Fed‐batch fermentation of olive mill wastewaters for lipase production

In the Mediterranean basin countries, huge amounts of olive mill wastewaters (OMW) are produced by the olive oil industry. It constitutes a serious environmental problem, nevertheless its composition turns OMW into a potential growth medium to lipolytic microorganisms. The aim of this work was to study lipase production as well as OMW degradation in fed‐batch cultures of Candida cylindracea CBS 7869, Candida rugosa CBS 2275 and Yarrowia lipolytica W29 (ATCC 20460). Besides the improvement of lipase production, the fed‐batch approach enhanced the effluent degradation, since it led to good COD and lipids reduction, both higher than 50%. C. rugosa achieved the highest value of lipase productivity (130 U L^?1 h^?1), in parallel with highest lipids reduction (77%). This study demonstrates that OMW are becoming a competitive and valuable growth medium in fermentation processes with lipolytic microorganisms. The fed‐batch strategy used proved to be an efficient approach to enhance lipase production from OMW and to reduce significantly the final organic load of the medium. Copyright © 2012 Society of Chemical Industry     

Citric acid,biomass and cellular lipid production by Yarrowia lipolytica strains cultivated on olive mill wastewater‐based media

BACKGROUND: Olive mill wastewaters (OMWs) are an important residue and several physico‐chemical and/or biotechnological methods have been proposed for their treatment. RESULTS: The ability of three Yarrowia lipolytica strains to grow on and convert glucose‐enriched OMWs into added‐value compounds in carbon‐ and nitrogen‐limited shake‐flask cultures was assessed. Remarkable decolorization (up to 63%) and non‐negligible removal of phenolic compounds (up to 34%, w/w) occurred. In nitrogen‐limited cultures, the accumulation of cellular lipids was favored by OMW addition into the medium. In contrast, although remarkable quantities of citric acid (Cit) were produced in control experiments (cultures without OMW addition), in which Cit up to 18.9 g L^?1 was produced with yield of Cit synthesized per sugar consumed ～0.73 g g^?1), adaptation of cultures to media supplemented with OMWs reduced the final Cit quantity and conversion yield values achieved. In OMW‐based media, the highest concentration of citric acid produced was 18.1 g L^?1, with conversion yield ～0.51 g g^?1. In carbon‐limited cultures, despite the presence of inhibitory compounds in the medium (e.g. phenols), biomass production was enhanced with the addition of OMWs. The highest biomass concentration achieved was 12.7 g L^?1, with biomass conversion yield per sugar consumed ～0.45 g g^?1. Fatty acid analysis of cellular lipid produced demonstrated that adaptation of all strains in OMW‐based media favored the synthesis of cellular lipids that contained increased concentrations of cellular oleic acid. CONCLUSIONS: The Y. lipolytica strains tested can be regarded as possible candidates for simultaneous OMWs remediation and production of added‐value compounds. Copyright © 2011 Society of Chemical Industry     

Lipase Induction in <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> for Castor Oil Hydrolysis and Its Effect on γ-Decalactone Production

γ-Decalactone is an aromatic compound of industrial interest, resulting from the biotransformation of ricinoleic acid, the major constituent of castor oil. In order to increase the availability of the substrate to the cells for the aroma production, castor oil previously hydrolyzed can be used. This hydrolysis may be promoted by enzymatic action, more specifically by lipases. In this work, the influence upon the aroma production of the lipase produced by Yarrowia lipolytica, a microorganism able to carry out the biotransformation, was studied. In a first approach, lipase induction conditions were analyzed using different Y. lipolytica strains and culture conditions, such as the inoculation mode of the lipase production medium. Lipase production was not affected by the cells centrifugation, so this step was eliminated, reducing the time and phases of the process. Moreover, Y. lipolytica W29 was shown to be the most adequate strain for lipase production. To investigate the importance of castor oil hydrolysis, the pre-addition of an inducer of lipase production (olive oil) to the biotransformation medium was tested. Results showed that the highest aroma production (1,600 mg L⁻¹) was obtained without a lipase inducer. However, the pre-induction of lipase decreased the lag phase for γ-decalactone secretion.     

