Lactate limits CNS autoimmunity by stabilizing HIF-1α in dendritic cells.

Dendritic cells (DCs) have a role in the development and activation of self-reactive pathogenic T cells1,2. Genetic variants that are associated with the function of DCs have been linked to autoimmune disorders3,4, and DCs are therefore attractive therapeutic targets for such diseases. However, developing DC-targeted therapies for autoimmunity requires identification of the mechanisms that regulate DC function. Here, using single-cell and bulk transcriptional and metabolic analyses in combination with cell-specific gene perturbation studies, we identify a regulatory loop of negative feedback that operates in DCs to limit immunopathology. Specifically, we find that lactate, produced by activated DCs and other immune cells, boosts the expression of NDUFA4L2 through a mechanism mediated by hypoxia-inducible factor 1α (HIF-1α). NDUFA4L2 limits the production of mitochondrial reactive oxygen species that activate XBP1-driven transcriptional modules in DCs that are involved in the control of pathogenic autoimmune T cells. We also engineer a probiotic that produces lactate and suppresses T cell autoimmunity through the activation of HIF-1α-NDUFA4L2 signalling in DCs. In summary, we identify an immunometabolic pathway that regulates DC function, and develop a synthetic probiotic for its therapeutic activation.

Population genomics of the Viking world.

The maritime expansion of Scandinavian populations during the Viking Age (about AD 750-1050) was a far-flung transformation in world history1,2. Here we sequenced the genomes of 442 humans from archaeological sites across Europe and Greenland (to a median depth of about 1×) to understand the global influence of this expansion. We find the Viking period involved gene flow into Scandinavia from the south and east. We observe genetic structure within Scandinavia, with diversity hotspots in the south and restricted gene flow within Scandinavia. We find evidence for a major influx of Danish ancestry into England; a Swedish influx into the Baltic; and Norwegian influx into Ireland, Iceland and Greenland. Additionally, we see substantial ancestry from elsewhere in Europe entering Scandinavia during the Viking Age. Our ancient DNA analysis also revealed that a Viking expedition included close family members. By comparing with modern populations, we find that pigmentation-associated loci have undergone strong population differentiation during the past millennium, and trace positively selected loci-including the lactase-persistence allele of LCT and alleles of ANKA that are associated with the immune response-in detail. We conclude that the Viking diaspora was characterized by substantial transregional engagement: distinct populations influenced the genomic makeup of different regions of Europe, and Scandinavia experienced increased contact with the rest of the continent.

Added Value of 13C Analysis in Breath Tests in H2-Negative Subjects to Diagnose Lactose Malabsorption: A Proof of Concept Study.

INTRODUCTION: Diagnosing lactose malabsorption is usually based on hydrogen excretion in breath after a lactose challenge. However, a proportion of subjects with lactose malabsorption will not present a rise in hydrogen. Measuring excretion of methane or stable isotope labeled 13CO2 after ingestion of 13C-lactose has been proposed to mitigate this problem. OBJECTIVE: The aim of the study was to assess the performance of measuring methane and 13CO2 in individuals with normal hydrogen excretion compared to a genetic lactase non-persistence test. METHODS: Individuals referred for lactose breath testing and healthy controls were included. Participants received 13C-enriched lactose, performed breath testing, and underwent genotyping for a marker of lactase non-persistence (13910C*T). Using genotype as gold standard, the performance of measuring methane and 13CO2 excretion was assessed. RESULTS: 151 subjects participated in the study, 50 of which presented a lactase non-persistent genotype. Of these, 72% were correctly diagnosed through hydrogen excretion of ≥ 20 ppm above baseline. In subjects with normal hydrogen excretion, cumulative 13C excretion had an area under the curve (AUC) of the receiver operating characteristics (ROC) curve of 0.852. Sensitivity was 93% and specificity was 51% for the current cutoff of 14.5%. The optimal cutoff was 12.65% (sensitivity 93%, specificity 70%). The ROC curve of peak methane had an AUC of 0.542 (sensitivity of 14%, specificity of 91% for cutoff ≥ 10 ppm). CONCLUSIONS: In individuals with genetically demonstrated lactase non-persistence and negative hydrogen breath test, the use of 13C-lactose with measurement of 13CO2 excretion and hydrogen is a well-performing test to detect the lactose malabsorption and performs better than methane in our cohort.

