A re-appraisal of lactose intolerance

Probiotic potential of β‑galactosidase‑producing lactic acid bacteria from fermented milk and their molecular characterization

Probiotics have attained significant interest in recent years as a result of their gut microbiome modulation and gastrointestinal health benefits. Numerous fermented foods contain lactic acid bacteria (LAB) which are considered as GRAS and probiotic bacteria. The present study aimed to investigate indigenous LAB from homemade fermented milk samples collected in remote areas of Karnataka (India), in order to isolate the most potent and well-adapted to local environmental conditions bacteria, which were then evaluated using a step-by-step approach focused on the evaluation of probiotic traits and β-galactosidase-producing ability. LAB were screened using 5-bromo-4-chloro-3-indole-D-galactopyranoside (X-Gal) and O-nitrophenyl-β-D-galactopyranoside (ONPG) as substrate, and exhibited β-galactosidase activity ranging from 728.25 to 1,203.32 Miller units. The most promising isolates were selected for 16S rRNA gene sequence analysis and identified as Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Lactiplantibacillus pentosus and Lactiplantibacillus sp. Furthermore, these isolates were evaluated by in vitro, viz., survival in gastrointestinal tract, antibiotic susceptibility, antimicrobial activity, cell surface characteristics, and haemolytic activity. All eight isolates demonstrated strong adherence and prevented pathogen penetration into HT-29 cells, indicating potential of the bacteria to scale up industrial level production of milk products for lactose intolerants.

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.

Construction and Analysis of Food-Grade Lactobacillus kefiranofaciens β-Galactosidase Overexpression System

Lactobacillus kefiranofaciens contains two types of β-galactosidase, LacLM and LacZ, belonging to different glycoside hydrolase families. The difference in function between them has been unclear so far for practical application. In this study, LacLM and LacZ from L. kefiranofaciens ATCC51647 were cloned into constitutive lactobacillal expression vector pMG36e, respectively. Furtherly, pMG36n-lacs was constructed from pMG36e-lacs by replacing erythromycin with nisin as selective marker for food-grade expressing systems in Lactobacillus plantarum WCFS1, designated recombinant LacLM and LacZ respectively. The results from hydrolysis of o-nitrophenyl-β-galactopyranoside (ONPG) showed that the β-galactosidases activity of the recombinant LacLM and LacZ was 1460% and 670% higher than that of the original L. kefiranofaciens. Moreover, the lactose hydrolytic activity of recombinant LacLM was higher than that of LacZ in milk. Nevertheless, compare to LacZ, in 25% lactose solution the galacto-oligosaccharides (GOS) production of recombinant LacLM was lower. Therefore, two β-galactopyranosides could play different roles in carbohydrate metabolism of L. kefiranofaciens. In addition, the maximal growth rate of two recombinant strains were evaluated with different temperature level and nisin concentration in fermentation assay for practical purpose. The results displayed that 37°C and 20-40 U/ml nisin were the optimal fermentation conditions for the growth of recombinant β-galactosidase strains. Altogether the food-grade Expression system of recombinant β-galactosidase was feasible for applications in the food and dairy industry.

Differential Diagnosis of Diarrhea in Patients With Neuroendocrine Tumors

Patients with neuroendocrine tumors (NETs) and carcinoid syndrome experience diarrhea that can have a debilitating effect on quality of life. Diarrhea also may develop in response to other hormonal syndromes associated with NETs, surgical complications, medical comorbidities, medications, or food sensitivities. Limited guidance on the practical approach to the differential diagnosis of diarrhea in these patients can lead to delays in appropriate treatment. This clinical review and commentary underscore the complexity in identifying the etiology of diarrhea in patients with NETs. Based on our collective experience and expertise, we offer a practical algorithm to guide medical oncologists and other care providers to expedite effective management of diarrhea and related symptoms in patients with NETs.

Lactose Maldigestion, Malabsorption, and Intolerance: A Comprehensive Review with a Focus on Current Management and Future Perspectives

Milk is a fundamental component of the diet of every mammal; nevertheless, not every individual can tolerate this kind of food, especially in adulthood. However, lactose intolerance has only been recognized in the last 50 years, and currently, lactose intolerance is defined as a clinical syndrome characterized by pain, abdominal distention, flatulence, and diarrhoea that occur after lactose consumption. Lactose is currently a common disaccharide in human nutrition, both in breastfed infants and in adults, but its digestion requires a specialized enzyme called lactase. The genetically programmed reduction in lactase activity during adulthood affects most of the world’s adult population and can cause troublesome digestive symptoms, which may also vary depending on the amount of residual lactase activity; the small bowel transit time; and, especially, the amount of ingested lactose. Several diagnostic tests are currently available for lactose intolerance, but the diagnosis remains challenging. The treatment for lactose intolerance mainly consists of reducing or eliminating the dietetic amount of lactose until the symptoms disappear, but this is hard to achieve, as lactose is present in dairy products and is even commonly used as a food additive. In addition to dietetic restriction of lactose-containing foods, lactase can be administered as an enzymatic food supplement, but its efficacy is still controversial. Recently, probiotics have been proposed for the management of lactose intolerance; certain probiotic strains have shown specific β-galactosidase activity, thus aiding in the digestion of lactose. The aim of this paper was to review the current knowledge about lactose intolerance and to discuss the potential for the use of specific probiotic strains such as dietary supplements in lactose-intolerant patients.

