Purification and biochemical characterization of a moderately halotolerant NADPH dependent xylose reductase from Debaryomyces nepalensis NCYC 3413

A Xylose reductase (XR) from the halotolerant yeast, Debaryomyces nepalensis NCYC 3413 was purified to apparent homogeneity. The enzyme has a molecular mass of 74 kDa with monomeric subunit of 36.4 kDa (MALDI-TOF/MS) and pI of 6.0. The enzyme exhibited its maximum activity at pH 7.0 and 45 °C (21.2U/mg). In situ gel digestion and peptide mass fingerprinting analysis showed 12-22% sequence homology with XR from other yeasts. Inhibition of the enzyme by DEPC (diethylpyrocarbonate) confirmed the presence of histidine residue in its active site. The enzyme exhibited high preference for pentoses over hexoses with greater catalytic efficiency for arabinose than xylose. The enzyme also showed absolute specificity with NADPH over NADH. The enzyme retained 90% activity with 100 mM of NaCl or KCl and 40% activity with 1 M KCl which suggest that the enzyme is moderately halotolerant and can be utilized for commercial production of xylitol under conditions where salts are present.     

Purification and characterization of an organic solvent-tolerant alkaline cellulase from a halophilic isolate of Thalassobacillus

An extracellular cellulase from Thalassobacillus sp. LY18 was purified 4.5-fold with a recovery of 21 % and a specific activity of 52.4 U mg(-1) protein. Its molecular mass was 61 kDa estimated by SDS-PAGE. It was an endoglucanase for soluble cellulose with optimal activity was at 60 °C and pH 8 with 10 % (w/v) NaCl. It was stable from 30 to 80 °C and from pH 7 to 11 with NaCl from 5 to 17.5 % (w/v). EDTA inhibited activity indicating it was a metalloenzyme. Inhibition by diethyl pyrocarbonate and β-mercaptoethanol suggested that histidine residues and disulfide bonds may play important roles in its catalytic function. The cellulase was highly active in non-ionic surfactants and was stable in water-insoluble organic solvents with log P (ow) ≥ 2.13.     

Purification and characterization of novel organic-solvent-tolerant β-amylase and serine protease from a newly isolated Salimicrobium halophilum strain LY20

A halophilic isolate Salimicrobium halophilum strain LY20 producing extracellular amylase and protease was isolated from Yuncheng, China. Production of both enzymes was synchronized with bacterial growth and reached a maximum level during the early-stationary phase. The amylase and protease were purified to homogeneity with molecular weights of 81 and 30?kDa, respectively. Optimal amylase activity was observed at 70?°C, pH 10.0% and 10% NaCl. Complete inhibition by EDTA, diethyl pyrocarbonate (DEPC), and phenylarsine oxide (PAO) indicated that the amylase was a metalloenzyme with histidine and cysteine residues essential for its catalysis. Maltose was the main product of starch hydrolysis, indicating an β-amylase activity. The purified protease from LY20 showed highest activity at 80?°C, pH 10.0% and 12.5% NaCl. Complete inhibition was shown by phenylmethylsulfonyl fluoride, DEPC, and PAO, indicating that the enzyme probably belonged to the subclass of the serine proteases with histidine and cysteine residues essential for catalysis. Furthermore, both enzymes were highly stable over broad temperature (30-80?°C), pH (6.0-12.0) and NaCl concentration (2.5-20%) ranges, showing excellent thermostable, alkalistable, and halotolerant nature. The surfactants (SDS, Tween 80, and Triton X-100) did not affect their activities. In addition, both enzymes from LY20 displayed remarkable stability in the presence of water-soluble organic solvents with log P(ow) (?) ≤?-0.24.     

Characterization of an organic solvent‐tolerant thermostable glucoamylase from a halophilic isolate,Halolactibacillus sp. SK71 and its application in raw starch hydrolysis for bioethanol production

