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Microalgae, due to its rapid growth, low nutritional requirements, and versatility of adaptation to different environmental conditions, has aroused the biotechnological interest, synthesizing novel molecules with antioxidant, anticoagulant, anti‐inflammatory, antitumor, and antimicrobial activities. In this sense, we carried out the bioprospection of Chaetoceros muelleri, a marine diatom employed in aquaculture, as a candidate to the development of new drugs for the treatment of bacterial infections. The chemical profile of extracts in different solvents (hexane, chloroform, methylene chloride, ethyl acetate, methanol, and acetone) were analyzed by 1H‐NMR. The hexane extract was the most active against all bacteria species tested, including Mycobacterium tuberculosis, with a minimum inhibitory concentration of 100 μg/ml. Contrarily, the methanol extract was inactive against all tested microorganisms and, in addition, was the only one with IC50 >800 μg/mL, showing no cytotoxicity in VERO cell lines. All other extracts showed antibacterial potential and IC50 values varying between 267.58 and 142.47 μg/ml. The fact that C. muelleri is a microalga easily grown on bioreactors on a large scale may promote its biotechnological use, especially as scaffolds for the development of new compounds against bacterial species of clinical and public health interest.

Natural products from the marine environment as well as microalgae, have been known for the complexity of the metabolites they produce due to their adaptability to different environmental conditions, which has been an inexhaustible source of several bioactive properties, such as antioxidant, anti-tumor, and antimicrobial. This study aims to characterize the main metabolites of three species of microalgae (Nannochloropsis oceanica, Chaetoceros muelleri, and Conticribra weissflogii), which have important applications in the biofuel and nutrition industries, by 1H High-resolution magic angle spinning nuclear magnetic resonance (1H HR-MAS NMR), a method which is non-destructive, is highly reproducible, and requires minimal sample preparation. Even though the three species were found in the same ecosystem and a superior production of lipid compounds was observed, important differences were identified in relation to the production of specialized metabolites. These distinct properties favor the use of these compounds as leaders in the development of new bioactive compounds, especially against environmental, human, and animal pathogens (One Health), and demonstrate their potential in the development of alternatives for aquaculture.

Proteases are one of the largest groups of industrial enzymes, participating in the detergent industry, leather, food and medicine. The detergent industry is a large consumer of hydrolytic enzymes. New methodologies for the purification of biomolecules are of great interest to the industry for its potential applications. The aim of this work was to produce and purify extracellular proteases from Penicillium restrictum under submerged fermentation. The strain of Penicillium restrictum isolated from cerrado soil was able to produce extracellular protease after 7 days of cultivation at 28°C and 150 rpm in medium with wheat bran. After 7 days of fermentation, broth culture was submitted to ultrafiltration process through a membrane of 100 kDa. Ultrafiltered fraction was added to SMDFA under different conditions, purification being evaluated through a factorial design 2³ with three replications at center point. The results showed that the SMDFA was effective in partitioning of proteases present in the fraction <100 kDa poor phase micelles, with a partition coefficient (k) less than 1 for all tested systems. The system 3 showed 80 mass balance and 138.24% yield. These results being the best mass balance and the best performance. Based on the k values in the mass balance and income values, the system containing 10% Triton X-114, 10% of broth and separated at 31°C was chosen to continue the process of purification of the enzyme of interest. Micelles poor fraction was ultrafiltered through a membrane of 30 kDa and the purification factor of this fraction was equal to 10.4. The partial purification of two extracellular proteases was confirmed by SDS-PAGE followed by zymography. The proteolytic activity showed bands with molecular weights of approximately 19.2 and 30.5 kDa. The partially purified protease showed maximum activity at pH 8.0 and the optimum temperature was estimated at 55 ° C. The enzyme was slightly inhibited by PMSF and quite inhibited by metal ions Fe and Zn and the metal ion Mg +2 induced an increased enzyme activity. Partially purified enzymes were applied to commercial detergent Ypê Premium® where the detergent has potential for possible application in the detergent industry aiding the detergent in removing proteinaceous stains.

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