A glycerol-inducible thermostable lipase fromBacillussp.: medium optimization by a Plackett–Burman design and by response surface methodology

A thermostable organic solvent-tolerant lipase from Brevibacillus sp.: production and integrated downstream processing using an alcohol-salt-based aqueous two-phase system

Lipases are used for the synthesis of different compounds in the chemical, pharmaceutical, and food industries. Most of the reactions are carried out in non-aqueous media and often at elevated temperature, requiring the use of organic solvent-tolerant thermostable lipases. However, most known lipases are not stable in the presence of organic solvents and at elevated temperature. In this study, an organic solvent-tolerant thermostable lipase was obtained from Brevibacillus sp. SHI-160, a moderate thermophile isolated from a hot spring in the East African Rift Valley. The enzyme was optimally active at 65°C and retained over 90% of its activity after 1 h of incubation at 70°C. High lipase activity was measured in the pH range of 6.5 to 9.0 with an optimum pH of 8.5. The enzyme was stable in the presence of both polar and non-polar organic solvents. The stability of the enzyme in the presence of polar organic solvents allowed the development of an efficient downstream processing using an alcohol-salt-based aqueous two-phase system (ATPS). Thus, in the presence of 2% salt, over 98% of the enzyme partitioned to the alcohol phase. The ATPS-recovered enzyme was directly immobilized on a solid support through adsorption and successfully used to catalyze a transesterification reaction between paranitrophenyl palmitate and short-chain alcohols in non-aqueous media. This shows the potential of lipase SHI-160 to catalyze reactions in non-aqueous media for the synthesis of valuable compounds. The integrated approach developed for enzyme production and cheap and efficient downstream processing using ATPS could allow a significant reduction in enzyme production costs. The results also show the potential of extreme environments in the East African Rift Valley as sources of valuable microbial genetic resources for the isolation of novel lipases and other industrially important enzymes.

Lipase from new isolate Bacillus cereus ATA179: optimization of production conditions, partial purification, characterization and its potential in the detergent industry

In this study, 341 Bacillus sp. strains were isolated from agricultural soils of Turkey. The potent extracellular lipase producer was selected. It was identified by 16S rRNA, named as Bacillus cereus ATA179. Optimal nutritional and physical parameters for lipase production were determined. Sucrose as the carbon source, (NH₄)₂HPO₄ as the nitrogen source, CaCl₂ as the metal ion were obtained. The best results of physical parameters were stated at 45°C, pH 7.0, shaking rate 50 rpm, inoculation amount 7% and inoculum age 24 h. ATA179 strain showed a 51% increase in enzyme production in the modified medium created by optimizing nutritional and physical conditions. Optimum pH value and temperature were found as 6.0 and 55 °C, respectively. CaCl₂, Tween 20, Triton X-100 had an activating effect on enzyme activity. V_max and K_m kinetic values were found as 18.28 U/mL and 0.11 mM, respectively. The molecular weight was determined as 47 kDa. Lipase was found to be stable up to 75 days at -20 ºC. The potential of the enzyme in detergent industry was also investigated. It was not affected by detergent additives, but was found to be effective in removing oils from contaminated fabrics. This new lipase may have potential to be used in detergent industry.

Optimization of extracellular lipase production by halotolerant Bacillus sp. VITL8 using factorial design and applicability of enzyme in pretreatment of food industry effluents