A halophilic bacterium Halolactibacillus sp. SK71 producing extracellular glucoamylase was isolated from saline soil of Yuncheng Salt Lake, China. Enzyme production was strongly influenced by the salinity of growth medium with maximum in the presence of 5% NaCl. The glucoamylase was purified to homogeneity with a molecular mass of 78.5 kDa. It showed broad substrate specificity and raw starch hydrolyzing activity. Analysis of hydrolysis products from soluble starch by thin‐layer chromatography revealed that glucose was the sole end‐product, indicating the enzyme was a true glucoamylase. Optimal enzyme activity was found to be at 70°C, pH 8.0, and 7.5% NaCl. In addition, it was highly active and stable over broad ranges of temperature (0–100°C), pH (7.0–12.0), and NaCl concentration (0–20%), showing excellent thermostable, alkali stable, and halotolerant properties. Furthermore, it displayed high stability in the presence of hydrophobic organic solvents. The purified glucoamylase was applied for raw corn starch hydrolysis and subsequent bioethanol production using Saccharomyces cerevisiae. The yield in terms of grams of ethanol produced per gram of sugar consumed was 0.365 g/g, with 71.6% of theoretical yield from raw corn starch. This study demonstrated the feasibility of using enzymes from halophiles for further application in bioenergy production. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1262–1268, 2014     

Characterization of a metagenome-derived halotolerant cellulase

Metagenomes of uncultured microorganisms represent a sheer unlimited resource for discovery of novel biocatalysts. Here, we report on the biochemical characterisation of a novel, soil metagenome-derived cellulase (endoglucanase), Cel5A. The deduced amino acid sequence of Cel5A was similar to a family 5, single domain cellulase with no distinct cellulose binding domain from Cellvibrio mixtus. The 1092bp ORF encoding Cel5A was overexpressed in Escherichia coli and the corresponding 42.1 kDa protein purified using three-step chromatography. The recombinant Cel5A protein was highly active against soluble cellulose substrates containing beta-1,4 linkages, such as lichenan and barley beta-glucan, and not active against insoluble cellulose. Glucose was not among the initial hydrolysis products, indicating an endo mode of action. Cel5A displayed a wide range of pH activity with a maximum at pH 6.5 and at least 60% activity at pH 5.5 and 9.0. The enzyme was highly stable at 40 degrees C for up to 11 days, and retained 86-87% activity after incubation with 3M NaCl, 3M RbCl or 4M KCl for 20 h. Cel5A was also active in the presence of diverse divalent cations, detergents and EDTA. This highly stable, salt and pH tolerant cellulase is an ideal candidate for industrial applications.     

A novel halotolerant xylanase from marine isolate Bacillus subtilis cho40: gene cloning and sequencing

Although several xylanases have been studied, only few xylanases from marine micro-organisms have been reported. We report here a novel halotolerant xylanase from marine bacterium Bacillus subtilis cho40 isolated from Chorao island of mandovi estuary Goa, India. Extracellular xylanase was produced by using agricultural residue such as wheat bran as carbon source under solid-state fermentation (SSF). The optimal pH and temperature of xylanase were reported to be 6.0 and 60°C, respectively. Xyn40 was highly salt-tolerant, and showed highest activity at 0.5M NaCl. Xylanase activity was greatly induced (140%) when pre-incubated with 0.5M NaCl for 4h. The xylanase gene, xyn40, from marine bacterium B. subtilis cho40 was cloned, and expressed in Escherichia coli. The xylanase gene was 645 bp long and had a 215 amino acid ORF protein with a molecular mass of 22.9 kDa. It had all features of xylanase enzyme and showed homology to xylanases reported from B. subtilis. It differs from the earlier reported xylanase sequences by the presence of more serine residues compared to threonine and also by the presence of polar (hydrophilic) amino acids in higher abundance (61%) than non-polar amino acids (39%). The novel xylanase, reported in this study is a halotolerant enzyme from marine isolate and can play a very important role in bioethanol production from marine seaweeds.     

The unique GH5 cellulase member in the extreme halotolerant fungus Aspergillus glaucus CCHA is an endoglucanase with multiple tolerance to salt,alkali and heat: prospects for straw degradation applications

In a halotolerant fungus Aspergillus glaucus CCHA, several functional proteins with stress-tolerant activity have been studied, but no secretory enzymes have been identified yet. The unique GH5 cellulase candidate from A. glaucus, an endoglucanase termed as AgCMCase, was cloned, expressed in the Pichia pastoris system and the purified enzyme was characterized. A large amount of recombinant enzyme secreted by the P. pastoris GS115 strain was purified to homogeneity. The molecular weight of the purified endoglucanase is about 55.0 kDa. The AgCMCase exhibited optimum catalytic activity at pH 5.0 and 55 °C. However, it remained relatively stable at temperatures ranging from 45 to 80 °C and pH ranging from 4.0 to 9.0. In addition, it showed higher activity at extreme NaCl concentrations from 1.0 to 4.0 M, suggesting it is an enzyme highly stable under heat, acid, alkaline and saline conditions. To evaluate the catalytic activity of AgCMCase, the hydrolysis products of rice and corn straws were successfully studied. In conclusion, the AgCMCase is a thermostable and salt-tolerant cellulase with potential for industrial application.

