Research On Kefir Galactose In Mold Isolation And Identification And Open Field Lactobacillus Interaction

Recent research showed that kefir has some physiological functions, such as, anti tumor activity,reducing blood pressure, blood lipids and blood sugar, anti bacteria activity, protecting stomach and bowel, reducing inflammation, boosting fat consumption and antioxidant activity. However, the fungus product is quite complex, and the fermentation process is not easily to control, the quality of the product is not stable and very difficult to industrial-scale produce, which make the research on the fungus phases of kefir get more and more attention. The predominant fungus was isolated and characterized from the water kefir by the classical and molecular biological method. The structure, properity and interactions were investigated in this study, which can provide some theory to exploit and use kafir.A yeast-like fungus strain wk1 was isolated from water kefir grains and characterized as Galactomyces geotrichum through classical method and DNA sequencing. The further research on symbiotic relationship between Galactomyces geotrichum and Lactobacillus kefir was carried out. It was observed that great adhesion ability existed between Galactomyces geotrichum and Lactobacillus kefir.The surface abilities of Galactomyces geotrichum were also investigated in this study and the Galactomyces geotrichum was proved to be alkaline electron donor with strong hydrophobicity.Different influences of the pretreatment of heating, acetic acid(AA), NaOH and LiCl on the surface abilities of Galactomyces geotrichum were observed. For instance, the ability of hydrophobicity and alkaline electron donor could be significantly weakened after heat treatment, especially, the surface ability decreased 50% compared with the control, when the heat treatment time is between 5-10 min;however, there were no obvious change was found when the heat treatment time is less than 5 min or more than 10 min. On the contrary, the cell surface of Galactomyces geotrichum showed strong hydrophilic after the treatment of AA or NaOH. The hydrophobicity ability was not affected, but the properties of acidity and electronic withdrawing were enhanced by the treatment of LiCl. n addition, the auto-aggregation ability of Galactomyces geotrichum and the co-aggregation ability of Lactobacillus kefir were also researched in this paper. The Galactomyces geotrichum showed significant autoaggregation ability. In the early stage of the culture, the proportion of the auto-aggregation performance of Galactomyces geotrichum reached 70% compared with the control, and the ratio were increasing with prolonged treatment time, and the proporation was as high as 97.48% after 3h of culture, and the autoaggregation performance was completely finished after 4h.Meanwhile, the results also showed that the co-aggregation ability between Galactomyces geotrichum and Lactobacillus kefirwas not obvious at the begining of culture stage, with about7% higher than that in the control; the co-aggregation ability made a significant improvement during the period of 1-3 h; while the co-aggregation performance decreased sharply during the mid- and late stage of culture(3-5h), e.g. the proportion of the co-aggregation ability was 36% after the treatment of5 h.The auto-aggregation ability of Galactomyces geotrichum and co-aggregation ability with Lactobacillus kefir showed different performance with the different treatments. In the early stage of the culture, the auto-aggregation performance of Galactomyces geotrichum and the co-aggregation with Lactobacillus kefir were reduced by heat treatment, but in the late stage of the reaction, both of the abilities recovered quickly. The auto-aggregation ability of Galactomyces geotrichum could be weakened with a slight extent by pretreatment of NaOH, while the co-aggregation ability of Galactomyces geotrichum and Lactobacillus kefir got a significant decrease. With the extended culture of time, to some extent, the auto-aggregation ability of Galactomyces geotrichum and the co-aggregation ability with Lactobacillus kefir could be recovered at the early stage of the culture, but they still kept at a lower level.The auto-aggregation ability of Galactomyces geotrichum and co-aggregation ability with Lactobacillus kefir varied with the different alcohol concentration.The significant influence on the auto-aggregation ability of Galactomyces geotrichum was observed by pretreated of Li Cl, which not only decreased auto-aggregation ability, but also made the recovery rate keeping at a uniform level. Unlike the auto-aggregation ability, no significant weakness was observed by pretreated of LiCl at the early stage of the culture, but the treatment of Li Cl could significantly suppress the recovery rate at the late stage of the culture. Similiarly, the LiCl concentration did not affect the two abilities. Taken together, Galactomyces geotrichum, isolated in this study, is one of the most important strains, with strong hydrophobicity on the surface of the cell and alkaline electron donor, meanwhile, it has strong auto-aggregation ability and co-aggregation ability with other bacteria, which may be related with surface active substance such as, polysaccharides and proteins.