Thermostable lipase of Bacillus Stearothermophilus: high-level production, purification, and calcium-dependent thermostability

Production, purification, properties and current perspectives for modification and application of microbial lipases

With the industrialization and development of modern science, the application of enzymes as green and environmentally friendly biocatalysts in industry has been increased widely. Among them, lipase (EC. 3.1.1.3) is a very prominent biocatalyst, which has the ability to catalyze the hydrolysis and synthesis of ester compounds. Many lipases have been isolated from various sources, such as animals, plants and microorganisms, among which microbial lipase is the enzyme with the most diverse enzymatic properties and great industrial application potential. It therefore has promising applications in many industries, such as food and beverages, waste treatment, biofuels, leather, textiles, detergent formulations, ester synthesis, pharmaceuticals and medicine. Although many microbial lipases have been isolated and characterized, only some of them have been commercially exploited. In order to cope with the growing industrial demands and overcome these shortcomings to replace traditional chemical catalysts, the preparation of new lipases with thermal/acid-base stability, regioselectivity, organic solvent tolerance, high activity and yield, and reusability through excavation and modification has become a hot research topic.

Biochemical characterization, substrate and stereoselectivity of an outer surface putative α/β hydrolase from the pathogenic Leptospira

The genome of pathogenic leptospira encodes a plethora of outer surface and secretory proteins. The outer surface or secreted α/β hydrolases in a few pathogenic organisms are crucial virulent factors. They hydrolyze host immune factors and pathogen's immune-activating ligands, which help pathogens to evade the host's innate immunity. In this study, we report biochemical characterizations, substrate and stereoselectivity of one of the leptospiral outer surface putative α/β hydrolases, IQB77_09235 (LABH). Purified LABH displayed better kinetic parameters towards small water-soluble esters such as p-nitrophenyl acetate and p-nitrophenyl butyrate. The LABH exhibited moderate thermostability and displayed a pH optimum of 8.5. Remarkably, a phylogenetic study suggested that LABH does not cluster with other characterized bacterial esterases or lipases. Protein structural modeling revealed that some structural features are closely associated with Staphylococcus hycus lipase (SAH), a triacylglycerol hydrolase. The hydrolytic activity of the protein was found to be inhibited by a lipase inhibitor, orlistat. Biocatalytic application of the protein in the kinetic resolution of racemic 1-phenylethyl acetate reveals excellent enantioselectivity (E > 500) in the production of (R)-1-phenylethanol, a valuable chiral synthon in several industries. To our knowledge, this is the first detailed characterization of outer surface α/β hydrolases from leptospiral spp.

The main Aflatoxin B1 degrading enzyme in Pseudomonas putida is thermostable lipase

Aflatoxin B1 is a carcinogenic and mutagenic mycotoxin mainly produced by Aspergillus flavus and A. parasiticus, and prevalent in food and feed. Microbial degradation is a promising strategy which can be performed in mild and environmental friendly condition. This work is a step towards identifying the enzyme responsible for biodegradation of AFB1 by P. putida. Experiments were performed with P. putida lysate and compared with commercial lipase to see the degradation efficiency and the temperature stability. The cell free lysate of P. putida efficiently degraded AFB1 in a range of temperature from 20 to 90 °C. The lysate is thermostable and could retain its activity on pre-incubation up to 90 °C. Highest rate of degradation was observed at 70 °C. These observations show that the P. putida lysate is not only stable at higher temperatures but its enzymatic activity increases after incubation. Similarly, the commercial lipase degraded AFB1 efficiently. However, both, the P. putida lysate and lipase ceased degradation in presence of a lipase inhibitor, HgCl₂. The Hill function accurately predicted enzyme activity at various times and temperatures. Like lipase, the lysate also hydrolyses the p-nitrophenyl palmitate to p-nitrophenol. Kinetic parameters such as V_max, K_m and n values are good measures to characterize the lysate response with respect to changing paranitro phenyl palmitate levels. The substrate specificity test of lipase showed linear correlation between the absorbance at 410 nm vs amount of product paranitro phenol. The value of Km, Vmax and n are 0.62 mM, 355.7 μmol min⁻¹ and 1.29, respectively. The lipase gene presence in P. putida was confirmed using PCR technique. These observations indicate that the main enzyme responsible for AFB1 degradation by P. putida is lipase. Thus, lipase as a multifunctional biocatalyst provides a promising future for a variety of industries and may also help to ensure the food safety by degrading the mycotoxins.