The effect of macro and micronutrients of media components on lipase production by Bacillus sp. VITL8 was investigated using classical as well as statistical methods. Initially, the carbon source, nitrogen source, inducer and metal ions that affect lipase production were selected using the classical approach. Subsequently, selected nutrients along with other key factors (such as pH, agitation rate, gum acacia and tween 80) were investigated using Placket Burman design. Finally, three significant factors, viz., olive oil, peptone and tween 80 were studied using a 2² full factorial central composite design. Under optimized condition [6% (v/v) of olive oil, 0.7% peptone, 0.9% tween 80 and 25 h of incubation], the enzyme production was found to be 2.2 times higher with an overall enzyme production of 325.0 ± 1.4 U mL^-1. Laboratory scale experiment proved that the enzyme could be utilized for pretreatment of food industry effluent rich in fat and oil (dairy, bakery and poultry). The enzyme was capable of hydrolyzing more than 50% of the initial fat present in all these effluents and enabled the reduction in the levels of biological oxygen demand (BOD) and chemical oxygen demand (COD) of the effluent samples. The study thus reveals the utility of the lipase produced by the halotolerant bacterium Bacillus sp. VITL8 in the pretreatment of industrial effluents contaminated with oil and fat.HighlightsLipase production was enhanced by 2.2-fold using statistical methodsOne of the few reports on lipase production by a halotolerant bacterium, especially by Bacillus sp.Production of 325.0 ± 1.4 U mL^-1 lipase within 25 h by a halotolerant bacteriumPretreatment of food industry effluents using Bacillus sp. VITL8 lipaseImprovement in effluent quality within 8 h of treatment.

Enzymatic characterization of a NADH-dependent diaphorase from Lysinibacillus sp. strain PAD-91

Diaphorases are flavin-containing enzymes with potential applications in biotransfomation reactions, biosensor design and in vitro diagnostic tests. In this paper, we present recombinant expression, characterization and medium optimization of a lipoamide dehydrogenase (DLD) with NADH-dependent diaphorase activity from a Lysinibacillus sp. strain. DLD encoding sequence showed an open reading frame of 1413-bp encoding a 470 amino acid chain. Lysinibacillus sp. DLD catalyzed the NADH-dependent reduction of electron acceptors and exhibited diaphorase activity. The molecular mass of the isolated enzyme was found to be about 50 kDa, and determined to be a monomeric protein. The optimum pH and temperature for the catalytic activity of the enzyme was about pH 7.5 and 30 °C. The K_m and V_max values were estimated to be 0.025 mM and 1.33 μmol/min, respectively. Recombinant enzyme was optimally produced in fermentation medium containing 10 g/L sucrose, 25 g/L yeast extract, 5 g/L NaCl and 0.25 g/L MgSO₄. By Scaling up fermentation from flask to bioreactor, enzyme activity was increased to 487.5 U/ml. This study provides data on the identification, characterization and medium optimization of a NADH-dependent diaphorase from a newly isolated Lysinibacillus sp. PAD-91.

Medium Optimization for Improved Production of Dihydrolipohyl Dehydrogenase from Bacillus sphaericus PAD-91 in Escherichia coli

Dihydrolipohyl dehydrogenase (DLD) is a FAD-dependent enzyme that catalyzes the reversible oxidation of dihydrolipoamide. Herein, we report medium optimization for the production of a recombinant DLD with NADH-dependent diaphorase activity from a strain of Bacillus sphaericus PAD-91. The DLD gene that consisted of 1413 bp was expressed in Escherichia coli BL21 (DE3), and its enzymatic properties were studied. The composition of production medium was optimized using one-variable-at-a-time method followed by response surface methodology (RSM). B. sphaericus DLD catalyzed the reduction of lipoamide by NAD⁺ and exhibited diaphorase activity. The molecular weight of enzyme was about 50 kDa and determined to be a monomeric protein. Recombinant diaphorase showed its optimal activity at temperature of 30 °C and pH 8.5. K _m and V _max values with NADH were estimated to be 0.025 mM and 275.8 U/mL, respectively. Recombinant enzyme was optimally produced in fermentation medium containing 10 g/L sucrose, 25 g/L yeast extract, 5 g/L NaCl and 0.25 g/L MgSO₄. At these concentrations, the actual diaphorase activity was calculated to be 345.0 ± 4.1 U/mL. By scaling up fermentation from flask to bioreactor, enzyme activity was increased to 486.3 ± 5.5 U/mL. Briefly, a DLD with diaphorase activity from a newly isolated B. sphaericus PAD-91 was characterized and the production of recombinant enzyme was optimized using RSM technique.

