Evaluation and comparison of production of hyaluronic acid from Streptococcus salivarius subsp. thermophilus and isolated streptococcus thermophilus samples from yoghurt and Optimization of the growth conditions

Introduction: Hyaluronic acid (HA), also known by the brand name Hyaluronan. Streptococcus equi sub. Zooepidemicus is the primary strain from which the HA is produced; However, being pathogenic for humans and animals has led to the restriction of the use of this strain. The necessity for using this fabulous material lead to investigate non-pathogenic strains to produce this material. The most non-pathogenic strain is Streptococcus thermophilus. The lack of literature on microbial production of this substance by the strain prompted us to examine the microbial production of HA from it and also to examine optimization of culture conditions where HA is produced. Materials and Methods: The bacteria Streptococcus salvarius sub. thermophilus was prepared from the Bank of Scientific and Industrial Research of Iran (PTCC1738) . To separate Streptococcus thermophilus strains from yogurts, three types of yogurts were used. They were cultured by Pour-plate and surface methods on STA medium. To identify the isolated strains ,biochemical tests and polymerase chain reaction (PCR) were used. Bacterial strains isolated from yoghurts were identified as Streptococcus thermophilus MN-BM-A02, Streptococcus thermophilus JIM8231, Streptococcus thermophilus MN-ZLW- 002 . To separate the capsule strains, each strain was cultured on STB medium, then they were centrifuged. In order to purify the samples, ethanol and charcoal were used. To optimize production, variety of sources of carbon, nitrogen, medium, temperature and pH were studied. Conclusion: The data showed that glucose and fructose, yeast extract, Tryptone, Temperature 50 ° C, pH 6.2, STA-rich medium to increase growth and HA production in each 4-strain was effective.