产胞外黑色素海洋菌的鉴定及发酵条件优化

Identification and culture condition optimization for a marine extracellular melanin producing bacterium

从山东近海海域沉积物的微生物筛选中获得了一株高产胞外黑色素的菌株QJNY82,通过对该菌株菌落形态特征观察、生理生化检验及16S rDNA序列测定,初步确定该菌株为发光杆菌属细菌.通过对菌株QJNY82的胞外产物进行红外光谱分析,得到该细菌的胞外产物为黑色素,纯化后的黑色素的红外光谱图与标准黑色素(SIGMA)的红外光谱图一致,且该细菌所产黑色素的理化性质与标准黑色素具有一致性.该海洋菌株具有产黑色素速度快,产量高且不需要L-酪氨酸诱导的特点,而且经L-酪氨酸诱导后,可显著提高菌株QJNY82胞外黑色素的产量,在L-酪氨酸的含量为0.75 g/dm3、盐度为30、pH值为8.0、温度为28℃的条件下,菌株黑色素产量是未加L-酪氨酸的3.5倍,其产量达1.325g/dm3.鉴于菌株QJNY82具有产黑色素的特性,将成为发光杆菌属的一个新的菌种资源.

One bacterial strain（QJNY82）that can produce melanin was isolated from a sample from Shandong coastal sediment by our laboratory. Strain QJNY82 was identified as Photobacterium sp. based on morphological,physiological and biochemical tests as well as the 16S rDNA sequence analysis. We confirm the extracellular products of melanin through the infrared spectrum. The FT-IR spectra of its pigment is similar to that of the standard melanin（SIGMA）. Moreover the physicochemical properties of melanin are similar to that of the standard melanin. StrainQJNY82 has advantages that it can produce melanin with a high yield in the absense of L-tyrosine. Induced by Ltyrosine,the melanin production could increases sharply. The results showed that the optimum condition was as follows,i. e. L-tyrosine 0. 75 g / dm3,pH =8. 0,salinity 30,temperature 28℃. Its production reached 1. 325 g/dm3in the optimum condition. Strain QJNY82 may be identified as Photobacterium sp.,a new strain for melanin producing bacterium.