Optimization Of The Conditions For Phospholipase A₂ Production With Streptomyces Lividans And Enzymic Hydrolysis Of Lecithin

In this text, the hydrolysis was studied by using the natural soybean phospholipid as substrate and first with phospholipase A₂ produced by Streptomyces lividans 1326. The factors, such as technology of enzyme hydrolysis phospholipids, activities of emulsification of lysophospholipid, had been discussed with emphasis. The modified phospholipid has a good stability of emulsion with high salt and over a wide range of pH. As an additive in food, it prevents unwanted colorization of food or contamination with microbial spore, and plays a role in taste by coating bitter taste substances. As a good emulsifier, it enhances emulsion stability and increases solubility of hydrophobic drugs as well as hydrophilic compounds in oil phase. As a mild detergent and anti-fungal agent, lysophospholipid can be also used in protein purification and in agrochemicals, respectively. So the study of enzyme-modified phospholipid is a very significant work. The results offered important data in producing of the enzyme-modified phospholipid. The results are as follows:The lysophospholipid was first produced with phospholipase A₂, which was produced by Streptomyces lividans 1326. The fermentation conditions of this strain were researched by measuring the activity of the enzyme. The optional fermentation conditions were: concentration of cultural medium 2%, pH 8.0, inoculation quantity 5%, 100 ml cultural medium per 250 ml taper bottle, the activity of the enzyme reaching 0.95 IU/ml after about 55h.The soybean phospholipid was selected as substrate and the phospholipase A₂ produced by Streptomyces lividans 1326 as the hydrolysis tool enzyme. The enzyme reaction was carried in quiescent warm water. The optimum condition is: concentration of substrate 4%, enzyme dosage 0.10 IU/ml, CaCl₂ 0.03%, initiative reaction pH 7.5, reaction temperature 30℃ and 11 h of hydrolysis. In this condition the conversion of lecithin to lysophospholipid was 86.3% determined by acid base titration and HPLC.The method of testing emulsification of lysolecithin at the optimum is: 50 mg lysolecithin added to 30 ml oil, emulsifying 2 min. The emulsifying capacity can reach 354 ml oil per g lysolecithin.