aes, the gene encoding the esterase B in Escherichia coli, is a powerful phylogenetic marker of the species

Background  

Previous studies have established a correlation between electrophoretic polymorphism of esterase B, and virulence and phylogeny of Escherichia coli. Strains belonging to the phylogenetic group B2 are more frequently implicated in extraintestinal infections and include esterase B₂ variants, whereas phylogenetic groups A, B1 and D contain less virulent strains and include esterase B₁ variants. We investigated esterase B as a marker of phylogeny and/or virulence, in a thorough analysis of the esterase B-encoding gene.     

Phylogenetic classification of <Emphasis Type="Italic">Aureobasidium pullulans</Emphasis> strains for production of feruloyl esterase

Objective

The objective was to phylogenetically classify diverse strains of Aureobasidium pullulans and determine their production of feruloyl esterase.

Results

Seventeen strains from the A. pullulans literature were phylogenetically classified. Phenotypic traits of color variation and endo-β-1,4-xylanase overproduction were associated with phylogenetic clade 10 and particularly clade 8. Literature strains used for pullulan production all belonged to clade 7. These strains and 36 previously classified strains were tested for feruloyl esterase production, which was found to be associated with phylogenetic clades 4, 11, and particularly clade 8. Clade 8 strains NRRL 58552 and NRRL 62041 produced the highest levels of feruloyl esterase among strains tested.

Conclusions

Production of both xylanase and feruloyl esterase are associated with A. pullulans strains in phylogenetic clade 8, which is thus a promising source of enzymes with potential biotechnological applications.

     

Profiling and functional classification of esterases in olive (Olea europaea) pollen during germination

Background and Aims

A pollen grain contains a number of esterases, many of which are released upon contact with the stigma surface. However, the identity and function of most of these esterases remain unknown. In this work, esterases from olive pollen during its germination were identifided and functionally characterized.

Methods

The esterolytic capacity of olive (Olea europaea) pollen was examined using in vitro and in-gel enzymatic assays with different enzyme substrates. The functional analysis of pollen esterases was achieved by inhibition assays by using specific inhibitors. The cellular localization of esterase activities was performed using histochemical methods.

Key Results

Olive pollen showed high levels of non-specific esterase activity, which remained steady after hydration and germination. Up to 20 esterolytic bands were identified on polyacrylamide gels. All the inhibitors decreased pollen germinability, but only diisopropyl fluorophosphate (DIFP) hampered pollen tube growth. Non-specific esterase activity is localized on the surface of oil bodies (OBs) and small vesicles, in the pollen intine and in the callose layer of the pollen tube wall. Acetylcholinesterase (AChE) activity was mostly observed in the apertures, exine and pollen coat, and attached to the pollen tube wall surface and to small cytoplasmic vesicles.

Conclusions

In this work, for the first time a systematic functional characterization of esterase enzymes in pollen from a plant species with wet stigma has been carried out. Olive pollen esterases belong to four different functional groups: carboxylesterases, acetylesterases, AChEs and lipases. The cellular localization of esterase activity indicates that the intine is a putative storage site for esterolytic enzymes in olive pollen. Based on inhibition assays and cellular localization of enzymatic activities, it can be concluded that these enzymes are likely to be involved in pollen germination, and pollen tube growth and penetration of the stigma.     

Phenotypical characterization and molecular identification of clinical isolates of Candida tropicalis

Background

Candida tropicalis is an increasingly important human pathogen which usually affects neutropenic oncology patients with common hematogenous seeding to peripheral organs and high mortality rates. Candida pathogenicity is facilitated by several virulence attributes, including secretion of hydrolytic enzymes; however, little is known regarding the C. tropicalis ability to secrete them and their role in the disease.

Discovery of novel feruloyl esterase activity of BioH in <Emphasis Type="Italic">Escherichia coli</Emphasis> BL21(DE3)

Objectives

To characterize a novel feruloyl esterase from Escherichia coli BL21 DE3.