Serratia sp. scl1: isolation of a novel thermostable lipase producing microorganism which holds industrial importance

Lipase being a hydrolysable enzyme plays a major role in serving various purposes of the industries. Thus, it is very important to have a sustainable and efficient source of this enzyme. In this present study, several microorganisms were isolated from medicinal effluent of a pharmaceutical industry that could produce efficient lipase activity. Among these isolates, a designated strain scl1 was isolated and based on the molecular and biochemical characterisation was tentatively assigned to the genus Serratia. Preliminary studies confirmed the strain scl1 was found to exhibit the highest production of lipase at a temperature and pH of 35 °C and 7, respectively under the incubation for 48 h. Further, the lipase activity was measured by following spectrophotometric method using pNPP as the substrate in which the Km and Vmax of the crude enzyme was found to be 3.349 × 10^-3 M and 5.68 × 10^-1 unit/mL, respectively. The extracellular crude lipase was found to show a temperature and pH optima of 75 °C and 8, respectively which gave a strong indication that the enzyme appeared to be highly thermostable. This study revealed the strain scl1 is able to produce a thermostable lipase which can meet the needs of the modern-day industrialization techniques. However, more work is required to purify the enzyme and get it ready for commercial applications.

Extremophilic lipases for industrial applications: A general review

With industrialization and development in modern science enzymes and their applications increased widely. There is always a hunt for new proficient enzymes with novel properties to meet specific needs of various industrial sectors. Along with the high efficiency, the green and eco-friendly side of enzymes attracts human attention, as they form a true answer to counter the hazardous and toxic conventional industrial catalyst. Lipases have always earned industrial attention due to the broad range of hydrolytic and synthetic reactions they catalyse. When these catalytic properties get accompanied by features like temperature stability, pH stability, and solvent stability lipases becomes an appropriate tool for use in many industrial processes. Extremophilic lipases offer the same, thermostable: hot and cold active thermophilic and psychrophilic lipases, acid and alkali resistant and active acidophilic and alkaliphilic lipases, and salt tolerant halophilic lipases form excellent biocatalyst for detergent formulations, biofuel synthesis, ester synthesis, food processing, pharmaceuticals, leather, and paper industry. An interesting application of these lipases is in the bioremediation of lipid waste in harsh environments. The review gives a brief account on various extremophilic lipases with emphasis on thermophilic, psychrophilic, halophilic, alkaliphilic, and acidophilic lipases, their sources, biochemical properties, and potential applications in recent decades.

Thermostable lipases and their dynamics of improved enzymatic properties

Thermal stability is one of the most desirable characteristics in the search for novel lipases. The search for thermophilic microorganisms for synthesising functional enzyme biocatalysts with the ability to withstand high temperature, and capacity to maintain their native state in extreme conditions opens up new opportunities for their biotechnological applications. Thermophilic organisms are one of the most favoured organisms, whose distinctive characteristics are extremely related to their cellular constituent particularly biologically active proteins. Modifications on the enzyme structure are critical in optimizing the stability of enzyme to thermophilic conditions. Thermostable lipases are one of the most favourable enzymes used in food industries, pharmaceutical field, and actively been studied as potential biocatalyst in biodiesel production and other biotechnology application. Particularly, there is a trade-off between the use of enzymes in high concentration of organic solvents and product generation. Enhancement of the enzyme stability needs to be achieved for them to maintain their enzymatic activity regardless the environment. Various approaches on protein modification applied since decades ago conveyed a better understanding on how to improve the enzymatic properties in thermophilic bacteria. In fact, preliminary approach using advanced computational analysis is practically conducted before any modification is being performed experimentally. Apart from that, isolation of novel extremozymes from various microorganisms are offering great frontier in explaining the crucial native interaction within the molecules which could help in protein engineering. In this review, the thermostability prospect of lipases and the utility of protein engineering insights into achieving functional industrial usefulness at their high temperature habitat are highlighted. Similarly, the underlying thermodynamic and structural basis that defines the forces that stabilize these thermostable lipase is discussed. KEY POINTS: • The dynamics of lipases contributes to their non-covalent interactions and structural stability. • Thermostability can be enhanced by well-established genetic tools for improved kinetic efficiency. • Molecular dynamics greatly provides structure-function insights on thermodynamics of lipase.

