Mussel processing wastewater: a low-cost substrate for the production of astaxanthin by Xanthophyllomyces dendrorhous.

Isabel Rodríguez Amado,José Antonio Vázquez

doi:10.1186/s12934-015-0375-5

Isabel Rodríguez Amado, José Antonio Vázquez

Open Access

https://doi.org/10.1186/s12934-015-0375-5

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Abstract

BackgroundThe use of astaxanthin in different industries such as the chemical, pharmaceutical, food, animal feed and cosmetic has been receiving increasing attention in recent years. Natural supplies of the pigment include crustacean by-products, algal, and microbial cultivation, being the yeast Xanthophyllomyces dendrorhous together with the alga Haematococcus pluvialis the most promising microorganisms for this bioproduction. Different vegetable by-products of the food industry have been explored so far as low-cost substrates for the production of astaxanthin by X. dendrorhous. This study focuses for the first time on the use of a low-cost formulated medium from a marine by-product, mussel-processing wastewater, for the production of astaxanthin by the yeast X. dendrorhous.ResultsThe yeast was able to grow in non-saccharified mussel broth, revealing the ability of the microorganism to hydrolyze glycogen. However, partial glycogen saccharification with α-amylase was needed for astaxanthin biosynthesis, obtaining maximal productions of 22.5–26.0 mg/L towards the end of the culture and coinciding with yeast highest amylolytic activity. Cultivations in totally-saccharified media revealed an increase in maximal cell concentrations and a decrease in maximal growth rates and astaxanthin production with increasing glucose initial concentration.ConclusionsAstaxanthin production was higher in partially-saccharified mussel-processing waste than in synthetic medium (yeast peptone dextrose) containing glucose as carbon source (13 mg/L), suggesting this by-product is a promising nutritive medium for astaxanthin production. The use of this effluent also contributes towards the recycling and depuration of this highly pollutant effluent.

Highlights

The use of astaxanthin in different industries such as the chemical, pharmaceutical, food, animal feed and cosmetic has been receiving increasing attention in recent years
The synthesis of astaxanthin by several yeast species belonging to the genera Rhodotorula and Phaffia, and by the microalgae Chlorella zofingiensis, Chlorococcum sp. and Haematococcus pluvialis has led to consider these microorganisms as potential pigment sources [5]
Selection of astaxanthin‐producing strain Astaxanthin-producing strains CECT 1690, CECT 11028 and ATCC 74219 were screened in Yeast Peptone Dextrose (YPD) and Yeast Complex Medium (YCM, Table 1)

Summary

Results

The yeast was able to grow in non-saccharified mussel broth, revealing the ability of the microorganism to hydrolyze glycogen. Partial glycogen saccharification with α-amylase was needed for astaxanthin biosynthesis, obtaining maximal productions of 22.5–26.0 mg/L towards the end of the culture and coinciding with yeast highest amylolytic activity. Cultivations in totally-saccharified media revealed an increase in maximal cell concentrations and a decrease in maximal growth rates and astaxanthin production with increasing glucose initial concentration

Conclusions

Background

Results and discussion

Methods