Establishment of culture conditions for bio-transformation of R-(+)-limonene to limonene-1,2-diol by Colletotrichum nymphaeae CBMAI 0864

Abstract

Abstract Before reaching commercial scale, a biotechnological process must be well characterized in terms of process conditions. Thus, this study aimed to investigate the culture conditions in limonene bio-transformation to limonene-1,2-diol by Colletotrichum nymphaeae. The results revealed that this bio-process was aerobic, suggesting that aeration is an important parameter to be considered on a larger scale (e.g. bio-reactors). Moreover, a single feeding of R-(+)-limonene (15 g.L−1) at the start of the bio-transformation resulted in the highest concentration (4.19 g.L−1) and yield (27.9%, w. w−1) of limonene-1,2-diol, indicating that fed-batch operation was not a good choice. In terms of biomass age, 72 h-old biomass performed better when compared to 24 or 48 h-old biomasses. Substrate induction test suggested that this bio-transformation is carried out by non-inducible enzymes. Three successive freeze-thawing processes did not present any observable change in the production, indicating that the biomass could be stored frozen. It was also evidenced that the use of resting cells was as efficient as growing cells, and, therefore, biomass recovery/re-suspension was unnecessary. Although feasible, the bio-transformation in an aqueous-hexadecane biphasic system was not indicated for this process, since lower concentration of diol was obtained. These results are very important to guide scaled-up studies of this bio-transformation process.