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Natural red pigments have been widely used as food and cosmetics additives. However, due to toxic byproducts or allergen issues, it is still necessary to look for some other red pigment products. This study proposed combinatorial strategies to improve production of a new kind of red pigments from the fungus Geomyces WNF-15A, isolated from Antarctica. A high-production medium was developed by statistical experimental design, which was further simplified for industrial use by single-factor experiments. Strain breeding by atmospheric room temperature plasma mutagenesis generated a mutant, Geomyces sp. WNF-15A-M210, which increased production of red pigments by 24.4% and shortened culture phase by 33.3% comparing with the wild-type. The production of red pigments by this mutant favored a weak alkaline condition but required only mild dissolved oxygen tension. Control of initial pH 8.5 (process pH around 7.5) increased red pigments production by 19% comparing with natural condition. Precursor and inhibitor addition experiments indicated that the red pigments were synthesized by polyketide pathway, and feeding 6 mmol/L precursor of sodium acetate by three aliquots at days 3 to 5 improved biosynthesis of red pigments by 27%. Finally, the developed culture process was verified in a 5-L stirred tank bioreactor. The red pigments production of the pH regulation group reached 1.11-fold of the control and 1.95-fold of the precursor regulation group, respectively. This study provides high-production strain, optimized medium, and bioprocess for the possible industrial production of Antarctic Geomyces red pigments in future. PRACTICAL APPLICATION: Antarctic Geomyces red pigments showed high color value, nontoxic characteristic, and good water solubility. It holds potential for industrial use and is under development for food additive in China currently. This study provides an optional manufacturing process for this new kind of red pigments., (© 2020 Institute of Food Technologists®.)

Concern about finding new antibiotics against drug-resistant pathogens is increasing every year. Antarctic bacteria have been proposed as an unexplored source of bioactive metabolites; however, most biosynthetic gene clusters (BGCs) producing secondary metabolites remain silent under common culture conditions. Our work aimed to characterize elicitation conditions for the production of antibacterial secondary metabolites from 34 Antarctic bacterial strains based on MS/MS metabolomics and genome mining approaches. Bacterial strains were cultivated under different nutrient and elicitation conditions, including the addition of lipopolysaccharide (LPS), sodium nitroprusside (SNP), and coculture. Metabolomes were obtained by HPLC-QTOF-MS/MS and analyzed through molecular networking. Antibacterial activity was determined, and seven strains were selected for genome sequencing and analysis. Biosynthesis pathways were activated by all the elicitation treatments, which varies among strains and dependents of culture media. Increased antibacterial activity was observed for a few strains and addition of LPS was related with inhibition of Gram-negative pathogens. Antibiotic BGCs were found for all selected strains and the expressions of putative actinomycin, carotenoids, and bacillibactin were characterized by comparison of genomic and metabolomic data. This work established the use of promising new elicitors for bioprospection of Antarctic bacteria and highlights the importance of new "-omics" comparative approaches for drug discovery.

Aim: To evaluate the effect of temperature on growth parameters and on extracellular polymeric substance (EPS) production for Pseudoalteromonas antarctica NF(3)., Methods and Results: For this purpose, three growth parameters, lag time (lambda), maximum growth rate (mu) and maximum population density (A), were calculated with the predictive Gompertz model. To evaluate the variations in mu with respect to temperature, the secondary Arrhenius and the square root models were used. Below the optimal growth temperature (17.5 degrees C), the growth of P. antarctica was separated into two domains at the critical temperature of 12 degrees C. Within the suboptimal domain (12-17.5 degrees C), the temperature characteristic was the lowest (5.29 kcal mol(-1)). Growth population densities were maintained over the entire physiological portion assayed (5-17.5 degrees C). Higher crude EPS production was found at temperatures included in the cold domain (5-12 degrees C)., Conclusions: All calculated parameters revealed an optimal adaptation of this strain to cold temperatures., Significance and Impact of the Study: The knowledge of the influence of temperature on growth parameters of P. antarctica NF(3) and on EPS production could improve the production of this extracellular polymeric substance that is currently being used in the cosmetic and pharmaceutical industries.