Anti-bacterial and anti-biofilm activity of probiotic bacteria against oral pathogens

In this study, three lactic acid bacteria (LAB), isolated from barley, traditional dried meat and fermented olive were characterized and tested for their anti-bacterial and anti-biofilm activities against oral bacteria. Our results revealed that the tested LAB were γ-hemolytic and were susceptible to four antibiotics. All the strains were resistant to low pH, bile salt, pepsin and pancreatin. Furthermore, FB2 displayed a high aut-oaggregative phenotype (99.54%) while FF2 exhibited the best co-aggregation rate. Concerning the microbial adhesion to solvent, FB2 was the most hydrophobic strain (data obtained with chloroform and n-hexadecane). In addition Pediococcus pentosaceus FB2 and Lactobacillus brevis FF2 displayed a significant inhibitory effect against Streptococcus salivarius B468 (MIC = 10%). Moreover the selected strains were able to inhibit biofilm formation of Bacillus cereus ATCC14579 (MBIC50 = 28.16%) and S. salivarius B468 (MBIC50 = 42.28%). The selected LAB could be considered as candidate probiotics for further application in functional food and mainly in the prevention of oral diseases.

Ultrasonic Monitoring of Enzyme Catalysis; Enzyme Activity in Formulations for Lactose-Intolerant Infants

The paper introduces ultrasonic technology for real-time, nondestructive, precision monitoring of enzyme-catalyzed reactions in solutions and in complex opaque media. The capabilities of the technology are examined in a comprehensive analysis of the effects of a variety of diverse factors on the performance of enzyme β-galactosidase in formulations for reduction of levels of lactose in infant milks. These formulations are added to infant's milk bottles prior to feeding to overcome the frequently observed intolerance to lactose (a milk sugar), a serious issue in healthy development of infants. The results highlight important impediments in the development of these formulations and also illustrate the capability of the described ultrasonic tools in the assessment of the performance of enzymes in complex reaction media and in various environmental conditions.

Enteric-coated capsule containing β-galactosidase-loaded polylactic acid nanocapsules: enzyme stability and milk lactose hydrolysis under simulated gastrointestinal conditions

In order to protect peroral β-galactosidase from being degraded and hydrolyse milk lactose efficiently in the environments of gastrointestinal tract, a double-capsule delivery system composed of enteric-coated capsule and polylactic acid (PLA) nanocapsules (NCs) was developed for encapsulation of β-galactosidase. β-galactosidase-loaded PLA NCs in the size range of 100–200 nm were prepared by a modified w1/o/w2technique. During the encapsulation process, dichloromethane/ethyl acetate (1 : 1, v/v) as the solvent composition, high-pressure homogenisation (150 bar, 3 min) as the second emulsification method and polyvinyl alcohol or Poloxamer 188 as a stabiliser in the inner phase could efficiently improve the activity retention of β-galactosidase (>90%). Subsequently, the prepared NCs were freeze-dried and filled in a hydroxypropyl methylcellulose phthalate (HP55)-coated capsule. In vitro results revealed that the HP55-coated capsule remained intact in the simulated gastric fluid and efficiently protected the nested β-galactosidase from acidic denaturation. Under the simulated intestinal condition, the enteric coating dissolved rapidly and released the β-galactosidase-loaded PLA NCs, which exhibited greater stability against enzymatic degradation and higher hydrolysis ratio (∼100%) towards milk lactose than the free β-galactosidase. These results suggest that this double-capsule delivery system represents promising candidate for efficient lactose hydrolysis in the gastrointestinal tract.

