Production of acetone butanol (AB) from liquefied corn starch,a commercial substrate,using <Emphasis Type="Italic">Clostridium beijerinckii</Emphasis> coupled with product recovery by gas stripping

A potential industrial substrate (liquefied corn starch; LCS) has been employed for successful acetone butanol ethanol (ABE) production. Fermentation of LCS (60 g l⁻¹) in a batch process resulted in the production of 18.4 g l⁻¹ ABE, comparable to glucose: yeast extract based medium (control experiment, 18.6 g l⁻¹ ABE). A batch fermentation of LCS integrated with product recovery resulted in 92% utilization of sugars present in the feed. When ABE was recovered by gas stripping (to relieve inhibition) from the fed-batch reactor fed with saccharified liquefied cornstarch (SLCS), 81.3 g l⁻¹ ABE was produced compared to 18.6 g l⁻¹ (control). In this integrated system, 225.8 g l⁻¹ SLCS sugar (487 % of control) was consumed. In the absence of product removal, it is not possible for C. beijerinckii BA101 to utilize more than 46 g l⁻¹ glucose. A combination of fermentation of this novel substrate (LCS) to butanol together with product recovery by gas stripping may economically benefit this fermentation. Mention of trade names of commercial products in this article/publication is solely for the purpose of providing scientific information and does not imply recommendation or endorsement by the United States Department of Agriculture.     

Recent advances in ABE fermentation: hyper-butanol producing Clostridium beijerinckii BA101

This is an overview of the mutant strain Clostridium beijerinckii BA101 which produces solvents (acetone–butanol–ethanol, ABE) at elevated levels. This organism expresses high levels of amylases when grown on starch. C. beijerinckii BA101 hydrolyzes starch effectively and produces solvent in the concentration range of 27–29 g l⁻¹. C. beijerinckii BA101 has been characterized for both substrate and butanol inhibition. Supplementing the fermentation medium (MP2) with sodium acetate enhances solvent production to 33 g l⁻¹. The results of studies utilizing commercial fermentation medium and pilot plant-scale reactors are consistent with the results using small-scale reactors. Pervaporation, a technique to recover solvents, has been applied to fed-batch reactors containing C. beijerinckii BA101, and solvent production as high as 165 g l⁻¹ has been achieved. Immobilization of C. beijerinckii BA101 by adsorption and use in a continuous reactor resulted in reactor productivity of 15.8 g l⁻¹ h⁻¹. Recent economic studies employing C. beijerinckii BA101 suggested that butanol can be produced at US$0.20–0.25 lb⁻¹ by employing batch fermentation and distillative recovery. Application of new technologies such as pervaporation, fed-batch culture, and immobilized cell reactors is expected to further reduce these prices. Journal of Industrial Microbiology & Biotechnology (2001) 27, 287–291. Received 12 September 2000/ Accepted in revised form 27 January 2001     

Soy molasses as fermentation substrate for production of butanol using Clostridium beijerinckii BA101

Spray-dried soy molasses (SDSM) contains the sugars dextrose, sucrose, fructose, pinitol, raffinose, verbascose, melibiose, and stachyose. Of the 746 g kg⁻¹ total sugars in SDSM, 434 g kg⁻¹ is fermentable using Clostridium beijerinckii BA101. SDSM was used to produce acetone, butanol, and ethanol (ABE) by C. beijerinckii BA101 in batch cultures. Using 80 g l⁻¹ SDSM, 10.7 g l⁻¹ ABE was produced in P2 medium. Higher concentrations of SDSM resulted in poor solvent production due to the presence of excessive salt and inhibitory components. C. beijerinckii BA101 in SDSM at 80 g l⁻¹ concentration produced 22.8 g l⁻¹ ABE when supplemented with 25.3 g l⁻¹ glucose. SDSM contains 57.4 g kg⁻¹ mineral ash and 2% tri-calcium phosphate. Tri-calcium phosphate up to 43.1 g l⁻¹ was not inhibitory and at a tri-calcium phosphate concentration of 28.8 g l⁻¹, the culture produced more solvents (30.1 g l⁻¹) than the control experiment (23.8 g l⁻¹). In contrast, sodium chloride was a strong inhibitor of C. beijerinckii BA101 cell growth. At a concentration of 10 g l⁻¹ sodium chloride, a maximum cell concentration of 0.6 g l⁻¹ was achieved compared to 1.7 g l⁻¹ in the control experiment. The effects of two salts on specific growth rate constant (μ) and specific rate of ABE production (ν) for C. beijerinckii BA101 were examined. Journal of Industrial Microbiology & Biotechnology (2001) 26, 290–295. Received 20 September 2000/ Accepted in revised form 16 February 2001     