Host and gut microbial tryptophan metabolism and type 2 diabetes: an integrative analysis of host genetics, diet, gut microbiome and circulating metabolites in cohort studies.

OBJECTIVE: Tryptophan can be catabolised to various metabolites through host kynurenine and microbial indole pathways. We aimed to examine relationships of host and microbial tryptophan metabolites with incident type 2 diabetes (T2D), host genetics, diet and gut microbiota. METHOD: We analysed associations between circulating levels of 11 tryptophan metabolites and incident T2D in 9180 participants of diverse racial/ethnic backgrounds from five cohorts. We examined host genome-wide variants, dietary intake and gut microbiome associated with these metabolites. RESULTS: Tryptophan, four kynurenine-pathway metabolites (kynurenine, kynurenate, xanthurenate and quinolinate) and indolelactate were positively associated with T2D risk, while indolepropionate was inversely associated with T2D risk. We identified multiple host genetic variants, dietary factors, gut bacteria and their potential interplay associated with these T2D-relaetd metabolites. Intakes of fibre-rich foods, but not protein/tryptophan-rich foods, were the dietary factors most strongly associated with tryptophan metabolites. The fibre-indolepropionate association was partially explained by indolepropionate-associated gut bacteria, mostly fibre-using Firmicutes. We identified a novel association between a host functional LCT variant (determining lactase persistence) and serum indolepropionate, which might be related to a host gene-diet interaction on gut Bifidobacterium, a probiotic bacterium significantly associated with indolepropionate independent of other fibre-related bacteria. Higher milk intake was associated with higher levels of gut Bifidobacterium and serum indolepropionate only among genetically lactase non-persistent individuals. CONCLUSION: Higher milk intake among lactase non-persistent individuals, and higher fibre intake were associated with a favourable profile of circulating tryptophan metabolites for T2D, potentially through the host-microbial cross-talk shifting tryptophan metabolism toward gut microbial indolepropionate production.

Whole-Genome Sequencing Reveals Lactase Persistence Adaptation in European Dogs.

Coexistence and cooperation between dogs and humans over thousands of years have supported convergent evolutionary processes in the two species. Previous studies found that Eurasian dogs evolved into a distinct geographic cluster. In this study, we used the genomes of 242 European dogs, 38 Southeast Asian indigenous (SEAI) dogs, and 41 gray wolves to identify adaptation of European dogs . We report 86 unique positively selected genes in European dogs, among which is LCT (lactase). LCT encodes lactase, which is fundamental for the digestion of lactose. We found that an A-to-G mutation (chr19:38,609,592) is almost fixed in Middle Eastern and European dogs. The results of two-dimensional site frequency spectrum (2D SFS) support that the mutation is under soft sweep . We inferred that the onset of positive selection of the mutation is shorter than 6,535 years and behind the well-developed dairy economy in central Europe. It increases the expression of LCT by reducing its binding with ZEB1, which would enhance dog's ability to digest milk-based diets. Our study uncovers the genetic basis of convergent evolution between humans and dogs with respect to diet, emphasizing the import of the dog as a biomedical model for studying mechanisms of the digestive system.

Lactase bacteria in intestinal mucosa are associated with diarrhea caused by high-fat and high-protein diet.

