A Study on the Antibacterial Property Ofacid-Hydrolyzed k-Carrageenan Against Bacillus subtilis and Vibrio Cholerae

Abstract

Carrageenan oligosaccharides are produced from the hydrolysis of carrageenans from red seaweeds. It has been reported that there exists a correlation between hydrolysis time and oligosaccharide size. The antibacterial properties of acid-hydrolyzed kappa and carrageenan were pre-determined using the Kirby-Bauer method and turbidometric study. The best antibacterial agent was subjected to a 12-hr time-kill series. The 5% kappa carrageenan sample hydrolyzed for 30 minutes was added to cultures of Bacillus subtilis and Vibrio cholerae. Aliquots were taken from the cultures and plated during intervals over a 12-hr period. Populations of the bacterial cultures were estimated using the Miles and Misra technique. The results showed that the carrageenan oligosaccharides have antibacterial activity for both cultures. There was an initial decline in population from the period of second to sixth hour and logarithmic growth in population was observed from the seventh hour onwards. Statistical tests were used to correlate oligosaccharide size with antibacterial activity. The population of the treated B. subtilis culture was the same with the untreated culture at 12 hours. While the population of the treated V. cholerae culture was greater compared to the untreated culture at 12 hours. This study has concluded that only specific oligosaccharide sizes have optimal antibacterial activity against B. subtilis and V. cholerae.