Development of an Alternative Enzyme-assisted Dehairing Method of Animal Skins using Proteases from Bacillus licheniformis MZK05M9

Abstract

The present study was aimed to develop an enzyme assisted dehairing method as an alternative and ecofriendly technique to reduce the use of harsh chemicals in leather manufacturing. For this purpose, two proteases namely alkaline protease (601 U/ml) and keratinase (132 U/ml) were produced by Bacillus licheniformis MZK05M9 (BlM9) in Soya molasses medium and Feather mill medium respectively, in 7.0 L bioreactor at pH 7.5 and 37°C. The cell free enzyme preparations were used together at 2.5% level in dehairing experiments. Three sets of experiments for dehairing of goat skins were performed with (1) enzymes; (2) enzymes and 5% lime (CaO) and (3) 2% sodium sulfide (Na2S) and 5% lime. The treatment with enzymes removed 85% of hair from goat skin after 24 hrs under mild shaking condition at room temperature where as the treatment with enzymes and 5% lime together resulted in 100% dehairing under similar conditions. Sodium sulfide along with lime also removed 100% hair faster (with 20 hrs) than other two treatments. The grain surface of the enzyme treated skin was smoother and silkier than that of the chemicals treatment as revealed by Scanning Electron Microscopy. Thus these results indicated that, the enzyme assisted method can be applied in largescale dehairing trial to reduce the use of harsh sodium sulfide.Bangladesh J Microbiol, Volume 32, Number 1-2,June-Dec 2015, pp 33-37

Evaluation of the Effectiveness of Different Enzyme Formulations in the Unhairing Process of Goatskins

“…A mixture of lipase and protease, keratinase and Protease and amylase and protease enzymes had 100% complete unhairing but the resulting pelts were very soft. A similar study by Mamun et al, (2015), found that a mixture of 2.5% of keratinase and 2.5% of protease enzymes were able to unhair 85% of the pelt area for a period of 26 hours. The addition of calcium oxide to keratinase and protease enzymes improved the performance of the enzymes and the pelt area was unhaired 100% for a period of 24 hours (Mamun et al, 2015).…”

“…A similar study by Mamun et al, (2015), found that a mixture of 2.5% of keratinase and 2.5% of protease enzymes were able to unhair 85% of the pelt area for a period of 26 hours. The addition of calcium oxide to keratinase and protease enzymes improved the performance of the enzymes and the pelt area was unhaired 100% for a period of 24 hours (Mamun et al, 2015). Several formulations gave a complete unhairing as indicated in Table 3.…”

Comparative Genomics of Bacillus Subtilis MZK05 and Its Mutant Strain Revealed Genetic Factors Responsible for Enhanced Serine Protease Expression

“…With a view to increasing the performance, the bacterium was subjected to random mutagenesis using both chemical (ethyl methane sulfonate) and UV radiation 18 that eventually generated a mutant strain, B. subtilis M9 from a selection of potential strains, able to produce more efficient extracellular protease than that of the wild type. This was demonstrated in unhairing and bating of skin and hides, a performance comparable to that of the commercial enzymes, thereafter was applied successfully in leather industries 19 , 20 , 21 . Therefore, we attempted here to compare the genome sequencing of the two strains to pinpoint the probable cause of high-level expression of serine proteases in B. subtilis M9 mutant, the number of proteases, and other industrially useful enzymes and metabolites, genes responsible for extracellular protease secretion, genome variation in between the strains studied here with that of strains from different countries of origin, and evolutionary relationships present with other bacterial species of Bacillus subtilis group.…”