Improvement in lactic acid production from starch using α-amylase-secreting <Emphasis Type="Italic">Lactococcus lactis</Emphasis> cells adapted to maltose or starch

To achieve direct and efficient lactic acid production from starch, a genetically modified Lactococcus lactis IL 1403 secreting α-amylase, which was obtained from Streptococcus bovis 148, was constructed. Using this strain, the fermentation of soluble starch was achieved, although its rate was far from efficient (0.09 g l⁻¹ h⁻¹ lactate). High-performance liquid chromatography revealed that maltose accumulated during fermentation, and this was thought to lead to inefficient fermentation. To accelerate maltose consumption, starch fermentation was examined using L. lactis cells adapted to maltose instead of glucose. This led to a decrease in the amount of maltose accumulation in the culture, and, as a result, a more rapid fermentation was accomplished (1.31 g l⁻¹ h⁻¹ lactate). Maximum volumetric lactate productivity was further increased (1.57 g l⁻¹ h⁻¹ lactate) using cells adapted to starch, and a high yield of lactate (0.89 g of lactate per gram of consumed sugar) of high optical purity (99.2% of l-lactate) was achieved. In this study, we propose a new approach to lactate production by α-amylase-secreting L. lactis that allows efficient fermentation from starch using cells adapted to maltose or starch before fermentation.     

Lactic acid production from cellulosic waste by immobilized cells of Lactobacillus delbrueckii

Industrial waste corn cob residue (from xylose manufacturing) without pretreatment was hydrolyzed by cellulase and cellobiase. The cellulosic hydrolysate contained 52.4 g l⁻¹ of glucose and was used as carbon source for lactic acid fermentation by cells of Lactobacillus delbrueckii ZU-S2 immobilized in calcium alginate gel beads. The final concentration of lactic acid and the yield of lactic acid from glucose were 48.7 g l⁻¹ and 95.2%, respectively, which were comparative to the results of pure glucose fermentation. The immobilized cells were quite stable and reusable, and the average yield of lactic acid from glucose in the hydrolysate was 95.0% in 12 repeated batches of fermentation. The suitable dilution rate of continuous fermentation process was 0.13 h⁻¹, and the yield of lactic acid from glucose and the productivity were 92.4% and 5.746 g l⁻¹ h⁻¹, respectively. The production of lactic acid by simultaneous saccharification and fermentation (SSF) process was carried out in a coupling bioreactor, the final concentration of lactic acid was 55.6 g l⁻¹, the conversion efficiency of lactic acid from cellulose was 91.3% and the productivity was 0.927 g l⁻¹ h⁻¹. By using fed-batch technique in the SSF process, the final concentration of lactic acid and the productivity increased to 107.6 g l⁻¹ and 1.345 g l⁻¹ h⁻¹, respectively, while the dosage of cellulase per gram substrate decreased greatly. This research work should advance the bioconversion of renewable cellulosic resources and reduce environmental pollution.     

Pullulan content of the ethanol precipitate from fermented agro-industrial wastes

Ethanol-precipitated substances after fermentation of various agro-industrial wastes by Aureobasidium pullulans were examined for their pullulan content. Grape skin pulp extract, starch waste, olive oil waste effluents and molasses served as substrates for the fermentation. A glucose-based defined medium was used for comparison purposes. Samples were analysed by an enzyme-coupled assay method and by high-performance anion-exchange chromatography with pulsed amperometric detection after enzymic hydrolysis with pullulanase. Fermentation of grape skin pulp extract gave 22.3 g l⁻¹ ethanol precipitate, which was relatively pure pullulan (97.4% w/w) as assessed by the coupled-enzyme assay. Hydrolysed starch gave only 12.9 g l⁻¹ ethanol precipitate, which increased to 30.8 g l⁻¹ when the medium was supplemented with NH₄NO₃ and K₂HPO₄; this again was relatively pure pullulan (88.6% w/w). Molasses and olive oil wastes produced heterogeneous ethanol-precipitated substances containing small amounts of pullulan, even when supplemented with nitrogen and phosphate. Overall, grape skin pulp should be considered as the best substrate for pullulan production. Starch waste requires several hydrolyis steps to provide a usable carbon source, which reduces its economic attraction as an industrial process. Received: 24 October 1997 / Received revision: 10 February 1998 / Accepted: 15 February 1998     

