Metabolomic analysis of marine and mud crabs based on antibacterial activity

Abstract Isolated compounds from marine invertebrates are being increasingly known to possess various pharmacological activities with which many useful drugs have been developed. Crabs contain bioactive compounds including antibacterial, antifungal and antiviral metabolites, isolated from various tissues and organs that have revolutionized treatment of serious diseases. The present study represents the first attempt to investigate and compare the natural antibacterial properties from whole extract of marine blue swimmer crab, Portunus pelagicus , and mud crab, Scylla tranquebarica , against fish pathogenic bacteria. Liquid chromatography/mass spectrometry utilizing a time-of-flight (TOF) mass analyser (LC/MS-QTOF) based metabolomics approach was used to characterize the variation in secondary metabolite production in P. pelagicus and S. tranquebarica crab habitats in Malaysia. Different metabolites are evaluated in both crab species using LC/MS-QTOF. Initially a total of 75 metabolites were identified and only 19 metabolites satisfied the P-Corr cut-off point of less than 0.01 and at least 2-fold change. These metabolites, which contain anti-inflammatory and antibacterial properties, were down regulated in S. tranquebarica samples and up regulated in P. pelagicus samples. In vitro bioassay of methanolic P. pelagicus extracts showed the best antimicrobial response against Gram positive bacteria, Streptococcus agalactiae , and Gram negative bacteria, Vibrio alginolyticus, Klebsiella pneumoniae, and Escherichia coli, with a statistically significant difference ( P   0.05) of P. pelagicus extracts as compared to S. tranquebarica . The results indicate that both types of crab extracts are bactericidal at higher concentrations and bacteriostatic at lower concentrations. This manuscript reports the role of marine and mud crabs with specific emphasis on their secondary metabolites, and discusses current and future developments in both the production of desired crab metabolites and their potential uses in pharmaceutical industries.