Isolation of a yeast,Trichosporon cutaneum,able to use low molecular weight phenolic compounds: application to olive mill waste water treatment

This study deals with the degradation of phenolic compounds in olive oil mill waste; a highly polluting material in olive oil‐producing countries because of its abundance and the toxicity of its phenolic compound content. This investigation confirms the ability of an isolated yeast, identified as Trichosporon cutaneum, to degrade phenolic compounds extracted from olive mill waste water (OMW). The yeast was adapted to the OMW by an enrichment culture. The results of this biotransformation were a decrease in the phenolic content and hence a reduction in the phytotoxic effects of the effluent after the yeast treatment. The kinetic growth of the isolated yeast on phenol over a range of concentrations (0.3–3.0 g dm^?3) was studied. The ability of the strain to assimilate simple monomeric phenols and alkyl phenols, at a concentration of 1 g dm^?3, in a synthetic liquid medium used as the sole carbon source was investigated in a batch culture. The aromatic ring cleavage pathway occurred in the yeast through catechol oxidation. Using various concentrations of ethyl acetate extract from OMW as the sole carbon source, the yeast exhibited growth on the substrate up to 7 g dm^?3 equivalent of phenols. A significant reduction of COD after the treatment of the OMW extract by the yeast isolate was noticed. The removal of phenol and COD exceeded 80% of the original loading after 8 days of treatment, for extracts containing initial COD in the range 19 to 72 g dm^?3. Copyright © 2004 Society of Chemical Industry     

Effect of lipids and surfactants on extracellular lipase production by Yarrowia lipolytica

The production of extracellular lipase in submerged cultures of Yarrowia lipolytica CECT 1240 has been investigated. Several compounds have been added to the culture medium, in order to assess their efficiency as inducers of lipase production. First, the effect of triglycerides (olive oil, sunflower oil, tributyrin) and fatty acids (oleic acid) has been studied. The highest activity level was obtained with sunflower oil (58 U cm^?3), followed by olive oil (49 U cm^?3). The cultures with tributyrin and oleic acid attained similar activities (33 U cm^?3). Then, several surfactants (Tween 80, Triton X‐100, gum arabic, polyethylene glycol 200) were added to the cultures with sunflower oil, in an attempt to increase the levels of extracellular lipase activity. The obtained activities were slightly lower than those achieved without surfactants. The assay of a wide range of surfactant concentrations in the case of PEG‐200 (with which the highest activity levels had been attained) did not improve the results. This strain secreted lipase concentrations two‐fold higher and showed significantly different behaviour towards the presence of surfactants in the culture medium, compared with other wild‐type Yarrowia lipolytica strains. Copyright © 2003 Society of Chemical Industry     

High level of laccases production by Trametes trogii culture on olive mill wastewater‐based media,application in textile dye decolorization

BACKGROUND: Laccases are receiving increasing attention as potential industrial enzymes in various applications. Therefore, it is important to find inexpensive and optimized media for large‐scale commercial production. The present work aims to valorize olive mill wastewater (OMW) by its use as base media for laccases production by Trametes trogii and use of the laccases produced for decolorizing textile dyes. RESULTS: A high yield of 25 120 U L^?1 of laccases was obtained at an OMW:water ratio of 80:20 enriched with 2 g L^?1 of urea corresponding to initial biochemical oxygen demand (BOD₅), chemical oxygen demand (COD) and total phenol concentrations of 18.4, 46 and 4.6 g L^?1 respectively. The partially purified laccases resulted in 85% decolorization of blue tubantin GLL 300 and black tubantin VSF 600, and 45% decolorization of blue solophenyl after 6 h of incubation. Subsequent additions of the same dye dose to the reaction mixture resulted in a very significant decrease in laccases activity after the third dye addition. CONCLUSION: The use of OMW for laccases production is a cost effective process. The laccases produced can be applied to the decolorization of textile wastewaters. Copyright © 2009 Society of Chemical Industry     

