Diversity of bacterial lactase genes in intestinal contents of mice with antibiotics-induced diarrhea

AIM To investigate the diversity of bacterial lactase genes in the intestinal contents of mice with antibiotics-induced diarrhea.METHODS Following 2 d of adaptive feeding, 12 specific pathogenfree Kunming mice were randomly divided into the control group and model group. The mouse model of antibiotics-induced diarrhea was established by gastric perfusion with mixed antibiotics(23.33 m L·kg^(-1)·d^(-1)) composed of gentamicin sulfate and cephradine capsules administered for 5 days, and the control group was treated with an equal amount of sterile water. Contents of the jejunum and ileum were then collected and metagenomic DNA was extracted, after which analysis of bacterial lactase genes using operational taxonomic units(OTUs) was carried outafter amplification and sequencing.RESULTS OTUs were 871 and 963 in the model group and control group, respectively, and 690 of these were identical. There were significant differences in Chao1 and ACE indices between the two groups(P < 0.05). Principal component analysis, principal coordination analysis and nonmetric multidimensional scaling analyses showed that OTUs distribution in the control group was relatively intensive, and differences among individuals were small, while in the model group, they were widely dispersed and more diversified. Bacterial lactase genes from the intestinal contents of the control group were related to Proteobacteria, Actinobacteria, Firmicutes and unclassified bacteria. Of these, Proteobacteria was the most abundant phylum. In contrast, the bacterial population was less diverse and abundant in the model group, as the abundance of Bradyrhizobium sp. BTAi1, Agrobacterium sp. H13-3, Acidovorax sp. KKS102, Azoarcus sp. KH32 C and Aeromonas caviae was lower than that in the control group. In addition, of the known species, the control group and model group had their own unique genera, respectively.CONCLUSION Antibiotics reduce the diversity of bacterial lactase genes in the intestinal contents, decrease the abundance of lactase gene, change the lactase gene strains, and transform their structures.

Dietary Control of Lactase Expression in the Weaning Rat

The decline in lactase activity during weaning has been well established. However, its molecuIar mechanism remains to be explored. We studied changes in the expression of lactase in terms of the transcription and translation processes in rat microvillus membrane by Northern blot and Western blot analysis, respectively. To examine the effect of dietary change from a milk to a non-milk diet on the developmental pattern of lactase expression, weaning was prevented by keeping the rats under suckling conditions for 27 days after birth. This treatment only suppressed the extent of decline: while the weanlings showed 17 percent activity compared to that of 4-day-old rats, the prolonged suckling rats showed only 42 percent. The changes in the expression of lactase mRNA and protein were parallel with the change of lactase activity. In other words, the fundamental pattern of significant depression of lactase expression occurred relatively independent of dietary modification.This observation indicates that the regulation of lactase expression is firmly determined at the transcriptional level, and that dietary factor such as the termination of lactose ingestion has only a relatively minor effect

Characterization of putative mannoprotein in Kluyveromyces lactis for lactase production

Lactase is a member of theβ-galactosidase family of enzymes that can hydrolyze lactose into galactose and glucose.However,extracellular lactase production was still restricted to the process of cell lysis.In this study,lactase-producing Kluyveromyces lactis JNXR-2101 was obtained using a rapid and sensitive method based on the fluorescent substrate 4-methylumbelliferyl-β-D-galactopyranoside.The purified enzyme was identified as a neutral lactase with an optimum pH of 9.To facilitate extracellular production of lactase,a putative mannoprotein KLLA0_E01057g of K.lactis was knocked out.It could effectively promote cell wall degradation and lactase production after lyticase treatment,which showed potential on other extracellular enzyme preparation.After optimizing the fermentation conditions,the lactase yield from mannoprotein-deficient K.lactis JNXR-2101ΔE01057g reached 159.62 U/mL in a 5-L fed-batch bioreactor.