Butanol production by Clostridium beijerinckii ATCC 55025 from wheat bran

Wheat bran, a by-product of the wheat milling industry, consists mainly of hemicellulose, starch and protein. In this study, the hydrolysate of wheat bran pretreated with dilute sulfuric acid was used as a substrate to produce ABE (acetone, butanol and ethanol) using Clostridium beijerinckii ATCC 55025. The wheat bran hydrolysate contained 53.1 g/l total reducing sugars, including 21.3 g/l of glucose, 17.4 g/l of xylose and 10.6 g/l of arabinose. C. beijerinckii ATCC 55025 can utilize hexose and pentose simultaneously in the hydrolysate to produce ABE. After 72 h of fermentation, the total ABE in the system was 11.8 g/l, of which acetone, butanol and ethanol were 2.2, 8.8 and 0.8 g/l, respectively. The fermentation resulted in an ABE yield of 0.32 and productivity of 0.16 g l⁻¹ h⁻¹. This study suggests that wheat bran can be a potential renewable resource for ABE fermentation.     

Batch and repeated batch production of l(+)-lactic acid by Enterococcus faecalis RKY1 using wood hydrolyzate and corn steep liquor

Lactic acid production was investigated for batch and repeated batch cultures of Enterococcus faecalis RKY1, using wood hydrolyzate and corn steep liquor. When wood hydrolyzate (equivalent to 50 g l⁻¹ glucose) supplemented with 15–60 g l⁻¹ corn steep liquor was used as a raw material for fermentation, up to 48.6 g l⁻¹ of lactic acid was produced with, volumetric productivities ranging between 0.8 and 1.4 g l⁻¹ h⁻¹. When a medium containing wood hydrolyzate and 15 g l⁻¹ corn steep liquor was supplemented with 1.5 g l⁻¹ yeast extract, we observed 1.9-fold and 1.6-fold increases in lactic acid productivity and cell growth, respectively. In this case, the nitrogen source cost for producing 1 kg lactic acid can be reduced to 23% of that for fermentation from wood hydrolyzate using 15 g l⁻¹ yeast extract as a single nitrogen source. In addition, lactic acid productivity could be maximized by conducting a cell-recycle repeated batch culture of E. faecalis RKY1. The maximum productivity for this process was determined to be 4.0 g l⁻¹ h⁻¹.     

Optimization of polyhydroxybutyrate production by <Emphasis Type="Italic">Bacillus</Emphasis> sp. CFR 256 with corn steep liquor as a nitrogen source

Polyhydroxyalkanotes (PHAs), the eco-friendly biopolymers produced by many bacteria, are gaining importance in curtailing the environmental pollution by replacing the non-biodegradable plastics derived from petroleum. The present study was carried out to economize the polyhydroxybutyrate (PHB) production by optimizing the fermentation medium using corn steep liquor (CSL), a by-product of starch processing industry, as a cheap nitrogen source, by Bacillus sp. CFR 256. Response surface methodology (RSM) was used to optimize the fermentation medium using the variables such as corn steep liquor (5–25 g l⁻¹), Na₂HPO₄ 2H₂O (2.2–6.2 g l⁻¹), KH₂PO₄ (0.5–2.5 g l⁻¹), sucrose (5–55 g l⁻¹) and inoculum concentration (1–25 ml l⁻¹). Central composite rotatable design (CCRD) experiments were carried out to study the complex interactions of the variables. The optimum conditions for maximum PHB production were (g l⁻¹): CSL-25, Na₂HPO₄ 2H₂O-2.2, KH₂PO₄ − 0.5, sucrose − 55 and inoculum − 10 (ml l⁻¹). After 72 h of fermentation, the amount of PHA produced was 8.20 g l⁻¹ (51.20% of dry cell biomass). It is the first report on optimization of fermentation medium using CSL as a nitrogen source, for PHB production by Bacillus sp.     

