Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A classical chemical mutagenesis protocol was evaluated for increasing beta-galactosidase production by probiotic bacteria to improve their potential to treat symptoms of lactose malabsorption in humans. Two Bifidobacterium species (B. breve and B. longum) and one strain each of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus were tested by a single exposure to two chemical mutagens, ethyl methanesulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). To screen for beta-galactosidase (beta-gal) overproducing mutants, optimized EMS and MNNG mutant pots for each strain were plated on BHI agar containing 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal). Colonies that exhibited a blue color were selected for quantitative beta-gal activities using the o-nitrophenyl-beta-galactoside (ONPG) assay. Seventy-five mutants were obtained out of more than 2 million colonies screened and showed increased beta-galactosidase activities compared with the wild-type strains. EMS gave a higher frequency of beta-gal overproducing mutants than MNNG for three of the four strains, S. thermophilus, B. breve, and B. longum, whereas the frequency of L. delbrueckii ssp. bulgaricus beta-gal mutants was similar with both mutagens. The highest beta-gal increases, when induced during growth in lactose, for mutants of each culture were 137% for L. delbrueckii ssp. bulgaricus; 104% for S. thermophilus; 70% for B. breve; and 222% for B. longum mutants. This food-grade classical approach has the ability to moderately increase beta-gal concentrations in probiotic cultures to improve their potential for treating the symptoms of lactose malabsorption in humans.
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PMID:Use of chemical mutagenesis for the isolation of food grade beta-galactosidase overproducing mutants of bifidobacteria, lactobacilli and Streptococcus thermophilus. 1082 66

Malabsorption of dietary sugars is a common cause of gastrointestinal discomfort, affecting up to one in three people with debilitating symptoms, such as abdominal pain, osmotic diarrhoea, bloating and flatulence. Besides dietary interventions, it has been suggested that ingestion of lactobacilli may alleviate these symptoms. The objectives of this study were to generate strains with improved potential to ameliorate sugar malabsorption related gastrointestinal disorders. Initial selection was made from 183 natural isolates of lactic acid bacteria, on the basis of broad sugar fermentation ability, absence of gas production, gastrointestinal survival and susceptibility to important medical antimicrobials. Two strains of L. plantarum (KR6 and M5) exhibited favourable characteristics for all criteria, and were further optimised through random mutagenesis and selection approaches. Ultraviolet light (UV) exposure resulted in mutants characterized by better survival (for 1.9 log and 1.4 log) in gastrointestinal conditions. Subsequent exposure to ethyl methanesulfonate (EMS) provided mutants with greater tolerance to glucose induced catabolic repression. UV and UV-EMS mutants of L. plantarum M5 showed improved adhesion ability. As a result of this optimisation, L. plantarum MP2026 and L. plantarum MP2420 have been identified as promising candidates for probiotics, intended for alleviation of gastrointestinal discomfort originating from sugar malabsorption.
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PMID:Generation of Lactobacillus plantarum strains with improved potential to target gastrointestinal disorders related to sugar malabsorption. 2829 Mar 66