Isolation and screening of Streptomyces sp. Al-Dhabi-49 from the environment of Saudi Arabia with concomitant production of lipase and protease in submerged fermentation

In this study, Streptomyces sp. Al-Dhabi-49 was isolated from the soil sample of Saudi Arabian environment for the simultaneous production of lipase and protease in submerged fermentation. The process parameters were optimized to enhance enzymes production. The production of protease and lipase was found to be maximum after 5 days of incubation (139.2 ± 2.1 U/ml, 253 ± 4.4 U/ml). Proteolytic enzyme increases with the increase in pH up to 9.0 (147.2 ± 3.6 U/ml) and enzyme production depleted significantly at higher pH values. In the case of lipase, production was maximum in the culture medium containing pH 8.0 (166 ± 1.3 U/ml). The maximum production of protease was observed at 40 °C (174 ± 12.1 U/ml) by Streptomyces sp. Lipase activity was found to be optimum at the range of temperatures (30–50 °C) and maximum production was achieved at 35 °C (168 ± 7.8 U/ml). Among the evaluated carbon sources, maltose significantly influenced on protease production (218 ± 12.8 U/ml). Lipase production was maximum when Streptomyces sp. was cultured in the presence of glucose (162 ± 10.8U/ml). Among various concentrations of peptone, 1.0% (w/v) significantly enhanced protease production. The lipase production was very high in the culture medium containing malt extract as nitrogen source (86 ± 10.2 U/ml). Protease production was maximum in the presence of Ca²⁺ as ionic source (212 ± 3.8 U/ml) and lipase production was enhanced by the addition of Mg²⁺ with the fermentation medium (163.7 ± 6.2 U/ml).     

Purification and characterization of two thermostable protease fractions from Bacillus megaterium

Protease enzyme from Bacillus megaterium was successively purified by ammonium sulfate precipitation, ion exchange chromatography on DEAE-cellulose and gel filtration chromatography on Sephadex G-200. The purification steps of protease resulted in the production of two protease fractions namely protease P1 and P2 with specific activities of 561.27 and 317.23 U mg^?1 of protein, respectively. The molecular weights of B. megaterium P1 and P2 were 28 and 25 KDa, respectively. The purified fractions P1 and P2 were rich in aspartic acid and serine. Relatively higher amounts of alanine, leucine, glycine, valine, thereonine valine and glutamic acid were also present. The maximum protease activities for both enzyme fractions were attained at 50 °C, pH 7.5, 1% of gelatine concentration and 0.5 enzyme concentrations. P1 and P2 fractions were more stable over pH 7.0–8.5 and able to prolong their thermal stability up to 80 °C. The effect of different inhibitors on the protease activity of both enzyme fractions was also studied. The enzyme was found to be serine active as it had been affected by lower concentrations of phenylmethylsulfonyl fluoride (PMSF). Complete dehairing of the enzyme-treated skin was achieved in 12 h, at room temperature.     

Partial purification of extracellular exo-inulinase from Ulocladium atrum

Eight fungal species were cultivated on the Czapek liquid medium and a good starting extracellular and intracellular exo-inulinase were selected. Extracellular inulinase from Ulocladium atrum was prepared in the presence of 1% inulin source and 0.2% sodium nitrate as the best carbon and nitrogen sources. Incubation for the U. atrum was increased till it reached its maximum (36 U/ml) at the sixth day of incubation at 30 °C which was the best temperature for the production of exo-inulinase. Effect of all metal ions inhibited inulase production by U. atrum. Exo-inulinase was purified by using ammonium sulfate precipitation, ion exchange chromatography on DEAE-cellulose. Three active inulinase forms INI, INII and INIII were resolved, each for DEAE cellulose. The specific activity of INI was 1915 U/mg protein which represented 2.65-fold purification over the crude extract with 42.8% recovery pooling of INI placed on CM cellulose chromatography and INI was resolved into INIa, INIb and INIc. The specific activity of INIa was 2479.2 U/mg protein which represented 3.43-fold purification over the crude extract with 24.2% recovery.     

