Critical evaluation of a putative glucosamine excretion by Aspergillus niger CBS120.49 and Penicillium ochrochloron CBS123.824 under citric acid producing conditions

Chitosan-based supramolecular aerogel with "skeletal structure" constructed in natural deep eutectic solvents for medical dressings

Bacterial infection of wounds remains one of the major clinical challenges, calling for the urgent development of novel multifunctional biological dressings. In this study, we developed a chitosan-based supramolecular aerogel NADES/PVA/CS, constructed by hydrogen bonding between chitosan, a natural deep eutectic solvents and polyvinyl alcohol, as a novel wound dressing against bacterial infections. The effect of polyvinyl alcohol content and its incorporation within chitosan-based supramolecular aerogels were investigated. The results of antibacterial test and MTT assay showed that it has obvious inhibitory effect on Staphylococcus aureus and Escherichia coli, showing excellent biocompatibility and effectively promotes wound healing. The microstructure of chitosan-based supramolecular aerogel showed that by adjusting the addition amount of polyvinyl alcohol, it could exhibit a perfect skeleton-type 3D network structure, which also made it possess smaller density and larger porosity and exhibit excellent water absorption property, contributing to the wetting of wound surface. More importantly, chitosan-based supramolecular aerogel is an environment-friendly biomaterial, which has been verified by degradability experiment. In a word, these unique advantages provide a broad prospect for the medical application of chitosan-based supramolecular aerogel NADES/PVA/CS, and provide a new strategy for the construction of green polysaccharide medical materials.

Genome mining reveals the genes of carboxypeptidase for OTA-detoxification in Bacillus subtilis CW14

Bacillus subtilis CW14, isolated from fresh elk droppings in Beijing Zoo, is a Gram-positive, conferred Generally Recognized as Safe (GRAS) bacterium with the capacity of ochratoxin A (OTA) detoxification. The genome sequence of the CW14 strain showed a size of 4,287,522 bp with 44.06% GC content. It was predicted many putative enzymes involved in degrading mycotoxin by analyzing the signal peptides and the transmembrane regions. Nine extracellular enzymes were predicted relating to OTA detoxification, including four D-Ala-D-Ala carboxypeptidases, two hydrolases, two amidases, and one lactamase. Indeed, two of the carboxypeptidase genes dacA and dacB, expressed in Escherichia coli, were verified contributing to OTA detoxification. DacA and OTA were mixed incubated for 24 h, and the degradation rate reached 71.3%. After purification, the concentration of recombinant DacA protein was 0.5 mg/mL. Bacillus subtilis CW14 and its carboxypeptidases may be used as OTA detoxification agents in food and feed industry production.

Animal Fat as a Substrate for Production of n-6 Fatty Acids by Fungal Solid-State Fermentation

The method of solid-state fermentation (SSF) represents a powerful technology for the fortification of animal-based by-products. Oleaginous Zygomycetes fungi are efficient microbial cell factories used in SSF to valorize a wide range of waste and rest cereal materials. The application of this fermentation technique for utilization and biotransformation of animal-based materials represents a distinguished step in their treatment. In this study, for the first time, the strain Umbelopsis isabellina CCF2412 was used for the bioconversion of animal fat by-products to the fermented bioproducts enriched with n-6 polyunsaturated fatty acids, mainly γ-linolenic acid (GLA). Bioconversion of both cereals and the animal fat by-product resulted in the production of fermented bioproducts enriched with not just GLA (maximal yield was 6.4 mg GLA/g of fermented bioproduct), but also with high yields of glucosamine. Moreover, the fermentation on the cornmeal matrix led to obtaining bioproduct enriched with β-carotene. An increased amount of β-carotene content improved the antioxidant stability of obtained fermented bioproducts. Furthermore, the application of Fourier-transform infrared spectroscopy for rapid analysis and characterization of the biochemical profile of obtained SSF bioproducts was also studied.