Kinetic and thermodynamic characterization of novel alkaline lipase from halotolerant Bacillus gibsonii

A halotolerant bacterial strain isolated and identified as Bacillus gibsonii was used for extracellular lipase production. The bacterial strain was able to grow up to 1200 mM salt concentration and showed maximum growth at 600 mM NaCl concentration. The present study includes production of extracellular lipase enzyme and characterization of partially purified lipase with respect to its kinetic and thermodynamic behaviour. Maximum lipase activity was observed at 60 °C under alkaline pH (9.0) condition. The kinetic parameters such as V_max, K_m and K_cat were calculated as 158.73 U/mL, 0.539 mM and 483.93 min^-1 at 60 °C, respectively, suggested thermostable nature of the enzyme. The thermal inactivation energy [E_a(d)] was calculated as 66.98 kJ/mol. The values of Gibb's free energy (86.31 kJ/mol), enthalpy (64.26 kJ/mol) and entropy (- 66.21 × 10^-3 kJ/mol/K) for the enzyme inactivation obtained at 60 °C corroborated the assumption that 60 °C was the optimum temperature. Further, the deactivation rate constant (k_d) values calculated at 60 °C and 80 °C were found to be 0.0907 and 0.182 min^-1, respectively, which suggested that enzyme was more stable at 60 °C and it was partly inactivated at 80 °C.

Recent advances in biocatalysts engineering for polyethylene terephthalate plastic waste green recycling

The massive waste of poly(ethylene terephthalate) (PET) that ends up in the landfills and oceans and needs hundreds of years for degradation has attracted global concern. The poor stability and productivity of the available PET biocatalysts hinder their industrial applications. Active PET biocatalysts can provide a promising avenue for PET bioconversion and recycling. Therefore, there is an urgent need to develop new strategies that could enhance the stability, catalytic activity, solubility, productivity, and re-usability of these PET biocatalysts under harsh conditions such as high temperatures, pH, and salinity. This has raised great attention in using bioengineering strategies to improve PET biocatalysts' robustness and catalytic behavior. Herein, historical and forecasting data of plastic production and disposal were critically reviewed. Challenges facing the PET degradation process and available strategies that could be used to solve them were critically highlighted and summarized. In this review, we also discussed the recent progress in enzyme bioengineering approaches used for discovering new PET biocatalysts, elucidating the degradation mechanism, and improving the catalytic performance, solubility, and productivity, critically assess their strength and weakness and highlighting the gaps of the available data. Discovery of more potential PET hydrolases and studying their molecular mechanism extensively via solving their crystal structure will widen this research area to move forward the industrial application. A deeper knowledge of PET molecular and degradation mechanisms will give great insight into the future identification of related enzymes. The reported bioengineering strategies during this review could be used to reduce PET crystallinity and to increase the operational temperature of PET hydrolyzing enzymes.

