A practical evaluation of detergent and disinfectant solutions on cargo container surfaces for bacteria inactivation efficacy and effect on material corrosion

Cleaning and disinfection agents were evaluated against selected bacteria on three surfaces: aluminium, stainless steel and fibre re-enforced plastic, used as cargo container linings and to access their effect on the surface integrity. Nine sanitation chemical solutions: benzalkonium chloride, sodium hypochlorite, nitric acid, levulinic acid, peracetic acid sodium hydroxide, sodium dodecyl sulphate, AT special (commercial detergent) and Disinfect Maxi (commercial disinfectant) were tested against seven bacteria strains: Escherichia coli K12, E. coli DSM 682, Salmonella Senftenberg DSM 10062, Salmonella Typhimurium P6, Pseudomonas aeruginosa DSM 939, Listeria monocytogenes Scott A and Listeria innocua P577 in dirty condition as described by standard bactericidal test both in suspension and on the three surfaces. With the exception of sodium dodecyl sulphate (SDS) and AT Special (ATS), the others were efficient in reducing the live bacteria counts as required by the standards for six of the bacteria both in suspension and on the three surfaces; L. monocytogenes Scott A was the exception. Only peracetic acid was able to disinfect all seven strains on all surfaces (> 4 log CFU reduction) as well as in suspension (> 5 log CFU reduction) as required by the standards. Accelerated corrosion tests also showed that most of the disinfectant will likely compromise the integrity of the surfaces. Only peracetic acid at the concentration used had minimal corrosion effect. A novel index for practical usability was created to take into account disinfection efficacy and low corrosiveness; peracetic acid had the highest usability index from the chemicals tested. Peracetic acid based disinfectants will be appropriate for an environment with the composite materials studied as found in some cargo containers. Combining disinfection studies, corrosion studies and the index of the two can assist the food and allied industries in making cost-effective choices for disinfectants depending on surface materials present.Keywords: Detergents, bacteria, cargo container surfaces, disinfectantAfrican Journal of Biotechnology Vol. 12(23), pp. 3689-369

Esterase and protease activities of Bacillus spp. from afitin, iru and sonru; three African locust bean (Parkia biglobosa) condiments from Benin

Fifty strains of Bacillus spp. comprising Bacillus subtilis and Bacillus licheniformis previously isolated from afitin, iru and sonru were examined for esterase and protease activities. The electrophoretic profiles of fermented African locust bean protein (ALBP), using strains presenting the highest protease activities in casein agar, were analyzed by SDS-PAGE to select strains with good ability to be used as starter cultures. All the Bacillus spp. tested showed esterase activity against tributyrin with high variability among strains. Strains showing the highest esterase activities were B. subtilis, primarily isolated from iru, sonru and lastly in afitin. Only 62% (31/50) of the Bacillus strains tested showed perceptible, but highly variable protease activity in casein agar. Bacillus strains showing the highest protease activities comprised strains of B. subtilis isolated from afitin and iru and strains of B. licheniformis isolated from iru and sonru. A B. subtilis strain isolated from afitin showed high esterase as well as high protease activity. The electrophoretic profile by SDS-PAGE of ALBP fermented by the Bacillus spp. having the highest protease activities showed degradation products with a wide range of molecular size between 4 and 250 kDa. Variability of the characteristics of the Bacillus spp. tested give new opportunities for their use as starter culture for products development.Keywords: Bacillus subtilis, bacillus licheniformis, fermentation, esterase and protease activity, SDS-PAG