Results

The gene encoding BioH was cloned and overexpressed in E. coli. The protein was purified and its catalytic activity was assessed. BioH exhibited feruloyl esterase activity toward a broad range of substrates, and the corresponding kinetic constants for the methyl ferulate, ethyl ferulate, and methyl p-coumarate substrates were: K _m values of 0.48, 6.3, and 1.9 mM, respectively, and k _cat /K _m values of 9.3, 3.8, and 3.8 mM^?1 s^?1, respectively.

Conclusions

Feruloyl esterase from E. coli was expressed for the first time. BioH was confirmed to be a feruloyl esterase.

     

Bacteriuria amongst Pregnant Women in the Buea Health District,Cameroon: Prevalence,Predictors, Antibiotic Susceptibility Patterns and Diagnosis

Background

Bacteriuria is associated with significant maternal and foetal risks. However, its prevalence is not known in our community.

Objectives

This study was carried out to determine the prevalence and predictors of bacteriuria in pregnant women of the Buea Health District (BHD) as well as the antibiotic sensitivity patterns of bacterial isolates. It also sought to determine the diagnostic performance of the nitrite and leucocyte esterase tests in detecting bacteriuria in these women.

Methods

An observational analytic cross-sectional study was carried out amongst pregnant women attending selected antenatal care centres in Buea. We recruited 102 consenting pregnant women for the study. Demographic and clinical data were collected using structured questionnaires. Clean catch midstream urine was collected from each participant in sterile leak proof containers. Samples were examined biochemically, microscopically and by culture. Significant bacteriuria was defined as the presence of ≥10⁸ bacteria/L of cultured urine. Identification and susceptibility of isolates was performed using API 20E and ATB UR EU (08) (BioMerieux, Marcy l''Etoile, France).

Results

Significant bacteriuria was found in the urine of 24 of the 102 women tested giving a bacteriuria prevalence of 23.5% in pregnant women of the BHD. Asymptomatic bacteriuria was detected in 8(7.8%) of the women. There was no statistically significant predictor of bacteriuria. Escherichia coli were the most isolated (33%) uropathogens and were 100% sensitive to cefixime, cefoxitin and cephalothin. The nitrite and leucocyte esterase tests for determining bacteriuria had sensitivities of 8%, 20.8% and specificities of 98.7% and 80.8% respectively.

Conclusion

Bacteriuria is frequent in pregnant women in the BHD suggesting the need for routine screening by urine culture. Empiric treatment with cefixime should be instituted until results of urine culture and sensitivity are available. Nitrite and leucocyte esterase tests were not sensitive enough to replace urine culture as screening tests.     

Molecular cloning and characterization of a novel pyrethroid-hydrolyzing esterase originating from the Metagenome

Background  

Pyrethroids and pyrethrins are widely used insecticides. Extensive applications not only result in pest resistance to these insecticides, but also may lead to environmental issues and human exposure. Numerous studies have shown that very high exposure to pyrethroids might cause potential problems to man and aquatic organisms. Therefore, it is important to develop a rapid and efficient disposal process to eliminate or minimize contamination of surface water, groundwater and agricultural products by pyrethroid insecticides. Bioremediation is considered to be a reliable and cost-effective technique for pesticides abatement and a major factor determining the fate of pyrethroid pesticides in the environment, and suitable esterase is expected to be useful for potential application for detoxification of pyrethroid residues. Soil is a complex environment considered as one of the main reservoirs of microbial diversity on the planet. However, most of the microorganisms in nature are inaccessible as they are uncultivable in the laboratory. Metagenomic approaches provide a powerful tool for accessing novel valuable genetic resources (novel enzymes) and developing various biotechnological applications.     

Efficient kinetic resolution of secondary alcohols using an organic solvent-tolerant esterase in non-aqueous medium

Objective

To identify an esterase-mediated kinetic resolution of secondary alcohols in non-aqueous medium.

