**2. Materials and methods**

#### **2.1 Organisms used and culture conditions**

*Mucor circinelloides* strain YR-1 originally isolated from petroleum-contaminated soil in Salamanca, Guanajuato, Mexico was used as enzymatic source. A defined media containing yeast-peptone-glucose-agar (YPGA) (Bartnicki-García & Nickerson, 1962) was used for strain maintenance, spore collection and mycelium growth. Aerobic mycelium growth was also carried out on salt minimal medium (Alvarado et al. 2002) added with 0.1% (w/v) peptone (sMMP). As a carbon source we added D-glucose (1% w/v) or glycerol (1.0% v/v) or ethanol (2.0% v/v) or *n*-decanol (1.0% v/v) or *n-*pentane (1.0% v/v) or *n-*decane, (1.0% v/v) or *n-*hexadecane (1.0% w/v) or naphthalene (0.5% w/v) or anthracene (0.5% v/v) or phenanthrene (0.5% w/v) or pyrene (0.5% w/v). Liquid cultures (600 ml) inoculated with spores at a final cell density of 5 x 105/ml were propagated in 2-l Erlenmeyer flasks and incubated in a reciprocating water bath at 28°C for 22 h at 125 rpm for all substrates except glucose that was incubated for 12 h at same other conditions.