Butanol production by Clostridium beijerinckii BA101 using cassava flour as fermentation substrate: enzymatic versus chemical pretreatments

Cassava flour (CF), a cost-effective source of starch, was employed as a substrate for successful acetone-butanol-ethanol (ABE) production by batch-fermentation with Clostridium beijerinckii. The effect of temperature, initial concentration of CF and chemical/enzymatic hydrolysis were studied in a 2³ factorial design. Results revealed that temperature and initial concentration of substrate exert a significant effect on ABE production, as well as interactions of temperature with the other variables. Solvent production was maximized when working at 40°C, 60 g l⁻¹ CF and enzymatic pretreatment. An average of 31.38 g l⁻¹ ABE was produced after 96 h, with a productivity of 0.33 g l⁻¹ h⁻¹. A posterior randomized block design (3 × 2) showed that enzymatic hydrolysis (with saccharification periods of 6 h at 60°C) enhances both reducing sugar and solvent production if compared to chemical pretreatments. Average ABE production in this case was 27.28 g l⁻¹, with a productivity of 0.28 g l⁻¹ h⁻¹. Results suggest that CF may be a suitable substrate for industrial ABE production.     

Ethanol production from hydrolysed agricultural wastes using mixed culture of <Emphasis Type="Italic">Zymomonas mobilis</Emphasis> and <Emphasis Type="Italic">Candida tropicalis</Emphasis>

Acid, alkaline and enzymatic hydrolysis of agricultural crop wastes were compared for yields of total reducing sugars with the hydrolysates being evaluated for ethanol production using a mixed culture of Zymomonas mobilis and Candida tropicalis. Acid hydrolysis of fruit and vegetable residues gave 49–84 g reducing sugars l⁻¹ and 29–32 g ethanol l⁻¹ was then obtained. Alkaline hydrolysis did not give significant amount of reducing sugars. Enzymatic hydrolysis of fruit and vegetable residues yielded 36–123 g reducing sugars l⁻¹ and 11–54 g ethanol l⁻¹.     

Butanol production from wheat straw hydrolysate using <Emphasis Type="Italic">Clostridium beijerinckii</Emphasis>

In these studies, butanol (acetone butanol ethanol or ABE) was produced from wheat straw hydrolysate (WSH) in batch cultures using Clostridium beijerinckii P260. In control fermentation 48.9 g L⁻¹ glucose (initial sugar 62.0 g L⁻¹) was used to produce 20.1 g L⁻¹ ABE with a productivity and yield of 0.28 g L⁻¹ h⁻¹ and 0.41, respectively. In a similar experiment where WSH (60.2 g L⁻¹ total sugars obtained from hydrolysis of 86 g L⁻¹ wheat straw) was used, the culture produced 25.0 g L⁻¹ ABE with a productivity and yield of 0.60 g L⁻¹ h⁻¹ and 0.42, respectively. These results are superior to the control experiment and productivity was improved by 214%. When WSH was supplemented with 35 g L⁻¹ glucose, a reactor productivity was improved to 0.63 g L⁻¹ h⁻¹ with a yield of 0.42. In this case, ABE concentration in the broth was 28.2 g L⁻¹. When WSH was supplemented with 60 g L⁻¹ glucose, the resultant medium containing 128.3 g L⁻¹ sugars was successfully fermented (due to product removal) to produce 47.6 g L⁻¹ ABE, and the culture utilized all the sugars (glucose, xylose, arabinose, galactose, and mannose). These results demonstrate that C. beijerinckii P260 has excellent capacity to convert biomass derived sugars to solvents and can produce over 28 g L⁻¹ (in one case 41.7 g L⁻¹ from glucose) ABE from WSH. Medium containing 250 g L⁻¹ glucose resulted in no growth and no ABE production. Mixtures containing WSH + 140 g L⁻¹ glucose (total sugar approximately 200 g L⁻¹) showed poor growth and poor ABE production. Mention of trade names or commercial products in this article is solely for the purpose of providing scientific information and does not imply recommendation or endorsement by the United States Department of Agriculture.     

Laccase and Manganese Peroxidase Activities of Phellinus Robustus and Ganoderma Adspersum Grown on Food Industry Wastes in Submerged Fermentation

Phellinus robustus produced both laccase (700–4,000 U l⁻¹) and manganese peroxidase (MnP) (1,000–11,300 U l⁻¹) in fermentation of nine food wastes, whereas Ganoderma adspersum produced only laccase (600–34,000 U l⁻¹). Glucose provided high laccase and MnP activity of P. robustus but repressed enzyme production by G. adspersum. Ammonium sulphate and ammonium tartrate increased the P. robustus laccase yield (3-fold), whereas the accumulation of MnP was not enhanced by additional nitrogen.     

