Fermentation Of Sea Cucumber Ovum And Tilapia Skin By Bacillus Subtilis: Fermentation Condition Optimization And Product Bioactivity

The by-product of aquatic food processing is mostly used for feeding production or is discarded directly,which caused serious economic loss and even environment pollution.Thus the diversified ways and high utilization ratio for the comprehensive use of these by-product is a critical problem for the development of aquatic industry in China.In this presentation,using soybean meal as control,tilapia skin,abalone gonad,sea cucumber ovum and scallop skirt were used as fermentation substrate for Bacillus subtilis.According to the resultant product bioacitivity,the optimal substrate was screened for further optimization of the fermentation condition and the study of the bioactivity of the fermentation products.All the above work is conducted to lay a solid basis for increasing the value of these by-products.Primary screening results showed that,the above four by-products could be utilized by Bacillus subtilis,and the fermentation product demonstrated fibrinolytic and ACE inhibition activities.The fermentation product from tilapia skin and sea cucumber ovum also showed anti-coagulation activity.They also both showed peak value of fibrinolytic activity after 36 h.According the above results,setting the fermentation time for 36h,tilapia skin and sea cucumber ovum were selected for further research on the optimization of fermentation condition,and the bioactivities of the result products.The fermentation results of sea cucumber ovum demonstrated that the optimum carbon source was glucose,with an optimum addition of 2%(m/v).Other optimized condition included initial pH 7.0,5%inoculation amount(v/v),fermentation temperature 37 ?,loading volume 20%(v/v),solid-liquid ratio 1:30(m/v)and rotation speed 180 rpm/min,respectively.The fibrinolytic activity in the supernatant of fermentation product was strong,with fibrinolysin activity as high as 6723 FU/mL at a final protein concentration of 20 mg/mL;at the same time,ACE inhibition activity also demonstrated a high inhibition ratio of 90%.Activated partial thromboplastin time(APTT)and thrombin time(TT)were extended by the supernatant significantly as the protein level was in a range of 5-20 mg/mL.FIB content was also decreased but PT was not influenced.Comparing with the fermentation product of soybean meal,the molecular weight of that of sea cucumber ovum was far more lower(lower than 14.2 KD,of which 84%was lower than 1 KD,10.5%ranged in 1-5 KD,and 4.8%r anged in 5-10 KD);Product derived from sea cucumber ovum showed lower protease activity than that of soybean meal;Fibrinolysin in the fermentation product of sea cucumber ovum seemed outweighed that of soybean meal with one more species,but the total fibrinolysin activity seemed almost the same.The content of hydrophobic Asp,Glu,Lys and Leu is relatively higher in the fermentation product,and the necessary amino acid increased from 22.96%to 37.32%.The fermentation results of tilapia skin demonstrated that the optimum carbon source was fructose,with an optimum addition of 3%(m/v).Other optimized condition included initial pH 8.0,5%inoculation amount(v/v),fermentation temperature 37 ?,loading volume 20%(v/v),solid-liquid ratio 1:40(m/v)and rotation speed 180 rpm/min,respectively.The molecular weight of that of sea cucumber ovum was all lower than 10 KD(of which 47.7%was lower than 1 KD,50.2%ranged in 1-5 KD,and 1.75%ranged in 5-10 KD);the content of necessary amino acid increased from 7.3%to 15.1%.Comparing with the fermentation product of soybean meal,product derived from tilapia skin showed higher protease activity,almost similar fibrinolytic activity with more species than that of soybean meal;fibrinolysin activity as high as 6929 FU/mL at a final protein concentration of 20mg/mL;prolonged TT and lower FIB in the serum,the effect on TT was equivalent to 1?g/mL heparin;At the same time,ACE inhibition activity also demonstrated a high inhibition ratio of 60%.In conclusion,the above results showed that,the bioactivities of the fermented sea cucumber ovum and tilapia skin by Bacillus subtilis were significantly enriched and increased by optimizing the fermentation condition.The resultant product demonstrated relatively strong fibrinolytic,ACE inhibition and anti-coagulation activities,which could be used as basic material for developing fermentation product with auxiliary therapeutic effect on thrombolysis,anti-hypertension and other cardiovascular and cerebrovascular diseases.Thus this research could provide theory and technique basis for large-scale fermentation of these by-produts.