Sequential optimization of culture medium composition for extracellular lipase production by Bacillus sphaericus using statistical methods

A sequential optimization strategy with the aid of statistical design of experiments was used to enhance the lipase (triacylglycerol acylhydrolases, EC 3.1.1.3) production by Bacillus sphaericus in submerged cultivation. A Plackett–Burman experimental design was used to evaluate the twelve medium components. Various vegetable oil inducers were tested for lipase production in the second step and the third step was to identify the optimal values of the significant medium components with sesame oil as the inducer using response surface methodology. A predictive model of the combined effects of the independent variables using response surface methodology and an artificial neural network was proposed. Unstructured kinetic models, a logistic model and a Luedeking–Piret model, were used to describe the cell mass and lipase production respectively. The significant variables affecting lipase production were found to be glucose, olive oil, peptone, NaCl and MnSO₄.H₂O. Sesame oil was found to be the best inducer for lipase production by Bacillus sphaericus. The maximum lipase activity of 4.45 U mL^?1, which was 1.5 times the maximum activity obtained in the Plackett–Burman experimental trials, was obtained at the optimum combination of medium constituents containing 12.695 g L^?1 glucose, 13.161 mL L^?1 sesame oil, 9.947 g L^?1 peptone, 3.25 g L^?1 NaCl, 0.5917 g L^?1 MnSO₄.H₂O and other insignificant components at the fixed level. The statistical design of experiments offers an efficient methodology to identify the significant variables and to optimize the factors with a minimum number of experiments for lipase production by Bacillus sphaericus. Copyright © 2007 Society of Chemical Industry     

Production of organic solvent tolerant lipase by Staphylococcus caseolyticus EX17 using raw glycerol as substrate

BACKGROUND: In this work we used Plackett–Burman statistical design and central composite design in order to optimize culture conditions for lipase production by Staphylococcus caseolyticus strain EX17 growing on raw glycerol, which was obtained as a by‐product of the enzymatic synthesis of biodiesel. The stability of lipase was verified over several organic solvents, such as methanol, ethanol and n‐hexane. RESULTS: Optimal culture conditions for lipase production were found to be 36 °C, initial pH 8.12, glycerol 30 g L^?1, olive oil 3.0 g L^?1, and soybean oil 2.5 g L^?1, with 145.8 U L^?1 of enzyme activity. When commercial glycerol was substituted by the raw glycerol from biodiesel synthesis, lipolytic activity was 127.3 U L^?1. Experimental validation of enzyme production matched values predicted by the mathematical model, which was 138.3 U L^?1. Stability tests showed that lipase from S. caseolyticus EX17 was stable in methanol, ethanol, and n‐hexane. CONCLUSIONS: Results obtained in this work suggest that raw glycerol can be used for lipase production by S. caseolyticus EX17 and that this enzyme has a potential application in the synthesis of biodiesel. Copyright © 2008 Society of Chemical Industry     

Treatment of wastewaters from the olive mill industry by sonication

BACKGROUND: In this study, the effects of additives (manganese (III) oxide (Mn₃O₄), Cu⁺², Fe⁰ and potassium iodate (KIO₃)) and radical scavengers (sodium carbonate (Na₂CO₃), perfluorohexane (C₆F₁₄) and t‐buthyl alcohol (C₄H₁₀O)) on the dephenolization, decolorization, dearomatization and detoxification of olive mill wastewater (OMW) by sonication were investigated because wastewaters from this industry are not removed effectively. RESULTS: The maximum COD, color, total phenol and total aromatic amines (TAAs) removal efficiencies were 63, 82, 78 and 71%, respectively, at 60 °C with sonication only. The TAAs and phenol yields were increased to 96 and 97% with 6 mg L^?1 KIO₃ and 3 mg L^?1 Fe⁰ while color removal reached 97% with 6 mg L^?1 C₆F_14. The total annual cost with sonication only was 665 € m^?3 year^?1 while the cost slightly increased (666€ m³ year^?1) with C₆F₁₄. The maximum acute toxicity removals were 97‐98% in Daphnia magna and Vibrio fischeri The Microtox acute toxicity test was more sensitive than the Daphnia magna to the OMW samples. CONCLUSION: COD, color, total phenol, TAAs and toxicity in an OMW were removed efficiently and cost‐effectively by sonication. © 2012 Society of Chemical Industry     

