Tyrosinase inhibitors and insecticidal materials produced by Burkholderia cepacia using squid pen as the sole carbon and nitrogen source

Abstract

Reports of tyrosinase inhibitors from microorganisms are rare. A tyrosinase inhibitor- and insecticidal materials-producing bacterium, strain TKU026, was isolated from Taiwanese soil and identified as Burkholderia cepacia. Among the tested chitin-containing materials, squid pen best enhanced the production of tyrosinase inhibitors and insecticidal materials. The tyrosinase inhibitory activity (5,000 U/mL) and insecticidal activity (81 %) against Drosophila larvae was maximised after cultivation on 1 % squid pen-containing medium for 3 days. The tyrosinase inhibitory activity persisted even when the culture was treated with acidic or alkaline conditions of pH 3 or 11. The activities of both tyrosinase inhibitors and insecticide remained at 100 %, even after treatment at 100 °C for 30 min. The culture supernatant after 3 days of cultivation also showed antifungal activity against Aspergillus fumigatus and Fusarium oxysporum with maximal activities of 100 and 80 %, respectively, but no antibacterial activity against Escherichia coli was observed. The tyrosinase inhibitors were assumed to be polyphenolic compounds according to the results of chromatography.