The prevalence of lactase deficiency and lactose intolerance in Chinese children of different ages

To determine lactose metabolism and lactase activity in Chinese children of different ages, prevalence of lactase deficiency (LD), and lactose intolerance (LI) Methods All 1168 healthy subjects between 3 and 13 years were recruited from schools in four large cities in China They were screened by a 25?g lactose tolerance test Some subjects were challenged with 50?g milk powder on different days Both indicators, the expiratory H 2 concentration and intolerance symptoms, were analyzed Results LD occurred in 38 5% of children in the 3-5 year age group, and 87% of the 7-8 year and 11-13 year old groups The age of occurrence for LD may be at 7-8 years among Chinese children The prevalence of LI among Chinese children was 12 2% at age 3-5 years, 33 1% at age 7-8 years, and 30 5% at age 11-13 years, respectively Conclusion The results demonstrate that LD is very common in Chinese children from these four cities LD and LI have a dose dependent response: lactose absorption and symptoms are based on lactase activity The relationship between breast feeding history (or the history of cow milk intake) and lactase activity among Chinese children has not been established

Protective actions of salvianolic acid A on hepatocyte injured by peroxidation in vitro

INTRODUCTION Salvianolic radix,one of the most commonly usedtraditional Chinese herbs,was widely studied aboutits actions against liver injury and fibrosis,and wasone of the focuses of recent research.Salvianolic acid-A(SA-A)was an aqueous solublecomponent of Salvianolic radix.In our

Update on diagnostic value of breath test in gastrointestinal and liver diseases

In the field of gastroenterology,breath tests(BTs) are used intermittently as diagnostic tools that allow indirect,non-invasive and relatively less cumbersome evaluation of several disorders by simply quantifying the appearance in exhaled breath of a metabolite of a specific substrate administered.The aim of this review is to have an insight into the principles,methods of analysis and performance parameters of various hydrogen,methane and carbon BTs which are available for diagnosing gastrointestinal disorders such as Helicobacter pylori infection,small intestinal bacterial overgrowth,and carbohydrate malabsorption.Evaluation of gastric emptying is routinely performed by scintigraphy which is however,difficult to perform and not suitable for children and pregnant women,this review has abridged the 13C-octanoic acid test in comparison to scintigraphy and has emphasized on its working protocol and challenges.A new development such as electronic nose test is also highlighted.Moreover we have also explored the limitations and constraints restraining the wide use of these BT.We conclude that breath testing has an enormous potential to be used as a diagnostic modality.In addition it offers distinct advantages over the traditional invasive methods commonly employed.

Patients with functional bowel disorder have disaccharidase deficiency:A single-center study from Russia

BACKGROUND Functional bowel disorder(FBD)may be caused by a decrease in disaccharidase activity.Thus,the timely diagnosis of disaccharidase deficiency could lead to a better prognosis in patients with this condition.AIM To determine the potential value of intestinal disaccharidases glucoamylase,maltase,sucrase,and lactase in understanding the etiology and pathogenesis of FBD.METHODS A total of 82 FBD patients were examined.According to the Rome IV criteria(2016),23 patients had diarrhea-predominant irritable bowel syndrome(IBS),33 had functional diarrhea,10 had constipation-predominant IBS,4 had functional constipation,and 12 had mixed IBS.The Dahlqvist method was used to measure disaccharidase activity in the brush-border membrane of mature enterocytes of the small intestine,in duodenal biopsies obtained during esophagogastroduodenoscopy.RESULTS Lactase deficiency was detected in 86.5%of patients,maltase deficiency in 48.7%,sucrase deficiency in 50%,and glucoamylase deficiency in 84.1%.The activities of all enzymes were reduced in 31.7%of patients,and carbohydrase deficiency was detected in 63.5%of patients.The low activity of enzymes involved in membrane digestion in the small intestine was found in 95.2%of patients.CONCLUSION In 78 of the 82 patients with FBD,gastrointestinal symptoms were associated with disaccharidase deficiency.