Colorectal cancer and nonfermented milk, solid cheese, and fermented milk consumption: a systematic review and meta-analysis of prospective studies

Colorectal cancer is the second most prevalent cancer worldwide. A systematic review and meta-analysis of prospective studies was conducted to examine the association between intake of different types of dairy foods during adulthood and the development of colorectal cancer, specifically comparing nonfermented milk, solid cheese, and fermented milk. Seven databases were systematically searched and 15 cohort studies selected for inclusion, involving over 900,000 subjects and over 5200 colorectal cancer cases. Meta-analysis resulted in an overall relative risk of colon cancer of 0.74 (95% confidence interval 0.60-0.91) in men consuming nonfermented milk (highest intake category averaging 525 g/day). No association was found between consumption of nonfermented milk and rectal cancer in men or nonfermented milk and colon or rectal cancer in women. No protective association was found between consumption of solid cheese or fermented milk and colorectal cancer. Reasons for the differences in the impact of nonfermented milk, solid cheese, and fermented milk in the colon are discussed. This meta-analysis supports the inverse association between nonfermented milk consumption and risk of colon cancer in men, and provides an evidence base to assist in the formulation of dietary guidelines involving dairy foods.

Poly(lactic acid) nanoparticles coated with combined WGA and water-soluble chitosan for mucosal delivery of β-galactosidase

A combinatorial design, physical adsorption of water-soluble chitosan (WSC) to particle surface and covalent conjugation of wheat germ agglutinin (WGA) to WSC, was applied to surface modification of poly(lactic acid) nanoparticles (NPs) for targeted delivery of β-galactosidase to the intestinal mucosa. All the surface-engineered NPs in the size range of 500-600 nm were prepared by a w/o/w solvent diffusion/evaporation technique. β-Galactosidase encapsulated in these NPs was well protected from external proteolysis and exerted high hydrolytic activity on the permeable lactose. The presence of WSC coating, whether alone or with WGA, highly improved the suspension stability of NPs and tailored the particle surface positively charged. In comparison to NPs modified with WGA or WSC alone, the synergistic action of WGA and WSC greatly enhanced the NP-mucin interactions in vitro. The highest amount of NPs was found in the small intestine at 24 h after oral administration in rats. Notably, calculated half-life of WGA-WSC-NPs in the small intestine was 6.72 h, resulting in 2.1- and 4.3-fold increase when compared to WGA-polyvinylalcohol (PVA)-NPs and WSC-NPs, much longer than that of control PVA-NPs (6.9-fold). These results suggest that NPs with the combined WGA and WSC coating represent promising candidates for efficient mucosal drug delivery as well as biomimetic treatment of lactose intolerance.

A novel cold-adapted β-galactosidase isolated from Halomonas sp. S62: gene cloning, purification and enzymatic characterization

A novel 1,170 bp β-galactosidase gene sequence from Halomonas sp. S62 (BGalH) was identified through whole genome sequencing and was submitted to GenBank (Accession No. JQ337961). The BGalH gene was heterologously expressed in Escherichia coli BL21(DE3) cells, and the enzymatic properties of recombinant BGalH were studied. According to the polyacrylamide gel electrophoresis results and the sequence alignment analysis, BGalH is a dimeric protein and cannot be classified into one of the known β-galactosidase families (GH1, GH2, GH35, GH42). The optimal pH and temperature were determined to be 7.0 and 45 °C, respectively; the K m and K cat were 2.9 mM and 390.3 s(-1), respectively, for the reaction with the substrate ortho-nitrophenyl-β-D-galactopyranoside. At 0-20 °C, BGalH exhibited 50-70 % activity relative to its activity under the optimal conditions. BGalH was stable over a wide range of pHs (6.0-8.5) after a 1 h incubation (>93 % relative activity) and was thermostable at 50 °C and below (>60 % relative activity). The enzyme hydrolyzes lactose completely in milk over 24 h at 7 °C. The characteristics of this novel β-galactosidase suggest that BGalH may be a good candidate for medical researches and food industry applications.

Lactose intolerance: diagnosis, genetic, and clinical factors

Most people are born with the ability to digest lactose, the major carbohydrate in milk and the main source of nutrition until weaning. Approximately 75% of the world’s population loses this ability at some point, while others can digest lactose into adulthood. This review discusses the lactase-persistence alleles that have arisen in different populations around the world, diagnosis of lactose intolerance, and its symptomatology and management.

Self-perceived lactose intolerance results in lower intakes of calcium and dairy foods and is associated with hypertension and diabetes in adults

BACKGROUND

Self-perceived lactose intolerance may result in adverse dietary modifications; thus, more studies are needed to understand the prevalence of self-perceived lactose intolerance and how it relates to calcium intake and selected health conditions.

OBJECTIVE

The objective was to examine the effects of self-perceived lactose intolerance as it relates to calcium intake and specific health problems that have been attributed to reduced intakes of calcium and dairy foods in a nationally representative multiethnic sample of adults.

DESIGN

This was a cross-sectional study in a national sample of 3452 adults. The relation between self-perceived lactose intolerance, calcium intakes, and physician-diagnosed health conditions was analyzed by using linear regression analyses.

