Elsevier

Process Biochemistry

Volume 64, January 2018, Pages 9-15
Process Biochemistry

Solid state fermentation for the production of γ-decalactones by Yarrowia lipolytica

https://doi.org/10.1016/j.procbio.2017.10.004Get rights and content

Highlights

  • Novel alternative process to improve the production of lactones.

  • Biofilm-like Y. lipolytica on the solid support presents specific morphological and metabolic characteristics.

  • SSF reactor types for different aeration conditions.

  • Forced aeration in SSF mini-reactors resulted in the stripping of lactone compounds.

Abstract

The production of γ-decalactones as aroma compounds is highly dependent on the access of the biocatalyst to substrate and co-substrate (oxygen). In this work, the potential of solid state fermentation (SSF) is investigated for this production with Y. lipolytica W29. Luffa sponge was used as an inert support and the investigation focused on the impact of aeration on metabolites. In that goal, experiments were carried out in three different SSF reactor types, wide-mouth Erlenmeyer flask (static aeration), forced aeration mini-reactor, and small-headspace bottle (without aeration). Four lactones were detected by GC–MS during the degradation of ricinoleic acid from castor oil by Y. lipolytica W29: 3-hydroxy-γ-decalactone, which reached the high concentration of 5 g/L (in wide-mouth Erlenmeyer flask), γ-decalactone, dec-2-en-4-olide and dec-3-en-4-olide. In this study, some yeast cells changed their morphological properties from the yeast-like shape to pseudo-mycelium and mycelium. These cells may undergo a metabolic shift resulting in the high production of 3-hydroxy-γ-decalactone. The yield of lactone in the small-headspace bottle was very low suggesting insufficient oxygen availability. For their part, forced-aeration conditions in mini-reactors resulted in the stripping of lactone compounds. From the present work, an alternative process is proposed as a novel model for lactone production.

Introduction

Lactones are aroma compounds present naturally in many fruits and fermented foods. Their biotechnological synthesis comes from C18-hydroxylated fatty acids. Five lactones may be detected during the degradation of ricinoleic acid, by yeast cells: 5-hydroxy-ε-dodecalactone, γ-decalactone, 3-hydroxy-γ-decalactone, dec-2-en-4-olide and dec-3-en-4-olide [1], [2], [3] (the latter decalactones are shown in Fig. 1). During the peroxisomal β-oxidation of hydroxylated fatty acids by the yeast Y. lipolytica, which is considered as a model organism for the metabolism of hydrophobic compounds [38], the four γ-decalactones encountered above have been detected [2], [3], [4], [5].

The production of lactones in submerged cultures has been widely investigated, including the metabolic pathway and the improvement of the β-oxidation flux which has been studied on genetically modified yeast strains [6], [7], [8], [9], [10]. Some authors have focused on the effect of environmental condition changes by modifying pH, substrate concentration, inoculum density, or aeration to improve the production of active compounds [11], [12], [13], [14]. From their studies, oxygen availability appears to be a key parameter driving the extent of oxidation [11], [12], [13], [14], [15]. Interestingly, an airlift biofilm reactor explored by Escamilla-García et al. [13] led to the formation of adhering biofilms of Y. lipolytica and to the concomitant stimulation of the production of 3-hydroxy-γ-decalactone with a ten-fold concentration increase. These results drove us to get interested in a solid state fermentation (SSF) process which would allow the microorganisms to keep in tight contact with the substrate to be in a direct contact with the air oxygen. Y. lipolytica has been widely used in submerged cultures in large applications such as the production of lipases, organic acids and lactones. Only few research works have investigated SSF for production by this species and these papers were limited to the production of lipase [22], [23], [24], [25]. In recent years, SSF has greatly expanded its application to the production of various metabolites [16], [39], [40], [41], [42], [43], [44]. It was found that SSF has various advantages compared to submerged fermentation [17], [18], [19], [20], [21]. In our aim to produce lactone in SSF, by taking into account the oxygen availability as the main factor involving peroxisomal β-oxidation in lactone production, different aeration conditions will be studied. When the substrate structure does not enable microorganisms to grow in SSF, inert supports have to be used. In our study, different inert supports and substrate were selected for the first time to study the growth of Y. lipolytica and the production of γ-decalactones in SSF. Inert supports were used after impregnation with the liquid biotransformation medium containing castor oil as the substrate. The most efficient inert support or substrate for lactone production was selected for the study of the importance of oxygen in SSF. Experiments with three different conditions in SSF reactor types, wide-mouth Erlenmeyer flask (static aeration), forced aeration mini-reactor and small-headspace bottle (without aeration) have been carried out. An alternative system for lactone production by Y. lipolytica is proposed for the first time in this study.

