Anti-Bacterial Activity of Carrageenan Oligosaccharides

Abstract

Carrageenan oligosaccharides are produced from the hydrolysis of carrageenans. They have been reported to have anti-coagulant, anti-browning and antibacterial activities. Carrageenans are galactan polysaccharides from red seaweeds. They have a variety of applications, ranging from food stabilizers to antiviral agents. In this study, the antibacterial property of carrageenan oligosaccharides was determined in a 12-hr time-kill series. A concentration of 5% weight/volume was added to cultures of Bacillus subtilis, Staphylococcus aureus and Citrobacter freundii. Aliquots were taken from the cultures and plated during intervals over a 12-hr period. Populations of the bacterial cultures were assessed using the viable cell counts obtained via Miles and Misra technique, and the percent kill values for B. subtilis. The results showed that the carrageenan oligosaccharides have an antibacterial activity against B. subtilis. There was an initial decline in population during the first hour and bactericidal activity occurred afterwards and this continued until the twelfth hour. Although the following hours produced fluctuations, the populations of the untreated culture were lower than the treated culture. There was no decrease in the populations of S. aureus and C. freundii. However, the colonies of S. aureus were smaller compared to the control. The population counts of the treatment and the control were the same after 48 hrs. This study has concluded that carrageenan oligosaccharides appear to have anti-bacterial activity against B. subtilis but not against S. aureus and C. freundii.