Isolation of Cordyceps ophioglossoides L2 from Fruit Body and Optimization of Fermentation Conditions for Its Mycelial Growth

Improvement of nucleotide content of Cordyceps tenuipes by Schisandra chinensis: fermentation process optimization and application prospects

Nucleotides are important components and the main indicators for judging Cordyceps quality. In this paper, the mixed fermentation process of Schisandra chinensis and Cordyceps tenuipes was systematically studied, and it was proposed that the fermentation products aqueous extract (S-ZAE) had antioxidant activity and anti-AChE ability. Herein, the results of a single factor showed that S. chinensis, yeast extract, inoculum amount, and pH had significant effects on nucleotide synthesis. The fermentation process optimization results were 3% glucose, 0.25% KH2PO4, 2.1% yeast extract, and S. chinensis 0.49% (m/v), the optimal fermentation conditions were 25℃, inoculum 5.8% (v/v), pH 3.8, 6 d. The yield of total nucleotides in the scale-up culture was 0.64 ± 0.027 mg/mL, which was 10.6 times higher than before optimization. S-ZAE has good antioxidant and anti-AChE activities (IC50 0.50 ± 0.050 mg/mL). This fermentation method has the advantage of industrialization, and its fermentation products have the potential to become good functional foods or natural therapeutic agents.

Enhanced protein glutaminase production from Chryseobacterium proteolyticum combining physico-chemical mutagenesis and resistance screening and its application to soybean protein isolates

BACKGROUND

Protein glutaminase (PG) is a novel protein modification biotechnology that is increasingly being used in the food industry. However, the current level of fermentation of PG-producing strains still does not meet the requirements of industrial production. To obtain the mutant strains with high PG production, the atmospheric and room temperature plasma (ARTP) combined with LiCl chemical mutagen were used in mutagenesis of a PG producing Chryseobacterium proteolyticum 1003.

RESULTS

A mutant strain (WG15) was successfully obtained based on malonic acid resistance screening after compound mutagenesis of the starting strain C. proteolyticum 1003 using ARTP with LiCl, and it was confirmed to be genetically stable in PG synthesis after 15 generations. The protein glutaminase production of WG15 was 2.91 U mL^-1 after optimization of fermentation conditions, which is 48.69% higher than the original strain C. proteolyticum 1003. The PG obtained from fermentation showed good activities in deamidation of soy protein isolate. The solubility and foaming properties of the PG-treated soy protein isolate were significantly increased by 36.50% and 10.03%, respectively, when PG was added at the amount of 100 U mL^-1 . In addition, the emulsifying activity and emulsion stability of the treated soy protein isolate were improved by 12.44% and 10.34%, respectively, on the addition of 10 U mL^-1 PG. The secondary structure of the soy protein isolate changed after PG treatment, with an increased proportion of glutamate.

CONCLUSION

The results of the present study indicate that the PG produced by this mutant strain could improve the functional properties of soybean protein isolate and the C. proteolyticum mutant WG15 has great potential in food industry. © 2023 Society of Chemical Industry.

An efficient genetic transformation system for Chinese medicine fungus Tolypocladium ophioglossoides

Tolypocladium ophioglossoides is a rare and valuable fungus extensively used in Chinese medicine for relieving postmenopausal syndrome in women yet its bioactive molecules are unknown. To explore its molecular mechanisms, we have developed a reliable Agrobacterium-mediated transformation system using the selective marker: the chlorimuron ethyl-resistance gene sur. For this purpose, we firstly constructed a T-DNA binary vector system and then improved the transformation efficiency by optimizing conditional parameters including the Agrobacterium tumefaciens concentration, the conidia number of T. ophioglossoides, the co-culture time and the concentration of acetosyringone. Furthermore, we have knocked-out the ku70 gene，which is a key gene in non-homologous end joining (NHEJ) DNA repair pathway，and the effect of the length of the homologous arms (HA) on the genetic transformation efficacy was also examined, which increased by 60% when HA was about 3 kb in length. Our results suggest that the genetic transformation system is efficient and feasible for the truffle-parasite fungus T. ophioglossoides, which can further be used in large-scale experiments for characterization of genes of interest in future work.