The effect of solids on the electrochemical treatment of olive mill effluents

The electrochemical oxidation of an olive mill effluent over Ti–Pt anodes was studied. The effluent had an average total chemical oxygen demand (COD) value of 234 g L^?1, soluble COD of 61 g L^?1, soluble phenolic content 3.4 g L^?1, total solids of 80 g L^?1 and pH = 5.1. Experiments were conducted in a 10 L vessel with the effluent recirculating at 1 L s^?1. The applied current was varied between 5 and 20 A, the salinity between 1 and 4% NaCl, and experiments were performed with the effluent diluted with water to achieve the desired initial concentration. Emphasis was given to the effect of the presence of solids as well as of varying operating conditions on process performance as assessed in terms of COD, color and phenols removal. In general, degradation of phenols occurred relatively fast with conversion increasing with increasing applied current and decreasing initial organic loading and this was accompanied by low COD removal levels and moderate decolorization. The presence of solids had practically no effect on phenols removal, which, in most cases, was complete in less than about 180 min of reaction. However, oxidation in the presence of solids resulted in a substantial solid fraction being dissolved and this consequently increased sample color and the soluble COD content. The solid content typically found in olive mill effluents may partially impede its treatment by electrochemical oxidation, thus requiring more severe operating conditions and greater energy consumption. Copyright © 2007 Society of Chemical Industry     

Conversions of olive mill wastewater‐based media by Saccharomyces cerevisiae through sterile and non‐sterile bioprocesses

BACKGROUND: Olive mill wastewaters (OMWs) are an important residue and several methods have been proposed for their treatment. RESULTS: Remarkable decolorization (~63%) and phenol removal (~34% w/w) from OMW was achieved. In glucose‐based flask sterile cultures, enrichment with OMWs increased ethanol and biomass production compared with cultures without OMWs added. Flask sterile and un‐sterilized cultures demonstrated similar kinetic results. Batch‐bioreactor trials performed showed higher ethanol and lower biomass quantities compared with the respective shake‐flask experiments, while cultures used under un‐sterilized conditions revealed equivalent results to the sterile ones. In non‐sterile bioreactor cultures, OMWs addition enhanced biomass production in comparison with culture with no OMWs added, whereas ethanol biosynthesis was not affected. The maximum ethanol quantity achieved was 52 g L^?1 (conversion yield per sugar consumed of 0.46 g g^?1) in a batch bioreactor non‐sterilized trial with OMW–glucose enriched medium used as substrate, that presented initial reducing sugars concentration at ~115 g L^?1. Fatty acid analysis of cellular lipids demonstrated that in OMW‐based media, cellular lipids containing increased concentrations of oleic and linoleic acid were produced in comparison with cultures with no OMWs added. CONCLUSIONS: S. cerevisiae simultaneously produced bio‐ethanol and biomass and detoxified OMWs, under non‐sterile conditions. © 2012 Society of Chemical Industry     

