Mortierella Species (Fungi): Production of C20 Polyunsaturated Fatty Acids

Abstract

Mortierella is one of the largest genera of Mucorales and many of its species are among the most common soil-inhabiting fungi. Following Turner's recognition of the Mortierella isabellina group (Turner 1963), Gams (1977) subdivided the genus Mortierella into two subgenera, Micromucor and Mortierella, distinguishable from each other by their morphological and cultural characteristics. The former form a low-growing, velvety colony, lack a distinctive odor, and have sporangia that are usually pigmented and possess an often developed columella. Species of the latter typically develop delicate, white, cottony or arachnoid, freely anastomosed aerial hyphae forming simple or racemosely or cymosely branched sporangiospores bearing colorless sporangia. Columellae are absent or only rudimentary, and the diffluent sporangium wall lacks calcium oxalate spicules. Most species of the subgenus possess a distinctive garlic like odor, and though usually growing readily in culture often form sporangia only on nutrient-poor media. According to Amano et al. (1992), the two subgenera can also be distinguished on the basis of their mycelial fatty acid composition: polyunsaturated C20 is present only in Mortierella subgenus. Thus, Mortierella subgenus fungi are considered promising as producers of C20 polyunsaturated fatty acids (PUFA).