Selecting optimum thermal acid hydrolysis conditions for obtaining lactobacillus hydrolysates

Abstract

The conditions of thermal acid hydrolysis of lactobacillus mass were studied within the framework of the development of a new preparation possessing immunomodulating properties. The parameters for optimization were the process temperature and duration and pH of the medium. The optimization criteria were the contents of total and amine nitrogen, proteins, peptides, and amino sugars. The coefficients of hydrolysis and proteolysis were determined. Based on the analysis of data, hydrolysates containing 2% peptides and 0.02 -0.03% amino sugars were selected for subsequent investigations.Protein hydrolysates are promising pharmacologically active preparations, which can be obtained by various methods, including thermal acid hydrolysis, autolysis, their combination (autolysis + thermal acid hydrolysis), short-and long-term sterilization, and enzymatic hydrolysis. Within the framework of one method, technological processes can also substantially differ in the protein weight to water volume ratio, acid and enzyme types, the hydrolysis process duration, temperature, and pH, and the method used for the purification of hydrolysates from ballast substances.This study was aimed at establishing the optimum conditions for obtaining hydrolysates, based on protein (lactobacillus) substrates, using thermal acid hydrolysis technology. The substrate was the mass of lactobacillus species (Lactobacillus acidophilus B 2505), which were obtained from the Research Institute for Complex Usage of Lactic Products (Stavropol).The process was optimized with respect to the contents of total and amine nitrogen, proteins, peptides, and amino sugars. The main factors controlling the process of thermal-acid hydrolysis are pH of the reaction medium and the process temperature and duration. These factors have to be optimized so as to provide the maximum product yield and the efficiency of hydrolysis. This was achieved using the method of mathematical experiment planning according to the Plackett -Berman schedule [1]. This investigation is a necessary stage in the development of a new hydrolysate preparation containing a maximum amount of glucosaminylmuramyl dipeptide (GMD) -a structural fragment of peptidoglycans from bacterial cell wall.The GMD structure comprises a dipeptide (L-alanine-D-isoglutamine) linked to two sugar residues (N-glucosamine-N-acetylmuramyl). This substance is an absolute agonist of the recognition receptors of pathogenic bacteria, and its administration leads to strong activation of the inherent and adaptive immunity.