Precipitation and preservation of concentrated Chaetoceros (Chaetoceros gracilis)

Abstract

This research aimed to investigate the appropriate method for precipitation and preservation of concentrated Chaetoceros for larviculture of Pacific white shrimp (Litopenaeus vannamei). Chaetoceros precipitated by using of extracted chitosan from shrimp shell in polymer type (CPS), extracted chitosan in oligomer type of shrimp shell (COS) and extracted chitosan in oligomer type of crab shell (COC), respectively. The results showed that there were highest efficient of flocculation (> 90%) of CPS ranged from 40 to 60 mg/l and followed by using of COS and COC at 60 mg/l, respectively. Chaetoceros were precipitated with CPS can recovery well and not different in cell count (p > 0.05) with control while it was slower recovery when using COS. However, the characteristic of precipitated Chaetoceros with the use of COS was loose and small form which was suitable for larviculture of L. vannamei. Thus, precipitation of Chaetoceros can be used with COS and preserved at -20 OC combinations with and without 10% (v/v) glycerol (Gly) as cryoprotectant for further utilization. The survival rate of precipitated Chaetoceros after it had been preserved for 72 hours presented that Chaetoceros precipitated with COS, both of with and without Gly, were not different (p>0.05), but these rates were better than the regular method of using the fresh Chaetoceros for preserving without precipitation. Therefore, this method is one method for the cell harvesting in a concentrated form and can extend the preserved cells, which have some benefits in reducing and easing the space of storage, including to reduce the cost of commercial transportation in the future as well