Optimization and immobilization of amylase obtained from halotolerant bacteria isolated from solar salterns

The objective of the present study was to isolate halotolerant bacteria from the sediment sample collected from Marakanam Solar Salterns, Tamil Nadu, India using NaCl supplemented media and screened for amylase production. Among the 22 isolates recovered, two strains that had immense potential were selected for amylase production and designated as P1 and P2. The phylogenetic analysis revealed that P1 and P2 have highest homology with Pontibacillus chungwhensis (99%) and Bacillus barbaricus (100%). Their amylase activity was optimized to obtain high yield under various temperature, pH and NaCl concentration. P1 and P2 strain showed respective, amylase activity maximum at 35 °C and 40 °C; pH 7.0 and 8.0; 1.5 M and 1.0 M NaCl concentration. Further under optimized conditions, the amylase activity of P1 strain (49.6 U mL^?1) was higher than P2 strain. Therefore, the amylase enzyme isolated from P. chungwhensis P1 was immobilized in sodium alginate beads. Compared to the free enzyme form (49.6 U mL^?1), the immobilized enzyme showed higher amylase activity as 90.3 U mL^?1. The enzyme was further purified partially and the molecular mass was determined as 40 kDa by SDS–PAGE. Thus, high activity of amylase even under increased NaCl concentration would render immense benefits in food processing industries.     

Enhanced decolorization of Solar brilliant red 80 textile dye by an indigenous white rot fungus Schizophyllum commune IBL-06

An indigenously isolated white rot fungus, Schizophyllum commune IBL-06 was used to decolorize Solar brilliant red 80 direct dye in Kirk’s basal salts medium. In initial screening study, the maximum decolorization (84.8%) of Solar brilliant red 80 was achieved in 7 days shaking incubation period at pH 4.5 and 30 °C. Different physical and nutritional factors including pH, temperature and fungal inoculum density were statistically optimized through Completely Randomized Design (CRD), to enhance the efficiency of S. commune IBL-06 for maximum decolorization of Solar brilliant red 80 dye. The effects of inexpensive carbon and nitrogen sources were also investigated. Percent dye decolorization was determined by a reduction in optical density at the wavelength of maximum absorbance (λ_max, 590 nm). Under optimum conditions, the S. commune IBL-06 completely decolorized (100%) the Solar brilliant red 80 dye using maltose and ammonium sulfate as inexpensive carbon and nitrogen sources, respectively in 3 days. S. commune IBL-06 produced the three major ligninolytic enzymes lignin peroxidase (LiP), manganase peroxidase (MnP) and lacaase (Lac) during the decolorization of Solar brilliant red 80. LiP was the major enzyme (944 U/mL) secreted by S. commune IBL-06 along with comparatively lower activities of MnP and Laccase.     

Screening and characterization of alkaline protease produced by a pink pigmented facultative methylotrophic (PPFM) strain,MSF 46

Among the various bacterial isolates, the strain MSF 46 isolated from thorn forest soil samples, Tamil Nadu, India, was screened and characterized for its proteolytic activity. While the 16S rRNA sequencing and biochemical characterization revealed that the strain closely resembles Methylobacterium sp., methylotrophy of the strain was confirmed by the sequence homology of mxaF gene with other relative Methylobacterium sp. The alkaline protease was purified to homogeneity using DEAE cellulose ion exchange chromatography, with a 5.2-fold increase in specific activity and 34% recovery. The apparent molecular weight of the enzyme was determined as 40 kDa by SDS–PAGE study. The pH and temperature optima were 9.0 and 50 °C respectively with maximum protease activity of 1164 U/ml. Protease of MSF 46 was active in a broad pH range 7.0–11.0 with a maximum at pH 8.5 and exhibited thermostability at 50 °C. The enzyme activity was inhibited by PMSF but showed stability with Tween 20, Triton X-100 and hydrogen peroxide. Nearly 30% reduction in enzyme activity was observed in the presence of EDTA and DTT. The enzyme was effective in hydrolyzing gelatin, skimmed milk and blood clots and exhibited the potency for dehairing of goat skin and removing blood stain from cotton fabric. Significant morphological changes were observed under scanning electron microscope between cells grown in normal and casein amended medium. This first detailed report on the production of alkaline protease by a PPFM strain appears promising toward development of protocols for mass production, study of the molecular mechanism and other applications.     