Results

An esterase, EST4, from a marine mud metagenomic library, showed high activity and enantioselectivity for the kinetic resolution of secondary alcohols in non-aqueous medium. Using 1-phenylethanol as the model alcohol, the effects of organic solvents, acyl donors, molar ratio, temperatures and biocatalyst loading on the kinetic resolution catalyzed by the EST4 whole-cell biocatalyst were investigated and optimized. The optimized methodology was effective on resolving 16 various racemic secondary alcohols in neat n-hexane, providing excellent enantiomeric excess (up to 99.9 % ee). Moreover, EST4 exhibited a strong tolerance for high substrate concentration (up to 1 M), and the optical purity of the desired secondary alcohols was kept above 99 % ee.

Conclusion

The esterase EST4 is a promising biocatalyst for the enantioselective synthesis of various alcohols and esters with interesting practical applications.

     

Genetic and biochemical basis of scent in rice (Oryza sativa L.)

Summary The inheritance and biochemical basis of scent in rice was studied in the F₂ population along with the F₁ and its two parents, scented and non-scented Pokura rice strains. The F₁ plants were found to be nonscented while the F₂ plants seggregated into a 31 ratio (non-scented: scented). In scented F₂ seggregants and in the scented parental strain, a fast moving esterase isozyme, Rf 0.9, is missing whereas it is present in all nonscented F₂ seggregants, F₁s, and in the non-scented parent. This suggests that the absence of a specific esterase isozyme is associated with the scent character in rice.     

Purification and properties of a highly enantioselective l-menthyl acetate hydrolase from Burkholderia cepacia

A highly enantioselective l-menthyl acetate esterase was purified to homogeneity from Burkholderia cepacia ATCC 25416, with a recovery of 4.8% and a fold purification of 22.7. The molecular weight of the esterase was found to be 37 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The N-terminal amino acid sequence was “MGARTDA”, and there was no homology in contrast to other Burkholderia sp. esterases. This enzyme preferentially hydrolyzed short-chain fatty acid esters of menthol with high stereospecificity and high hydrolytic activity, while long-chain l-menthyl esters were poor substrates. Considered its substrate specificity and N-terminal sequence, this esterase was concluded as a new enzyme belonging to the carboxylesterase group (EC 3.1.1.1) of esterase family. The optimum temperature and pH for enzyme activity using racemic menthyl acetate as substrate were 30 °C and 7.0, respectively. The esterase was more stable in the pH range of 7.0–9.0 and temperature range of 30–40 °C. Hydrolytic activity was enhanced by Ca²⁺, K⁺ and Mg²⁺, but completely inhibited by Hg²⁺, Cu²⁺, ionic detergents and phenylmethylsulfonyl fluoride (PMSF) at 0.01 M concentration.     

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.     

A cold-adapted esterase of a novel marine isolate, Pseudoalteromonas arctica: gene cloning, enzyme purification and characterization

A gene encoding an esterase (estO) was identified and sequenced from a gene library screen of the psychrotolerant bacterium Pseudoalteromonas arctica. Analysis of the 1,203 bp coding region revealed that the deduced peptide sequence is composed of 400 amino acids with a predicted molecular mass of 44.1 kDa. EstO contains a N-terminal esterase domain and an additional OsmC domain at the C-terminus (osmotically induced family of proteins). The highly conserved five-residue motif typical for all α/β hydrolases (G × S × G) was detected from position 104 to 108 together with a putative catalytic triad consisting of Ser¹⁰⁶, Asp¹⁹⁶, and His²²⁵. Sequence comparison showed that EstO exhibits 90% amino acid identity with hypothetical proteins containing similar esterase and OsmC domains but only around 10% identity to the amino acid sequences of known esterases. EstO variants with and without the OsmC domain were produced and purified as His-tag fusion proteins in E. coli. EstO displayed an optimum pH of 7.5 and optimum temperature of 25°C with more than 50% retained activity at the freezing point of water. The thermostability of EstO (50% activity after 5 h at 40°C) dramatically increased in the truncated variant (50% activity after 2.5 h at 90°C). Furthermore, the esterase displays broad substrate specificity for esters of short-chain fatty acids (C₂–C₈).     

