Chitosan and chitooligosaccharides (COS), as derivatives of chitin through deacetylation reaction, have broad applications due to their good biodegradability, biocompatibility, and solubility. In addition, chitosan and COS are involved in cell wall morphogenesis and host–pathogen interactions in vivo. Chitin deacetylases (CDAs) are enzymes that can catalyze the de-N-acetylation of chitin. They are widely distributed in protozoa, algae, bacteria, fungi, and insects with important physiological functions. Compared with the traditional chemical method, enzymatic catalysis by CDAs provides an enzymatic catalysis method to produce chitosan and COS with controllable deacetylation site and environmental friendliness. These characteristics attract researchers to produce CDAs by fungicides or pesticides. However, researches on heterologous expression and directed evolution of CDAs are still lacking. In this review, we summarize the latest knowledge of CDAs, especially for heterologous expression systems and directed evolution strategies, which may contribute to the industrial production and future application of CDAs.
A new strategy was proposed to improve the utilization rate of corn straw by making non-ruminant feed products. The corn straw was ball milled, and the crushed straw was subjected to solid-state fermentation. After ball milling, the particle size of corn straw decreased significantly from 4.85 ± 0.07 cm to 10–100 μm, the content of neutral detergent fiber and acid detergent fiber decreased by 1.3% and 3.5%, respectively, and the total soluble sugar content increased by 16.2 mg/g. At the same time, the straw treated by ball milling as substrate could promote the rapid growth of Pediococcus acidilactici R30, the increase of organic acid production and further improvement of other nutrients during solid-state fermentation. In conclusion, the fermented straw products after ball milling could significantly improve the performance of pig feed in terms of digestibility and nutritional value, and better meet the feed needs of non-ruminant animals while saving resources.
Bioethanol is a renewable, clean energy and a very important basic chemical raw material, improving production efficiency and reducing production cost are the goals pursued by ethanol enterprises. Adding acid protease in the process of producing ethanol from grain will have many effects on fermentation, one of the most concerned effects is to increase liquor yield. Acid protease can hydrolyze the protein in cereals to produce free amino acids that can be used directly by yeast, thus reducing the amount of sugar consumed for amino acid metabolism, and allowing more sugar to be converted to ethanol. The application method and effect of acid protease in the industrial production of ethanol from corn were studied in this study, the results showed that the addition of acid protease at the dosage of 10 U/g (raw material) during yeast seeding could replace urea, promote yeast proliferation, reduce the infection rate, shorten the fermentation period by 7.5 h and increase the alcohol yield of raw materials by 0.33 percentage point. When acid protease was used in ethanol production line with an annual output of 180,000 tons, the net profit increased by at least US $4900/day compared with the control process. It is hoped that this study can lay a foundation for the application of acid protease in ethanol industry.
Microalgae are considered a rich source of high-value metabolites with an array of nutraceutical and pharmaceutical applications. Different strategies have been developed for cultivating microalgae at large-scale photobioreactors but high cost and low productivity are the major hurdles. Optimizing the composition of media for the cultivation of microalgae to induce biomass production and high-value metabolite accumulation has been considered as an important factor for sustainable product development. In this study, the effect of plant growth regulators together with basal microalgal cultivation medium on biomass, total lipid, and EPA production was studied using the Plackett–Burman model and Response surface methodology. The traditional one-factor-at-a-time optimization approach is laborious, time-consuming, and requires more experiments which makes the process and analysis more difficult. The Designed PB model was found to be significant for biomass (396 mg/L), lipid (254 mg/L), and EPA (5.6%) production with a P value < 0.05. The major objective of this study is to formulate a medium for EPA production without compromising the growth properties. Further, we had formulated a new media using RSM to achieve the goal and the significant variables selected were NaNO3, NaH2PO4, and IAA and was found to be significant with 16.72% EPA production with a biomass production of 893 mg/L with a P value < 0.05. The formulated medium can be used in large-scale cultivation systems which can enhance biomass production as well as the omega 3 fatty acid production in marine microalgae Nannochloropsis oceanica.
Burans is an evergreen tree that bears flowers with colors ranging from bright red to pink and are distributed throughout the world. The flowers of Burans exhibit many therapeutic, nutritional, and aromatic properties along with diverse health benefits. These characteristics of Burans can have a great impact on the quality of alcoholic wines and provide value addition to the Burans flowers as a fermented product, which is otherwise wasted. Thus, in this study, Burans flowers were used for the preparation of a new flavor of the wine to enhance the utility of this flower. Fermentation time (5, 8 and 11 days), temperature (30, 32 and 34 °C), pH (3.5, 4.0 and 4.50), and total soluble solids (TSS: 22, 24 and 26ºBx) were varied to identify the most suitable conditions for high-quality wine production. The titratable acidity, reducing sugar, pH, and TSS of Burans wine were analyzed after fermentation which ranged from 0.36 to 0.78%, 9.8 to 13.3%, 3.43 to 4.13, and 6.9 to 16.8ºBx, respectively. This study also provides a useful benchmark for the industrial production of Burans flower wine with a standard alcohol content of 14.1%.