Cold-active extracellular α-amylase production from novel bacteria Microbacterium foliorum GA2 and Bacillus cereus GA6 isolated from Gangotri glacier,Western Himalaya

Microbial cold-active α-amylases offer various economical and ecological benefits through energy savings by overcoming the heating requirements and also provide large biotechnological potentials. The objective of present study was to isolate new cold-adapted bacterial strains for production of cold-active α-amylases and their production optimization. Out of 30 cold-active α-amylase producing bacteria, isolated from soil of Gangotri glacier, Western Himalaya, India, two potential isolates, designated as GA2 and GA6, were selected for enzyme production. The α-amylase production was found maximum at 20 °C and pH 9 after 120 h incubation for GA2; and 20 °C and pH 10 after 96 h incubation for GA6. Among the carbon sources, lactose and glycerol was most suitable for GA2 and GA6, respectively. However, yeast extract and ammonium acetate was found best as nitrogen source by GA2 and GA6, respectively. Out of two potential isolates, maximum enzyme production (5870 units) was achieved with GA2 followed by GA6 (4746 units). GA2 was resistant to penicillin (10 μg) among tested antibiotics and as per plasmid curing results, amylase production was a plasmid mediated characteristic. The phylogenetic analysis revealed that GA2 and GA6 have highest homology with Microbacterium foliorum (99%) and Bacillus cereus (98%), respectively. This was the first report on cold-active α-amylase production by M. foliorum strain GA2 and B. cereus strain GA6, also their 16S rRNA sequences assigned an accession number HQ832574 and HQ832575, respectively from NCBI.     

Isolation of novel chitinolytic bacteria and production optimization of extracellular chitinase

Chitin is one of the most abundant biopolymers widely distributed in the marine and terrestrial environments. Chitinase enzyme has received increased attention due to its wide range of biotechnological applications, especially in agriculture for biocontrol of phytopathogenic fungi and harmful insects. In the present study, 58 bacterial isolates were screened for chitinolytic activity and on the basis of chitin hydrolysis zone 6 isolates were selected for chitinase production in broth media. Based on enzyme production, two most potent isolates identified as Aeromonas hydrophila HS4 and Aeromonas punctata HS6 were selected for further study. The effects of media composition and various fermentation conditions for optimization of chitinase production were studied. The maximum chitinase production was obtained at 37 °C and pH 8.0 after 24–48 h of incubation by HS4; and at 37 °C and pH 7 after 48 h incubation by HS6. Among the substrates colloidal chitin was the best for both the strains. Regarding carbon sources, starch (1%) was the best for both strains; while malt and yeast extract (1%) was found as the best nitrogen source for HS4 and HS6, respectively. Out of metal ions Mn²⁺ and Cu²⁺ enhanced enzyme production in the case of HS6. However, Co²⁺ was the most appropriate for HS4.     

Cyanobacterial biomass as N-supplement to agro-waste for hyper-production of laccase from Pleurotus ostreatus in solid state fermentation

The potential application of dry biomass of a cyanobacterium Anacystis nidulans as a supplement in SSF for the production of laccase from Pleurotus ostreatus was evaluated. Experiments were carried out in solid culture using groundnut shell as a basic substrate supplemented with four independent nitrogen sources (ammonium sulphate, urea, yeast extract and dry powder of cyanobacteria). All the four supplements enhanced the enzyme yield, and yeast extract showed precedence over inorganic nitrogenous sources. However, when dry biomass of A. nidulans was used as an additive to groundnut shell (agricultural residues), it supported maximum cell growth (56.83 ± 5.56 mg/g dry substrate) and laccase production (49.21 ± 4.89 U/g dry substrate). Addition of 1 mM copper salt in the medium containing groundnut shell supplemented with yeast extract gave laccase activity of 32.64 ± 3.4 U/g dry substrate. When dry powder of cyanobacterial biomass was used as N-supplement, laccase production enhanced to 65.42 ± 6.48 U/g dry substrate. In addition to the enhancement to enzyme production inhibitory effects of high concentrations of copper was also diminished in the medium having dry cyanobacterial biomass. This study, forms the first report on the potential application of cyanobacterial biomass as an additive for production of laccase by Pleurotus ostraetus MTCC 1804 in solid state fermentation and has relevance in scale-up production of this fungal enzyme of commercial significance.     

Purification and characterization of solvent stable,alkaline protease from Bacillus firmus CAS 7 by microbial conversion of marine wastes and molecular mechanism underlying solvent stability

A marine bacterium Bacillus firmus CAS 7 produced protease in the medium supplemented with 3:1 shrimp and crab shell powder at 55 °C and was purified with the specific activity of 473.4 U/mg. The purified protease was highly stable up to 70 °C, pH 11.0 and 30% NaCl. The protease purified was quite stable in the presence of anionic and non-ionic surfactants and organic solvents. The molecular dynamics simulation confirmed that the competition between organic solvent and water for the enzyme surface was comparatively higher in water–miscible organic solvent which is responsible for organic solvent stability. The purified protease from B. firmus CAS 7 could be greatly useful to develop industrial processes performed under harsh conditions or with denaturants and organic solvents. The protease production by microbial conversion of marine wastes suggested its potential utilization to generate high value-added products.     

