Solubilization of gliadins for use as a source of nitrogen in the selection of bacteria with gliadinase activity

Probiotic potential of gluten degrading Bacillus tequilensis AJG23 isolated from Indian traditional cereal-fermented foods as determined by Multiple Attribute Decision-Making analysis

The present study reported the characterization of gluten hydrolyzing strains of Bacillus sp. from fermented cereal dough. The strains were characterized for probiotic as well as technological attributes. A total of 45 presumptive gluten degrading isolates were obtained on gliadin agar plate assay. Based on hemolytic and antibiotic susceptibility pattern, only six isolates were considered safe which also indicated gliadinase activity on zymography. All the six strains were able to resist the pH 2.0, 0.25% bile and also possessed ability to adhere to the organic solvents and mucin. The cell free supernatant of five strains exhibited antimicrobial activities against Gram-positive and Gram-negative pathogens. A more than 50% survival of the isolated strains was obtained at a salt concentration of 2%, phenol concentration of 0.1% and temperature upto 45 °C. All the strains exhibited antioxidant activities and biofilm forming ability. Furthermore, the ranking of strains based on probiotic as well as other functional attributes was determined using multidimensional Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). A matrix of multidimensional indicators was prepared using alternatives and criteria, the analysis indicated the strain Bacillus tequilensis AJG23 as the potential probiotic candidate based on all screening criteria. Further work still needs to be done about the protective role of the potential strain against gluten sensitivity using in vitro models.

Screening of Spore-Forming Bacteria with Probiotic Potential in Pristine Algerian Caves

The interest and exploration of biodiversity in subsurface ecosystems have increased significantly during the last 2 decades. The aim of this study was to investigate the in vitro probiotic properties of spore-forming bacteria isolated from deep caves. Two hundred fifty spore-forming microbes were enriched from sediment samples from 10 different pristine caves in Algeria at different depths. Isolates showing nonpathogenic profiles were screened for their potential to produce digestive enzymes (gliadinase and beta-galactosidase) in solid and liquid media, respectively. Different probiotic potentialities were studied, including (i) growth at 37°C, (ii) survival in simulated gastric juice, (iii) survival in simulated intestinal fluid, and (iv) antibiotic sensitivity and cell surface properties. The results showed that out of 250 isolates, 13 isolates demonstrated nonpathogenic character, probiotic potentialities, and ability to hydrolyze gliadin and lactose in solution. These findings suggest that a selection of cave microbes might serve as a source of interesting candidates for probiotics.

IMPORTANCE Previous microbial studies of subsurface ecosystems like caves focused mainly on the natural biodiversity in these systems. So far, only a few studies focused on the biotechnological potential of microbes in these systems, focusing in particular on their antibacterial potential, antibiotic production, and, to some extent, enzymatic potential. This study explores whether subsurface ecosystems can serve as an alternative source for microbes relevant to probiotics. The research focused on the ability of cave microbes to degrade two substrates (lactose and gliadin) that cause common digestive disorders. Since these enzymes may prove to be useful in food processing and in reducing the effect of lactose and gliadin digestion within intolerant patients, isolation of microbes such as in this study may expand the possibilities of developing alternative strategies to deal with these intolerances.

Characterization of Bacillus cereus AFA01 Capable of Degrading Gluten and Celiac-Immunotoxic Peptides

Wheat gluten elicits a pro-inflammatory immune response in patients with celiac disease. The only effective therapy for this disease is a life-long gluten-free diet. Gluten detoxification using glutenases is an alternative approach. A key step is to identify useful glutenases or glutenase-producing organisms. This study investigated the gluten-degrading activity of three Bacillus cereus strains using gluten, gliadin, and highly immunotoxic 33- and 13-mer gliadin peptides. The strain AFA01 was grown on four culture media for obtaining the optimum gluten degradation. Complete genome sequencing was performed to predict genes of enzymes with potential glutenase activity. The results showed that the three B. cereus strains can hydrolyze gluten, immunotoxic peptides, and gliadin even at pH 2.0. AFA01 was the most effective strain in degrading the 33-mer peptide into fractions containing less than nine amino acid residues, the minimum peptide to induce celiac responses. Moreover, growth on starch casein broth promoted AFA01 to degrade immunotoxic peptides. PepP, PepX, and PepI may be responsible for the hydrolysis of immunotoxic peptides. On the basis of the potential of gluten degradation, AFA01 or its derived enzymes may be the best option for further research regarding the elimination of gluten toxicity.

Significant Hydrolysis of Wheat Gliadin by Bacillus tequilensis (10bT/HQ223107): a Pilot Study

Peptidase therapy is suggested to be effective to minimize gliadin toxicity in celiac disease (CD). Hence, present study deals with gliadin-hydrolysing peptidases. The efficient peptidase from the Bacillus tequilensis was purified using ammonium sulfate fractionation and preparative electrophoresis. Analysis of in-solution and in-gel hydrolysis of gliadin using one and two-dimensional SDS-PAGE revealed nearly complete hydrolysis of gliadin peptides after 180 min of incubation with B. tequilensis protease. Purified peptidase was found to be stable at acidic (pH 3.5) to neutral (pH 7.2) pH range. The molecular mass and isoelectric point of the peptidase were observed around 29 kDa and 5.2, respectively. The internal protein sequence obtained through mass spectrometric analysis suggested that peptidase might belong to peptidase S9 family known for prolyl-specific peptidases. This study recommends the possible applicability of this peptidase for elimination of immunotoxic gliadin peptides and may prove useful in CD treatment.

Screening sourdough samples for gliadin-degrading activity revealed Lactobacillus casei strains able to individually metabolize the coeliac-disease-related 33-mer peptide

A selective culture medium containing acid-hydrolyzed gliadins as the sole nitrogen source was used in the search for sourdough-indigenous lactic acid bacteria (LAB) with gliadin-metabolizing activity. Twenty gliadin-degrading LAB strains were isolated from 10 sourdoughs made in different ways and from different geographical regions. Fifteen of the 20 isolated strains were identified as Lactobacillus casei, a species usually reported as subdominant in sourdough populations. The other 5 gliadin-degrading strains belonged to the more commonly encountered sourdough species Leuconostoc mesenteroides and Lactobacillus plantarum. All these strains were shown to be safe in terms of their resistance to antimicrobial agents. When individually incubated with the α2-gliadin-derived immunotoxic 33-mer peptide (97.5 ppm), half of the L. casei strains metabolized at least 50% of it within 24 h. One strain metabolized 82% of the 33-mer peptide within 8 h and made it fully disappear within 12 h. These results reveal for the first time the presence in sourdough of proteolytic L. casei strains with the capacity to individually metabolize the coeliac-disease-related 33-mer peptide.