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Screening of Fermentative Strains for Reducing the Allergenicity of a Whey Protein-Soy Protein System and Genomic Characterization of the Selected Strain.

Dual-protein systems combining whey protein isolate (WPI) and soy protein isolate (SPI) offer complementary nutritional benefits but are limited by the presence of major allergens. Lactic acid bacteria (LAB) fermentation provides a promising strategy to mitigate this limitation. In this study, Lacticaseibacillus paracasei JM053, selected from 13 LAB strains based on phenotypic screening, significantly reduced the in vitro allergenicity of the dual-protein system, increasing the IgE-binding inhibition rate to 48.75%. Whole-genome sequencing and characterization of JM053 revealed a comprehensive proteolytic system, including the proline-specific peptidase genes pepX and pepQ, which may contribute to the degradation of allergenic peptide sequences. Combined with in silico bioinformatic analysis, potential cleavage sites within the linear epitopes of the dual-protein system were predicted based on the substrate specificity of the identified proteases, offering a testable hypothesis for the strain's mechanism of action. In addition, in vitro safety assessment and genomic analysis supported the safety potential, stress tolerance, and probiotic characteristics of JM053. Collectively, this study provides a valuable candidate strain for the development of hypoallergenic dual-protein products and offers preliminary genomic insights into LAB-mediated allergenicity reduction.

Lacticaseibacillus paracasei

[Nitrogen balance in adults and experimental study in rats fed with rice, beans and manioc flour supplemented with proteins].

Rice, beans and manioc flour are foods eaten daily in Northeast Brazil. Manioc flour is a source of energy, having a low protein content. There has been a great interest to supplement manioc flour with proteins. The present study was planned to show the nutritive value of a basic diet including rice, beans, manioc flour and other local foods, supplemented with different sources of proteins. The experiment was carried out in humans and rats. The supplements used were casein (Ca), isolated soy protein (PS) and a dry residue of a soymilk preparation (RSLS). Through nitrogen balance studies in adults it was shown that the diets with casein or isolated soy protein had a good absorption and retention of nitrogen. The addition of the soymilk residue resulted in a poor acceptance of the experimental diet; negative nitrogen retention was observed in the three persons who accepted the food and completed the balances studies. The same diets offered to humans, with the same protein supplements, were fed to rats. The nutritive value measured in the animals were similar, in all diets with all supplements, including the one with the dry residue of soymilk. The present results call the attention to the problems of transfering animal results to humans. It was also discussed the possibility of adding casein or isolated soy protein as an eventual protein supplement to manioc flour for human feeding.

Adolescent

Inhibitory effect of mercaptoamino acids on lysino-alanine formation during alkali treatment of proteins.

Alkali treatment of food proteins converts some amino acid residues to the unnatural amino acid lysinoalanine which has been found to cause kidney damage when fed to rats. Formation of lysinoalanine was essentially prevented when isolates of soy protein and casein were exposed to alkali in the presence of thio-alamino acids such as cysteine. The results suggest that added thiols minimize the formation of potentially toxic lysinoalanine.

Alanine

Isolation and purification of Flavobacterium alpha-1,3-glucanase-hydrolyzing, insoluble, sticky glucan of Streptococcus mutans.

Studies were made on the physical and chemical properties of polysaccharides synthesized by cell-free extracts of Streptococcus mutans, Streptococcus sanguis, and Streptococcus sp. and their susceptibilities to dextranases. Among the polysaccharides examined, insoluble glucans were rather resistant to available dextranase preparations, and the insoluble, sticky glucan produced by S. mutans OMZ 176, which could be important in formation of dental plaques, was the most resistant. By enrichment culture of soil specimens, using OMZ 176 glucans as the sole carbon source, an organism was isolated that produced colonies surrounded by a clear lytic zone on opaque agar plates containing the OMZ 176 glucan. The organism was identified as a strain of Flavobacterium and named the Ek-14 bacterium. EK-14 bacterium was grown in Trypticase soy broth, and an enzyme capable of hydrolyzing the OMZ 176 glucan was concentrated from the culture supernatant and purified by negative adsorption on a diethylaminoethyl-cellulose (DE-32) column and gradient elution chromatography with a carboxymethyl-cellulose (CM-32) column. The enzyme was a basic protein with an isoelectric point of pH 8.5 and molecular weight of 65,000. Its optimum pH was 6.3 and its optimal temperature was 42 C. The purified enzyme released 11% of the total glucose residues of the OMZ 176 glucan as reducing sugars and solubilized about half of the substrate glucan. The products were found to be isomaltose, nigerose, and nigerotriose, with some oligosaccharides. The purified enzyme split the alpha-1,3-glucan endolytically and was inactive toward glucans containing alpha-1,6, alpha-1,4, beta-1,3, beta-1,4, and/or beta-1,6 bonds as the main linkages.

Cell-Free System

Hemolysins of Edwardsiella tarda.

Isolates of Edwardsiella tarda from four sources produced nonfilterable hemolsin in trypticase soy broth. The cell-associated hemolysin was partially heat labile, destroyed by formalin and sensitive to treatment with trypsin. These characteristics, and the observation that Ca++ or Mg++ ions enhanced activity, suggest that a proteinaceous, enzymic component may be responsible for the hemolytic activity.

Animals