Anaerobic Growth and Fermentation Characteristics of Paecilomyces lilacinus Isolated from Mullet Gut

The anaerobic growth and fermentation of a marine isolate of Paecilomyces lilacinus is described. The fungus was isolated from mullet gut and grew optimally at 30°C and at a salinity of ≥10%. The best growth was obtained with glucose or laminarin as substrate, and the growth yield was 5.0 g (dry weight of fungus) per mol of hexose fermented. Moles of products as a percentage of moles of hexose fermented were acetate, 29.0%; ethanol, 156.6%; CO₂, 108.0%; and lactate, 4.3%. Together these products accounted for >80% of hexose carbon. Hydrogen and formate were not detectable as fermentation end products (<0.5%). Other substrates utilized for growth, although less effectively than laminarin or glucose, included the monosaccharides galactose, fructose, arabinose, and xylose and the disaccharides maltose and cellobiose. No growth of the fungus occurred on cellulose, and of a variety of other polysaccharides tested only xylan supported growth.