The evaluation of mixtures of yeast and potato extracts in growth media for biomass production of lactic cultures

Abstract

The effectiveness of yeast extracts (YE) and potato extracts (PE) to promote growth of seven lactic cultures was evaluated by automated spectrophotometry (AS). Two aspects of the growth curve were analysed: (1) maximum biomass obtained (using ODmax) and (2) highest specific growth rate mu(max)) Eleven lots from the same PE-manufacturing process were examined for lot-to-lot variability. The ODmax values of three of the seven strains were significantly affected by lot source, but mu(max) was not significantly affected. The growth of bacteria was systematically lower in base medium containing 100% PE than in base medium containing 100% YE for both ODmax or mu(max) data, which could be related to the lower content in nitrogen-based compounds in PE. In AS assays, highest OD values for Lactobacillus casei EQ28, Lactobacillus rhamnosus R-011, Lactobacillus plantarum EQ12, and Streptococcus thermophilus R-083 were obtained with a mixture of PE and YE. Fermentations (2 L) were also carried out to determine the accuracy of AS to predict biomass levels obtained under fermentation trials. In these fermentations, replacement of 50% YE with PE was shown to enable good growth of S. thermophilus. With L. rhamnosus R-011, a high correlation (R2 = 0.95) was found between ODmax data obtained in the AS assays and that of the 2-L bioreactor when the same growth medium was used for both series of fermentations. However, AS was not as efficient when industrial media were used for the bioreactor assays. The relationship was still good for ODmax between AS data and that of the bioreactor data with L. rhamnosus R-011 in industrial LBS medium (R2 = 0.87), but was very poor with the S. thermophilus R-083 on Rosell #43 industrial medium (R2 = 0.33). Since PE cost 40% less than YE, there are strong economic advantages in considering such a partial replacement of YE by PE.

Sweet Potatoes as a Basic Component in Developing a Medium for the Cultivation of Lactobacilli

“…[9][10][11] Hence several studies have been carried out to replace expensive nitrogen sources with ingredients at low cost such as food by-products or agricultural wastes. With this aim, whey and buttermilk, 12) de-lipidated egg yolk and yeast autolysate, 9) fish viscera, 8) cassava bagasse and sugarcane bagasse, 13) spent cabbage juice, 14) a mixture of yeast and potato extracts, 15) juice of pineapple peel, 16) and corn steep liquor 17) have been tested. The growth and functionality of Lactobacillus in the tested products were compared to that in standard lactobacilli MRS.…”

Optimization of Low-Cost Culture Media for the Production of Biomass and Bacteriocin by a Urogenital Lactobacillus salivarius Strain

“…However, other inexpensive nutrients can be used as ingredients of the fermentation medium, which could further reduce the cost of production. Several studies have replaced the expensive MRS medium for lactobacilli with supplemented whey permeate [11,32] or several carbon and nitrogen sources of vegetal origin, such as potato extracts [13], molasses, soy milk [34] and corn syrup [12]. Continuous control of pH has also been used to improve the growth and metabolite production of LAB [11,32].…”

Optimization of probiotic lactobacillus casei ATCC 334 production using date powder as carbon source

“…The optimum point medium investigated by Oh et al was found to be approximately twice more productive than the center-point medium, and more economical than the MRS medium [5]. The maximum biomass for L. casei EQ28, L. rhamnosus R-011, L. plantarum EQ12, and Streptococcus thermophilus R-083 was also obtained with a mixture of yeast and potato extracts [8]. Thus, through partial replacement of yeast extract with the less expensive 40 % potato extract, strong economical advantages could be observed.…”

“…The effectiveness of yeast extracts and potato extracts has been evaluated to promote the growth of lactic acid bacteria (LAB) such as L. casei EQ28, L. rhamnosus R-011, L. plantarum EQ12 and Streptococcus thermophilus R-083 by automated spectrophotometry [8]. The growth kinetics of several LAB (L. fermentum, L. reuteri, L. acidophilus and L. plantarum) that have potential to be used as probiotics in cereal-based substrates such as wheat, barley and malt have been reported [9].…”