The Effect of Insecticide Synergists on the Response of Scabies Mites to Pyrethroid Acaricides

Background

Permethrin is the active component of topical creams widely used to treat human scabies. Recent evidence has demonstrated that scabies mites are becoming increasingly tolerant to topical permethrin and oral ivermectin. An effective approach to manage pesticide resistance is the addition of synergists to counteract metabolic resistance. Synergists are also useful for laboratory investigation of resistance mechanisms through their ability to inhibit specific metabolic pathways.

Methodology/Principal Findings

To determine the role of metabolic degradation as a mechanism for acaricide resistance in scabies mites, PBO (piperonyl butoxide), DEF (S,S,S-tributyl phosphorotrithioate) and DEM (diethyl maleate) were first tested for synergistic activity with permethrin in a bioassay of mite killing. Then, to investigate the relative role of specific metabolic pathways inhibited by these synergists, enzyme assays were developed to measure esterase, glutathione S-transferase (GST) and cytochrome P450 monooxygenase (cytochrome P450) activity in mite extracts. A statistically significant difference in median survival time of permethrin-resistant Sarcoptes scabiei variety canis was noted when any of the three synergists were used in combination with permethrin compared to median survival time of mites exposed to permethrin alone (p<0.0001). Incubation of mite homogenates with DEF showed inhibition of esterase activity (37%); inhibition of GST activity (73%) with DEM and inhibition of cytochrome P450 monooxygenase activity (81%) with PBO. A 7-fold increase in esterase activity, a 4-fold increase in GST activity and a 2-fold increase in cytochrome P450 monooxygenase activity were observed in resistant mites compared to sensitive mites.

Conclusions

These findings indicate the potential utility of synergists in reversing resistance to pyrethroid-based acaricides and suggest a significant role of metabolic mechanisms in mediating pyrethroid resistance in scabies mites.     

A Novel Alkaliphilic Bacillus Esterase Belongs to the 13th Bacterial Lipolytic Enzyme Family

Background

Microbial derived lipolytic hydrolysts are an important class of biocatalysts because of their huge abundance and ability to display bioactivities under extreme conditions. In spite of recent advances, our understanding of these enzymes remains rudimentary. The aim of our research is to advance our understanding by seeking for more unusual lipid hydrolysts and revealing their molecular structure and bioactivities.

Methodology/Principal Findings

Bacillus. pseudofirmus OF4 is an extreme alkaliphile with tolerance of pH up to 11. In this work we successfully undertook a heterologous expression of a gene estof4 from the alkaliphilic B. pseudofirmus sp OF4. The recombinant protein called EstOF4 was purified into a homologous product by Ni-NTA affinity and gel filtration. The purified EstOF4 was active as dimer with the molecular weight of 64 KDa. It hydrolyzed a wide range of substrates including p-nitrophenyl esters (C2–C12) and triglycerides (C2–C6). Its optimal performance occurred at pH 8.5 and 50°C towards p-nitrophenyl caproate and triacetin. Sequence alignment revealed that EstOF4 shared 71% identity to esterase Est30 from Geobacillus stearothermophilus with a typical lipase pentapeptide motif G91LS93LG95. A structural model developed from homology modeling revealed that EstOF4 possessed a typical esterase 6α/7β hydrolase fold and a cap domain. Site-directed mutagenesis and inhibition studies confirmed the putative catalytic triad Ser93, Asp190 and His220.

Conclusion

EstOF4 is a new bacterial esterase with a preference to short chain ester substrates. With a high sequence identity towards esterase Est30 and several others, EstOF4 was classified into the same bacterial lipolytic family, Family XIII. All the members in this family originate from the same bacterial genus, bacillus and display optimal activities from neutral pH to alkaline conditions with short and middle chain length substrates. However, with roughly 70% sequence identity, these enzymes showed hugely different thermal stabilities, indicating their diverse thermal adaptations via just changing a few amino acid residues.     

Positional specifity of acetylxylan esterases on natural polysaccharide: An NMR study

Background

Microbial degradation of acetylated plant hemicelluloses involves besides enzymes cleaving the glycosidic linkages also deacetylating enzymes. A detailed knowledge of the mode of action of these enzymes is important in view of the development of efficient bioconversion of plant materials that did not undergo alkaline pretreatment leading to hydrolysis of ester linkages.

