ABSTRACT
Marine microalgae have been reported as an excellent source of bioactive compounds. The present study analyzesthe existence of bioactive phytochemicals and their efficacy in antimicrobial activity against aquatic pathogens.The antimicrobial compounds were extracted from three marine microalgae, namely Chlorella sp., Pavlova sp., andChaetoceros sp., and Pavlova sp. showed a broad spectrum of activity. Pavlova sp. extracts were tested against theselected aquatic pathogens, such as Vibrio harveyi, Vibrio parahaemolyticus, Pseudomonas aeroginosa, Aeromonashydrophila, and Staphylococcus aureus, and the result showed the inhibiting activity against aquatic pathogens. Theminimum inhibitory concentration and minimum bactericidal concentration, cytotoxic assay, and mode of actionwere also studied. The effective five crude extracts were purified by column chromatography and tested against thepathogens; then, the active fraction was partially characterized by Fourier transform infrared (FTIR) analysis. TheFTIR result suggested the presence of bioactive groups, such as amines, alkane, carboxylic acid, sulfoxide, alcohol,boron, etc. From the five extracts, two active extracts were selected and subjected to TLC (Thin layer chromatography).The cytotoxic activity (LD-50) indicates that the compound may be safe and effective for clinical trial. Finally, thealgal cytotoxic assay concluded that the isolated compound can also be used as an algicide to control algal blooms.This study proves that Pavlova sp. is an excellent source of pharmacologically active resourceful algae and showseffective activity against aquatic pathogens.
ABSTRACT
Abstract (1) Background: The aim of this study was to evaluate the production and partial characterization of xylanase and avicelase by a newly isolated Penicillium sp. in solid-state fermentation, using soybean hulls as substrate. (2) Methods: Temperature, time, number of spores, and substrate moisture on xylanase and avicelase bioproduction were evaluated, maximizing activity with 30°C, 1x106 spores/g substrate, 14 and 7 days of fermentation with 70 and 76% substrate moisture contents, for xylanase and avicelase, respectively. (3) Results: Different solvents, temperatures, and agitation in the enzymatic extraction were evaluated, obtaining higher activities, 430.77 and 26.77 U/g for xylanase and avicelase using 30 min extraction and 0.05 M citrate buffer solution (pH 4.5 ), respectively at 60°C and 175 rpm and 50°C and 125 rpm. The optimum pH and temperature for enzymatic activity determination were 5.3 and 50°C. Enzyme extract stability was evaluated, obtaining higher stability with pH between 4.5 and 5.5, higher temperature of up to 40°C. The kinetic thermal denaturation (Kd), half-life time, D-value, and Z-value were similar for both enzymes. The xylanase Ed value (89.1 kJ/mol) was slightly lower than the avicelase one (96.7 kJ/mol), indicating higher thermostability for avicelase. (4) Conclusion: In this way, the production of cellulases using alternative substrates is a way to reduce production costs, since they represent about 10% of the world demand of enzymes, with application in animal feed processing, food production and breweries, textile processing, detergent and laundry production, pulp manufacturing and the production of biofuels.