Disease relevance of lacZ

• Development of Streptococcus thermophilus lacZ as a reporter gene for Candida albicans [1].
• Lactobacillus acidophilus strains with varying resistance to bile and total beta-galactosidase-producing potential were also tested [2].
• The production of the lactose-hydrolysing enzyme (i.e. beta-galactosidase) was also investigated within the digestive tract, using a chromosomal reporter system based on luciferase genes from Photorhabdus luminescens under the control of the plac promoter [3].

High impact information on lacZ

• Lactose in yogurt with live bacteria is better tolerated than lactose in other dairy foods, partly because of the activity of microbial beta-galactosidase (beta-gal), which digests lactose in vivo [4].
• Using lacZ fusion constructs it was shown that the cadmium-dependent expression of CadA(St) is mediated by the negative regulator CadC(St) [5].
• The main result is that the bacterium was able to produce an active beta-galactosidase in the digestive tract, although it did not multiply during its transit [6].
• Control of lactose transport, beta-galactosidase activity, and glycolysis by CcpA in Streptococcus thermophilus: evidence for carbon catabolite repression by a non-phosphoenolpyruvate-dependent phosphotransferase system sugar [7].
• These constructs were each integrated into the C. albicans genome and beta-galactosidase activity was readily detected from these strains, but only under the appropriate growth conditions [1].

Chemical compound and disease context of lacZ

• The activity of the lactose transporter from Streptococcus thermophilus is increased by phosphorylated IIA and the action of beta-galactosidase [8].
• The influence of carbonation on the evolution of lactose, galactose and glucose in fermented milks with added probiotic bacteria (Lactobacillus casei, Lactobacillus acidophilus and/or Bifidobacterium bifidum) was evaluated and related to beta-galactosidase activity of starter strains [9].
• Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus cultures were treated with ethanol and tested for viability and beta-galactosidase activity [10].

Biological context of lacZ

• The phi 31 promoter lacZ cassette was cloned into a low-copy-number vector plasmid containing the phi 31 origin of replication (ori31) and the resulting low-copy-number plasmid exhibited negligible beta-galactosidase production in L. lactis [11].
• In this paper we show that CcpA plays a crucial role in the fine-tuning of lactose transport, beta-galactosidase (LacZ) activity, and glycolysis to yield optimal glycolytic flux and growth rate [7].
• Use of chemical mutagenesis for the isolation of food grade beta-galactosidase overproducing mutants of bifidobacteria, lactobacilli and Streptococcus thermophilus [12].
• The rate of hydrolysis of lactose given by the predominant beta-galactosidase activity from each of the bacteria studied was in all cases enhanced by Mg2+, while the effect of K+ and Na+ differed from strain to strain [13].
• Individual and mixed strain cultures of S. thermophilus (St 3642, St14485) and L. bulgaricus (Lb11842, Lb880) were examined for growth (OD at 600 nm and viable cell counts), acid production, and beta-galactosidase activity (expressed as a function of recoverable TCA-precipitable cellular protein) [14].

Anatomical context of lacZ

• Beta-galactosidase production by Streptococcus thermophilus is higher in the small intestine than in the caecum of human-microbiota-associated mice after lactose supplementation [3].

Associations of lacZ with chemical compounds

• This fusion construct, pDOC99, expressed beta-galactosidase in L. lactis ATCC 11454 growing in M17 medium containing glucose (M17G) [15].
• Exposure of the biomass of test cultures to 30%-55% ethanol (vol/vol) caused a 100% loss of viability and up to 15-fold increase in measurable beta-galactosidase activity in both streptococci and lactobacilli [10].
• 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 [12].
• 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) [12].
• The effect of cations on the hydrolysis of lactose and the transferase reactions catalysed by beta-galactosidase from six strains of lactic acid bacteria [13].

Analytical, diagnostic and therapeutic context of lacZ

• Cell debris and intact cells were removed by centrifugation and the cell-free extract evaluated for beta-galactosidase activity using o-nitrophenyl-beta-D-galactopyranoside as substrate [14].

References