ABE production from corn: a recent economic evaluation

This article details an economic assessment of butanol production from corn using the newly developed hyper-butanol-producing strain of Clostridium beijerinckii BA101. Butanol is produced in batch reactors and recovered by distillation. For a plant with 153,000 metric tons of acetone, butanol, and ethanol (ABE) production capacity, the production equipment cost and total working capital cost is US$33.47×10⁶ and US$110.46×10⁶, respectively. Based on a corn price (C _p) of US$79.23 ton⁻¹ (US$2.01 bushel⁻¹), an ABE yield of 0.42 (g ABE/g glucose) butanol price is projected to be US$0.34 kg⁻¹. An improved yield of 0.50 will reduce this price to US$0.29 kg⁻¹. Assumptions, such as by-product credit for gases and complete conversion of corn steep liquor (CSL) to fermentation by-products, have been taken into consideration. An increased price of corn to US$197.10 ton⁻¹ would result in a butanol price of US$0.47 kg⁻¹. A grass-rooted plant would result in a butanol price of US$0.73 kg⁻¹ (C _p US$79.23 ton⁻¹). In a worst case scenario, the price of butanol would increase to US$1.07 kg⁻¹ (C _p 197.10 ton⁻¹ for a grass-rooted plant and assuming no credit for gases). This is based on the assumption that corn price would not increase to more than US$197.10 ton⁻¹. Journal of Industrial Microbiology & Biotechnology (2001) 27, 292–297. Received 12 September 2000/ Accepted in revised form 12 January 2001     

<Emphasis Type="Italic">Clostridium beijerinckii</Emphasis> mutant with high inhibitor tolerance obtained by low-energy ion implantation

Clostridium beijerinckii mutant strain IB4, which has a high level of inhibitor tolerance, was screened by low-energy ion implantation and used for butanol fermentation from a non-detoxified hemicellulosic hydrolysate of corn fiber treated with dilute sulfuric acid (SAHHC). Evaluation of toxicity showed C. beijerinckii IB4 had a higher level of tolerance than parent strain C. beijerinckii NCIMB 8052 for five out of six phenolic compounds tested (the exception was vanillin). Using glucose as carbon source, C. beijerinckii IB4 produced 9.1 g l⁻¹ of butanol with an acetone/butanol/ethanol (ABE) yield of 0.41 g g⁻¹. When non-detoxified SAHHC was used as carbon source, C. beijerinckii NCIMB 8052 grew well but ABE production was inhibited. By contrast, C. beijerinckii IB4 produced 9.5 g l⁻¹ of ABE with a yield of 0.34 g g⁻¹, including 2.2 g l⁻¹ acetone, 6.8 g l⁻¹ butanol, and 0.5 g l⁻¹ ethanol. The remarkable fermentation and inhibitor tolerance of C. beijerinckii IB4 appears promising for ABE production from lignocellulosic materials.     

Production of 1,3-Propanediol by Clostridium butyricum VPI 3266 in continuous cultures with high yield and productivity

The effects of dilution rate and substrate feed concentration on continuous glycerol fermentation by Clostridium butyricum VPI 3266, a natural 1,3-propanediol producer, were evaluated in this work. A high and constant 1,3-propanediol yield (around 0.65 mol/mol), close to the theoretical value, was obtained irrespective of substrate feed concentration or dilution rate. Improvement of 1,3-propanediol volumetric productivity was achieved by increasing the dilution rate, at a fixed feed substrate concentration of 30, 60 or 70 g l⁻¹. Higher 1,3-propanediol final concentrations and volumetric productivities were also obtained when glycerol feed concentration was increased from 30 to 60 g l⁻¹, at D=0.05–0.3 h⁻¹, and from 60–70 g l⁻¹, at D=0.05 and 0.1 h⁻¹·30 g l⁻¹ of 1,3-propanediol and the highest reported value of productivity, 10.3 g l⁻¹ h⁻¹, was achieved at D=0.30 h⁻¹ and 60 g l⁻¹ of feed glycerol. A switch to an acetate/butyrate ratio higher than one was observed for 60 g l⁻¹ of feed glycerol and a dilution rate higher than 0.10 h⁻¹; moreover, at D=0.30 h⁻¹ 3-hydroxypropionaldehyde accumulation was observed for the first time in the fermentation broth of C. butyricum.     

Repeated Batch Cultivation of Ralstonia eutropha for Poly (β-hydroxybutyrate) Production

Batch cultivation of Ralstonia eutropha NRRL B14690 attained 21 g biomass l⁻¹ and 9.4 g poly(β-hydroxybutyrate) l⁻¹ (0.45 g PHB g⁻¹ dry wt⁻¹) in 60 h. Repeated batch operation (empty-and-fill protocol) to remove 20% (v/v) of the culture broth and to supplement an equal volume of fresh media resulted in 49 g biomass l⁻¹ and 25 g PHB l⁻¹ (0.51 g PHB g⁻¹ dry wt⁻¹) with an overall productivity of 0.42 g PHB l⁻¹ h⁻¹ in 67 h. In the two cycles of repeated batch fermentation there was a 3-fold increase in productivity as compared to batch.     

