Microbial Quality Management And Shelf Life Determination Of Water-Based Paints

ABSTRACT

The microbial quality of materials and final products of Chemical and Allied Products Limited (CAPL), rentable paint industry in Lagos area were analyzed. The bacterial population in the fresh paint samples monitored at two weeks intervals for a period of ten months ranged from 16x 10 - 7x10 ml while the fungal population ranged from 10 x 10-55 x 10 cfu/ml. The isolated bacterial sits were identified as Bacillus polymyxa, B. brevis, B.laterosporus, Proteus mirabilis, Escherichia coli, Pseudomonas aeruginosa, Lactobacillus gasseri and L.brevies based on standard cultural and biochemical techniques and isolates phenotypic profiles, using the Analytical Profile Index (APT) ID 32 E test systems. The fungal isolates were Aspergillus niger, A. flavus and Penicillium. The physico-chemical parameters such as optical density (OD), specific gravity (SG), transmittance (TR) pH and viscosity (VIS) of freshly made point samples were monitored every two weeks over the study period to evaluate the biodegradative activities of the indigenous microorganisms. The Optical density increased from 149 - 391, while TR. pH, SG and VIS decreased from 69-23,8.5 56.2.8658 -1.0053, and 117-108 est respectively over the period. The microbial population count and physicochemical parameters of the spoilt paint samples which served as the control samples were also determined.

The aesthetic qualities of the paint samples were observed to deteriorate with time as indicated try the measured parameters Pseudomonas aeruginosa, which was repeatedly isolated in spill paints was observed to be the highest cellulose-utilizing organism. Ps. aeruginosa also harboured two plasmids with molecular weights ranging from 0.032 - 0112 kb while the other isolated organisms had one. The cured strains of songs lo the existing plasmids and the initial resistance to amikacin, gentamycin and torment. Therefore, the genes for cellulite utilization and paint degradation in bacterial string from this study probably reside on the plasmid DNA. These results were further corroborated by the comparative evaluation of the biodegradative potential of the wild send the cured strains of Ps. aeruginosa on the physico-chemical parameters of fresh print samples. The shelf life of water-based paints was determined to be 2 years, based on the predictive models developed in the study.