Statistical optimization of medium components and physicochemical parameters to simultaneously enhance bacterial growth and esterase production by Bacillus thuringiensis

Bacillus thuringiensis is a genus extensively studied because of its high potential for biotechnological application, principally in biocontrol techniques. However, the optimization of esterase production by this strain has been scarcely studied. The aim of this work was to select and optimize the physicochemical and nutritional parameters that significantly influence the growth and esterase production of B. thuringiensis. To this purpose, 6 nutritional factors and 2 physicochemical parameters were evaluated using a Plackett-Burman design. Significant variables were optimized using a Box-Behnken design and through the desirability function to select the levels of the variables that simultaneously maximize microbial growth and esterase production. The optimum conditions resulting from simultaneous optimization of the responses under study were found to be 1 g/L glucose, 15 g/L peptone, and 3.25 g/L NaCl. Under these optimal conditions, it was possible to achieve a 2.5 log CFU/mL increase in bacterial growth and a 113-fold increase in esterase productivity, compared with minimal medium without agitation.

Lipase production from a novel thermo-tolerant and extreme acidophile Bacillus pumilus using palm oil as the substrate and treatment of palm oil-containing wastewater

The thermo-tolerant and extreme acidophilic microorganism Bacillus pumilus was isolated from the soil collected from a commercial edible-oil extraction industry. Optimisation of conditions for the lipase production was conducted using response surface methodology. The optimum conditions for obtaining the maximum activity (1,100 U/mL) of extremely acidic thermostable lipase were fermentation time, 96 h; pH, 1; temperature, 50 °C; and concentration of palm oil, 50 g/L. After purification, a 7.1-fold purity of lipase with specific activity of 5,173 U/mg protein was obtained. The molecular weight of the thermo-tolerant acidophilic lipase (TAL) was 55 kDa. The predominant amino acid in the TAL was glycine. The functional groups of lipase were determined by Fourier transform infrared spectroscopy. TAL exhibited enhanced activity (114 %) with dimethyl sulphoxide (20 %, v/v), and it showed a moderate activity with methanol, hexane and benzene. The optimum conditions for the treatment of palm oil in wastewater using the TAL were found to be time, 3 h; pH, 1; temperature, 50 °C with pseudo second-order kinetic constant of 1.88 × 10(-3) L mol(-1) min(-1). The Michaelis-Menten enzyme kinetic model and the nonlinear kinetic model were evaluated for the TAL. TAL established hydrolysis efficiency of 96 % for palm oil in wastewater at 50 °C.

Lipase production by Botryosphaeria ribis EC-01 on soybean and castorbean meals: optimization, immobilization, and application for biodiesel production

The effects of soybean and castorbean meals were evaluated separately, and in combinations at different ratios, as substrates for lipase production by Botryosphaeria ribis EC-01 in submerged fermentation using only distilled water. The addition of glycerol analytical grade (AG) and glycerol crude (CG) to soybean and castorbean meals separately and in combination, were also examined for lipase production. Glycerol-AG increased enzyme production, whereas glycerol-CG decreased it. A 2(4) factorial design was developed to determine the best concentrations of soybean meal, castorbean meal, glycerol-AG, and KH2PO4 to optimize lipase production by B. ribis EC-01. Soybean meal and glycerol-AG had a significant effect on lipase production, whereas castorbean meal did not. A second treatment (2(2) factorial design central composite) was developed, and optimal lipase production (4,820 U/g of dry solids content (ds)) was obtained when B. ribis EC-01 was grown on 0.5 % (w/v) soybean meal and 5.2 % (v/v) glycerol in distilled water, which was in agreement with the predicted value (4,892 U/g ds) calculated by the model. The unitary cost of lipase production determined under the optimized conditions developed ranged from US$0.42 to 0.44 based on nutrient costs. The fungal lipase was immobilized onto Celite and showed high thermal stability and was used for transesterification of soybean oil in methanol (1:3) resulting in 36 % of fatty acyl alkyl ester content. The apparent K m and V max were determined and were 1.86 mM and 14.29 μmol min(-1) mg(-1), respectively.

