Antibiotic activity of marine algae extracts against marine vibrios
Date Issued
2008
Date
2008
Author(s)
Tsai, Yu-Hsuan
Abstract
Safety and freshness of aquatic products are important for consumers, and bacteria are the main resources of infection of aquatic products. Previous studies indicated that many marine algae could inhibit growth and reproduction of pathogenic bacterium. In this study, we extracted substances from marine microalgae and seaweeds to examine their antibiotic activity against marine vibrios. There are three parts of the experiment. The first is to assay and screen for antibacterial activity from 25 species of marine algae, including 14 species of seaweeds and 11 species of marine microalgae. Seaweeds were collected from seashores of Taiwan and microalgae were isolated and cultured in the laboratory. Algal materials were freezing-dried, ground generally and extracted with phosphate buffer saline (PBS) and ethanol solution. The results showed that PBS extracts of seaweeds had remarkable inhibitory activity towards the bacteria used, but marine microalgae didn’t. To find out the most appropriate method of extraction, we furthur treated algal materials with 30%, 60%, and 80% ethanol solutions for extraction. The results showed that 80% ethanolic extracts presented the best antibacterial activity for microalgae and seaweeds. The second part is to assay the antibacterial activity of the chrysophyte Nannochloropsis oculata which was cultured under different light intensities and nutrient conditions. The results showed that antibacterial activity of N. oculata decreased notably as the alga was placed under higher light intensity or provided with less N/P ratio of the medium. The last part is trying to isolate and purify antibacterial compounds of proteinaceous substances from the red algae Gracilaria tenuistipitata, which were using gel filtration column chromatography. The results showed that the chromatography produced three peaks, two of which were active in inhibition towards Vibrio pelagius growth. However, antibacterial substances and their biochemical characteristics of the alga needs further study.
Subjects
antibacterial activity
seaweeds
micro-algae
Nannochloropsis oculata
extracts
SDGs
Type
thesis
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