RESULTS

Of the total sample, 12.3% of respondents perceived themselves to be lactose intolerant. The age-adjusted prevalence of self-perceived lactose intolerance was 7.8% for non-Hispanic whites, 20.1% for non-Hispanic blacks, and 8.8% for Hispanics. Respondents with self-perceived lactose intolerance had significantly lower (P < 0.05) average daily calcium intakes from dairy foods than did those without self-perceived lactose intolerance. A significantly higher (P < 0.05) percentage of respondents with self-perceived lactose intolerance than of respondents without self-perceived lactose intolerance reported having physician-diagnosed diabetes and hypertension. The odds of self-reported physician-diagnosed diabetes or hypertension decreased by factors of 0.70 and 0.60, respectively, for a 1000-mg increase in calcium intake from dairy foods per day.

CONCLUSIONS

Self-perceived lactose-intolerant respondents had a significantly lower calcium intake from dairy foods and reported having a significantly higher rate of physician-diagnosed diabetes and hypertension.

MALDI-TOF MS characterization of glycation products of whey proteins in a glucose/galactose model system and lactose-free milk

The major modifications induced by thermal treatment of whey proteins α-lactalbumin (α-La) and β-lactoglobulin (β-Lg) in a model system mimicking lactose-free milk (L(-) sugar mix) were investigated by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The analysis of the intact α-La revealed species with up to 7 and 14 adducts from lactose and sugar mix, respectively, whereas for β-Lg 3 and up to 5 sugar moieties were observed in the case of lactose and sugar mix experiments, respectively. A partial enzymatic hydrolysis with endoproteinase AspN prior to mass spectrometric analysis allowed the detection of further modifications and their localization in the amino acid sequence. Using α-cyano-4-chlorocinnamic acid as MALDI matrix, it could be shown that heating α-La and β-Lg with glucose or galactose led to the modification of lysine residues that are not glycated by lactose. The higher glycation degree of whey proteins in a lactose-free milk system relative to normal milk with lactose reflects the higher reactivity of monosaccharides compared to the parent disaccharide. Finally, the analysis of the whey extract of a commercial lactose-free milk sample revealed that the two whey proteins were present as three main forms (native, single, and double hexose adducts).

Crystal structures of Trichoderma reesei β-galactosidase reveal conformational changes in the active site

We have determined the crystal structure of Trichoderma reesei (Hypocrea jecorina) β-galactosidase (Tr-β-gal) at a 1.2Å resolution and its complex structures with galactose, IPTG and PETG at 1.5, 1.75 and 1.4Å resolutions, respectively. Tr-β-gal is a potential enzyme for lactose hydrolysis in the dairy industry and belongs to family 35 of the glycoside hydrolases (GH-35). The high resolution crystal structures of this six-domain enzyme revealed interesting features about the structure of Tr-β-gal. We discovered conformational changes in the two loop regions in the active site, implicating a conformational selection-mechanism for the enzyme. In addition, the Glu200, an acid/base catalyst showed two different conformations which undoubtedly affect the pK(a) value of this residue and the catalytic mechanism. The electron density showed extensive glycosylation, suggesting a structure stabilizing role for glycans. The longest glycan showed an electron density that extends to the eighth monosaccharide unit in the extended chain. The Tr-β-gal structure also showed a well-ordered structure for a unique octaserine motif on the surface loop of the fifth domain.

Targeted PLGA microparticles as a novel concept for treatment of lactose intolerance

BACKGROUND

Peroral β-galactosidase preparations for the management of lactose intolerance need to be administered in large doses (1500 to 6000 U) immediately before or together with a lactose-containing meal.

AIM

Therefore, this work aimed at developing an innovative long-acting formulation. For this purpose, biodegradable polymeric microcarriers were functionalized with β-galactosidase and targeted with wheat germ agglutinin (WGA) for bioadhesion and thus prolonged residence time in the small intestine.

METHODS

Spray-dried poly(D,L-lactide-co-glycolide) (PLGA) particles with 2.78±1.05µm in diameter were functionalized with β-galactosidase from Kluyveromyces lactis and WGA using different types of spacers (polyethyleneimine, hexamethylene diamine, 6-aminocaproic acid) and coupling methods (carbodiimide and glutaraldehyde). The particle-bound enzyme activity was determined, and the bioadhesive characteristics were assessed by interaction with mucin coatings and Caco-2 cell monolayers.

RESULTS

Up to 1470 U β-galactosidase per gram PLGA were immobilized. The best results were obtained with hexamethylene diamine as a spacer applying the carbodiimide method. Thereby, a nearly 6-fold increase in enzyme activity was obtained as compared to particles without spacer. Upon targeting with WGA, binding to artificial human intestinal epithelium was increased considerably.

CONCLUSIONS

For the delivery of β-galactosidase WGA-targeted PLGA microparticles were prepared, which represent promising candidates for a convenient biomimetic treatment regimen of lactose intolerance.