BACKGROUND: Excessive fat and protein in food can cause diarrhea by disturbing the intestinal microecology. Lactase is a functional enzyme strongly associated with diarrhea, while lactase bacteria in the intestine are an important source of microbial lactase. Therefore, we reconnoiter the relationship between diarrhea induced by a high-fat and high-protein diet (HFHPD) and intestinal mucosal lactase bacteria from the perspective of functional genes. RESULT: Operational Taxonomic Units (OTUs) were 23 and 31 in the normal group (NM) and model group (MD), respectively, and 11 of these were identical. The Chao1 and Observed specie indexes in the MD were higher than those in the NM, but this was not significant (P > 0.05). Meanwhile, the Principal coordinate analysis (PCoA) and Adonis test showed that the community structures of lactase bacteria in NM and MD were significantly different (P < 0.05). In taxonomic composition, lactase bacteria on the intestinal mucosa were sourced from Actinobacteria and Proteobacteria. Where Actinobacteria were higher in NM, and Proteobacteria were higher in MD. At the genus level, Bifidobacterium was the dominant genus (over 90% of the total). Compared to NM, the abundance of Bifidobacterium were lower in MD, while MD added sources for lactase bacteria of Rhizobium, Amycolatopsis, and Cedecea. CONCLUSIONS: Our data demonstrate that HFHPD altered the community structure of lactase bacteria in the intestinal mucosa, decreased the abundance of the critical lactase bacteria, and promoted the occurrence of diarrhea.

Development of a novel SNP assay to detect lactase persistence associated genetic variants.

BACKGROUND: In adulthood the activity of the lactase enzyme is inherited as autosomal dominant form associated to Single nucleotide polymorphisms (SNPs). The present research was aimed to develop a novel genetic method to test lactase non persistence more powerfully. METHODS AND RESULTS: In our study, we selected eight different SNPs that are associated with lactase persistence from Caucasian, Arabian Bedouins, sub-Saharian Africans and Asian populations to set up an approach to detect all the eight different SNPs at the same time in the same sample. This technique is centred on the identification of SNPs with a single nucleotide primer extension method using Sanger sequencing and capillary electrophoresis. CONCLUSIONS: Our method allowed us to check the genotype asset of eight SNPs related to lactase persistence simultaneously and in a very efficient manner. It could be applied to a higher number of SNPs in a single reaction.

Effect of lactose hydrolysis on the milk-fermenting properties of Lactobacillus delbrueckii ssp. bulgaricus 2038 and Streptococcus thermophilus 1131.

Yogurt is a well-known nutritious and probiotic food and is traditionally fermented from milk using the symbiotic starter culture of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. However, yogurt consumption may cause health problems in lactose-intolerant individuals, and the demand for lactose-free yogurt has been increasing. The standard method to prepare lactose-free yogurt is to hydrolyze milk by lactase; however, this process has been reported to influence the fermentation properties of starter strains. This study aimed to investigate the fermentation properties of an industrial starter culture of L. bulgaricus 2038 and S. thermophilus 1131 in lactose-hydrolyzed milk and to examine the metabolic changes induced by glucose utilization. We found that the cell number of L. bulgaricus 2038, exopolysaccharide concentration, and viscosity in the coculture of L. bulgaricus 2038 and S. thermophilus 1131 was significantly increased in lactose-hydrolyzed milk compared with that in unhydrolyzed milk. Although the cell number of S. thermophilus 1131 showed no difference, production of formic acid and reduction of dissolved oxygen were enhanced in lactose-hydrolyzed milk. Further, in lactose-hydrolyzed milk, S. thermophilus 1131 was found to have increased the expression of NADH oxidase, which is responsible for oxygen reduction. These results indicated that glucose utilization promoted S. thermophilus 1131 to rapidly reduce the dissolved oxygen amount and produce a high concentration of formic acid, presumably resulting in the increased cell number of L. bulgaricus 2038 in the coculture. Our study provides basic information on the metabolic changes in starter strains in lactose-hydrolyzed milk, and demonstrates that lactose-free yogurt with increased cell number of L. bulgaricus can be prepared without delay in fermentation and decrease in the cell number of S. thermophilus.

Fermented foods and probiotics: An approach to lactose intolerance.

The aim of this review was to present various topics related to lactose intolerance with special attention given to the role of fermented foods and probiotics in alleviating gastrointestinal symptoms. Lactose intolerance is a common digestive problem in which the human body is unable to digest lactose, known as milk sugar. Lactose intolerance can either be hereditary or a consequence of intestinal diseases. Recent work has demonstrated that fermented dairy products and probiotics can modify the metabolic activities of colonic microbiota and may alleviate the symptoms of lactose intolerance. We suggest that, lactose free dairy products could be recommended as alternatives for the alleviation of lactose intolerance and for the promotion of human health and wellness.