Production of acetone,butanol and ethanol by Clostridium beijerinckii BA101 and in situ recovery by gas stripping

We examined the effect of gas-stripping on the in situ removal of acetone, butanol, and ethanol (ABE) from batch reactor fermentation broth. The mutant strain (Clostridium beijerinckii BA101) was not affected adversely by gas stripping. The presence of cells in the fermentation broth affected the selectivities of ABE. A considerable improvement in the productivity and yield was recorded in this work in comparison with the non-integrated process. In an integrated process of ABE fermentation-recovery using C. beijerinckii BA101, ABE productivities and yield were improved up to 200 and 118%, respectively, as compared to control batch fermentation data. In a batch reactor C. beijerinckii BA101 utilized 45.4 g glucose l^–1 and produced 17.7 g total ABE l^–1, while in the integrated process it utilized 161.7 g glucose l^–1 and produced total ABE of 75.9 g l^–1. In the integrated process, acids were completely converted to solvents when compared to the non-integrated process (batch fermentation) which contained residual acids at the end of fermentation. In situ removal of ABE by gas stripping has been reported to be one of the most important techniques of solvent removal. During these studies we were able to maintain the ABE concentration in the fermentation broth below toxic levels.     

Optimization of fed-batch fermentation for xylitol production by Candida tropicalis

Xylitol, a functional sweetener, was produced from xylose by biological conversion using Candida tropicalis ATCC 13803. Based on a two-substrate fermentation using glucose for cell growth and xylose for xylitol production, fed-batch fermentations were undertaken to increase the final xylitol concentration. The effects of xylose and xylitol on xylitol production rate were studied to determine the optimum concentrations for fed-batch fermentation. Xylose concentration in the medium (100 g l⁻¹) and less than 200 g l⁻¹ total xylose plus xylitol concentration were determined as optimum for maximum xylitol production rate and xylitol yield. Increasing the concentrations of xylose and xylitol decreased the rate and yield of xylitol production and the specific cell growth rate, probably because of an increase in osmotic stress that would interfere with xylose transport, xylitol flux to secretion to cell metabolism. The feeding rate of xylose solution during the fed-batch mode of operation was determined by using the mass balance equations and kinetic parameters involved in the equations in order to increase final xylitol concentration without affecting xylitol and productivity. The optimized fed-batch fermentation resulted in 187 g l⁻¹ xylitol concentration, 0.75 g xylitol g xylose⁻¹ xylitol yield and 3.9 g xylitol l⁻¹ h⁻¹ volumetric productivity. Journal of Industrial Microbiology & Biotechnology (2002) 29, 16–19 doi:10.1038/sj.jim.7000257 Received 15 October 2001/ Accepted in revised form 30 March 2002     

Fermentative production of lactic acid from biomass: an overview on process developments and future perspectives

The concept of utilizing excess biomass or wastes from agricultural and agro-industrial residues to produce energy, feeds or foods, and other useful products is not necessarily new. Recently, fermentation of biomass has gained considerable attention due to the forthcoming scarcity of fossil fuels and also due to the necessity of increasing world food and feed supplies. A cost-effective viable process for lactic acid production has to be developed for which several attempts have been initiated. Fermentation techniques result in the production of either d (−) or l (+) lactic acid, or a racemic mixture of both, depending on the type of organism used. The interest in the fermentative production of lactic acid has increased due to the prospects of environmental friendliness and of using renewable resources instead of petrochemicals. Amylolytic bacteria Lactobacillus amylovorus ATCC 33622 is reported to have the efficiency of full conversion of liquefied cornstarch to lactic acid with a productivity of 20 g l⁻¹ h⁻¹. A maximum of 35 g l⁻¹ h⁻¹ was reported using a high cell density of L. helveticus (27 g l⁻¹) with a complete conversion of 55- to 60-g l⁻¹ lactose present in whey. Simultaneous saccharification and fermentation is proved to be best in the sense of high substrate concentration in lower reactor volume and low fermentation cost. In this review, a survey has been made to see how effectively the fermentation technology explored and exploited the cheaply available source materials for value addition with special emphasis on lactic acid production.