Delayed lactose fermentation occurs in bacteria that produce reduced (sub-optimal) levels of beta-galactoside permease; the enzyme that transports lactose across the membrane into the cell for metabolism. However, they produce optimal levels of the lactose splitting enzyme, beta-galactosidase. There therefore exists a time lag in their ability to transport sufficient molecules of lactose across the membrane to provide the needed metabolic cue for hydrolysis of the sugar. In other words, lactose accumulates too slowly within cells of delayed lactose fermenters to threshold levels required for activation of the lactose hydrolytic process.

Hi,

I think because of the lactose dehydrogenase needs some of the co-enzyme to become active

The permease is required for the lactose molecule to penetrate the bacterial cell where the β-galactosidase can cleave the galactoside bond, producing glucose and galactose. ... So called late lactose fermenters may be delayed in their production of acid from lactose because of sluggish permease activity. https://microbeonline.com/onpg-test-%CE%B2-galactosidase-principle-procedure-results/

If you understand the question and the answer is / Lactose-carrying blood or lactase deficiency is a disease characterized by the inability of adults to digest lactose, which is a sugar present in milk and in a smaller amount in dairy products, which causes side effects due to the lack of lactase enzyme, such as bloating, diarrhea or pain in Belly. Congenital lactase deficiency, that is, from birth, makes infants intolerant to drinking milk to breastmilk; They suffer bloating, intestinal cramps or diarrhea.