Optimization of lipase production by Penicillium simplicissimum in soybean meal

BACKGROUND: Lipase production by Penicillium simplicissimum using soybean meal as substrate has been investigated. A factorial design technique was used to evaluate the effects of incubation temperature, initial moisture of the meal and substrate supplementation with low cost supplements, on lipase production. Soybean oil and wastewater from a slaughterhouse, which is rich on oil and fat, corn steep liquor and yeast hydrolysate, were tested as supplementary carbon and nitrogen sources. RESULTS Cultivation conditions were optimized for the production of lipase by factorial design and response surface methodology. Results show that the microorganism produces very low protease activity (0.21 U gds^?1 dry substrate), which helps to maximize lipase production. Soybean meal without supplements appears to be the best medium of those tested for lipase production by P. simplicissimum. CONCLUSION: This work showed that temperature and moisture are the factors that most strongly influence lipase production by P. simplicissimum using soybean meal as substrate. The growth conditions that optimize lipase production are 27.5 °C using substrate with 550 g kg^?1 of initial moisture. In optimum conditions lipase activity of 30 U gds^?1 dry substrate was obtained. Copyright © 2007 Society of Chemical Industry     

The effects of emulsified polydimethylsiloxane FG‐10 on the oxygen transfer coefficient (kLa) and lipase production by Staphylococcus warneri EX17

BACKGROUND: In this study the effects of the addition of emulsified polydimethylsiloxane (PMDS) FG‐10 on the oxygen transfer coefficient (k_La) of submerged cultures of Staphylococcus warneri EX17 and its lipase production is described. FG‐10 is an emulsified silicone capable of dissolving 50 times more oxygen than water. The combined effects of FG‐10 concentration and different conditions of agitation were optimized in bioreactors using statistical design tools, and the cultures were run using raw glycerol from biodiesel synthesis as the sole carbon source. RESULTS: The optimal conditions found to improve lipase production were FG‐10 concentration of 11.2% (v/v) and speed agitation of 527 rpm, respectively, producing around 861 U L^?1 of lipolytic activity, a maximal cell concentration of 8.4 g L^?1, and a k_La of 99 h^?1, values that are approximately 3 times higher than cultures without FG‐10. CONCLUSIONS: This is the first report in the literature on the use of this class of chemicals as oxygen carriers in microbial cultures and its effect on k_La and lipase production, demonstrating the potential use of FG‐10 in microbial cultures. Copyright © 2012 Society of Chemical Industry     

Daily doses of light in relation to the growth of Scenedesmus obliquus in diluted three‐phase olive mill wastewater

BACKGROUND: The use of olive‐oil mill wastewater (OMW) from a three‐phase centrifugation process used in the olive‐oil industry, has been studied in relation to the production of the microalga Scenedesmus obliquus CCAP 276/3A. The chemical characteristics of OMW indicated nitrogen deficiency. RESULTS: S. obliquus is able to assimilate nutrients present in a culture medium (water‐OMW 5%) and grow at its maximum specific growth rate of 0.026 h^?1, both under mixotrophic as well as heterotrophic conditions. The different daily doses of light (DDL) used, in the range 0–36 E m^?2 d^?1, determined light‐limited and light‐inhibited cultures. The light‐inhibited mixotrophic cultures bore characteristics similar to those of the heterotrophic cultures, and became more so when the dose of light received was higher. The low protein yield (258 mg g^?1) and high percentage of carbohydrates of the biomass (65.8%) confirmed a nutritional‐stress situation associated with nitrogen limitation. CONCLUSION: The similarity between the fatty‐acid composition of the heterotrophic and mixotrophic cultures strongly inhibited by light appeared to indicate the cancelling of the photosynthetic behaviour of the cells at high DDL values. The biomass generated can be used for biofuels. The maximum elimination of biological oxygen demand (BOD₅) per unit of biomass was achieved in the heterotrophic cultures. Copyright © 2009 Society of Chemical Industry     

