Empirical analysis of amylolytic and proteolytic activities of microbial isolates recovered from deteriorating painted wall surfaces in Lagos Nigeria

The biodeterioration of painted walls have been associated with several biological mechanisms such as organic acid production and enzymatic activity of microorganisms amongst other factors. Therefore, this study aims to reveal the involvement of amylases and proteases from indigenous microbes on biodeteriorating painted walls. Microbial strains isolated from biodeteriorating painted walls of selected buildings in Lagos, Nigeria and previously characterized as belonging to the genera Pseudomonas, Candida, Fusarium, Aspergillus, Cerrena and Meyerozyma were used in this study. Amylolytic and proteolytic activities at varying conditions of temperature, pH, incubation time and substrate concentrations were tested. To bridge the knowledge gaps regarding statistical quantification of enzymatic mechanisms in biodeterioration, the Wilcoxon signed rank sum test was used to test the hypothesis that amylolytic/proteolytic activities are equal at all conditions tested. The conditions for optimal activity were observed to be 24h, 37oC, pH 2 and 0.01% substrate concentration and 48h, 25oC, pH 2, and 1% substrate concentration for amylase and protease respectively. Wilcoxon signed rank test revealed that amylolytic and proteolytic activities do not impact aesthetics on painted walls equally at all environmental conditions considered.