Yeast screening and cell immobilization on inert supports for ethanol production from cheese whey permeate with high lactose loads

Abstract

Eight yeast strains of the genera Saccharomyces and Kluyveromyces were screened to ferment high lactose-load cheese whey permeate (CWP) (>130 g/L lactose) without nutrient supplementation. The fermentation conditions (temperature, pH and time) were optimized to maximize the fermentation performance (ethanol titer, ethanol yield and lactose consumption) for the two preselected strains, K. marxianus DSM 5422 and S. cerevisiae Ethanol Red, using a response surface methodology (RSM). Under optimized conditions, K. marxianus DSM 5422 attained ethanol titers of 6% (v/v) in only 44 h. Moreover, the feasibility of immobilizing this strain on four different inorganic supports (plastic, glass and Tygon silicone Raschig rings and alumina beads) was assessed. Glass Raschig rings and alumina beads showed a more stable performance over time, yielding ethanol titers of 60 g/L during 1,000 hours, which remarkably reduces yeast cultivation costs. Results demonstrate the feasibility of using CWP for successful ethanol production in a simple and economical process, which represents an attractive alternative for waste treatment in dairy industries.

Integrated Process for Bioenergy Production and Water Recycling in the Dairy Industry: Selection of Kluyveromyces Strains for Direct Conversion of Concentrated Lactose-Rich Streams into Bioethanol

“…In the NF retentate, under mild oxygen-limiting conditions, the strain was unable to exhaust lactose (30% of lactose remains in the medium at 120 h fermentation). It is important to note that the ethanol yield and productivity values determined in our study for the reference strain K. marxianus CBS 397 are similar to those reported by other researchers for fermentations with this strain in synthetic medium with 200 g/L lactose and 0.2 vvm aeration (0.43 g/g and 2.12 g/L/h, respectively) [38], and in concentrated whey powder (0.44 g/g and 1.3 g/L/h, respectively) [27]. Comparable parameters were also reported for fermentation of cheese whey, despite the lower lactose content (50 to 59 g/L) [28,39].…”

“…To study the ability of Kluyveromyces strains to directly use NF and RO retentates as a substrate for ethanol production (without supplementation), the following ten lactose-fermenting strains were selected from a yeast culture collection (PYCC): five K. marxianus strains and five K. lactis strains (Table 1). The K. marxianus CBS 397 (PYCC 3884) strain was expressly included in this screening for benchmarking, as this strain has been often described as one of the best lactose-fermenting yeasts, both in terms of ethanol production rate and maximum ethanol titer [27,28,29,30].…”

Jamaican Domestic Ethanol Fuel Feasibility and Benefits Analysis

“…If we assume that between 5% and 10% of milk consumption in the country is used for cheese production, between 429,000 kg and 857,000 kg of cheese is produced in Jamaica annually. About 10 liters of cheese whey are generated for each kg of cheese manufactured; thus, the amount of cheese whey in the country could be in the range of 4.3 and 8.6 million liters per year (Díez-Antolínez et al 2018). Lactose content in cheese whey is about 0.05 kg/liter, on average, thus between 215,000 kg and 430,000 kg of lactose could be generated annually (Koushki 2012).…”

Lignocellulosic ethanol production: Evaluation of new approaches, cell immobilization and reactor configurations

“…Similarly, Diez-Antolinez et.al (2018) screened different yeast and immobilization materials for ethanol production from cheese whey permeate. They reported that Glass Rasching rings and alumina beads showed stable performance over 1,000 hours, yielding ethanol titers of 60 g/L, which substantially reduced yeast cultivation costs (Diez-Antolinez, et al, 2018). The economic benefits associated with cell immobilization and recycling, such as increased yields and productivities and lower capital costs due to shorter residence times should encourage researchers to do further, detailed techno-economic analyses.…”