Methods

In this work deacetylation of hardwood acetylglucuronoxylan by acetylxylan esterases from Streptomyces lividans (carbohydrate esterase family 4) and Orpinomyces sp. (carbohydrate esterase family 6) was monitored by ¹H-NMR spectroscopy.

Results

The ¹H-NMR resonances of all acetyl groups in the polysaccharide were fully assigned. The targets of both enzymes are 2- and 3-monoacetylated xylopyranosyl residues and, in the case of the Orpinomyces sp. enzyme, also the 2,3-di-O-acetylated xylopyranosyl residues. Both enzymes do not recognize as a substrate the 3-O-acetyl group on xylopyranosyl residues α-1,2-substituted with 4-O-methyl-d-glucuronic acid.

Conclusions

The ¹H-NMR spectroscopy approach to study positional and substrate specificity of AcXEs outlined in this work appears to be a simple way to characterize catalytic properties of enzymes belonging to various CE families.

Significance

The results contribute to development of efficient and environmentally friendly procedures for enzymatic degradation of plant biomass.     

Olive phenols efficiently inhibit the oxidation of serum albumin-bound linoleic acid and butyrylcholine esterase

Background

Olive phenols are widely consumed in the Mediterranean diet and can be detected in human plasma. Here, the capacity of olive phenols and plasma metabolites to inhibit lipid and protein oxidations is investigated in two plasma models.

Methods

The accumulation of lipid oxidation products issued from the oxidation of linoleic acid bound to human serum albumin (HSA) by AAPH-derived peroxyl radicals is evaluated in the presence and absence of phenolic antioxidants. Phenol binding to HSA is addressed by quenching of the Trp214 fluorescence and displacement of probes (quercetin, dansylsarcosine and dansylamide). Next, the esterase activity of HSA-bound butyrylcholine esterase (BChE) is used as a marker of protein oxidative degradation.

Results

Hydroxytyrosol, oleuropein, caffeic and chlorogenic acids inhibit lipid peroxidation as well as HSA-bound BChE as efficiently as the potent flavonol quercetin. Hydroxycinnamic derivatives bind noncompetitively HSA subdomain IIA whereas no clear site could be identified for hydroxytyrosol derivatives.

General significance

In both models, olive phenols and their metabolites are much more efficient inhibitors of lipid and protein oxidations compared to vitamins C and E. Low postprandial concentrations of olive phenols may help to preserve the integrity of functional proteins and delay the appearance of toxic lipid oxidation products.     

Isolation and Characterization of a GDSL Esterase from the Metagenome of a Marine Sponge-associated Bacteria

Using a metagenome library constructed from a bacterial associated with a marine sponge Hyrtios erecta, we identified a novel esterase that belongs to the SGNH hydrolase superfamily of esterases. The substrate specificity of EstHE1 was determined using p-nitrophenyl (pNP) ester (C2: acetate, C4: butylate, C6: caproate, C12: laurate, C16: palmitate). EstHE1 exhibited activity against C2 (5.6 U/mg), C4 (5.1 U/mg), and C6 (2.8 U/mg) substrates. The optimal temperature for EstHE1 esterase activity of the pNP acetate substrate was 40°C, and EstHE1 retained 60% of its enzymatic activity in the 30–50°C range. This esterase showed moderate thermostability, retaining 58% of its activity even after preincubation for 12 h at 40°C. EstHE1 also maintained activity in high concentrations of NaCl, indicating that this esterase is salt-tolerant. Thus, EstHE1 has the thermal stability and salt tolerance necessary for use as an industrial enzyme.     

Biochemical Characterization of a First Fungal Esterase from Rhizomucor miehei Showing High Efficiency of Ester Synthesis

Background

Esterases with excellent merits suitable for commercial use in ester production field are still insufficient. The aim of this research is to advance our understanding by seeking for more unusual esterases and revealing their characterizations for ester synthesis.