Screening of white rot fungi for the treatment of olive mill waste-waters

Several white rot fungi were evaluated for their ability to decolorize olive mill waste-waters (OMW). Among these, Phanerochaete chrysosporium showed the highest potential for the biological depollution of OMW. Approximately 65% of the color and 73% of the chemical oxygen demand (COD) were removed by P. chrysosporium strain HD. Phlebia radiata, Dichomitus squalens, Polyporus frondosus and Coriolus versicolor could also decolorize the OMW but to a lesser extent. The different abilities of these white rot fungi to decolorize OMW correlated with their rates of depolymerization of high molecular weight aromatics and the degradation of the low molecular weight aromatic compounds. Fourteen strains of P. chrysosporium were compared on the basis of their lignin peroxidase (LiP) production, OMW decolorization and residual material dry weight. High lignin peroxidase producer strains, such as strains HD and BKM-F-1767, showed the highest rates of OMW decolorization, P. chrysosporium strains 79–36 and FP 104297 (low LiP producer strains) did not exhibit any decolorization activity.     

Enhanced lipase production from Aeromonas sp. S1 using Sal deoiled seed cake as novel natural substrate for potential application in dairy wastewater treatment

BACKGROUND: Sal (Shorea robusta) deoiled seed cake extract (SDOCE) was assessed for its suitability as a cheap natural substrate for lipase production under submerged fermentation. The bacterial isolate Aeromonas sp. S1 isolated from dairy industry was used for lipase production. Both the isolate and its lipase were shown to be potential tools for treatment of dairy wastewater containing higher organic load. RESULTS: On substituting tributyrin with SDOCE, lipase production was enhanced 24‐fold (195 U mL^?1) compared with the initial 8.13 U mL^?1 lipase activity. Maximum lipase production was obtained at pH 8.0 and incubation temperature 30 °C. The lipase had pH and temperature optima of 10.0 and 55 °C, respectively. The isolate and its crude enzyme preparation were checked separately for applicability in dairy wastewater treatment. The isolate was able to reduce chemical oxygen demand (COD) by 93%, oil and grease (O&G) by 75%, and total suspended solids (TSS) by 47% after 96 h of treatment. Enzymatic preparation gave 86% reduction of COD after 12 h and 75 and 45% reduction of O&G and TSS, respectively, after 96 h of treatment. CONCLUSION: Overall, the study shows the usefulness of Sal seed deoiled cake, a cheap agro‐industrial by‐product for the production of lipase. The isolate and its lipase can also be used effectively for the treatment of dairy wastewater. Copyright © 2011 Society of Chemical Industry     

Biodegradation and utilization of waste cooking oil by Yarrowia lipolytica CECT 1240

Biodegradation of waste cooking oil and its application as lipase production inducer in cultures of Yarrowia lipolytica CECT 1240 have been investigated, both in shake flasks and a bench‐scale bioreactor. The ability of this strain to degrade the spent oil was evaluated by monitoring COD throughout the cultures, and a remarkable decrease was recorded (almost 90% decrease in oil COD after 3 days in bioreactor). Moreover, the addition of waste cooking oil to the medium led to a significant augmentation in extracellular lipase production by the yeast, compared to oil‐free cultures. This confirms the suitability of the studied residue as an inducer of lipase biosynthesis, which is a very interesting fact, from an economic standpoint. These results were confirmed when a fed‐batch strategy was proposed. Finally, some properties of the crude enzyme were studied, and compared to the enzymes obtained when non‐used oil was added to the medium. Practical application : New strategies to valorize wastes from the food and agro industries are attracting a great scientific interest due to the important advantages offered from an economic and environmental point of view. For this reason, the yeast Yarrowia lipolytica CECT 1240 is proposed for degrading waste cooking oils. This approach entails also another benefit in terms of lipolytic enzyme synthesis, since the addition of used up oils has a lipase inducer effect. The enormous interest in lipases is reflected in the number of applications that they present. The process was successfully carried out both in shake flasks and a bench‐scale bioreactor, allowing producing high levels of lipolytic activity at the same time that the COD was diminished up to nearly 90%.     