Optimized extraction, composition, antioxidant and antimicrobial activities of exo and intracellular polysaccharides from submerged culture of Cordyceps cicadae

BACKGROUND

Cordyceps cicadae is known as Jin Chan Hua in Traditional Chinese Medicine and known to possess different pharmacological activities. Presently, it was collected from the wild and isolated. Mycelial culture was optimized for extraction of polysaccharides under submerged culture conditions. Besides antioxidant, antibacterial activities of extracted polysaccharides were tested for first time.

METHODS

Exo-polysaccharides (EPS) and intracellular polysaccharides (IPS) production was tested under different factors (medium capacity, rotation speed, pH, incubation time, temperature, carbon, nitrogen, minerals sources and carbon to nitrogen ratio) by orthogonal experiments using one-factor-at-a-time method. Monosaccharides composition of polysaccharides produced by C. cicadae was determined using high performance liquid chromatography. Antioxidant and antimicrobial activities on eight bacterial strains were checked by different standard procedures.

RESULTS

Factors viz., medium capacity, rotation speed, incubation time, pH and temperature affected the EPS and IPS production under submerged culture conditions. EPS and IPS production was observed to vary with different carbon and nitrogen sources as well as C/N ratio. Glucose was the major component of polysaccharides (63.10 ± 4.15 %). Extracted EPS and IPS showed higher antioxidant potential with significant DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power and iron chelating activity. Antimicrobial activities of EPS and IPS varied among the tested bacterial strains. IPS showed slightly higher inhibition rate to all the tested bacterial strains as compared to EPS. Maximum inhibition zones of IPS (12.9 ± 0.2 mm) and EPS (12.5 ± 0.3 mm) was observed against Pseudomonas aeruginosa at 10 % con. However, both EPS and IPS fractions showed broad spectrum for all the pathogenic microbial strains tested. The MIC of both the extracts ranged from 60-100 mg/mL.

CONCLUSIONS

EPS and IPS production from submerged culture of C. cicadae with significant antioxidant and antibacterial potential can be enhanced with the combination of several factors which can be used for large scale industrial fermentation of C. cicadae.

Optimization, Composition, and Antioxidant Activities of Exo- and Intracellular Polysaccharides in Submerged Culture of Cordyceps gracilis (Grev.) Durieu & Mont

Under present experiments, EPS and IPS production, monosaccharide composition, and antioxidant activities of C. gracilis were studied for the first time under submerged culture conditions. Effect of different factors on polysaccharides production was studied by orthogonal experiments using one-factor-at-a-time method. Incubation of culture in the medium with capacity 200 mL (675.12 ± 5.01 and 385.20 ± 5.01 mg/L), rotation speed 150 rpm (324.62 ± 3.32 and 254.62 ± 4.62 mg/L), 6-day culture incubation time (445.24 ± 1.11, 216.60 ± 1.71 mg/L), pH 6.0 (374.81 ± 2.52 and 219.45 ± 2.59 mg/L), and temperature 23°C (405.24 ± 1.11 and 215.60 ± 1.71 mg/L) produced higher EPS and IPS, respectively. Maximum EPS and IPS production was observed in the medium supplemented with glucose as a carbon source (464.82 ± 2.12 and 264.42 ± 2.62 mg/L) and yeast extract as a nitrogen source (465.21 ± 3.11 and 245.17 ± 3.24 mg/L), respectively. Carbon to nitrogen ratio for maximum EPS and IPS production was observed as 10 : 1 (395.29 ± 2.15 and 235.62 ± 1.40 mg/L), respectively. Glucose was found to be the major monosaccharide (62.15 ± 7.33%). Both EPS and IPS of C. gracilis showed significant DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power, and iron chelating activity.