Isolation Of Phospholipase D Producing Strains And Their Evolution Based On 16S RDNA Sequence Analysis

Phospholipase D (PLD; EC 3.1.4.4) catalyzes the hydrolysis of phospholipids to phosphatidic acids (PA) as well as transphosphatidylation of the naturally abundant phosphatidylcholine to a large group of natural or unnatural phospholipids. The transphosphatidylation reaction is an indispensable tool for the synthesis of some phospholipids which are rare naturally and some artificial phospholipids. Up to now, several PLD producing strains have been successfully isolated. However, more available PLD producing strains are needed in industry production. Therefore, we tried to screen good PLD producing strains.Five phospholipase D (PLD) producing actinomycete strains (HF-0, HF-2, HF-9, HF-23 and HF-36) were isolated from the nearby region of a lecithin producing factory. The five strains show different properties. PLD produced by HF-23 showed the highest hydrolytic activity (6.8 U/mg) and the best transphosphatidylation ability from phosphatidylcholine (PC) to phosphatidylserine (PS) compared with the other four strains, indicating the commercial value of HF-23 in phosphatidylserine production. In addition, the presence of Ca2+ decreased the transphosphatidylation activity but increase the hydrolytic activity of HF-2, HF-9, HF-9, as HF-36 didn't influence by it.Results of 16S rDNA analysis proved that they are all Streptomyces.A phylogenetic tree was constructed based on 16S rDNA sequences of those five PLD producing strains and known PLD producing bacteria. It was demonstrated that the five strains belong to two clusters (HF-23 in clusterⅠand the other four strains in clusterⅡ). Interesting, most known bacteria producing PLD with high catalytic activities also belong to clusterⅠ, indicating that clusterⅠstrains tend to produce converse and stable PLD.