Fermentation

In this research, cattle manure, macroalgae, and cheese whey were mixed in various proportions (cattle manure:macroalgae:cheese whey ratios of 50:30:20, 30:20:50 and 20:50:30) and subjected to co-digestion under laboratory conditions at two different digestion temperatures (30 and 45 °C). The modified Gompertz and first-order kinetic models were used to predict biomethane potentials. The highest experimental biochemical methane potential of 0.373 Nm³CH₄/kgVS was obtained from Mixture-2 at 45 °C, while the lowest, 0.154 Nm³CH₄/kgVS, was achieved with Mixture-1 at 30 °C. Feedstock rates in the mixture and digestion temperature significantly influenced the biochemical methane potential (p < 0.05). Cheese whey was observed to positively contribute to increasing biomethane potential. Increasing the whey ratio in the mixture from 20% to 50% resulted in a 62.5% increase in biomethane production. While R² values for the modified Gompertz model ranged from 0.993 to 0.999, those of the first-order model varied between 0.968 and 0.984. Of the two kinetic models employed for estimating biomethane potentials, the modified Gompertz model yielded values closer to the experimental biomethane potentials.

The massive annual production of tea generates substantial underutilized by-products, leading to resource waste. This study aimed to develop an efficient process for converting these by-products into high-quality feed via fermentation with Lentilactobacillus buchneri (L. buchneri). Using a response surface methodology, the key fermentation parameters (time, temperature, inoculum size, and moisture) were optimized to target pH and crude protein (CP) content. The optimal conditions (4.5 days, 34.5 °C, 5.00 × 10⁶ CFU/g, 54% moisture) yielded a product with a pH of 3.72 and CP content of 17.96%, which was similar to the predictions. Fermentation successfully reduced ether extract (EE), tea tannin (TTN), and propionic acid (PA), while increasing lactic acid (LA) and lowering pH. This process was driven by the dominance of Lactobacillus (99.29% relative abundance), as revealed by microbial analysis. This work provides a viable and optimized strategy for valorizing tea by-products into nutritionally enhanced feed, thereby contributing to sustainable agricultural practices.

Background: Staurosporine is a potent broad-spectrum alkaloid antibiotic originally isolated from Streptomyces sp. It is renowned for its strong inhibitory activity against protein kinases by competitively binding to their ATP-binding sites. Therefore, staurosporine and its derivatives have been extensively investigated for their potential as anticancer agents. However, a major challenge in its utilization is the low production yield in wild-type strains. To overcome this limitation, this study aimed to enhance staurosporine yield in marine-derived staurosporine-producing strain OUCMDZ-3118. Methods: The fermentation conditions were tested by single-factor experiment, Plackett–Burman experiment, steepest ascent path and Box–Benhnken response surface method. Subsequently, the ultraviolet mutagenesis was employed to generate high-yielding mutant strain. Results: The optimal culture conditions were 50 g/L rice, 50 g/L soybean powder, 3 g/L NaCl, 10 g/L L-tryptophan, inoculum concentration of 3% (v/v) in 150 mL of medium within a 500 mL flask, and fermentation time of 10 days. Following UV mutagenesis, the mutant strain produced a final staurosporine titer of 496 mg/L, an approximately 9.5-fold higher titer than that of the wild-type strain. In a 30-day solid-state fermentation under the conditions of 40 g rice, 40 g soybean powder, moistened with 80 mL water containing NaCl (3 g/L) and L-tryptophan (10 g/L), a yield of 578 mg per 80 g of substrate was also achieved. A consistent yield of 7.22 g/kg was achieved across approximately 1000 replicate fermentations under identical conditions, demonstrating the robustness of the process. Conclusions: This study yielded a stable, high-yielding strain for staurosporine production, paving the way for the development of staurosporine-based antitumor drugs and their derivatives.