Section snippets

Solid supports

Corncob, luffa sponge and cellulose sponge were used as the solid supports and castor seed was used as the substrate in this study. Corncob (Grits®, France) was used without any pretreatment. Luffa sponge was obtained from the dried fruit of Luffa free of seeds (Fig. 2) (origin Cambodia). It was cut into rectangular prism shape (approximately 1 cm by 1 cm by 0.5 cm). The pretreatment procedure was modified from Pazzetto et al. [26]: The rectangular prisms of luffa sponge were washed thoroughly

Static aeration using wide-mouth Erlenmeyer flasks

To investigate the potential of SSF for lactone production, supports such as cellulose sponge, corncob and luffa sponge, and castor seeds as a substrate were used. Y. lipolytica W29 grew well on all supports and on the substrate used. When using logistic differential equation for the growth study in different supports, the specific growth rates of Y. lipolytica on luffa sponge and cellulose sponge were not significantly different (approximately 0.12 h−1) with the maximum biomass concentration of

Discussion

It is the first study which emphasizes the SSF process in lactones production by Y. lipolytica. We have investigated an adaptation from submerged fermentation to SSF by using different solid supports and a substrate using wide-mouth Erlenmeyer flask (static aeration). In SSF for lactones production, it is necessary to use a higher yeast cells inoculum density compared to the submerged fermentation. This may result from the fact that, in SSF, microbial cells are generally fixed on the solid

Conclusion

A new system of lactone production in SSF using inert support impregnated with the biotransformation medium was studied for the first time in this work. Luffa sponge was found as an efficient solid support compared to the other support/substrate used. Different aeration conditions were also emphasized. Interestingly, the yield of 3-hydroxy-γ-decalactone was very high. This may be related to the morphological change of yeast cells during SSF. To gain a deeper understanding of cells morphological

Acknowledgments

It is a pleasure to acknowledge with gratitude the scholarship support of the French Embassy in Cambodia as well as an attribution of financial support from AUF (Agence Universitaire de la Francophonie). We are also thankful to C. Bernard-Rojas, G. Pescher, and B. N. Pham-Hoang, for technical help.

References (44)

  • T. Aggelopoulos et al.

    Solid state fermentation of food waste mixtures for single cell protein, aroma volatiles and fat production

    Food Chem.

    (2014)
  • H.H.M. Fadel et al.

    Characterization and evaluation of coconut aroma produced by Trichoderma viride EMCC-107 in solid state fermentation on sugarcane bagasse

    Electron. J. Biotechnol.

    (2015)
  • L. Thomas et al.

    Current developments in solid-state fermentation

    Biochem. Eng. J.

    (2013)
  • C.S. Farinas

    Developments in solid-state fermentation for the production of biomass-degrading enzymes for the bioenergy sector

    Renew. Sustain. Energy Rev.

    (2015)
  • M. Okui

    Metabolism of hydroxy fatty acids II. intermediates of the oxidative breakdown of ricinoleic acid by genus candida

    J. Biochem.

    (1963)
  • Y. Waché et al.

    Role of β-oxidation enzymes in γ-decalactone production by the yeast Yarrowia lipolytica

    Appl. Environ. Microbiol.

    (2001)
  • I. Gatfield et al.

    Some aspects of the microbiological production of flavor-active lactones with particular reference to γ-decalactone, chemie, mikrobiologie

    Technol. Lebensm.

    (1993)
  • Y. Waché et al.

    Catabolism of hydroxyacids and biotechnological production of lactones by Yarrowia lipolytica

    Appl. Microbiol. Biotechnol.

    (2003)
  • I.L. Gatfield

    Biotechnological production of natural flavor materials

  • Y. Pagot et al.

    Peroxisomal β-oxidation activities and γ-decalactone production by the yeast Yarrowia lipolytica

    Appl. Microbiol. Biotechnol.

    (1998)
  • H. Wang et al.

    Cloning and characterization of the peroxisomal acyl CoA oxidase ACO3 gene from the alkane-utilizing yeast Yarrowia lipolytica

    Yeast

    (1998)
  • Y. Waché et al.

    Involvement of acyl coenzyme a oxidase isozymes in biotransformation of methyl ricinoleate into γ-Decalactone by Yarrowia lipolytica

    Appl. Environ. Microbiol.

    (2000)
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