Camelina sativa meal hydrolysate as sustainable biomass for the production of carotenoids by Rhodosporidium toruloides

Stefano Bertacchi,Paola Branduardi,Danilo Porro,Maurizio Bettiga

doi:10.1186/s13068-020-01682-3

Stefano Bertacchi, Paola Branduardi + Show 2 more

Open Access

https://doi.org/10.1186/s13068-020-01682-3

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Abstract

BackgroundAs the circular economy advocates a near total waste reduction, the industry has shown an increased interest toward the exploitation of various residual biomasses. The origin and availability of biomass used as feedstock strongly affect the sustainability of biorefineries, where it is converted in energy and chemicals. Here, we explored the valorization of Camelina meal, the leftover residue from Camelina sativa oil extraction. In fact, in addition to Camelina meal use as animal feed, there is an increasing interest in further valorizing its macromolecular content or its nutritional value.ResultsCamelina meal hydrolysates were used as nutrient and energy sources for the fermentation of the carotenoid-producing yeast Rhodosporidium toruloides in shake flasks. Total acid hydrolysis revealed that carbohydrates accounted for a maximum of 31 ± 1.0% of Camelina meal. However, because acid hydrolysis is not optimal for subsequent microbial fermentation, an enzymatic hydrolysis protocol was assessed, yielding a maximum sugar recovery of 53.3%. Separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and SSF preceded by presaccharification of Camelina meal hydrolysate produced 5 ± 0.7, 16 ± 1.9, and 13 ± 2.6 mg/L of carotenoids, respectively. Importantly, the presence of water-insoluble solids, which normally inhibit microbial growth, correlated with a higher titer of carotenoids, suggesting that the latter could act as scavengers.ConclusionsThis study paves the way for the exploitation of Camelina meal as feedstock in biorefinery processes. The process under development provides an example of how different final products can be obtained from this side stream, such as pure carotenoids and carotenoid-enriched Camelina meal, can potentially increase the initial value of the source material. The obtained data will help assess the feasibility of using Camelina meal to generate high value-added products.

Highlights

As the circular economy advocates a near total waste reduction, the industry has shown an increased interest toward the exploitation of various residual biomasses
Here, we demonstrate that Camelina meal could be employed as residual biomass for the development of novel biorefineries based on microbial cell factories
This biomass was provided to the oleaginous yeast R. toruloides as a sole nutrient and energy source, and carotenoids production was assessed

Summary

Introduction

As the circular economy advocates a near total waste reduction, the industry has shown an increased interest toward the exploitation of various residual biomasses. The existing linear economy’s logic of “take, make, dispose” is generating a large amount of waste, including organic matter For these reasons, biorefineries based on residual biomasses have drawn increasing scientific and industrial interest. Microbial cell factories are especially attractive; conventional pretreatments and saccharification processes of residual biomasses often release toxic compounds that can impair microbial growth and synthesis of the target product [2]. These issues need to be factored in when developing robust biorefineries capable of generating high-value molecules from low-cost substrates

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