Localization and production of novel l-asparaginase from Pectobacterium carotovorum MTCC 1428

Bacterial l-asparaginase has been widely used as therapeutic agent in the treatment of various lymphoblastic leukemia diseases. Studies on localization and production of novel glutaminase-free l-asparaginase were performed using Pectobacterium carotovorum MTCC 1428. The localization of l-asparaginase was carried out using cell fractionation techniques. The activity of l-asparaginase was found to be 85 and 77% in the cytoplasm of P. carotovorum MTCC 1428 grown on medium containing l-asparagine and combination of l-asparagine and glucose respectively. Among the tested carbon sources, l-asparagine or the combination of l-asparagine and glucose was found to be the most suitable carbon sources to maximize the production of l-asparaginase. The maximum production of l-asparaginase was observed to be 14.56 U/ml (26.92 U/mg of protein) at 4 and 2 g/l of l-asparagine and glucose respectively. Yeast extract, l-asparagine and peptone have shown significant effect on the production of l-asparaginase. P. carotovorum MTCC 1428 has assimilated l-asparagine as an essential carbon source for maximizing the production of l-asparaginase.     

Purification and characterization of thermostable organic solvent-stable protease from Aeromonas veronii PG01

A mesophilic bacterium, Aeromonas veronii PG01, isolated from industrial wastes produced an extracellular thermostable organic solvent tolerant protease. The optimum condition for cell growth and protease production was pH 7.0 and 30 °C. The protease produced was purified 53-fold to homogeneity with overall yield of 32%, through ammonium sulphate precipitation, ion-exchange and gel permeation chromatography (GPC). The molecular weight, as determined by GPC–HPLC, was found to be about 67 kDa. SDS-PAGE revealed that the enzyme consisted of two subunits, with molecular weight of 33 kDa. The protease was active in broad range of pH from 6.0 to 10.0 with optimum activity at pH 7.5. The optimum temperature for this protease was 60 °C. The enzyme remained active after incubation at 50–60 °C for 1 h. This enzyme was stable and active after incubation with benzene and it was activated 1.3- and 1.5-fold by n-hexane and n-dodecane, respectively. This protease was inhibited completely by the classic metalloprotease inhibitor 1,10-phenanthroline and partially by the metal chelator EDTA but not by the serine protease inhibitor PMSF. The PG01 protease was found to contain 1.901 mol of zinc per mole of enzyme upon analysis by Inductively coupled plasma-optical emission spectroscopy. The thermostable and solvent tolerance property make it an attractive and promising biocatalyst for enzyme mediated synthesis.     

Application of statistical experimental design for optimization of keratinases production by Bacillus pumilus A1 grown on chicken feather and some biochemical properties

A new keratinolytic enzyme-producing bacterium was isolated from slaughter house polluted water and identified as Bacillus pumilus A1. Medium composition and culture conditions for the keratinases production by B. pumilus A1 were optimized using two statistical methods: Plackett–Burman design applied to find the key ingredients and conditions for the best yield of enzyme production and central composite design used to optimize the concentration of the five significant variables: feathers meal, soy peptone, NaCl, KCl, and KH₂PO₄. The medium optimization resulted in a 3.4-fold increase in keratinase production (87.73 U/ml) compared to that of the initial medium (25.9 U/ml). The zymography analysis shows the presence of at least five keratinolytic enzymes. The keratinolytic activity of the extracellular proteinases was examined by incubation with non-autoclaved chicken feathers. Complete solubilisation of whole feathers was observed after a 6-h incubation at temperatures ranging from 45 °C to 60 °C. The crude enzyme exhibited maximal activity at 60 °C and pH 8.5 or 55 °C and pH 9.0 using casein or keratin as substrates, respectively.     

Parameter’s optimization and kinetics study of α-amylase enzyme of Bacillus sp. MB6 isolated from vegetable waste

α-Amylase, a very critical enzyme for hydrolysis of starch into simple sugar and it has various applications in industrial settings. This study reports the identification of Bacillus sp. MB6 which produces increased amount of enzyme from less required resources. To optimize the yield of enzyme, we used various combinations of parameters. The most optimized conditions for production of amylase enzyme from the bacterium Bacillus sp. MB6 are pH of 6, temperature of 37 °C, and incubation period of 48 h. Condition of enzymatic activity were also examined and the results show that pH of 6, a temperature of 55 °C, and a reaction time of 30 min are the best available conditions for its activity. Purification of enzyme by 1.63 fold enhanced the specific activity of enzyme based upon its activity analysis as compared with unpurified enzyme. Enzyme kinetics studies show the Michaelis constant (Km) to be 5.45 mg/ml and maximum velocity of the reaction (Vmax) to be 24.15 mg/ml/min. In conclusion, we report enzyme production and purification methodology that exhibit better yield of alpha-amylase for commercial applications.     