     

Characterization of an organic solvent-tolerant α-amylase from a halophilic isolate, <Emphasis Type="Italic">Thalassobacillus</Emphasis> sp. LY18

A halophilic isolate Thalassobacillus sp. LY18 producing extracellular amylase was isolated from the saline soil of Yuncheng Salt Lake, China. Production of the enzyme was synchronized with bacterial growth and reached a maximum level during the early stationary phase. The amylase was purified to homogeneity with a molecular mass of 31 kDa. Major products of soluble starch hydrolysis were maltose and maltotriose, indicating an α-amylase activity. Optimal enzyme activity was found to be at 70°C, pH 9.0, and 10 % NaCl. The α-amylase was highly stable over broad temperature (30–90°C), pH (6.0–12.0), and NaCl concentration (0–20 %) ranges, showing excellent thermostable, alkalistable, and halotolerant nature. The enzyme was stimulated by Ca²⁺, but greatly inhibited by EDTA, indicating it was a metalloenzyme. Complete inhibition by diethyl pyrocarbonate and β-mercaptoethanol revealed that histidine residue and disulfide bond were essential for enzyme catalysis. The surfactants tested had no significant effects on the amylase activity. Furthermore, it showed high activity and stability in the presence of water-insoluble organic solvents with log P _ow ≥ 2.13.     

Purification and characterization of a halophilic α-amylase with increased activity in the presence of organic solvents from the moderately halophilic Nesterenkonia sp. strain F

An extracellular halophilic α-amylase was purified from Nesterenkonia sp. strain F using 80 % ethanol precipitation and Q-Sepharose anion exchange chromatography. The enzyme showed a single band with an apparent molecular weight of 110 kDa by SDS-PAGE. The amylase exhibited maximal activity at pH 7-7.5, being relatively stable at pH 6.5-7.5. Optimal temperature for the amylase activity and stability was 45 °C. The purified enzyme was highly active in the broad range of NaCl concentrations (0-4 M) with optimal activity at 0.25 M NaCl. The amylase was highly stable in the presence of 3-4 M NaCl. Amylase activity was not influenced by Ca2?, Rb?, Li?, Cs?, Mg2? and Hg2?, whereas Fe3?, Cu2?, Zn2? and Al3?) strongly inhibited the enzyme activity. The α-amylase was inhibited by EDTA, but was not inhibited by PMSF and β-mercaptoethanol. K(m) value of the amylase for soluble starch was 6.6 mg/ml. Amylolytic activity of the enzyme was enhanced not only by 20 % of water-immiscible organic solvents but also by acetone, ethanol and chloroform. Higher concentration (50 %) of the water-miscible organic solvents had no significant effect on the amylase activity. To the best of our knowledge, this is the first report on increased activity of a microbial α-amylase in the presence of organic solvents.     

Purification and characterization of SepII a new restriction endonuclease from Staphylococcus epidermidis

A Type II restriction enzyme SepII has been purified to apparent homogeneity from the gram-positive coccus, Staphylococcus epidermidis. The purification included an ammonium sulfate precipitation followed by Q-sepharose, heparin-sepharose and MonoQ column chromatography on an FPLC system. SDS-PAGE analysis showed a denatured molecular weight of 29 kDa. The effects of temperature, pH, NaCl, Mn(2+), Ca(2+), and Mg(2+) ion concentrations were studied to determine the optimal reaction conditions. The enzyme exhibits near maximal levels of activity between pH 8-10, at 10-20mM MgCl(2), 100-150 mM NaCl and 1mM DTT. The results also show that in NEB Buffer 3 the enzyme is active over a broad temperature range from 0 to 70 °C, and in the absence of DNA, enzyme thermostability is observed up to 50 °C for 20 min, while most of the original activity is conserved in 50% glycerol for weeks at room temperature. Single and double digestion in presence of commercial restriction enzymes of known DNA substrates (lambda, pBR322, pET21, pTrcHisB, pPB67) showed that the purified SepII recognized and cleaved the same site as EcoRV. Genomic DNA modification status was also determined.     