Ion-Pair Interaction and Hydrogen Bonds as Main Features of Protein Thermostability in Mutated T1 Recombinant Lipase Originating from Geobacillus zalihae

A comparative structure analysis between space- and an Earth-grown T1 recombinant lipase from Geobacillus zalihae had shown changes in the formation of hydrogen bonds and ion-pair interactions. Using the space-grown T1 lipase validated structure having incorporated said interactions, the recombinant T1 lipase was re-engineered to determine the changes brought by these interactions to the structure and stability of lipase. To understand the effects of mutation on T1 recombinant lipase, five mutants were developed from the structure of space-grown T1 lipase and biochemically characterized. The results demonstrate an increase in melting temperature up to 77.4 °C and 76.0 °C in E226D and D43E, respectively. Moreover, the mutated lipases D43E and E226D had additional hydrogen bonds and ion-pair interactions in their structures due to the improvement of stability, as observed in a longer half-life and an increased melting temperature. The biophysical study revealed differences in β-Sheet percentage between less stable (T118N) and other mutants. As a conclusion, the comparative analysis of the tertiary structure and specific residues associated with ion-pair interactions and hydrogen bonds could be significant in revealing the thermostability of an enzyme with industrial importance.

Changes of Thermostability, Organic Solvent, and pH Stability in Geobacillus zalihae HT1 and Its Mutant by Calcium Ion

Thermostable T1 lipase from Geobacillus zalihae has been crystallized using counter-diffusion method under space and Earth conditions. The comparison of the three-dimensional structures from both crystallized proteins show differences in the formation of hydrogen bond and ion interactions. Hydrogen bond and ion interaction are important in the stabilization of protein structure towards extreme temperature and organic solvents. In this study, the differences of hydrogen bond interactions at position Asp43, Thr118, Glu250, and Asn304 and ion interaction at position Glu226 was chosen to imitate space-grown crystal structure, and the impact of these combined interactions in T1 lipase-mutated structure was studied. Using space-grown T1 lipase structure as a reference, subsequent simultaneous mutation D43E, T118N, E226D, E250L, and N304E was performed on recombinant wild-type T1 lipase (wt-HT1) to generate a quintuple mutant term as 5M mutant lipase. This mutant lipase shared similar characteristics to its wild-type in terms of optimal pH and temperature. The stability of mutant 5M lipase improved significantly in acidic and alkaline pH as compared to wt-HT1. 5M lipase was highly stable in organic solvents such as dimethyl sulfoxide (DMSO), methanol, and n-hexane compared to wt-HT1. Both wild-type and mutant lipases were found highly activated in calcium as compared to other metal ions due to the presence of calcium-binding site for thermostability. The presence of calcium prolonged the half-life of mutant 5M and wt-HT1, and at the same time increased their melting temperature (T_m). The melting temperature of 5M and wt-HT1 lipases increased at 8.4 and 12.1 °C, respectively, in the presence of calcium as compared to those without. Calcium enhanced the stability of mutant 5M in 25% (v/v) DMSO, n-hexane, and n-heptane. The lipase activity of wt-HT1 also increased in 25% (v/v) ethanol, methanol, acetonitrile, n-hexane, and n-heptane in the presence of calcium. The current study showed that the accumulation of amino acid substitutions D43E, T118N, E226D, E250L, and N304E produced highly stable T1 mutant when hydrolyzing oil in selected organic solvents such as DMSO, n-hexane, and n-heptane. It is also believed that calcium ion plays important role in regulating lipase thermostability.

X-ray structure and characterization of a thermostable lipase from Geobacillus thermoleovorans

Thermo-alkalophilic bacterium, Geobacillus thermoleovorans secrets many enzymes including a 43 kDa extracellular lipase. Significant thermostability, organic solvent stability and wide substrate preferences for hydrolysis drew our attention to solve its structure by crystallography. The structure was solved by molecular replacement method and refined up to 2.14 Å resolution. Structure of the lipase showed an alpha-beta fold with 19 α-helices and 10 β-sheets. The active site remains covered by a lid. One calcium and one zinc atom was found in the crystal. The structure showed a major difference (rmsd 5.6 Å) from its closest homolog in the amino acid region 191 to 203. Thermal unfolding of the lipase showed that the lipase is highly stable with T_m of 76 °C. ¹³C NMR spectra of products upon triglyceride hydrolysate revealed that the lipase hydrolyses at both sn-1 and sn-2 positions with equal efficiency.

