Production of phosphatase by microorganisms isolated from discolored painted walls in a typical tropical environment: a Non-Parametric analysis

The enzymatic activities occurring on painted walls in a tropical environment have become critical given the rate of aesthetic biodeterioration of such walls. Pigmented heterotrophic microorganisms isolated from discolored painted walls in Lagos, Nigeria were screened for their phosphatase activities. The strains were characterized by morphological methods and 16S rDNA analysis as belonging to the genera Aspergillus, Meyerozyma, Candida, Fusarium, Cerrena and Pseudomonas. The sequences were submitted to NCBI GenBank. Crude extracellular phosphatase from cell-free culture supernatant were reacted in p-nitrophenolphosphate. Subsequently, their alkaline phosphatase activities were compared. All tested strains produced phosphatase at different pH, temperature, incubation time and substrate concentration which were used as biomarkers for microbial metabolic activity. The order of optimal phosphatase production was observed as: Cerrena sp > Aspergillus sp >M. guilliermondii > A. aculeatus > F. proliferatum > P. aeruginosa > C. tropicalis > M. caribbica. Morphological studies and microbial enzymatic activity confirm the hypothesis that heavy pigmentation and phosphatase production are major indices of discoloration on biodeteriorating painted walls in a typical tropical environment like Nigeria. Kruskal-Wallis non-parametric test revealed that there was no statistically significant difference in phosphatase production at the different environmental conditions examined except at different time intervals