Characterization of an organic solvent-tolerant lipase from Idiomarina sp. W33 and its application for biodiesel production using Jatropha oil

A halophilic strain W33 showing lipolytic activity was isolated from the saline soil of Yuncheng Salt Lake, China. Biochemical and physiological characterization along with 16S rRNA gene sequence analysis placed the isolate in the genus Idiomarina. The extracellular lipase was purified to homogeneity by 75 % ammonium sulphate precipitation, DEAE-Sepharose anion exchange and Sephacryl S-200 gel filtration chromatography. The molecular mass of the purified lipase was estimated to be 67 kDa by SDS-PAGE. Substrate specificity test indicated that it preferred long-chain p-nitrophenyl esters. Optimal lipase activity was found to be at 60 °C, pH 7.0–9.0 and 10 % NaCl, and it was highly active and stable over broad temperature (30–90 °C), pH (7.0–11.0) and NaCl concentration (0–25 %) ranges, showing excellent thermostable, alkali-stable and halotolerant properties. Significant inhibition by diethyl pyrocarbonate and phenylarsine oxide was observed, implying histidine and cysteine residues were essential for enzyme catalysis. In addition, the lipase displayed high stability and activity in the presence of hydrophobic organic solvents with log P _ow ≥ 2.13. The free and immobilized lipases produced by Idiomarina sp. W33 were applied for biodiesel production using Jatropha oil, and about 84 and 91 % of yields were achieved, respectively. This study formed the basic trials conducted to test the feasibility of using lipases from halophile for biodiesel production.     

Amide hydrolyzing potential of amidase from halotolerant bacterium Brevibacterium sp. IIIMB2706

Till date, amidases from halophiles and halotolerant micro-organisms have not been much explored. In the present study, Brevibacterium sp. IIIMB2706 strain was isolated from salt fields of Gujarat, India, using propionitrile as a nitrogen source in the mineral base media and explored for its amidase activity. Amidase from Brevibacterium sp. IIIMB2706 exhibited substrate affinity towards isobutyramide, propionamide and butyramide. The optimum temperature and pH required for its maximum activity was 45?°C and 7.0, respectively. Effect of salt concentration on amidase activity was also studied and maximum activity was observed in presence of 50?g L^?1 NaCl with significant activity up to 200?g L^?1 NaCl which justifies its halotolerant nature. Various organic solvents compatibility profile showed that the enzyme was highly active in presence of 10% methyl alcohol. Henceforth, halotolerant enzymes may find application in industrial processes where substrate requires organic solvents for solubilization.     

Extracellular production of beta-amylase by a halophilic isolate, <Emphasis Type="Italic">Halobacillus</Emphasis> sp. LY9

A moderately halophilic strain LY9 with high amylolytic activity was isolated from soil sample obtained from Yuncheng, China. Biochemical and physiological characterization along with 16S rRNA sequence analysis placed the isolate in the genus Halobacillus. Amylase production started from the post-exponential phase of bacterial growth and reached a maximum level during the early-stationary phase. The isolate LY9 was found to secrete the amylase, the production of which depended on the salinity of the growth medium. Maximum amylase production was observed in the presence of 10% KCl or 10% NaCl. Maltose was the main product of soluble starch hydrolysis, indicating a β-amylase activity. The enzyme showed optimal activity at 60°C, pH 8.0, and 10–12.5% of NaCl. It was highly active over broad temperature (50–70°C), NaCl concentration (5.0–20.0%), and pH (4.0–12.0) ranges, indicating its thermoactive and alkali-stable nature. However, activity dropped off dramatically at low NaCl concentrations, showing the amylase was halophilic. Ca²⁺ was found to stimulate the β-amylase activity, whereas ethylenediaminetetraacetic acid (EDTA), phenylarsine oxide (PAO), and diethyl pyrocarbonate (DEPC) strongly inhibited the enzyme, indicating it probably was a metalloenzyme with cysteine and histidine residues located in its active site. Moreover, the enzyme exhibited remarkable stability towards sodium dodecyl sulfate (SDS) and Triton X-100. This is the first report of β-amylase production from moderate halophiles. The present study indicates that the extracellular β-amylase of Halobacillus sp. LY9 may have considerable potential for industrial application owing to its properties.     