The Lid Domain in Lipases: Structural and Functional Determinant of Enzymatic Properties

Lipases are important industrial enzymes. Most of the lipases operate at lipid–water interfaces enabled by a mobile lid domain located over the active site. Lid protects the active site and hence responsible for catalytic activity. In pure aqueous media, the lid is predominantly closed, whereas in the presence of a hydrophobic layer, it is partially opened. Hence, the lid controls the enzyme activity. In the present review, we have classified lipases into different groups based on the structure of lid domains. It has been observed that thermostable lipases contain larger lid domains with two or more helices, whereas mesophilic lipases tend to have smaller lids in the form of a loop or a helix. Recent developments in lipase engineering addressing the lid regions are critically reviewed here. After on, the dramatic changes in substrate selectivity, activity, and thermostability have been reported. Furthermore, improved computational models can now rationalize these observations by relating it to the mobility of the lid domain. In this contribution, we summarized and critically evaluated the most recent developments in experimental and computational research on lipase lids.

Sequential Detection of Thermophilic Lipase and Protease by Zymography

Lipase and protease present in cell-free fractions of thermophilic Bacillus sp. cultures were analyzed by polyacrylamide gel (PAG) electrophoresis. After run, the gel is electrotransferred to another PAG copolymerized with glycerol tributyrate, olive oil, and gelatin. This multi-substrate gel was incubated first for lipase detection, until bands appeared, and then stained with Coomassie for protease detection. Advantages of this sequential procedure are the detection of two different enzyme activities on a single PAG, beside time and resource saving.

Cloning, expression, purification and characterization of lipase from Bacillus licheniformis, isolated from hot spring of Himachal Pradesh, India

In the present investigation, a gene encoding extracellular lipase was cloned from a Bacillus licheniformis. The recombinant protein containing His-tag was expressed as inclusion bodies in Esherichia coli BL21DE3 cells, using pET-23a as expression vector. Expressed protein purified from the inclusion bodies demonstrated ~22 kDa protein band on 12 % SDS-PAGE. It exhibited specific activity of 0.49 U mg⁻¹ and % yield of 8.58. Interestingly, the lipase displayed activity at wide range of pH and temperature, i.e., 9.0–14.0 pH and 30–80 °C, respectively. It further demonstrated ~100 % enzyme activity in presence of various organic solvents. Enzyme activity was strongly inhibited in the presence of β-ME. Additionally, the serine and histidine modifiers also inhibited the enzyme activities strongly at all concentrations that suggest their role in the catalytic center. Enzyme could retain its activity in presence of various detergents (Triton X-100, Tween 20, Tween 40, SDS). Sequence and structural analysis employing in silico tools revealed that the lipase contained two highly conserved sequences consisting of ITITGCGNDL and NLYNP, arranged as parallel β-sheet in the core of the 3D structure. The function of these conserve sequences have not fully understood.

Microbial-processing of fruit and vegetable wastes for production of vital enzymes and organic acids: Biotechnology and scopes

Wastes generated from fruits and vegetables are organic in nature and contribute a major share in soil and water pollution. Also, green house gas emission caused by fruit and vegetable wastes (FVWs) is a matter of serious environmental concern. This review addresses the developments over the last one decade on microbial processing technologies for production of enzymes and organic acids from FVWs. The advances in genetic engineering for improvement of microbial strains in order to enhance the production of the value added bio-products as well as the concept of zero-waste economy have been briefly discussed.

