Sunday, February 3, 2013

POTASSIUM REMOVAL FROM DISTILLERY SLOPS BY CANDIDA UTILISPROPAGATION


By
M.A. OTERO-RAMBLA, O.A. ALMAZAN-DEL OLMO, DANIEL BELLO-GIL, 
GUSTAVO SAURA-LARIA and JULIO A. MARTINEZ-VALDIVIESO 
Biotechnology Division, Cuban Institute for Research on Sugarcane By-Products (ICIDCA)
Vía Blanca # 804 and Carretera Central, 11000 Havana, Cuba
miguel.otero@icidca.edu.cu

KEYWORDS: Distillery Slops Decontamination,
Single Cell Protein, Feed Protein, Potassium Removal
.
Abstract 

YEASTSaccumulate varied amounts of most of the minerals present in their growth media.
Much of the 7.5–8.1% ash found in the yeast grown for baking or harvested from beer is
potassium phosphate, but yeast has the ability to accumulate other ions provided (but not
necessarily needed) in high concentration. Distillery slops still contain about 70% of all potassium contributed to the soil in cane fields as chemical fertiliser, thus fertigation with these wastewaters has to be carefully
calculated since otherwise soil salinisation can occur.
When grown in a medium composed of distillery slops, nutrient salts (ammonium
phosphate and sulfates) and a microbial growth enhancer Candida utilisshows a great
resistance to potassium concentration in continuous culture.
Yeast cells were propagated under the above conditions with increasing amounts of
K2O from 2.5 g/L concentration (distillery slops from molasses fermentation) up to 25 g/Lin propagation medium. Specific growth rate (µmax) ranged from 0.32 to 0.28 h–1 for the extreme values
mentioned above, while biomass-substrate yield coefficients were 0.23 to 0.18.
These results suggest that yeast propagated on supplemented distillery slops could
significantly reduce the potassium content of these wastes making them more suitable for
irrigation purposes. According to the nutritional assessment reported, the potassium accumulated has no
deleterious effect on animal health.

Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010

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