Characterization of Antibacterial proteins from epidermal mucus of some selected teleost fishes

MRP(S)-981/10-11/ KLMG 022/UGC-SWRO dated 22.12.2010

Dr. Jinsu Varghese, Asst. Professor, Department of Zoology
St. Thomas College, Kozhencherry-689641


Antimicrobial proteins and peptides play key roles in innate immunity and have been observed in a wide variety of organisms in the last few years. It is well established that mucus, along with having other important biological functions, contributes to the defense system of fish. The present study was undertaken to characterize antimicrobial proteins/ peptides from the epidermal mucus of some teleost fishes. Some locally available teleost fishes were screened for antibacterial properties and two fishes namely the Channa striatus and Clarias batrachus were finally taken for the characterization of proteins. The epidermal mucus sample from Channa striatus showed inhibition of the growth of six human pathogenic bacteria viz Staphylococcus aureus, Enterococcus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginos and Proteus vulgaris. The maximum zone of inhibition was observed against Pseudomonas aeruginosa (28mm). The epidermal mucus sample pooled from Clarias batracus have inhibited the growth of five pathogenic bacteria viz   Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Klebsiella pneumoniae, Pseudomonas aeruginosa. Among the pathogens, Escherichia coli and Pseudomonas aeruginosa exhibited a high sensitivity. The maximum zone of inhibition was observed against Escherichia coli (23.3 mm), and minimum against Proteus vulgaris(5.3 mm). The results of the present investigation reported that the epidermal mucus of Channa striatus and Clarias batrachus   extracted in cold acetone have remarkable antimicrobial activity. The acetone extract of mucus of the fishes namely Channa striatus and Clarias batrachus showed strong antibacterial activity which were further subjected to protein and free amino acid estimation.  SDS-PAGE showed the presence of two proteins/peptides of molecular masses 66kDa and 43kDa in case of Channa striatus while only one protein band was detected in Clarias batrachus. The molecular mass of the peptide was determined to be 43 kDa. The proteins/peptides contributed to the bactericidal activity against various human pathogens.

The findings thus support the use of fish mucus as ingredients of drugs to combat against the human pathogens. This study provides a better understanding of mucosal innate immunity. It highlights the presence of biologically active substances in epidermal mucus for fish and human health related applications. The results of present study support the folkloric usage of fishes in combating various diseases and wound healing. This study strongly suggests that the constituents present in the mucus can be used to formulate new drugs for the therapy of infectious diseases caused by pathogens. Active compounds present in the mucus samples can be isolated and new natural drugs against various diseases can be produced to replace the existing antibiotics.

The results of present study support the folkloric usage of fishes in combating certain infectious diseases. This study proposes that such bioactive peptides can be isolated and effective drugs can be formulated for human health related applications. Further investigations in active compounds present in the mucus samples will lead to find out new natural compounds against various diseases. This study will be a base for further in-depth investigation and structural elucidation.