Determination of the minimum inhibitory concentrations (MIC) of 212 common soap fragrance raw materials demonstrated that the paper disc-petri plate technique does not reflect the relative antimicrobial activity of these materials. Commonly used soap bacteriostats were shown to be 100 to 1000 times more effective than the most active fragrance materials. Of 521 fragrance materials initially screened by the petri plate method, 44% were inhibitory against one of the three test organisms, and 15% were effective against all three (Staphylococcus aureus, Escherichia coli, Candida albicans). Of a selected number (212) of these positive materials, subsequently screened against a lipophilic diphtheroid organism (Corynebacterium sp.), 64 materials (30%) were positive against all four test organisms. However, only nine materials (4%) had a MIC as low as 50 ppm compared to the common soap bacteriostat TCC | which had a MIC of 0.08 ppm (vs. S. aureus). In hand-degerming tests, no reduction of bacterial counts was obtained with a soap containing the most active fragrance materials. These results demonstrate that creation of a practical antimicrobial soap fragrance does not appear to be possible 9
Commercial microbial lipases have been used in dairy and other food processes, and lipases produced in situ by microorganisms are important in making foods palatable and acceptable. Microbial lipases have been used in detergents, pharmaceuticals, cosmetics, leather processing, production of aliphatic acids, and in the treatment of domestic and industrial wastes. Manufacturers offer lipolytic enzymes in powder form free of other enzymes, and sometimes they are microencapsulated for specialized applications.
Resting cell and cell-free extract experiments demonstrated the presence of citritase, oxaloacetic acid decarboxylase, α-acetolactic acid decarboxylase, and pyruvic acid decarboxylase in Streptococcus diacelilactis. Results indicated that citric acid or pyruvic acid was converted to diacetyl and acetylmethylcarbinol with intermediate synthesis of α-acetolactic acid. Acetylmethylcarbinol also was synthesized by condensation of active and free acetaldehyde. Evidence was obtained for the presence of diacetyl reductase and a reversible 2,3-butanediol dehydrogenase in cell-free extracts of S. diacetilactis. The data suggested that S. diacetilactis produced diacetyl from citrate with the intermediate production of oxaloacetate, pyruvate, and α-acetolactate in that order.
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