Characterization of a salt-tolerant family 42 beta-galactosidase from a psychrophilic antarctic Planococcus isolate

We isolated a gram-positive, halotolerant psychrophile from a hypersaline pond located on the McMurdo Ice Shelf in Antarctica. A phylogenetic analysis of the 16S rRNA gene sequence of this organism showed that it is a member of the genus Planococcus. This assignment is consistent with the morphology and physiological characteristics of the organism. A gene encoding a beta-galactosidase in this isolate was cloned in an Escherichia coli host. Sequence analysis of this gene placed it in glycosidase family 42 most closely related to an enzyme from Bacillus circulans. Even though an increasing number of family 42 glycosidase sequences are appearing in databases, little information about the biochemical features of these enzymes is available. Therefore, we purified and characterized this enzyme. The purified enzyme did not appear to have any metal requirement, had an optimum pH of 6.5 and an optimum temperature of activity at 42 degrees C, and was irreversibly inactivated within 10 min when it was incubated at 55 degrees C. The enzyme had an apparent K(m) of 4.9 micromol of o-nitrophenyl-beta-D-galactopyranoside, and the V(max) was 467 micromol of o-nitrophenol produced/min/mg of protein at 39 degrees C. Of special interest was the finding that the enzyme remained active at high salt concentrations, which makes it a possible reporter enzyme for halotolerant and halophilic organisms.     

Purification and characterization of a carboxymethyl cellulase from Artemia salina

Brine shrimp (Artemia salina) belong to a group of crustaceans that feed on microalgae and require a cellulase enzyme that can be used in ethanol production from marine algae. Protein with potential cellulase activity was purified and the activity analyzed under different conditions. After initial identification of cellulase activity by CMC cellulase, surface sterilization and PCR using 16s rRNA primers was conducted to confirm that the cellulase activity was not produced from contaminating bacteria. The enzyme was purified by ammonium sulfate fractionation, gel filtration, and ion exchange chromatography. After the final purification, a 70-fold increase in specific enzyme activity was observed. SDS–PAGE results revealed that the cellulase enzyme had a molecular mass of 96 kDa. Temperature, pH, and salinity values were found to be optimal at 55 °C, pH 8.0, and 600 mM NaCl, respectively. Specifically, the enzyme showed a fivefold increase in enzyme activity in seawater compared to 600 mM NaCl in phosphate buffer. Further analysis of the purified enzyme by molecular spectrometry showed no match to known cellulases, indicating this enzyme could be a novel halophilic cellulase that can be used for the production of bioethanol from marine macroalgae.     

Discovery and Characterization of a Thermostable and Highly Halotolerant GH5 Cellulase from an Icelandic Hot Spring Isolate

With the ultimate goal of identifying robust cellulases for industrial biocatalytic conversions, we have isolated and characterized a new thermostable and very halotolerant GH5 cellulase. This new enzyme, termed CelDZ1, was identified by bioinformatic analysis from the genome of a polysaccharide-enrichment culture isolate, initiated from material collected from an Icelandic hot spring. Biochemical characterization of CelDZ1 revealed that it is a glycoside hydrolase with optimal activity at 70°C and pH 5.0 that exhibits good thermostability, high halotolerance at near-saturating salt concentrations, and resistance towards metal ions and other denaturing agents. X-ray crystallography of the new enzyme showed that CelDZ1 is the first reported cellulase structure that lacks the defined sugar-binding 2 subsite and revealed structural features which provide potential explanations of its biochemical characteristics.     

Production and characterization of a novel extracellular metalloproteinase by a newly isolated moderate halophile, <Emphasis Type="Italic">Halobacillus</Emphasis> sp. LY6

A moderately halophilic bacterium LY6 with high proteolytic activity was isolated. Biochemical and physiological characterization, along with 16S rDNA sequence analysis placed the isolate in the genus Halobacillus. The salinity of the culture medium strongly influenced the proteinase production of LY6. Maximum enzyme production was observed in the medium containing 5% Na₂SO₄ or 10% NaCl. Proteinase production was synchronized with bacterial growth and reached a maximum level during the mid-stationary phase. Enzyme purification was carried out by a simple approach including a combination of ammonium sulfate precipitation and Sephacryl S-100 gel filtration chromatography. SDS-PAGE and gelatin zymography analysis revealed it was a monomer with high molecular weight of 69 kDa. Optimal proteinase activity was obtained at pH 10.0, 40°C, and 10% NaCl. It was high active over broad temperature (30–80°C), pH (6.0–12.0), and NaCl concentration (0–25%) ranges, indicating its thermostable, alkali-stable, and halotolerant nature. Moreover, the enzyme activity was markedly enhanced by Ca²⁺ and Cu²⁺, but strongly inhibited by EDTA, PAO, and DEPC, indicating that it probably was a metalloproteinase with cysteine and histidine residues located in its active site.     

