Study on Mixed Strain for Liquid State Fermentation of Animal Blood
|School||Nanjing Agricultural College|
|Course||Clinical Veterinary Medicine|
|Keywords||Gene library PCR-SSCP Hemoglobin Degradation bacterium Liquid state fermentation|
With the agricultural structure adjustment in our country, the animal husbandry gets a large improvement and it plays a great of role in agriculture, but most of feed resources are insufficient, especially protein feed. While there is a big livestock population in our country, which can produce a lot of blood resources.This is a huge resource to produce protein feed. But because of the poor palatability, difficult storage and digestion and low nutrition valency, this blood resource is seriously wasted. If blood slaughtered is discharged to the environment, it causes deterioration of water and soil pollution. Therefore, the comprehensive utilization of livestock and poultry blood can not only reduce the environment pollution, but also increase social benefits, economic benefits and environmental benefits. Blood microbial degradation needs low investment, less energy consumption, and high protein, amino acids and peptides, it is considered as a significantly comprehensive utilization of blood.The total DNA was made as the template, then analyzed the structure of the flora by PCR-SSCP. As a result, there was a total of ten kind of bacteria with the preliminary determination in this flora.Hemoglobin-degrading bacteria were screened by using blood screening medium which can exist a long-time stable only in the blood providing carbon sources, and then use PCR-SSCP to screen those strains again from former screened result. Three bacteria were finally got, named as NJYA, NJYB and NJYC respectively. These bacteria were initially identified as Alcaligenes faecalis, Bacillus cereus and Stenotrophomonas maltophilia respectively, based on morphological, physicochemical characteristics and 16S rRNA sequence anlysis.Monoxenie and mixture of these three kind of bacteria were used to survey the effect on the liquid state fermentation.As a result, the best combined one was got: NJYA with NJYB. Through changing the different test conditions including pH, temperature, inoculum size, bacteria age, inoculation proportion, inorganic salt and fermentation time the degradation rate of each test group were analyzed. At last, the best main medium was obtained:10% blood, K2HPO4 0.045 g·L-1, KH2PO4 0.54 g·L-1, NaCl 0.3 g·L-1; The best fermentation conditions:initial pH 7.5,6% inoculum size, bacteria age was 12 h, fermentation temperature was 37℃, the proportion of NJYA with NJYB was 1:2. These results showed that the degradation rate of blood was 67.2% with the optimized conditions for 84 h. This degradation rate was 32.8% larger than its without optimized.This test provided stable and high efficiency degradation bacteria for mixed culture fermentation of animal blood and a simple, convenient, practical and reliable method to screen bacteria.