Newly isolated yeasts from Tunisian microhabitats: Lipid accumulation and fatty acid composition

Newly isolated yeasts from different Tunisian microhabitats, such as soil, milk, olive brine, vinegar, and from olive mill wastewater-contaminated biotopes were extensively studied for their biochemical arsenal and morphological features, i.e. cell, ascospore, and lipid body morphology. All strains were classified into the Ascomycota phylum. However, they showed great functional diversity, including different morphological and biochemical features, lipid production ability, and fatty acid profiles. Accordingly, the strains were placed in three different groups: Group I, which includes Candida species; Group II (Pichia and related); and Group III (Kluyveromyces marxianus strain CC1). Group I and II were characterized by a high percentage of oleic acid (41.6-65.3% of total lipids) while in Group III, linoleic acid was the major fatty acid (37.2%). Members of Group I and II were further grouped into subgroups according to their fatty acid composition. Among the newly isolated strains, Pichia etchellsii BM1 was able to accumulate around 25% wt/wt lipid per dry cell mass and thus characterized as oleaginous. Some other strains, such as Candida metapsilosis strain EL2, C. parapsilosis strain LV2, C. pararugosa strain BM24, and K. marxianus strain CC1, which are able to produce extracellular lipases, may be of interest for specific environmental applications and/or for the production of novel lipases.

An organic solvent-stable lipase from a newly isolated Staphylococcus aureus ALA1 strain with potential for use as an industrial biocatalyst

In this study, a new strain, ALA1, was identified as Staphylococcus aureus by biochemical tests, and its 16S ribosomal DNA sequence was isolated from dromedary milk. ALA1 lipase production was optimized in shake flask experiments and measured with varying pH (3-11), temperature (20-55 °C) and substrate concentrations. The maximum lipase production was recorded at pH 8 and 30 °C for up to 30 H of culture period for the S. aureus ALA1 strain. Among the substrates tested, selected carbon sources, xylose, nitrogen source, yeast extract, and olive oil (1%) were suitable for maximizing lipase production. The effects of surfactants were investigated and showed that Tween 20, Tween 80, and Triton X-100 prevented lipase production. Interestingly, isolate ALA1 was able to grow in high concentrations of benzene or toluene (up to 50% (v/v)). Moreover, the lipolytic activity of the S. aureus ALA1 lipase was stimulated by diethyl ether, whereas almost 100% of S. aureus ALA1 lipase activity was retained in 25% acetone, acetonitrile, benzene, 2-propanol, ethanol, methanol, or toluene. Because of its stability in organic solvent, the S. aureus ALA1 lipase was used as a biocatalyst to synthesize high levels of added value molecules. S. aureus ALA1 lipase could be considered as an ideal choice for applications in detergent formulations because of its high stability and compatibility with various surfactants, oxidizing agents, and commercial detergents.

Purification and characterization of an extracellular cold-adapted alkaline lipase produced by psychrotrophic bacterium Yersinia enterocolitica strain KM1

An extracellular cold-adapted alkaline lipase from the psychrotrophic Yersinia enterocolitica strain KM1 was purified 26-fold to homogeneity. The enzyme was active over a broad range spanning 0-60 °C with an optimum activity at 37 °C, and it was found to be alkaline-preferring with an optimum activity at pH 9.0. The molecular weight was estimated to be 34.3 KDa and monomeric. The lipase could be activated by Ca(2+) and low concentration (10%) of ethanol, dimethyl sulphoxide, methanol, and acetonitrile, whereas it was strongly inhibited by Zn(2+), Cu(2+), SDS, EDTA, and PMSF. Using p-nitrophenyl butyrate as a substrate at 37 °C, the Km and Vmax of the enzyme were found to be 16.58 mM and 5.24 × 10(5)  μM · min(-1), respectively. This extracellular cold-adapted alkaline lipase may be a good candidate for detergents and biocatalysts at low temperature.

