Immobilization of Lactobacillus acidophilus β-galactosidase on chitosan obtained from the shells of the African giant snail, Achatina achatina

Abstract

Most GOS are classified as prebiotic food (since they are nondigestible) or Bifidus growth factor as they can stimulate the establishment of human colonic Bifidobacteria species. In addition, GOS, by suppressing the expression of bacterial quorum-sensing (QS) genes, could prevent the growth and production of biofilms by some possible harmful enteric bacteria. [10][11][12][13] Industrial β-galactosidases are usually sourced from microorganisms, especially fungi, bacteria, and yeasts. 8,9,14 Although many bacteria produce β-galactosidases, major β-galactosidase production has majorly focused on the use of some Lactobacillus species of the Lactic acid bacteria (LBA) with the "Generally Regarded As Safe (GRAS)" status. 15,16 LBA is naturally found in any environment rich in carbohydrates, such as decomposing plant materials, fermented foods, and in the feces of individuals on high milk, lactose, or dextrin diets. 17 Lactobacillus acidophilus ('acid-loving milk-bacillus') is a homofermentative species of Lactobacillus that grows at pH below 5.0 in the lumen of the gut, especially the lower end of the small intestine where it metabolizes any residual lactose, thus encouraging lactose digestion in individuals with low galactosidase activity. 15 Good thermostability and cost are major factors to consider in the industrial application of enzymes. 18 At higher temperatures, thermostable enzymes have increased activity, substrates maintain higher solubility and microbial fouling could be considerably reduced. 9 High cost is a critical issue in the industrial use of immobilized enzymes in relation to enzyme reusability and the regenerability of immobilization supports. This issue has been sufficiently addressed by the overwhelming choice of biopolymeric immobilization supports like some proteins and carbohydrates, but more especially the polysaccharides, chitin, and chitosan. [19][20][21] Chitin is one of the most abundant natural polymers. It can be easily obtained at a relatively low