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
Microalgae produce a wide range of compounds including pigments, protein, starch, and lipids, which havebeen extensively used for various applications. In the current scenario, microalgal lipids are considered as apromising source for the production of next-generation bioenergy, and a huge productivity is needed to meet thedemand. Thus, to increase the production of biomass and lipid content, physical conditions play an importantrole and necessary to be optimized. The present study made such an attempt to optimize the physical factors forthe growth and production of lipid from Nannochloropsis gaditana. The study aimed to determine the effect ofphysical parameters such as pH, temperature, light intensity, and salinity. The results showed that the maximumgrowth rate of the N. gaditana was noticed in the salinity of 25 ppt, pH of 8, temperature of 25°C, and 2,000 luxof light intensity. The highest lipid content of the N. gaditana was noticed in the salinity of 30 ppt, pH of 8, andtemperature of 30°C with 2,000 lux light intensity. After optimization, above 40% of lipid yield was obtained,and it can be effectively utilized in bioenergy production.
ABSTRACT
Objective: To study the influence of Calotropis procera (C. procera) active principles against aquatic microbial pathogens isolated from shrimp and fishes. Methods: C. procera leaf powder was serially extracted with hexane, ethyl acetate and methanol and screened by antibacterial, antifungal and antiviral activity against aquatic pathogens which isolated from shrimp/fish. After initial screening, the active extract was purified through column chromatography and again screened. Finally the active fractions were characterized by phytochemical analysis and GC-MS analysis. Results: In vitro antibacterial, antifungal and antiviral screening revealed that, the ethyl acetate extracts were effectively suppressed the bacterial pathogens Pseudomonas aeruginosa (P. aeruginosa), Vibrio harveyi (V. harveyi) and Aeromons hydrophila (A. hydrophila) of more than 20 mm zone of inhibition; the fungi Fusarium sp and the killer virus WSSV. The ethyl acetate extracts of C. procera incubated WSSV was failed to multiply its progeny in the in vivo system of shrimp P. monodon. The shrimp had 80% survival after WSSV challenge from the control group significantly (P<0.001) and also PCR detection confirmed that no WSSV transcription found in shrimp haemolymph. After purified the ethyl acetate extracts again antimicrobial screening performed and it concluded that the fraction namely F-II was effectively suppressed the bacterial growth and WSSV due to its enriched active principles such as cardiac glycosides, Phenols, alkaloids, Tannin and quinines. Surprisingly this fraction, F-II was effectively controlled the WSSV at 90% level at a highest significant level (P<0.001). Finally the structural characterization by GC-MS analysis revealed that, the F-II fraction contained Phenols including several other compounds such as 2,4-bis(1,1-dimethylethyl)-, Methyl tetradecanoate, Bicyclo[3.1.1] heptane, 2,6,6-trimethyl-, (1α,2β,5α)-and Hexadecanoic acid etc. Conclusions: The present study revealed that there is a possibility for developing new eco-friendly antibacterial and antiviral drugs from C. procera against aquatic important pathogens.