Methodology/Principal Findings

A novel esterase-encoding gene from Rhizomucor miehei (RmEstA) was cloned and expressed in Escherichia coli. Sequence analysis revealed a 975-bp ORF encoding a 324-amino-acid polypeptide belonging to the hormone-sensitive lipase (HSL) family IV and showing highest similarity (44%) to the Paenibacillus mucilaginosus esterase/lipase. Recombinant RmEstA was purified to homogeneity: it was 34 kDa by SDS-PAGE and showed optimal pH and temperature of 6.5 and 45°C, respectively. The enzyme was stable to 50°C, under a broad pH range (5.0–10.6). RmEstA exhibited broad substrate specificity toward p-nitrophenol esters and short-acyl-chain triglycerols, with highest activities (1,480 U mg⁻¹ and 228 U mg⁻¹) for p-nitrophenyl hexanoate and tributyrin, respectively. RmEstA efficiently synthesized butyl butyrate (92% conversion yield) when immobilized on AOT-based organogel.

Conclusion

RmEstA has great potential for industrial applications. RmEstA is the first reported esterase from Rhizomucor miehei.     

Expression, characterization and structural modelling of a feruloyl esterase from the thermophilic fungus Myceliophthora thermophila

A ferulic acid esterase (FAE) from the thermophilic fungus Myceliophthora thermophila (synonym Sporotrichum thermophile), belonging to the carbohydrate esterase family 1 (CE-1), was functionally expressed in methylotrophic yeast Pichia pastoris. The putative FAE from the genomic DNA was successfully cloned in P. pastoris X-33 to confirm that the enzyme exhibits FAE activity. The recombinant FAE was purified to its homogeneity (39 kDa) and subsequently characterized using a series of model substrates including methyl esters of hydroxycinnamates, alkyl ferulates and monoferuloylated 4-nitrophenyl glycosides. The substrate specificity profiling reveals that the enzyme shows a preference for the hydrolysis of methyl caffeate and p-coumarate and a strong preference for the hydrolysis of n-butyl and iso-butyl ferulate. The enzyme was active on substrates containing ferulic acid ester linked to the C-5 and C-2 linkages of arabinofuranose, whilst it was found capable of de-esterifying acetylated glucuronoxylans. Ferulic acid (FA) was efficiently released from destarched wheat bran when the esterase was incubated together with an M3 xylanase from Trichoderma longibrachiatum (a maximum of 41% total FA released after 1 h incubation). Prediction of the secondary structure of MtFae1a was performed in the PSIPRED server whilst modelling the 3D structure was accomplished by the use of the HH 3D structure prediction server.     

Cloning,expression and characterization of the esterase estUT1 from Ureibacillus thermosphaericus which belongs to a new lipase family XVIII

A new esterase gene from thermophilic bacteria Ureibacillus thermosphaericus was cloned into the pET32b vector and expressed in Escherichia coli BL21(DE3). Alignment of the estUT1 amino acid sequence revealed the presence of a novel canonical pentapeptide (GVSLG) and 41–47% identity to the closest family of the bacterial lipases XIII. Thus the esterase estUT1 from U. thermosphaericus was assigned as a member of the novel family XVIII. It also showed a strong activity toward short-chain esters (C2–C8), with the highest activity for C2. When p-nitrophenyl butyrate is used as a substrate, the temperature and pH optimum of the enzyme were 70–80 °C and 8.0, respectively. EstUT1 showed high thermostability and 68.9 ± 2.5% residual activity after incubation at 70 °C for 6 h. Homology modeling of the enzyme structure showed the presence of a putative catalytic triad Ser93, Asp192, and His222. The activity of estUT1 was inhibited by PMSF, suggesting that the serine residue is involved in the catalytic activity of the enzyme. The purified enzyme exhibited high stability in organic solvents. EstUT1 retained 85.8 ± 2.4% residual activity in 30% methanol at 50 °C for 6 h. Stability at high temperature and tolerance to organic solvents make estUT1 a promising enzyme for biotechnology application.