Biochemical Engineering Journal 27 (2006) 295–298 Short communication Ethanol production from crude whey by Kluyveromyces marxianus Salman Zafar, Mohammad Owais ∗ Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India Received 25 January 2005; received in revised form 31 May 2005; accepted 31 May 2005 Abstract Kluyveromyces marxianus strain MTCC 1288 was employed to study the batch kinetics of ethanol and biomass production from crude whey. The yeast was able to metabolize most of the lactose within 22 h to give 2.10 g L -1 ethanol and 8.9 g L -1 biomass. The growth rate reached the peak value of 0.157 h -1 during the exponential phase but decreased significantly after the fermentation time of 12 h, presumably due to product inhibition. The specific ethanol formation rate attained the maximum value of 0.046 h -1 between 6 and 8 h of batch fermentation. The relationship between ethanol concentration and specific growth rate suggested a strong inhibitory effect of ethanol on the specific culture growth rate. © 2005 Published by Elsevier B.V. Keywords: Fermentation; Whey; Ethanol; Batch kinetics; Biomass 1. Introduction Cheese whey represents an important source of environ- mental pollution due to its enormous global production rate (to make 1 kg of cheese, 9 kg whey is generated) and high organic matter content, exhibiting the BOD and COD val- ues of 50 and 80 g L -1 , respectively [9]. One of the most attractive options to check the proliferation of whey pollution is its bioconversion to ethanol employing yeast, especially Kluyveromyces species. The presence of lactose as the only fermentable carbohydrate in whey confines its use to selective fermentations involving microorganisms which are capable of breaking down lactose with the enzyme, -galactosidase [2–4]. Apart from lactose, whey also contains vitamins and minerals which may improve the physiological activity of the cells. Ethanol has tremendous applications in chemical, phar- maceutical and food industries in the form of raw material, solvent and fuel. The annual production of industrial ethanol is about four million tonnes, 80% of which is produced by fer- mentation. It is very important to choose a strain with suitable ∗ Corresponding author. Tel.: +91 571 2404025; fax: +91 571 2721776. E-mail address: owais lakhnawi@rediffmail.com (M. Owais). physiological characteristics to achieve a good utilization of lactose from whey. The main aspect of this investigation is to study the forma- tion of ethanol from crude whey with Kluyveromyces marx- ianus leading to maximum lactose utilization and ethanol. Although a great deal of research has been accomplished with the cultures of the yeast strains, such as K. marxianus, Kluyveromyces lactis, Kluyveromyces fragilis, Candida pseu- dotropicalis, Candida intermedia and Torula cremoris on deproteinized whey [1,2,4,7,8], the use of crude whey as a culture media has not been explored in a comprehensive manner. 2. Materials and methods 2.1. Culture medium Crude (non-deproteinized, non-diluted and non-sterilized) whey was used as a culture medium. It contained 3.45% lactose and was fortified with 0.45% (NH 4 ) 3 SO 4 , 0.1% yeast extract, 0.1% malt extract and with a trace element solution containing: CuSO 4 ·5H 2 O, 0.3 mL L -1 ; MnSO 4 ·H 2 O, 0.8 mL L -1 ; MoO 4 ·2H 2 O, 0.4 mL L -1 ; ZnSO 4 ·7H 2 O, 1369-703X/$ – see front matter © 2005 Published by Elsevier B.V. doi:10.1016/j.bej.2005.05.009