Metabolism of n-C_10:0 and n-C_11:0 fatty acids by Trichoderma koningii, Penicillium janthinellum and their mixed culture: I. Biomass and CO₂ production, and allocation of intracellular lipids

Abstract

The capacity of two soil fungi, Trichoderma koningii and Penicillium janthinellum, to oxidize n-C_10:0 and n-C_11:0 fatty acids to CO₂ and store intracellular lipids during growth is unknown. This article reports for the first time the metabolism of decanoic acid (DA, C_10:0), undecanoic acid (UDA, n-C_11:0), a mixture of the acids (UDA+DA) and a mixture of UDA+ potato dextrose broth (PDB) by T. koningii and P. janthinellum and their mixed culture. A control PDB complex substrate was used as a substrate control treatment. The fungal cultures were assayed for their capacity to: (1) oxidize n-C_10:0 and n-C_11:0 fatty acids to CO₂ and (2) store lipids intracellularly during growth. On all four fatty acid substrates, the mixed T. koningii and P. janthinellum culture produced more biomass and CO₂ than the individual fungal cultures. Per 150 mL culture, the mixed species culture grown on UDA+PDB and on PDB alone produced the most biomass (7,567 mg and 11,425 mg, respectively). When grown in DA, the mixed species culture produced the least amount of biomass (6,400 mg), a quantity that was lower than those obtained in UDA (7,550 mg) or UDA+DA (7,270 mg). Amounts of CO₂ produced ranged from 210 mg under DA to 618 mg under PDB, and these amounts were highly correlated with biomass (r² = 0.99). Fluorescence microscopy of stained lipids in the mixed fungal cell cultures growing during the exponential phase demonstrated larger fungal cells and higher accumulation of lipids in membranes and storage bodies than those observed during the lag and stationary phases. T. koningii and P. janthinellum grown on n-C_10:0 and n-C_11:0 fatty acids produced lower amounts of biomass and CO₂, but stored higher amounts of intracellular lipids, than when grown on PDB alone.

Keywords:

• Fatty acids
• fungal biomass
• carbon dioxide
• Trichoderma koningii
• Penicillium janthinellum
• fluorescence microscopy
• intracellular lipids