Structural basis for the Ca(2+)-enhanced thermostability and activity of PET-degrading cutinase-like enzyme from Saccharomonospora viridis AHK190

A cutinase-like enzyme from Saccharomonospora viridis AHK190, Cut190, hydrolyzes the inner block of polyethylene terephthalate (PET); this enzyme is a member of the lipase family, which contains an α/β hydrolase fold and a Ser-His-Asp catalytic triad. The thermostability and activity of Cut190 are enhanced by high concentrations of calcium ions, which is essential for the efficient enzymatic hydrolysis of amorphous PET. Although Ca(2+)-induced thermostabilization and activation of enzymes have been well explored in α-amylases, the mechanism for PET-degrading cutinase-like enzymes remains poorly understood. We focused on the mechanisms by which Ca(2+) enhances these properties, and we determined the crystal structures of a Cut190 S226P mutant (Cut190(S226P)) in the Ca(2+)-bound and free states at 1.75 and 1.45 Å resolution, respectively. Based on the crystallographic data, a Ca(2+) ion was coordinated by four residues within loop regions (the Ca(2+) site) and two water molecules in a tetragonal bipyramidal array. Furthermore, the binding of Ca(2+) to Cut190(S226P) induced large conformational changes in three loops, which were accompanied by the formation of additional interactions. The binding of Ca(2+) not only stabilized a region that is flexible in the Ca(2+)-free state but also modified the substrate-binding groove by stabilizing an open conformation that allows the substrate to bind easily. Thus, our study explains the structural basis of Ca(2+)-enhanced thermostability and activity in PET-degrading cutinase-like enzyme for the first time and found that the inactive state of Cut190(S226P) is activated by a conformational change in the active-site sealing residue, F106.

Isolation of lipase producing thermophilic bacteria: optimization of production and reaction conditions for lipase from Geobacillus sp

Lipases catalyze the hydrolysis and the synthesis of esters formed from glycerol and long chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. In the present study, thirty-two bacterial strains, isolated from soil sample of a hot spring were screened for lipase production. The strain TS-4, which gave maximum activity, was identified as Geobacillus sp. at MTCC, IMTECH, Chandigarh. The isolated lipase producing bacteria were grown on minimal salt medium containing olive oil. Maximal quantities of lipase were produced when 30 h old inoculum was used at 10% (v/v) in production medium and incubated in shaking conditions (150 rpm) for 72 h. The optimal temperature and pH for the bacterial growth and lipase production were found to be 60°C and 9.5, respectively. Maximal enzyme production resulted when mustard oil was used as carbon source and yeast extract as sole nitrogen source at a concentration of 1% (v/v) and 0.15% (w/v), respectively. The different optimized reaction parameters were temperature 65°C, pH 8.5, incubation time 10 min and substrate p-nitrophenyl palmitate. The Km and Vmax values of enzyme were found to be 14 mM and 17.86 μmol ml-1min-1, respectively, with p-nitrophenyl palmitate as substrate. All metal ions studied (1 mM) increased the lipase activity.

Purification and characterisation of an F16L mutant of a thermostable lipase

A mutant of the lipase from Geobacillus sp. strain T1 with a phenylalanine to leucine substitution at position 16 was overexpressed in Escherichia coli strain BL21(De3)pLysS. The crude enzyme was purified by two-step affinity chromatography with a final recovery and specific activity of 47.4 and 6,315.8 U/mg, respectively. The molecular weight of the purified F16L lipase was approximately 43 kDa by 12% SDS-PAGE analysis. The F16L lipase was demonstrated to be a thermophilic enzyme due its optimum temperature at 70 °C and showed stability over a temperature range of 40-60 °C. The enzyme exhibited an optimum pH 7 in phosphate buffer and was relatively stable at an alkaline pH 8-9. Metal ions such as Ca(2+), Mn(2+), Na(+), and K(+) enhanced the lipase activity, but Mg(2+), Zn(2+), and Fe(2+) inhibited the lipase. All surfactants tested, including Tween 20, 40, 60, 80, Triton X-100, and SDS, significantly inhibited the lipolytic action of the lipase. A high hydrolytic rate was observed on long-chain natural oils and triglycerides, with a notable preference for olive oil (C18:1; natural oil) and triolein (C18:1; triglyceride). The F16L lipase was deduced to be a metalloenzyme because it was strongly inhibited by 5 mM EDTA. Moderate inhibition was observed in the presence of PMSF at a similar concentration, indicating that serine residues are involved in its catalytic action. Further, the activity was not impaired by water-miscible solvents, including methanol, ethanol, and acetone.