No more cleaning up - Efficient lactic acid bacteria cell catalysts as a cost-efficient alternative to purified lactase enzymes.

ß-galactosidases, commonly referred to as lactases, are used for producing lactose-free dairy products. Lactases are usually purified from microbial sources, which is a costly process. Here, we explored the potential that lies in using whole cells of a food-grade dairy lactic acid bacterium, Streptococcus thermophilus, as a substitute for purified lactase. We found that S. thermophilus cells, when treated with the antimicrobial peptide nisin, were able to hydrolyze lactose efficiently. The rate of hydrolysis increased with temperature; however, above 50 °C, stability was compromised. Different S. thermophilus strains were tested, and the best candidate was able to hydrolyze 80% of the lactose in a 50 g/L solution in 4 h at 50 °C, using only 0.1 g/L cells (dry weight basis). We demonstrated that it was possible to grow the cell catalyst on dairy waste, and furthermore, that a cell-free supernatant of a culture of a nisin-producing Lactococcus lactis strain could be used instead of purified nisin, which reduced cost of use significantly. Finally, we tested the cell catalysts in milk, where lactose also was efficiently hydrolyzed. The method presented is natural and low-cost, and allows for production of clean-label and lactose-free dairy products without using commercial enzymes from recombinant microorganisms. KEY POINTS: • Nisin-permeabilized Streptococcus thermophilus cells can hydrolyze lactose efficiently. • A low-cost and more sustainable alternative to purified lactase enzymes. • Reduction of overall sugar content. • Clean-label production of lactose-free dairy products.

Real-time PCR based detection of the lactase non-persistence associated genetic variant LCT-13910C>T directly from whole blood.

Primary hypolactasia is the main cause of lactose intolerance in adults. It is strongly associated with the single genetic variant LCT-13910C>T, located upstream of the lactase encoding gene. Consequently, analysis of LCT-13910C>T has been recommended as a direct genetic test for the trait. The aim of our study was to develop a TaqMan probe based real-time PCR protocol for the detection of the LCT-13910C>T variant directly from whole blood, circumventing DNA isolation. The LCT-13910C>T variant was determined using the DirectBlood Genotyping PCR Kit (myPOLS Biotec, Konstanz, Germany) together with an in-house TaqMan primer-probe assay. Validity and specificity of the assay was evaluated using EDTA anti-coagulated whole blood samples and corresponding DNA samples. Results from real-time PCR were compared with results obtained by Sanger sequencing from 105 blinded whole blood samples. Validity and specificity of the assay using whole blood were comparable to those using purified genomic DNA as substrate in PCR. Genetic analysis of blood samples were in complete agreement with results obtained by Sanger sequencing. In conclusion, we present a reliable real-time PCR protocol for the detection of the LCT-13910C>T variant directly from whole blood further facilitating diagnosis of primary hypolactasia in symptomatic patients.

Effects of ad libitum milk replacer feeding and butyrate supplementation on the epithelial growth and development of the gastrointestinal tract in Holstein calves.

