title: Identification of bacteria with beta-galactosidase activity in faeces from lactase non-persistent subjects.
abstract: Previous studies suggest that, besides the maldigestion of lactose in the small intestine, the colonic processing of lactose might play a role in lactose intolerance. beta-Galactosidase is the bacterial enzyme which catalyzes the first step of lactose fermentation in the colon. We propose a practical method to differentiate and identify bacteria with beta-galactosidase activity in faeces which combines a colony-lift filter assay with X-gal (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside) as substrate for differentiation and the fluorescent in situ hybridization technique for identification. The method was applied to faeces from lactase non-persistent subjects. After 28 subjects had undergone one glucose and two lactose challenges, consistent intolerant (n=5) and tolerant (n=7) groups were defined according to their symptom scores. Of the 28 faecal samples, 80.6% (mean, SD: 12.1, range: 47.8-100%) of the total cultured bacteria were found to possess beta-galactosidase activity, which indicates that the bacterial beta-galactosidase is abundant in the colon. The tolerant and intolerant groups did not differ in the percentage or composition of the bacteria with beta-galactosidase activity or beta-galactosidase activity in faeces. Results suggest that the percentage or composition of the bacteria with beta-galactosidase activity in faeces do not play a role in lactose intolerance.
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700 RB Groningen, The Netherlands.
authors.forename: Tao
authors.initials: T
authors.lastname: He
authors.forename: Marion G
authors.initials: MG
authors.lastname: Priebe
authors.forename: Roel J
authors.initials: RJ
authors.lastname: Vonk
authors.forename: Gjalt W
authors.initials: GW
authors.lastname: Welling
mesh_terms: D000328:Adult; D044466:Asian People; D001421:Bacteria, Anaerobic / Q000201:enzymology* / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D005260:Female; D005697:Galactosides; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007211:Indoles; D007787:Lactose Intolerance / Q000201:enzymology*; D008297:Male; D018709:Statistics, Nonparametric; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D005697:Galactosides; D007211:Indoles; D001616:beta-Galactosidase; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside