BACKGROUND Lactose intolerance is a common health concern causing gastrointestinal symptoms and avoidance of dairy products by afflicted individuals. Since milk is a primary source of calcium and vitamin D, lactose intolerant individuals often obtain insufficient amounts of these nutrients which may lead to adverse health outcomes. Production of lactose-free milk can provide a solution to this ...

A mathematical model of the lactose (lac) operon was developed to study diauxic growth on glucose and lactose. The model includes catabolite repression, inducer exclusion, lactose hydrolysis to glucose and galactose, and synthesis and degradation of allolactose. Two models for catabolite repression were tested: (i) cyclic AMP (cAMP) synthesis inversely correlated with the external glucose conce...

Discontinuous and continuous processes of lactose hydrolysis and concomitant galacto-oligosaccharide (GalOS) formation were studied. To this end a wide experimental range of the main variables was evaluated, including the initial lactose concentration, the degree of lactose conversion, the pH value and the temperature for discontinuous transformations, while the initial lactose concentration an...

β-galactosidase simply known as lactase is a significant enzyme in food industry mainly used to hydrolyse lactose in milk. In addition to provide lactose free milk for lactose intolerant people, hydrolysis of lactose avoids textural problems in frozen milk products. β-galactaosidase from different sources has been immobilized on many various type of matrixes including chitosan, alginate, sepabe...

Bacteria used to ferment milk to obtain yogurt belong to thermophilic, bile-sensitive species of lactic acid bacteria, which are not ideally suited for survival into the human gut. However, assessing the viability of these bacteria through the digestive tract may be relevant to evaluate their potential to deliver some beneficial effects for the well-being of the consumer. The well-known reducti...

ebg enzyme, the second beta-galactosidase of Escherichia coli, does not normally convert lactose into an inducer of the lac operon. We previously reported the existence of a mutant ebg enzyme that does make such an inducer in vivo (Rolseth et al., J. Bacteriol. 142:1036-1039, 1980). Here I report that the mutant enzyme makes inducer from lactose in vitro and that the inducer is allolactose. Al...

Highly purified [D-glucose-1-14C]lactose has been used to study the transport of lactose by Klebsiella sp. strain CT-1. Strain CT-1 transports lactose by a lactose-inducible system that exhibited an apparent Km of 6 mM lactose and an apparent Vmax of 140 nmol/min per mg of cell protein. Lactose uptake was inhibited competitively by o-nitrophenyl-beta-D-galactoside with a Ki value of 8 mM, but w...