Intensive milk feeding and butyrate supplementation in calves stimulate body growth and affect gastrointestinal development. The aim of the present study was to investigate the synergistic effects of ad libitum milk replacer (MR) feeding and butyrate supplementation of MR on rumen and small intestinal growth and on gene expression in the small intestine related to growth and energy metabolism at weaning. Male Holstein calves (n = 32) received colostrum from birth to d 3 of age and MR either ad libitum (Adl) or restrictively (Res; 6 L of MR/d; 12.5% solids) with (AdlB+, ResB+) or without (AdlB-, ResB-) 0.24% butyrate from d 4 until wk 8 of age. From wk 9 to 10, all calves were weaned and were fed 2 L/d until the end of the trial. Concentrate, hay, and water were freely available. At d 80, calves were slaughtered, volatile fatty acids were measured in rumen fluid, and rumen and small intestine samples were taken for histomorphometric measurements. The expression of mRNA associated with the local insulin-like growth factor (IGF) system and glucose metabolism as well as lactase and maltase activities were measured in the intestinal mucosa. The small intestine was 3 m longer in Adl than in Res. In the atrium ruminis, papilla width was greater in Res than in Adl. Villus circumference, cut surface, and height in the duodenum, proximal jejunum, and ileum were greater in Adl than in Res and in the proximal, mid, and distal jejunum and ileum were greater in calves treated with butyrate. Crypt depth in the duodenum and proximal jejunum was greater in Adl than in Res and in the ileum was smaller in calves treated with butyrate. The villus height:crypt depth ratio was greatest in AdlB+ calves. In the proximal and mid jejunum, IGF1 mRNA abundance was lower in calves treated with butyrate. In the proximal jejunum, INSR mRNA abundance was greater in Res than in Adl. The abundance of PCK2 mRNA was greater in Res than in Adl in the duodenum and was greatest in ResB- in the mid jejunum. Lactase activity tended to be greater in Res than in Adl and after butyrate treatment in the proximal jejunum. The results indicated an elevated growth of the small intestinal mucosa at weaning due to intensive milk feeding and butyrate supplementation, and the local IGF system was involved in intestinal growth regulation. Rumen development was not affected by butyrate supplementation of MR and was slightly delayed due to ad libitum MR feeding.

Lactase persistence, milk intake, and mortality in the Danish general population: a Mendelian randomization study.

Meta-analyses have suggested no association between milk intake and mortality. Since only few studies have been conducted, we investigated the association between the lactase persistent genetic variant LCT-13910 C/T (rs4988235), a proxy for long-term low and high intake of milk, and mortality. We used two Danish population-based studies with self-reported intake of milk and genotyping for LCT-13910 C/T. We obtained information on all-cause and cause-specific mortality (cardiovascular and cancer) from the national Danish registries. We used multivariable adjusted Cox regression to assess the association between milk intake and mortality in 74,241 individuals, and both logistic and Cox-regression to assess the association between genetic lactase persistence and mortality in 82,964 individuals using a Mendelian randomization design. We applied per T-allele, co-dominant and dominant models. During a mean follow-up of 7 years, 9759 individuals died, 2166 from cardiovascular disease, and 2822 from cancer. Observationally, there was no association between intake of skimmed milk and all-cause or cardiovascular mortality, and we did not find any associations between intake of semi-skimmed or whole milk with all-cause or cause-specific mortality. Intake of skimmed milk was associated with lower cancer mortality with a hazard ratio of 0.97 (95% CI 0.96-1.00) per doubling in milk intake. Per T-allele, milk intake increased with 0.58 (0.50-0.68) glasses/week. Genetically, we found no associations between the lactase persistent LCT-13910 C/T genotype and all-cause or cause-specific mortality; per T-allele OR (95% CI) for all-cause mortality was 1.02 (0.97-1.06). Our study did not provide strong evidence of observational or genetic associations between milk intake and all-cause or cause-specific mortality.

Genetic origins of lactase persistence and the spread of pastoralism in Africa.

In humans, the ability to digest lactose, the sugar in milk, declines after weaning because of decreasing levels of the enzyme lactase-phlorizin hydrolase, encoded by LCT. However, some individuals maintain high enzyme amounts and are able to digest lactose into adulthood (i.e., they have the lactase-persistence [LP] trait). It is thought that selection has played a major role in maintaining this genetically determined phenotypic trait in different human populations that practice pastoralism. To identify variants associated with the LP trait and to study its evolutionary history in Africa, we sequenced MCM6 introns 9 and 13 and ~2 kb of the LCT promoter region in 819 individuals from 63 African populations and in 154 non-Africans from nine populations. We also genotyped four microsatellites in an ~198 kb region in a subset of 252 individuals to reconstruct the origin and spread of LP-associated variants in Africa. Additionally, we examined the association between LP and genetic variability at candidate regulatory regions in 513 individuals from eastern Africa. Our analyses confirmed the association between the LP trait and three common variants in intron 13 (C-14010, G-13907, and G-13915). Furthermore, we identified two additional LP-associated SNPs in intron 13 and the promoter region (G-12962 and T-956, respectively). Using neutrality tests based on the allele frequency spectrum and long-range linkage disequilibrium, we detected strong signatures of recent positive selection in eastern African populations and the Fulani from central Africa. In addition, haplotype analysis supported an eastern African origin of the C-14010 LP-associated mutation in southern Africa.

