Effect of alkaline pH on bioactive molecules of epidermal mucus from Labeo rohita (Rahu)

Objectives: The present study was carried out to asses the role of bioactive molecules in the epidermal mucus of Labeo rohita and their antimicrobial and lysozyme activities. Materials and Method: The fish mucus was collected by anaesthesia and alkali treatments. Total protein contents in mucus were estimated by Bradford assay and SDSPAGE was performed for the protein profiling. Antimicrobial and lysozyme activities of mucus were measured. Findings: Extraction by anaesthesia and alkali treatments produced 100+9.7 ml and 350+38.4 ml of mucus respectively. Significantly higher protein concentration (4.3 mg/ ml) was found in anaesthesia treated samples than alkali treated (1.5 mg/ml) and neutralized mucus samples (0.55 mg/ml).The highest antibacterial activity was seen against Escherichia coli where as the mucus supported the growth of Candida albicans. Lysozyme activity was significantly higher in anaesthesia treated mucus (74.3 units/ ml) in comparison to alkali treated (32 units/ml) and neutralized mucus (14 units/ml). Prominent peptide bands ranged between 13KD to 100KD were observed in anaesthesia treated mucus as compared to alkali treatment that denatured the most of the bands. Conclusion: Alkaline pH reduced the activity of bioactive components of fish mucus, although the volume of fish mucus increased but actual immune parameters such as total protein contents, lysozyme and antimicrobial activity were decreased. Further detailed studies are required to understand the role and nature of the bio molecules found in the mucus.