Kinetic study of an anaerobic fluidized bed system used for the purification of fermented olive mill wastewater

The anaerobic digestion of olive mill wastewater (OMW) in a fluidized bed, pretreated with Geotrichum candidum, has been studied. The bioreactor used (volume = 3.5 dm³; biomass concentration = 11.5 g VSS dm^?3) maintained satisfactory operation for 4 to 35 days, in terms of hydraulic retention time, and removed 92% of the initial COD. The system was used to develop and test a kinetic model which was subsequently employed to determine growth yield and maintenance coefficient. From the results obtained, the Michaelis-Menten equation accurately described the substrate uptake (i.e. COD removal) in the anaerobic fluidized bed system. Pretreatment of the OMW was found to increase the rate of substrate uptake by a factor of 3.2 when compared to untreated OMW.     

Batch treatment of saline wastewater by Halanaerobium lacusrosei in an anaerobic packed bed reactor

BACKGROUND: This study considers batch treatment of saline wastewater in an upflow anaerobic packed bed reactor by salt tolerant anaerobic organisms Halanaerobium lacusrosei . RESULTS: The effects of initial chemical oxygen demand (COD) concentration (COD₀ = 1880–9570 mg L^?1), salt concentration ([NaCl] = 30–100 g L^?1) and liquid upflow velocity (V_up = 1.0–8.5 m h^?1) on COD removal from salt (NaCl)‐containing synthetic wastewater were investigated. The results indicated that initial COD concentration significantly affects the effluent COD concentration and removal efficiency. COD removal was around 87% at about COD₀ = 1880 mg L^?1, and efficiency decreased to 43% on increasing COD₀ to 9570 mg L^?1 at 20 g L^?1 salt concentration. COD removal was in the range 50–60% for [NaCl] = 30–60 g L^?1 at COD₀ = 5200 ± .100 mg L^?1. However, removal efficiency dropped to 10% when salt concentration was increased to 100 g L^?1. Increasing liquid upflow velocity from V_up = 1.0 m h^?1 to 8.5 m h^?1 provided a substantial improvement in COD removal. COD concentration decreased from 4343 mg L^?1 to 321 mg L^?1 at V_up = 8.5 m h^?1, resulting in over 92% COD removal at 30 g L^?1 salt‐containing synthetic wastewater. CONCLUSION: The experimental results showed that anaerobic treatment of saline wastewater is possible and could result in efficient COD removal by the utilization of halophilic anaerobic bacteria. Copyright © 2008 Society of Chemical Industry     

Production of L‐lactic acid with very high gravity distillery wastewater from ethanol fermentation by a newly isolated Enterococcus hawaiiensis

BACKGROUND: A great amount of wastewater with high contents of chemical oxygen demand (COD) are produced by ethanol production. It would be useful to utilize distillery wastewater to produce L‐lactic acid, which could be a high additional value byproduct of ethanol production. The fermentation process of L‐lactic acid production by a newly isolated Enterococcus hawaiiensis CICIM‐CU B0114 is reported for the first time. RESULTS: The strain produced 56 g L^?1 of L‐lactic acid after cultivation for 48 h in optimized medium consisting of (g L^?1) 80 glucose, 10 peptone, 10 yeast extract, 1.5 Na₂HPO₄ and 0.2 MgSO₄. E. hawaiiensis CICIM‐CU B0114 was isolated and purified by subculture for growing and producing L‐lactic acid in distillery wastewater of very high gravity (VHG) from ethanol fermentation. L‐lactic acid fermentation was further studied with distillery wastewater substrate in 7 L and 15 L fermentors. The results showed that L‐lactic acid concentrations of 52 g L^?1 and 68 g L^?1 was achieved in 7 L and 15 L fermentors with the initial sugar concentrations of 67 g L^?1 and 87 g L^?1, respectively. CONCLUSION: The production of L‐lactic acid by the newly isolated E. hawaiiensis CICIM‐CU B0114 was carried out and the fermentation medium was optimized by orthogonal experimental design. This new strain holds the promise of L‐lactic acid production utilizing distillery wastewater from VHG ethanol fermentation. Copyright © 2010 Society of Chemical Industry