Lactase Non-persistence and Lactose Intolerance.

PURPOSE OF REVIEW: To evaluate the clinical and nutritional significance of genetically determined lactase non-persistence and potential lactose and milk intolerance in 65-70% of the world's adult population. RECENT FINDINGS: Milk consumption is decreasing in the USA and is the lowest in countries with a high prevalence of lactase non-persistence. The dairy industry and Minnesota investigators have made efforts to minimize the influence of lactose intolerance on milk consumption. Some lactose intolerant individuals, without co-existent irritable bowel syndrome, are able to consume a glass of milk with a meal with no or minor symptoms. The high frequency of lactase persistence in offspring of Northern European countries and in some nomadic African tribes is due to mutations in the promoter of the lactase gene in association with survival advantage of milk drinking. Educational and commercial efforts to improve calcium and Vitamin D intake have focused on urging consumption of tolerable amounts of milk with a meal, use of lowered lactose-content foods including hard cheeses, yogurt, and lactose-hydrolyzed milk products.

Leveraging Multiple Populations across Time Helps Define Accurate Models of Human Evolution: A Reanalysis of the Lactase Persistence Adaptation.

Access to a geographically diverse set of modern human samples from the present time and from ancient remains, combined with archaic hominin samples, provides an unprecedented level of resolution to study both human history and adaptation. The amount and quality of ancient human data continue to improve and enable tracking the trajectory of genetic variation over time. These data have the potential to help us redefine or generate new hypotheses of how human evolution occurred and to revise previous conjectures. In this article, we argue that leveraging all these data will help us better detail adaptive histories in humans. As a case in point, we focus on one of the most celebrated examples of human adaptation: the evolution of lactase persistence. We briefly review this dietary adaptation and argue that, effectively, the evolutionary history of lactase persistence is still not fully resolved. We propose that, by leveraging data from multiple populations across time and space, we will find evidence of a more nuanced history than just a simple selective sweep. We support our hypotheses with simulation results and make some cautionary notes regarding the use of haplotype-based summary statistics to estimate evolutionary parameters.

Effects of cow's milk beta-casein variants on symptoms of milk intolerance in Chinese adults: a multicentre, randomised controlled study.

BACKGROUND: A major protein component of cow's milk is ß-casein. The most frequent variants in dairy herds are A1 and A2. Recent studies showed that milk containing A1 ß-casein promoted intestinal inflammation and exacerbated gastrointestinal symptoms. However, the acute gastrointestinal effects of A1 ß-casein have not been investigated. This study compared the gastrointestinal effects of milk containing A1 and A2 ß-casein versus A2 ß-casein alone in Chinese adults with self-reported lactose intolerance. METHODS: In this randomised, crossover, double-blind trial, with a 3-day dairy washout period at baseline, subjects were randomised to consume 300 mL of milk containing A1 and A2 ß-casein (ratio 58:42; conventional milk) or A2 ß-casein alone; subjects consumed the alternative product after a 7-day washout period. Urine galactose was measured at baseline after a 15 g lactose load. Subjects completed 9-point visual analogue scales for gastrointestinal symptoms (borborygmus, flatulence, bloating, abdominal pain, stool frequency, and stool consistency) at baseline and at 1, 3, and 12 h after milk consumption. RESULTS: A total of 600 subjects were included. All six symptom scores at 1 and 3 h were significantly lower after consuming A2 ß-casein versus conventional milk (all P<0.0001). At 12 h, significant differences remained for bloating, abdominal pain, stool frequency, and stool consistency (all P<0.0001). Symptom scores were consistently lower with A2 ß-casein in both lactose absorbers (urinary galactose ≥0.27 mmol/L) and lactose malabsorbers (urinary galactose <0.27 mmol/L). CONCLUSION: Milk containing A2 ß-casein attenuated acute gastrointestinal symptoms of milk intolerance, while conventional milk containing A1 ß-casein reduced lactase activity and increased gastrointestinal symptoms compared with milk containing A2 ß-casein. Thus, milk-related gastrointestinal symptoms may result from the ingestion of A1 ß-casein rather than lactose in some individuals. TRIAL REGISTRATION: NCT02878876 , registered August 16, 2016. Retrospectively registered.

