Study On Enhancement Of Bacterial Cellulose Synthesis By Three Isolates From Fermented Coconut Water

Bacterial cellulose (BC) is focused by all the researchers in the world as its unique properties and widely application. Bacterial cellulose can be applied in food industry named "nata de coco". and Hainan is the main production base of nata de coco in China currently. They use coconut water as the main raw material for nata de coco fermentation. The natural coconut water (NCW) was fermented for few daysbecause the fermented coconut water had a significantly higher nata de coco production than natural coconut water. Therefore, it is necessary to explore the reasons why fermented coconut water is more suitable for the synthesis of nata de coco. This work has important practical significance for the healthy and continuous development of Hainan coconut fiber fruit industry.We had screened some natural fermented coconut water (NFC) microbes, here three isolated bacteriahave been chosed for in-depth study. Firstly, the strain was identified, and then the promoting action of the three isolated bacteria for Komagataeibacter nataicola Y19. The main results were as follows:(1) Species identificationThere are one bacterium and two strains of yeast, through16S rDNA or ITS sequence analysis and the morphological observation,4-17D,4-17B and7-22are Leuconostoc mesenteroides, Meyerozyma.sp and Saccharomyces cerevisiae, separately.(2) The influence of the isolated strains on the production of BC by Y19Komagataeibacter nataicola Y19was used as the strain for BC production to study in detail the three isolated strains of coconut water after fermentation processing effects on BC synthesis. The results show that the three bacteria before the single strain fermentation process can significantly improve the output of the BC, including S.cerevisiae7-22fermented coconut water (SFC), L.mesenteroides4-17D fermented coconut water (LFC) of BC yield were5.28g/L,5.09g/L, higher than the output of NFC4.98g/L, and Meyerozyma.sp4-17B fermented coconut water (MFC) production of BC4.93g/L the same as NFC products, but after the three isolates fermentation processing of BC yield were significantly higher than that of without fermentation processing (NCW) the production of2.10g/L.Then carries on the elaboration to the fermentation processing time before the research, the results show that the coconut water after three isolates fermentation of0-48h before BC yield showed a trend of steady growth, slow growth, after48h before than before for7d fermentation yield difference was not significant.Therefore, coconut water before fermentation processing time with2d is preferred.The influence of mixed isolates on the BC production:Coconut water through the primary fermentation by the mixed strains can improve the output of the BC,4-17b and S.cerevisiae7-22the mixed culture of the highest yield, even higher than the output of NFC is about10%. And other mixed strains fermentation of no significant difference between BC production, but production is much higher than BC production under NCW.The influence of isolates co-culture with Y19on the BC production:Two strains of yeast S.bayanus BV818.. S.cerevisiae7-22co-culture with Y19training don't produce BC;Meyerozyma.sp4-17B co-culture with Y19can produce a small amount of BC, and the resulting BC membrane has many visible pores;4-17D co-culture with Y19can improve the production of coconut water production BC by more than50%, rendering good cultivate relationships.Thus speculate that the three isolated bacteria in fermented coconut water is promote the synthesis of BC have important contribution to the members of the strain, so then an initial investigation on reasons for promoting effect.(3) The cause of the isolated bacteria promote the synthesis of BC"Subtraction" study:Through studying the thallus and the clear liquid of fermentation effects on BC synthesis. The results showed that the thallus on the BC yield was not significant, the influence of the fermentation supernatant on BC yield increase significantly."Addition"study:The effect of simulation added compounds on BC production. The results showed that ethanol, acetic acid, lactic acid for the promotion of BC Y19production effect is significant, especially sterilization after add0.5%ethanol yield the highest4.74g/L(The control group NCW under0.88g/L); Malic acid, succinic acid, tartaric acid, citric acid in the BC production was not significant;Pyruvic acid and oxalic acid inhibits production of BC. The isolated bacteria in coconut water when the first fermentation by glycolytic pathway to produce ethanol, acetic acid, lactic acid, etc., so as to promote the synthesis of BC is consistent with theoretical analysis."Composition analysis" study:To reveal the other ingredients except glycolysis contribution to BC synthesis, using HPLC and GC-MS on the fermentation process were analyzed by coconut water, before the determination of organic acids, free amino acids and volatile components, etc., and through comparing with NCW composition, looking for differences, to predict impact BC synthetic compounds. Results show that the amino acid content of the isolates fermenting liquid and NFC are higher than NCW.The lysine, isoleucine, alanine have detected in the fermented liquid, and did not check out or content less in NCW;In organic acid content analysis can be concluded that the accumulation of lactic acid and acetic acid can improve the ability of the BC Y19production;Active ingredients in GC-MS analysis can be concluded that the detection of effective component content in NCW under minimum, after the primary fermentation by isolates, the total volatile organic compounds were coconut water, ethanol, acetic acid,3-methyl butanol, furfural content different. To infer, acetic acid, ethanol,3-methyl butanol, furfural, lactic acid and some amino acids on the BC promotes contribution is bigger, but they are through what way can affect K nataicola BC of metabolic regulation of synthetic remains to be further in-depth study.This study first from the isolated bacteria of fermented coconut water to before fermentation processing of fresh coconut water, and compared with natural fermented coconut water, study them for the promotion of BC synthetic function and possible reasons.For exploring the pure strains fermented coconut water is used in the production of the coconut fiber fruit, improve the current raw material coconut water randomly placed in hainan,"without gauge control agnostic" approach for safety and quality of coconut fiber fruit the negative influence, for security, stability, high yield of coconut fiber fruit production new pattern laid a good foundation.