Degradation of chitin and production of bioactive materials by bioconversion of squid pens

Serratia marcescens TKU011, a protease- and chitosanase-producing bacterium, the optimized condition for protease and chitosanase production was found after the media were heated at 121 °C for 120 min and the culture was shaken at 25 °C for 5 days in 100 mL of medium containing 1% squid pen powder (SPP) (w/v), 0.1% K₂HPO₄, and 0.05% MgSO₄. An extracellular metalloprotease with novel properties of solvent stable, and alkaline was purified from the culture supernatant of S. marcescens TKU011 with squid pen wastes as the sole carbon/nitrogen source. The enzyme was a monomeric protease with a molecular mass of 48–50 kDa by SDS–PAGE and gel filtration chromatography. The optimum pH, optimum temperature, pH stability, and thermal stability of TKU011 protease were 8, 50 °C, pH 5–11, and <40 °C, respectively. Besides protease and chitosanase, with this method, deproteinization of squid pen for β-chitin, the production of peptide and reducing sugar may be useful for biological applications.     

Chitin and chitosan preparation from shrimp shells using optimized enzymatic deproteinization

Different crude microbial proteases were applied for chitin extraction from shrimp shells. A Box–Behnken design with three variables and three levels was applied in order to approach the prediction of optimal enzyme/substrate ratio, temperature and incubation time on the deproteinization degree with Bacillus mojavensis A21 crude protease. These optimal conditions were: an enzyme/substrate ratio of 7.75 U/mg, a temperature of 60 °C and an incubation time of 6 h allowing to predict 94 ± 4% deproteinization. Experimentally, in these optimized conditions, a deproteinization degree of 88 ± 5% was obtained in good agreement with the prediction and larger than values generally given in literature. The deproteinized shells were then demineralized to obtain chitin which was converted to chitosan by deacetylation and its antibacterial activity against different bacteria was investigated. Results showed that chitosan dissolved at 50 mg/ml markedly inhibited the growth of most Gram-negative and Gram-positive bacteria tested.     

Purification and characterization of an extremely dimethylsulfoxide tolerant esterase from a salt-tolerant Bacillus species isolated from the marine environment of the Sundarbans

A Bacillus sp. isolated from the Sundarbans region of the Bay of Bengal (NCBI GenBank Accession no. AY723697) which can tolerate 10% (w/v) NaCl, produces esterase optimally in Marine Broth 2216 medium containing 1% (w/v) NaCl. The enzyme was purified 42.7-fold with 6.4% recovery, (specific activity 569.2 U/mg protein) by ammonium sulphate precipitation followed by anion and cation exchange chromatography. The serine type esterolytic enzyme has a molecular weight of 35.0 kDa and is denatured into polypeptides of molecular weights 20 kDa and 15 kDa. The esterase was most active at pH 8.0, the pH of the seawater at the site of collection and is stable in the pH range 6.0–9.0. The optimum temperature of activity of this esterase is 45 °C and the enzyme is very stable after 1 h pre-incubation at 50 °C. Our esterase shows about 100% activity when incubated with 1 M NaCl, the activity drops to about 50% when incubated with 2.5 M sodium chloride and the enzyme is completely inactivated when 4 M NaCl is present during reaction. The esterase is almost inactivated by Ca²⁺, Hg²⁺ and Fe³⁺ ions, reducing agents and detergent. Interestingly, Co²⁺, a known inhibitor of many enzymes, preserved 70% of the activity of this esterase. Specific activity of the esterase increases more than twofold in the presence of water-miscible organic solvents as compared to that in aqueous buffer. When incubated for a period of 10 days in the presence of 30–70% dimethylsufoxide (DMSO), the specific activity increased by approximately two–threefold compared to the enzyme in aqueous buffer throughout the period of study. Specific activity between 1283 and 525 U/mg was maintained by our enzyme when incubated with 50% DMSO for 10 days. The enzyme was most active on p-nitrophenyl acetate, ethyl acetate, alpha isomer of naphthyl acetate but shows relatively lesser activity towards triglycerides of fatty acids. Certain characteristics, such as molecular weight, effects of NaCl, metal ions (Zn²⁺ and Mg²⁺) and reactivity towards para-nitrophenyl and aliphatic esters were strikingly similar to already described marine bacterial derived esterases. Extreme stability in DMSO could make this enzyme a potential immobilized biocatalyst for application in non-aqueous based continuous bioprocesses. Higher specific activity and purification factor, better thermo tolerance and solvent stability would make our enzyme more attractive for biotechnological applications than the marine microbial derived esterases described so far.     