Optimization of lipase production by Burkholderia sp. using response surface methodology

Response surface methodology (RSM) was employed to optimize the extracellular lipase production by Burkholderia sp. HL-10. Preliminary tests showed that olive oil, tryptone and Tween-80 exhibited significant effects on the lipase production. The optimum concentrations of these three components were determined using a faced-centered central composite design (FCCCD). The analysis of variance revealed that the established model was significant (p < 0.01). The optimized medium containing 0.65% olive oil (v/v), 2.42% tryptone (w/v) and 0.15% Tween-80 (v/v) resulted in a maximum activity of 122.3 U/mL, about three fold higher than that in basal medium. Approximately 99% of validity of the predicted value was achieved.

New tools for exploring "old friends-microbial lipases"

Fat-splitting enzymes (lipases), due to their natural, industrial, and medical relevance, attract enough attention as fats do in our lives. Starting from the paper that we write, cheese and oil that we consume, detergent that we use to remove oil stains, biodiesel that we use as transportation fuel, to the enantiopure drugs that we use in therapeutics, all these applications are facilitated directly or indirectly by lipases. Due to their uniqueness, versatility, and dexterity, decades of research work have been carried out on microbial lipases. The hunt for novel lipases and strategies to improve them continues unabated as evidenced by new families of microbial lipases that are still being discovered mostly by metagenomic approaches. A separate database for true lipases termed LIPABASE has been created recently which provides taxonomic, structural, biochemical information about true lipases from various species. The present review attempts to summarize new approaches that are employed in various aspects of microbial lipase research, viz., screening, isolation, production, purification, improvement by protein engineering, and surface display. Finally, novel applications facilitated by microbial lipases are also presented.

Lipase from marine strain using cooked sunflower oil waste: production optimization and application for hydrolysis and thermodynamic studies

The marine strain Pseudomonas otitidis was isolated to hydrolyze the cooked sunflower oil (CSO) followed by the production of lipase. The optimum culture conditions for the maximum lipase production were determined using Plackett-Burman design and response surface methodology. The maximum lipase production, 1,980 U/ml was achieved at the optimum culture conditions. After purification, an 8.4-fold purity of lipase with specific activity of 5,647 U/mg protein and molecular mass of 39 kDa was obtained. The purified lipase was stable at pH 5.0-9.0 and temperature 30-80 °C. Ca(2+) and Triton X-100 showed stimulatory effect on the lipase activity. The purified lipase was highly stable in the non-polar solvents. The functional groups of the lipase were determined by Fourier transform-infrared (FT-IR) spectroscopy. The purified lipase showed higher hydrolytic activity towards CSO over the other cooked oil wastes. About 92.3 % of the CSO hydrolysis was observed by the lipase at the optimum time 3 h, pH 7.5 and temperature 35 °C. The hydrolysis of CSO obeyed pseudo first order rate kinetic model. The thermodynamic properties of the lipase hydrolysis were studied using the classical Van't Hoff equation. The hydrolysis of CSO was confirmed by FT-IR studies.

Significant improvement of Geobacillus thermoleovorans CCR11 thermoalkalophilic lipase production using response surface methodology

The medium optimization for the production of the Geobacillus thermoleovorans CCR11 thermoalkalophilic lipase was carried out in shake flask cultures using safflower high oleic oil. In the first step of optimization, a two level fractional factorial design allowed the identification of the concentration of nutrient broth and temperature as the main variables significantly affecting lipase production (P<0.05). In a second step, a D-optimal design was applied to determine the variables optimal values, defined as those yielding maximal lipase production in shaken flasks, thus demonstrating that the optimal concentration of nutrient broth was 3.8 g/l and the optimal culture temperature was 39.5°C. The model was experimentally validated, yielding a lipase production of 2283.70 ± 118.36 U/mL which represents a 6.7-fold increase in comparison to the non-optimized medium.

