Effective ethanol production from whey powder through immobilizedE. coliexpressingVitreoscillahemoglobin

Abstract

Ethanol production from whey powder was investigated by using free as well as alginate immobilized E. coli and E. coli expressing Vitreoscilla hemoglobin (VHb) in both shake flask and fermenter cultures. Media with varying levels of whey (lactose contents of 3%, 5%, 8% or 15%) and yeast extract (0.3% or 0.5%) were evaluated with fermentation times of 48-96 h. Immobilization and VHb expression resulted in higher ethanol production with all media; the increases ranged from 2% to 89% for immobilization and from 2% to 182% for VHb expression. It was determined that growth medium containing 8% lactose with 0.5% yeast extract yielded the highest ethanol production for free or immobilized strains, with or without VHb expression, in both shake flask and fermenter cultures. Immobilization with alginate was found to be a promising process for ethanol production by VHb-expressing ethanologenic E. coli.

Repeated batch fermentation of immobilizedE. coliexpressingVitreoscillahemoglobin for long-term use

“…18 Briefly 6 % (w/v) alginate solution was prepared using sodium alginate powder (Sigma Aldrich, United Kingdom), sterilized by exposure to UV light for 30 min and diluted with sterilized distilled water.…”

“…33 Recently immobilization of strain TS3 was found to add an additional advantage to that afforded by VHb expression. 18 The purpose of the work reported here was to expand upon our previous work 18 and develop an efficient, reusable process for producing ethanol from whey powder containing medium using alginate immobilized strain TS3. It was found that the immobilized cells could be reused or stored for fairly extended times and retain both their ethanol producing ability and the increase in ethanol production coincident with VHb expression.…”

“…7,8,18 Efficient ethanol production is important from an economic viewpoint. For example, ethanologenic Escherichia coli strain FBR5 has advantages over yeast as a fermenting organism, since it is able to use various sugars to produce ethanol as the only end product from fermentation.…”

“…14,15 One such methodology, immobilization of microorganims, has been studied extensively in recent years. [16][17][18] It has been shown that the immobilization of ethanologenic microorganisms offers many advantages over planktonic cell cultures. These include easy separation of product from the growth medium, elimination of the need for a fresh inoculum for each batch, reuse of microorganisms for several cycles, enhanced productivity, lowered contamination risks, and enhanced stability of the ethanologenic strains.…”

Efecto de la relación leche-lactosuero sobre las propiedades fisicoquímicas y reológicas en una bebida láctea fermentada

“…Due to the high volume of whey production, about 180-190 million metric tons per year, traditionally much of the whey has been discharged into water sources such as rivers and seas and in other cases has been used on agricultural land as fertilizer (4)(5)(6)(7). However, as it is well known, the whey is one of the currents of food sector that major environmental problems generates when is poured both in water and on land due to its high biological oxygen demand (BOD) (> 35000 ppm) and high chemical oxygen demand (COD) (> 60000 ppm) (8)(9)(10).…”