Enhanced production of β-glucuronidase from Penicillium purpurogenum Li-3 by optimizing fermentation and downstream processes

Effect of Combined High-Pressure Homogenization and Biotechnological Processes on Chitin, Protein, and Antioxidant Activity of Cricket Powder-Based Ingredients

The main objective of this work was to evaluate the combined effect of a biotechnology process, based on selected yeast strains, and a high-pressure homogenization (HPH) treatment on the microbiological quality, structural organization of proteins, chitin content, and antioxidant activity of a mixture of cricket powder (Acheta domesticus) and water. Compared to untreated samples, the cricket matrix treated with HPH four times at 180 MPa promoted the growth of the inoculated Yarrowia lipolytica and Debaryomyces hansenii strains. HPH did not affect the concentration of chitin; however, the combination with microorganisms tended to reduce the content. Although the antioxidant activity increased from 0.52 to 0.68 TAC mM/TE after a 48 h incubation in the control, it was further improved by the combination of HPH and D. hansenii metabolism, reaching a value of 0.77 TAC mM/TE. The combination of the two approaches also promoted a reduction in the intensity of bands with molecular weights between 31 and 21.5 kDa in favor of bands with a lower molecular weight. In addition, HPH treatment reduced the number of accessible thiols, suggesting protein structure changes that may further impact the technological properties of cricket powder.

Endophytes: the novel sources for plant terpenoid biosynthesis

Terpenoids are natural compounds predominantly present in plants. They have many pharmaceutical and/or nutritional functions, and have been widely applied in medical, food, and cosmetics industries. Recently, terpenoids have been used in the clinical treatment of COVID-19 due to the good antiviral activities. The increasing demand for terpenoids in international markets poses a serious threat to many plant species. For environmentally sustainable development, microbial cell factories have been utilized as the promising platform to produce terpenoids. Nevertheless, the bioproduction of most terpenoids cannot meet commercial requirements due to the low cost-benefit ratio until now. The biosynthetic potential of endophytes has gained attention in recent decades owing to the continual discovery of endophytes capable of synthesizing plant bioactive compounds. Accordingly, endophytes could be alternative sources of terpenoid-producing strains or terpenoid synthetic genes. In this review, we summarized the research progress describing the main and supporting roles of endophytes in terpenoid biosynthesis and biotransformation, and discussed the current problems and challenges which may prevent the further exploitation. This review will improve our understanding of endophyte resources for terpenoid production in industry in the future. The four main research interests on endophytes for terpenoid production. A: Isolation of terpenoid-producing endophytes; B: The heterologous expression of endophyte-derived terpenoid synthetic genes; C: Endophytes promoting their hosts' terpenoid production. The blue dashed arrows indicate signal transduction; D: Biotransformation of terpenoids by endophytes or their enzymes. Key points• The mechanisms employed by endophytes in terpenoid synthesis in vivo and in vitro.• Endophytes have the commercial potentials in terpenoid bioproduction and biotransformation.• Synthetic biology and multiomics will improve terpenoid bioproduction in engineered cell factories.

Enhancement of anti-acne effect of Scutellaria baicalensis extract by fermentation with symbiotic fungus Penicillium decumbens

Inflammatory responses stimulated by Propionibacterium acnes have been shown to be major etiological factors in the pathogenesis of acne. Scutellaria baicalensis, a popular traditional Chinese medicine, has been widely shown to have anti-inflammatory effects. In this study, primary component analysis and primary effective component analysis were conducted. The results showed that wogonin (1.15 mg/g S. baicalensis extract) possessed better anti-acne effects than wogonoside (8.71 mg/g S. baicalensis extract) in inhibiting the up-regulation of IL-1β and IL-8 level caused by P. acnes via inactivation of the MAPK and NF-κB signaling pathways. To enhance the anti-acne effects of S. baicalensis extract, an environmentally friendly and healthy plant fermentation strategy was used to efficiently convert glycoside-type constituents into bioactive aglycone. S. baicalensis extract was fermented by symbiotic fungus Penicillium decumbens f3-1 to transform wogonoside into wogonin with a conversion rate of 91.0% after 4 days. Fermented S. baicalensis extract (FSE) showed higher potential anti-acne effects than non-fermented S. baicalensis extract (NSE) by inhibiting the up-regulation of IL-1β and IL-8. Thus, P. decumbens-fermented S. baicalensis Extract may be used for developing new anti-acne cosmetic ingredients.

Microparticle-enhanced Chaetomium globosum DX-THS3 β-d-glucuronidase production by controlled fungal morphology in submerged fermentation

Glycyrrhetinic acid monoglucuronide (GAMG) is a novel and low-calorie sweetener that is widely applied in the food industry. This study aimed to enhance the production of fungal β-d-glucuronidase (GUS) via a novel fermentation technique by evaluating the effects of the various microparticles on Chaetomium globosum DX-THS3 GUS production. Results showed that the silica microparticle greatly affected the morphology of DX-THS3 strain relative to the other microparticles. Microbial structure imaging results showed that the smallest average diameter of fungal pellets was achieved (0.7 ± 0.1 mm) by adding 10 g/L (600 mesh) of silica. The diameter of the control was 3.0 ± 0.5 mm in shake flask fermentation. The GUS activity and biomass of DX-THS3 reached 680 U/mL and 4.2 g/L, respectively, with the use of 10 g/L of silica microparticles, whereas those of the control were 210 U/mL and 2.8 g/L via shake flask fermentation. The findings in this study may provide a potential strategy for designing the morphology of filamentous fungi using microparticles in the industrial production of GAMG.

Tuning the pH profile of β-glucuronidase by rational site-directed mutagenesis for efficient transformation of glycyrrhizin

In this study, we aimed to shift the optimal pH of acidic β-glucuronidase from Aspergillus oryzae Li-3 (PGUS) to the neutral region by site-directed mutagenesis, thus allowing high efficient biotransformation of glycyrrhizin (GL) into glycyrrhetinic acid (GA) under higher pH where the solubility of GL could be greatly enhanced. Based on PGUS structure analysis, five critical aspartic acid and glutamic acid residues were replaced with arginine on the surface to generate a variant 5Rs with optimal pH shifting from 4.5 to 6.5. The catalytic efficiency (k_cat /K_m) value of 5Rs at pH 6.5 was 10.7-fold higher than that of PGUS wild-type at pH 6.5, even 1.4-fold higher than that of wild-type at pH 4.5. Molecular dynamics simulation was performed to explore the molecular mechanism for the shifted pH profile and enhanced pH stability of 5Rs.