Identification of variables and value optimization for optimum lipase production by Bacillus pumilus RK31 using statistical methodology

In an effort to optimize the medium components, the statistical methodology was applied to achieve the optimum lipase production under shake flask conditions. The study was conducted in three steps on newly isolated Bacillus pumilus RK 31. In the first step, 12 different variables viz., Glucose, Olive oil, Yeast extract, Peptone, Tween 80, KH(2)PO(4), MgSO(4), NaNO(3), CaCl(2), Temperature, pH and Inoculum size were used to identify the most significant variables affecting lipase production using Plackett-Burman statistical design. Variance analysis showed that Olive oil, Tween 80 and KH(2)PO(4) played significant role in lipase production. In the second step, the values of the above-identified three variables were optimized by central composite design using three-level-three-factor approach. The optimum values of Olive oil, Tween 80 and KH(2)PO(4) were found to be 10.0ml/l, 5.0ml/l and 8.0g/l, respectively. KH(2)PO(4) was found to be responsible for maximum lipase production of 5.59IU/ml, experimental and 5.03IU/ml, predicted. In the third step, the optimum predicted values of the three factors and lipase production were verified by experimental approach. The amount of lipase produced in the designated medium was in agreement with that of predicted values by statistical method.

Isolation and identification of a lipase producing Bacillus sp. from soil

Lipase production in an indigenous lipolytic Bacillus sp. was detected in media containing Tributyrin-Tween 80 and Rhodamine B-Olive oil. The statistical Taguchi model was used to predict the optimum experimental conditions for bacterial growth and lipase production. Partial optimization was carried out for selection of salt base, oil, glucose, NH4Cl and yeast extract concentrations, inoculum density, pH and agitation. Maximum lipase activity was detected in the cell free supernatants of cultures grown in a medium containing 10 g L(-1) yeast extract, 15 g L(-1) NH4Cl, 3 g L(-1) K2HPO4, 1 g L(-1) KH2PO4, 0.1 g L(-1) MgSO4 x 7H2O, 2 g L(-1) glucose, 0.6 mM MgCl2 and 15 ml L(-1) olive oil, pH 8.5 at 30 degrees C for 24 h and low agitation. The amount oflipase produced in the designed medium was in agreement with the predicted values by the statistical method. 16S rRNA cloning and sequencing identified the test organism as Bacillus pumilus.

Production of an extracellular thermohalophilic lipase from a moderately halophilic bacterium, Salinivibrio sp. strain SA-2

Fifty strains of moderately halophilic bacteria were isolated from various salty environments in Iran. A strain designated as SA-2 was shown to be the best producer of extracellular lipase and was selected for further studies. Biochemical and physiological characterization along with 16S rDNA sequence analysis placed SA-2 in the genus Salinivibrio. The optimum salt, pH, temperature and aeration for enzyme production were 0.1 M KCl, pH 8, 35 degrees C and 150 rpm, respectively. The enzyme production was synchronized bacterial growth and reached a maximum level during the early-stationary phase in the basal medium containing 1 M NaCl. Triacylglycerols enhanced lipase production, while carbohydrates had inhibitory effects on it. The maximum lipase activity was obtained at pH 7.5, 50 degrees C and CaCl(2) concentration of 0.01 M. The enzyme was stable at pH range of 7.5-8 and retained 90% of its activity at 80 degrees C for 30 min. Different concentrations of NaNO(3), Na(2)SO(4), KCl and NaCl had no affect on lipase stability for 3 h. These results suggest that the lipase secreted by Salinivibrio sp. strain SA-2 is industrially important from the perspective of its tolerance to a broad temperature range, its moderate thermoactivity and its high tolerance to a wide range of salt concentrations (0-3 M NaCl).