Expression,characterization and mutagenesis of an FAD-dependent glucose dehydrogenase from Aspergillus terreus

An FAD-dependent glucose dehydrogenase (FAD-GDH) from Aspergillus terreus NIH2624 was expressed in Escherichia coli with a yield of 228 ± 16 U/L of culture. Co-expression with chaperones DnaK/DnaJ/GrpE and osmotic stress induced by simple carbon sources enhanced productivity significantly, improving the yield to 23883 ± 563 U/L after optimization. FAD-GDH was purified in two steps with the specific activity of 604 U/mg. Using d-glucose as substrate, the optimal pH and temperature for FAD-GDH were determined to be 7.5 and 50 °C, respectively. Activity was stable across the pH range 3.5–9.0, and the half-life was 52 min at 42 °C. K_m and V_max were calculated as 86.7 ± 5.3 mM and 928 ± 35 U/mg, and the molecular weight was approximately 65.6 kDa based on size exclusion chromatography, indicating a monomeric structure. The 3D structure of FAD-GDH was simulated by homology modelling using the structure of A. niger glucose oxidase (GOD) as template. From the model, His551, His508, Asn506 and Arg504 were identified as key residues, and their importance was verified by site-directed mutagenesis. Furthermore, three additional mutants (Arg84Ala, Tyr340Phe and Tyr406Phe) were generated and all exhibited a higher degree of substrate specificity than the native enzyme. These results extend our understanding of the structure and function of FAD-GDH, and could assist potential commercial applications.     

Novel minor lipase from Rhizopus chinensis during solid-state fermentation: Biochemical characterization and its esterification potential for ester synthesis

Rhizopus chinensis produces two lipases that catalyze ester synthesis when cultured under solid-state fermentation. The Lip2 was purified to homogeneity by ammonium sulphate precipitation, hydrophobic interaction chromatography and gel filtration chromatography. It has an apparent molecular weight of 33 kDa estimated from SDS–PAGE and 32 kDa calculated from analytical gel permeation, with synthetic activity and purification fold of 96.8 U/mg and 138.3, respectively. Maximum hydrolytic activity was obtained at pH 8.0–8.5 and 40 °C using pNPP as substrate. Slight activation of the enzyme was observed when Mn²⁺ is present. The enzyme was most active on p-nitrophenyl laurate (C12). The purified lipase exhibited maximum synthetic activity at pH memory of 6.0 and 30 ^oC. Most of ethyl esters synthesized by lyophilized enzyme achieved good yields (>90%), and caprylic acid served as the best acyl donor. The enzyme presented a particular affinity for ethanol, n-propanol and n-hexanol, with conversion of 92%, 93% and 92%, respectively, after 20 h incubation.     

Immobilization of acidic lipase derived from Pseudomonas gessardii onto mesoporous activated carbon for the hydrolysis of olive oil

Mesoporous activated carbon (MAC) derived from rice husk is used for the immobilization of acidic lipase (ALIP) produced from Pseudomonas gessardii. The purified acidic lipase had the specific activity and molecular weight of 1473 U/mg and 94 kDa respectively. To determine the optimum conditions for the immobilization of lipase onto MAC, the experiments were carried out by varying the time (10–180 min), pH (2–8), temperature (10–50 °C) and the initial lipase activity (49 × 10³, 98 × 10³, 147 × 10³ and 196 × 10³ U/l in acetate buffer). The optimum conditions for immobilization of acidic lipase were found to be: time—120 min; pH 3.5; temperature—30 °C, which resulted in achieving a maximum immobilization of 1834 U/g. The thermal stability of the immobilized lipase was comparatively higher than that in its free form. The free and immobilized enzyme kinetic parameters (K_m and V_max) were found using Michaelis–Menten enzyme kinetics. The K_m values for free enzyme and immobilized one were 0.655 and 0.243 mM respectively. The immobilization of acidic lipase onto MAC was confirmed using Fourier Transform-Infrared Spectroscopy, X-ray diffraction analysis and scanning electron microscopy.