Comparison of the quantitative dry culture methods with both conventional media and most probable number method for the enumeration of coliforms and Escherichia coli/coliforms in food.

Sanita-kun™ CC (coliform count) and EC (Escherichia coli/coliform count), sheet quantitative culture systems which can avoid chromogenic interference by lactase in food, were evaluated in comparison with conventional methods for these bacteria. Based on the results of inclusivity and exclusivity studies using 77 micro-organisms, sensitivity and specificity of both Sanita-kun™ met the criteria for ISO 16140. Both media were compared with deoxycholate agar, violet red bile agar, Merck Chromocult™ coliform agar (CCA), 3M Petrifilm™ CC and EC (PEC) and 3-tube MPN, as reference methods, in 100 naturally contaminated food samples. The correlation coefficients of both Sanita-kun™ for coliform detection were more than 0·95 for all comparisons. For E. coli detection, Sanita-kun™ EC was compared with CCA, PEC and MPN in 100 artificially contaminated food samples. The correlation coefficients for E. coli detection of Sanita-kun™ EC were more than 0·95 for all comparisons. There were no significant differences in all comparisons when conducting a one-way analysis of variance (anova). Both Sanita-kun™ significantly inhibited colour interference by lactase when inhibition of enzymatic staining was assessed using 40 natural cheese samples spiked with coliform. Our results demonstrated Sanita-kun™ CC and EC are suitable alternatives for the enumeration of coliforms and E. coli/coliforms, respectively, in a variety of foods, and specifically in fermented foods. SIGNIFICANCE AND IMPACT OF THE STUDY: Current chromogenic media for coliforms and Escherichia coli/coliforms have enzymatic coloration due to breaking down of chromogenic substrates by food lactase. The novel sheet culture media which have film layer to avoid coloration by food lactase have been developed for enumeration of coliforms and E. coli/coliforms respectively. In this study, we demonstrated these media had comparable performance with reference methods and less interference by food lactase. These media have a possibility not only to be useful alternatives but also to contribute for accurate enumeration of these bacteria in a variety of foods, and specifically in fermented foods.

Effect of probiotic strain Lactobacillus acidophilus (LBKV-3) on fecal residual lactase activity in undernourished children below 10 years.

Clinically proven Lactobacillus acidophilus strain LBKV-3 intended as probiotic for humans was used to test its effect on fecal residual lactase activity in undernourished children below 10 years of age. The children were selected from malnutrition-declared area of Maharashtra (India). One of the major causes of malnutrition is lactose intolerance which leads to diarrhea. The basic consideration in selecting the probiotic strain of L. acidophilus (LBKV-3) in this investigation was the fact that the organism is isolated from human vaginal surface swab and it was found extensively studied for probiotic characteristic. LBKB3 is tested by several workers as probiotic for hypocholesterolemic activity, implantation ability, therapeutic effects on gastrointestinal (GI) and related ailments. The results of present investigation have shown that the fecal residual lactase activity significantly increased than its initial value (which was almost zero). It appeared that the fecal residual ß-galactosidase activity is an indication of positive implementation abilities of the cultures under investigation. These trends were compared with the control and blank group of children receiving Dahi and buffalo milk (BM). It was observed that both these products failed to exert any significant impact on increase in residual lactase activity.