Bacterial Species And Biochemical Characteristic Investigations Of Fresh Nostoc Flagelliforme Concentrate During Storage

Nostoc flagelliforme(N.flagelliforme)is a kind of edible terrestrial cyanobacterium with important herbal and dietary values,which can be used in pharmacy,food and aquaculture.The liquid suspension cultivation of N.flagelliforme cells has made great progress.The seed supply would also be a bottleneck in N.flagelliforme scale up cultivation.The artificial N.flagelliforme cells have great potential applications in aquaculture.So it is valuble to develop an appropriate preservation method to keep N.flagelliforme cells fresh and viable for its production and application.It is valuable to have a more comprehensive understanding of the spoilage of N.flagelliforme cells to develop more suitable preservation techniques of N.flagelliforme cells.Therefore,the changes of bacterial species,cell viability,and nutrient composition and other biochemical characteristics of fresh N.flagelliforme concentrate during natural storage were investigated in this article.It was found that the gross photosynthetic rate decreased drastically along with the storage time,which suggested that N.flagelliforme cells drastically lost their viability.The permeability of cells increased,cells shrunk and ruptured just as observed by scanning electron microscope and structure related to physiological functions disintegrated with storage time.The content of protein in N.flagelliforme cells decreased along with the storage time,while the content of fatty acid kept more stable during the whole storage period.It reminds that some measures should be taken to reduce the metabolism of N.flagelliforme cells.N.flagelliforme cells and keep the content of protein more stable.Fourteen bacteria strains in the algae concentrate were identified by PCR-DGGE.The changes of bacterial species might be attributed to differences in environmental conditions such as oxygen concentration and nutrition composition in N.flagelliforme sample.Among of the bacteria that were detected,Enterococcus viikkiensis is a spoilage organism and would be a concern in the preservation.So some measures,such as change of culture medium and the addition of antibiotic should be taken to inhibit the multiplication of bacteria and prolong the storage time of N.flagelliforme concentrate.Eleven Volatile organic compounds were identified from N.fagelliformecells,in which geosmin Geosmin would be treated as an indicator of the freshness of N.flagelliforme.The occurrence of indole could indicate the degradation of cells.