Fermentation Titer Optimization and Impact on Energy and Water Consumption during Downstream Processing

Abstract

A common focus of fermentation process optimization is the product titer. Different strategies to boost fermentation titer target whole‐cell biocatalyst selection, process control, and medium composition. Working at higher product concentrations reduces the water that needs to be removed in the case of aqueous systems and, therefore, lowers the cost of downstream separation and purification. Different approaches to achieve higher titer in fermentation are examined. Energy and water consumption data collected from different Cargill fermentation plants, i.e., ethanol, lactic acid, and 2‐keto‐L‐gulonic acid, confirm that improvements in fermentation titer play a decisive role in downstream economics and environmental footprint.

Engineered Production of Isobutanol from Sugarcane Trash Hydrolysates in Pichia pastoris

“…Notably, the isobutanol titers produced by our engineered strains PPY0311 and PPY0312 using sugarcane trash hydrolysates remain well below the grams/liter level obtained when using pure glucose as the carbon source described in our earlier work [ 14 , 15 ]. While product titers can typically be improved by increasing the amount of carbon source in the fermentation medium (though only to a certain point and product yield might be adversely affected) [ 32 ], in our case, however, increasing the concentration of sugarcane trash hydrolysates also means letting in higher concentrations of the toxic pretreatment inhibitors which would be detrimental to yeast growth. As such, we posit that our engineered strains would most benefit from increased tolerance to pretreatment inhibitors.…”

Up-concentration of succinic acid, lactic acid, and ethanol fermentations broths by forward osmosis

“…For instance, significant improvements in Cargill´s lactic production facility have been achieved in terms of water consumption. Boost in lactic acid titer by 19.7% resulted in an overall abatement in water consumption of 21% [52].…”

“…might lead to ≥ 160 g L -1 . Current fermentation yields and product titers greatly depend on the bacterial strains employed and the fermentation process conditions [52]. For example, Srivastava et al [54] were able to obtain a lactic acid concentration of 84.5 g L -1 from cane molasses with Lactobacillus delbrueckii NCIM 2025 strain, during 12 h fermentation.…”

Candida glabrata Yap6 Recruits Med2 To Alter Glycerophospholipid Composition and Develop Acid pH Stress Resistance

“…Although exogenous addition of alkaline reagents, such as NaOH and CaCO 3 , helps stabilizing the correct working pH, it increases the osmotic pressure and the cost of downstream separation and purification (6). Therefore, it is urgent to find efficient on November 1, 2020 by guest http://aem.asm.org/ Downloaded from strategies to improve the tolerance of C. glabrata to complex industrial environment conditions.…”

“…However, during the production, the accumulation of extracellular acids considerably decreases the pH of the fermentation broth, thereby inhibiting cell growth and ultimately reducing the production of the target acid ( 5 ). Although exogenous addition of alkaline reagents, such as NaOH and CaCO 3 , helps stabilize the correct working pH, it increases the osmotic pressure and the cost of downstream separation and purification ( 6 ). Therefore, it is urgent to find efficient strategies to improve the tolerance of C. glabrata to complex industrial environmental conditions.…”