Optimization of extracellular thermophilic highly alkaline lipase from thermophilic bacillus sp isolated from hotspring of Arunachal Pradesh, India

Studies on lipase production were carried out with a bacterial strain (Bacillus sp LBN 2) isolated from soil sample of hotspring of Arunachal Pradesh, India. The cells were cultivated in a mineral medium with maximum production at 1% groundnut oil. The optimum temperature and initial medium pH for lipase production by the organism were 50⁰C and 9.0 respectively. The molecular mass was found to be 33KDa by SDS PAGE. The optimal pH and temperature for activity were 10 and 60⁰C respectively. The enzyme was found to be stable in the pH range of 8–11 with 90% retention of activity at pH 11. The enzyme retained 90% activity at 60⁰C and 70% of activity at 70⁰C for 1h. The lipase was found to be stable in acetone followed by ethanol. The present findings suggested the enzyme to be thermophilic alkaline lipase.

Novel metagenome-derived, cold-adapted alkaline phospholipase with superior lipase activity as an intermediate between phospholipase and lipase

A novel lipolytic enzyme was isolated from a metagenomic library obtained from tidal flat sediments on the Korean west coast. Its putative functional domain, designated MPlaG, showed the highest similarity to phospholipase A from Grimontia hollisae CIP 101886, though it was screened from an emulsified tricaprylin plate. Phylogenetic analysis showed that MPlaG is far from family I.6 lipases, including Staphylococcus hyicus lipase, a unique lipase which can hydrolyze phospholipids, and is more evolutionarily related to the bacterial phospholipase A(1) family. The specific activities of MPlaG against olive oil and phosphatidylcholine were determined to be 2,957 ± 144 and 1,735 ± 147 U mg(-1), respectively, which means that MPlaG is a lipid-preferred phospholipase. Among different synthetic esters, triglycerides, and phosphatidylcholine, purified MPlaG exhibited the highest activity toward p-nitrophenyl palmitate (C(16)), tributyrin (C(4)), and 1,2-dihexanoyl-phosphatidylcholine (C(8)). Finally, MPlaG was identified as a phospholipase A(1) with lipase activity by cleavage of the sn-1 position of OPPC, interfacial activity, and triolein hydrolysis. These findings suggest that MPlaG is the first experimentally characterized phospholipase A(1) with lipase activity obtained from a metagenomic library. Our study provides an opportunity to improve our insight into the evolution of lipases and phospholipases.

Screening and characterization of a novel alkaline lipase from Acinetobacter calcoaceticus 1-7 Isolated from bohai bay in china for detergent formulation

A novel alkaline lipase-producing strain 1–7 identified as Acinetobacter calcoaceticus was isolated from soil samples collected from Bohai Bay, China, using an olive oil alkaline plate, which contained olive oil as the sole carbon source. The lipase from strain 1–7 showed the maximum activity at pH 9.0 under 40 °C. One interesting feature of this enzyme is that it exhibits lipase activity over a broad range of temperatures and good stability. It is also stable at a broad range of pHs from 4.0 to 10.0 for 24 h. Its catalytic activity was highly enhanced in the presence of Ca²⁺, Mg²⁺ and K⁺, but partially inhibited by Cu²⁺, Al³⁺, Fe³⁺, Ba²⁺and Zn²⁺. The fact that it displays marked stability and activity in the presence of TritonX-100, Tween-20, Tween-80, SDS, Hydrogen peroxide, Sodium perborate, Sodium hypochlorite, Sodium citrate, Sodium taurocholate, Glycerine and NaCl suggests that this lipase is suitable as an additive in detergent formulations.