant yeasts were obtained from eight samples of Laphet-so collected from southern Shan state, Myanmar. All isolates demonstrated the tannin tolerance, and six isolates were resistant to 5% (w/v) tannin concentration. All 18 isolates were capable of carboxy-methyl cellulose (CMC) degrading, but only the isolate DK showed ethanol production at 45 °C noticed by gas formation. This ethanol producing yeast was identified to be Cyberlindnera rhodanensis based on the sequence analysis of the D1/D2 domain on rRNA gene. C. rhodanensis DK produced 1.70 ± 0.01 U of thermostable extracellular β-glucosidase when cultured at 37 °C for 24 h using 0.5% (w/v) CMC as a carbon source. The best two carbon sources for extracellular β-glucosidase production were found to be either xylose or xylan, with β-glucosidase activity of 3.07-3.08 U/mL when the yeast was cultivated in the yeast malt extract (YM) broth containing either 1% (w/v) xylose or xylan as a sole carbon source at 37 °C for 48 h. The optimal medium compositions for enzyme production predicted by Plackett-Burman design and central composite design (CCD) was composed of yeast extract 5.83 g/L, peptone 10.81 g/L and xylose 20.20 g/L, resulting in a production of 7.96 U/mL, while the medium composed (g/L) of yeast extract 5.79, peptone 13.68 and xylan 20.16 gave 9.45 ± 0.03 U/mL for 48 h cultivation at 37 °C. Crude β-glucosidase exhibited a remarkable stability of 100%, 88% and 75% stable for 3 h at 35, 45 and 55 °C, respectively.

Isolation of the Thermostable β-Glucosidase-Secreting Strain Bacillus altitudinis JYY-02 and Its Application in the Production of Gardenia Blue

Gardenia blue (GB) is a natural blue pigment widely used in textiles and the pharmaceutical industry. The geniposide in gardenia fruits can be hydrolyzed by β-glucosidase to form genipin, which reacts with amino acids to produce GB. In this study, a bacterial strain which secreted thermostable β-glucosidase (EC 3.2.1.21) was isolated from soil and identified as Bacillus altitudinis JYY-02. This strain could potentially be used for GB production from geniposide by fermentation. Optimal fermentation results were achieved at pH 6.5 or 8.0 at 45°C for 45 h with additional sucrose. To obtain a large amount of β-glucosidase, the whole genome of B. altitudinis JYY-02 was sequenced and annotated; it is 3,727,518 bp long and contains 3,832 genes. The gene encoding β-glucosidase (bgl) in B. altitudinis JYY-02 was screened from the genome and overexpressed in Escherichia coli BL21(DE3). The recombinant β-glucosidase was purified by affinity chromatography on a Ni Sepharose 6 fast flow (FF) column. The optimal temperature, pH, and Km values for the recombinant β-glucosidase were 60°C, pH 5.6, and 0.331 mM, respectively, when p-nitrophenyl-β-d-glucopyranoside (pNPG) was used as the substrate. The recombinant β-glucosidase catalyzed the deglycosylation reaction of geniposide, which was then used to produce GB. IMPORTANCE β-Glucosidases are enzymes capable of hydrolyzing β-glucosidic linkages present in saccharides and glycosides and have many agricultural and industrial applications. Although they are found in all domains of living organisms, commercial β-glucosidases are still expensive, limiting their application in industry. In the present study, a thermostable β-glucosidase-producing strain was obtained for GB production by fermentation, engineered bacteria were constructed for preparing recombinant β-glucosidase, and a one-step method to purify the recombinant enzyme was established. A large amount of purified β-glucosidase was easily obtained from the engineered bacteria for industrial applications such as GB production.

Using response surface methodology in combination with Plackett-Burman design for optimization of culture media and extracellular expression of Trichoderma reesei synthetic endoglucanase II in Escherichia coli

Cellulases like endoglucanase II (EGII) from Trichoderma reesei are the industrial enzymes responsible for breakdown of cellulosic materials. Due to its importance for production of eco-friendly commercial products such as alternative biofuels, industrial EGII production and optimization of its production conditions merit consideration. The gene responsible for EGII expression was designed and sub-cloned in to pET26b expression vector and transformed into BL21 (DE3) pLysS cells. Protein expression and purification was followed by a RSM design (20 experiments) to optimize the IPTG Concentration, post induction period and cell density (OD₆₀₀). Thereafter, another RSM design (20 experiments) was performed to find and optimize the most important permeabilizing factors to achieve higher extracellular EGII expression. The EGII expression levels were assessed by Ghose method. The EGII gene was sub-cloned and protein expression and purification were successfully performed. The RSM experiments indicated that 0.331 mM for IPTG Concentration, 10.89 H for post induction period and 3.41 for cell density (OD₆₀₀) were the optimum culture. Glycine (0.99%), Triton X-100 (0.73%) and CaCl₂ (0.232) have been assigned as the most effective membrane permeabalizing factors. Optimization of culture medium components has led to a 3.06 fold increase in extracellular expression of EGII. RSM is an amenable method to optimize the expression of commercially significant enzymes. Our results indicated that optimization of IPTG concentration, post induction period and cell density along with glycine, Triton X-100 and Ca²⁺ concentration could lead to more cost effective industrial production of EGII.