An alkaline-active and alkali-stable pectate lyase from Streptomyces sp.?S27 with potential in textile industry

A pectate lyase gene (pl-str) was cloned from Streptomyces sp. S27 and expressed in Escherichia coli Rosetta. The full-length pl-str consists of 972 bp and encodes for a protein of 323 amino acids without signal peptide that belongs to family PF00544. The recombinant enzyme (r-PL-STR) was purified to electrophoretic homogeneity using Ni2?-NTA chromatography and showed apparent molecular mass of ~35 kDa. The pH optimum of r-PL-STR was found to be 10.0, and it exhibited >70% of the maximal activity at pH 12.0. After incubation at 37°C for 1 h without substrate, the enzyme retained more than 55% activity at pH 7.0-12.0. Compared with the commercial complex enzyme Scourzyme(@)301L from Novozymes, purified r-PL-STR showed similar efficacy in reducing the intrinsic viscosity of polygalacturonic acid (49.0 vs. 49.7%). When combined with cellulase and α-amylase, r-PL-STR had comparable performance in bioscouring of jute fabric (22.39 vs. 22.99%). Thus, r-PL-STR might represent a good candidate for use in alkaline industries such as textile.     

Production of two novel laccase isoforms by a thermotolerant strain of Pycnoporus sanguineus isolated from an oil-polluted tropical habitat

A thermotolerant and halotolerant strain of Pycnoporus sanguineus was isolated from an oil-polluted site in a tropical area located in Veracruz, Mexico. This strain was able to grow at 47 degrees C and in culture medium containing 500 mM NaCl. The strain was also tolerant to the presence of 30,000 ppm of crude Maya oil. A 68-kDa protein purified from submerged cultures exhibited laccase activity towards 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), guaiacol, syringaldazine, and o-dianisidine, for which it presented the highest affinity (Km = 43 microM). Two-dimensional gel electrophoresis analysis showed that, unusual for laccases, the enzyme has two active isoforms, with isoelectric points of 7.00 and 7.08. The purified enzyme showed high thermostability, retaining 40% of its original activity after 3 h at 60 degrees C. This property seems to correlate with a long "shelf-life," given that at 40 degrees C enzyme activity was only gradually lost over a 5-day period incubation. Both the fungus and its laccase are likely to have high potential for biotechnological applications.     

一株产纤维素酶菌株的分离、鉴定及产酶特性

【目的】筛选并鉴定一株产纤维素酶的菌株,初步探究该菌的产酶特性,为综合利用纤维素筛选菌源。【方法】在常温条件下,采用滤纸培养基对菌种富集,采用CMC-Na初筛纤维素降解菌,采用LB培养基分离纯化菌株,经形态学、生理生化特征试验、16S r RNA基因序列测定等分析筛选菌株的系统分类地位。单因素试验确定培养时间、培养温度、初始p H及Na Cl浓度对筛选菌株产酶活力的影响。【结果】从腐烂的玉米秸秆中分离出一株在常温下产纤维素酶细菌KZ-2,根据菌落形态特征、生理生化特征鉴定以及16S r RNA基因序列分析,初步鉴定KZ-2为肠杆菌(Enterobacter sp.),为潜在新种。产酶条件实验显示:该菌使用产酶发酵培养基120 h产酶量达到最大值,在25–35°C、初始p H 4.5–5.5、Na Cl浓度1.0%–2.0%范围内为最佳产酶条件,在最适条件下酶活可达80.93 U/m L。该菌株所产纤维素酶最适反应p H为7.0,最适反应温度为50°C。【结论】KZ-2是一株具有降解纤维素能力的细菌,在常温下即可分泌纤维素酶,并且该菌株为潜在新种,具有潜在的开发价值。