A xylanase with high pH stability from Streptomyces sp. S27 and its carbohydrate-binding module with/without linker-region-truncated versions

A xylanase gene, xynAS27, was isolated from a genomic library of Streptomyces sp. S27. The full-length gene consists of 1,434 bp and encodes 477 amino acids, including a putative signal peptide of 41 residues at its N-terminus. The mature xylanase comprises two functional domains, a family 10 glycoside hydrolase, and a family 13 carbohydrate-binding module (CBM), which were joined by a short Gly/Pro-rich linker region. The intact, the CBM-truncated and the CBM-linker-truncated versions of the mature proteins were expressed in Escherichia coli BL21 (DE3), purified to electrophoretic homogeneity and subsequently characterized. XynAS27 showed high pH stability over the pH range 2.2–12.0. XynAS27 may be a compelling tool for the food industry because it generates xylobiose (85% w/w) as the main product of xylan hydrolysis. The truncated versions showed less pH and thermal stability, and less affinity and hydrolytic activity to insoluble substrate than the intact one. These results indicate that the CBM of XynAS27 plays a key role in the hydrolysis of insoluble substrate, and the CBM and linker region are also important for the enzyme stability, and the linker region contributes more.     

Production of a cellulase-free xylanase from agricultural waste materials by a thermotolerant Streptomyces sp.

1444 microorganisms were isolated from soil samples from the northern Thai and screened at 55 °C by using basal medium supplemented with 1% carboxymethyl cellulose as a sole carbon source. One isolate, Streptomyces Ab106, had a high activity of a cellulase-free xylanase also without mannanase activity. The maximum cellulase-free xylanase activities of 3.5, 3.3, 3.1 and 2.7 IU were after growth of the organism with 1% (w/v) corn hull, corncob, bagasse and oat spelt xylan, respectively, at 55 °C for 6 days, respectively. The activity was more than 5 times higher than that at 35 °C.     

Cloning and Characterization of Alginate Lyase from a Marine Bacterium Streptomyces sp. ALG-5

A marine bacterium was isolated from seaweeds for its ability to degrade alginate. Analysis of 16S ribosomal DNA sequence and chemotaxonomic characterizations revealed that the strain belongs to Streptomyces. The alginate lyase gene of Streptomyces sp. ALG-5 was cloned by using PCR with the specific primer designed from homologous nucleotide sequences. The consensus sequences of N-terminal YXRSELREM and C-terminal YFKAGXYXQ were conserved in the ALG-5 alginate lyase gene. The recombinant alginate lyase was purified by using Ni-Sepharose affinity chromatography. The alginate lyase appears to be poly-guluronate lyase degrading poly-G block preferentially than poly-M block. The degraded products were determined to be di-, tri-, tetra- and pentasaccharides by using BioGel P-2 gel filtration chromatography and ionization mass spectroscopy method.     

Production and potential applications of a xylanase from a new strain of Streptomyces cuspidosporus

Enzyme production by a new mesophilic Streptomyces isolate was investigated which grew optimally on 1% (w/v) xylan and 10% (w/v) wheat bran at pH 7 and 37 °C. Xylan induced only CMCase (0.29 U/ml) besides xylanase (22–35 U/ml, 40–49 U/mg protein). Wheat bran induced xylanase (105 U/ml, 17.5 U/mg protein), CMCase (0.74 U/ml), -xylosidase (0.009 U/ml), -glucosidase (0.026 U/ml), -L-arabinofuranosidase (0.049 U/ml), amylase (1.6 U/ml) and phytase (0.432 U/ml). The isolate was amenable to solid state cultivation and produced increased levels of xylanase (146 U/ml, 28 U/mg protein). The pH and temperature optima of the crude xylanase activity were 5.5 and 65 °C respectively. The pI was 6.0 as determined by PEG precipitation. The crude enzyme was applied in treatment of paper pulp and predigestion of poultry feed and was found to be effective in releasing sugars from both and soluble phosphorus from the latter.     

Cloning and expression of a haloacid dehalogenase fromPseudomonas sp. strain 19 S

A dehalogenase gene specifying the utilization of a variety of haloacids byPseudomonas sp. Strain 19S has been cloned and expressed inE. coli. Our cloning strategy employed specific amplification of a fragment homologous toPseudomonas dehalogenase gene by Polymerase Chain Reaction (PCR). The PCR amplicon successfully acted as a probe to detect the dehalogenase gene in the Southern Blot of the digestedPseudomonas total DNA. Corresponding fragments were cloned into pUC 18 vector and amplified inE. coli MV 1190. One clone with a substantial dehalogenation activity carried a recombinant plasmid containing a 5.5 kb insert.Abbreviations 2-CPA 2-chloropropionate - MCA monochloro acetate - IPTG isopropyl-1-thio--D-galactoside - NBT nitroblue tetrazolium salt - PCR polymerase chain reaction - X-gal 5-bromo-4-chloro-3-indolyl--D-galactoside - X-phosphate 5-bromo-4-chloro-3-indolyl phosphate     

Cloning and characterization of a xylanase,KRICT PX1 from the strain Paenibacillus sp. HPL-001

The KRICT PX1 gene (GB: FJ380951) consisting of 996 bp encoding a protein of 332 amino acids (38.1 kDa) from the recently isolated Paenibacillus sp. strain HPL-001 (KCTC11365BP) has been cloned and expressed in Escherichia coli. The xylanase KRICT PX1 showed high activity on birchwood xylan, and was active over a pH range of 5.0 to 11.0, with two optima at pH 5.5 and 9.5 at 50 °C with K_m value of 5.35 and 3.23, respectively. The xylanase activity was not affected by most salts, such as NaCl, LiCl, KCl, NH₄Cl, CaCl₂, MgCl₂, MnCl₂, and CsCl₂ at 1 mM, but affected by CuSO₄, ZnSO₄, and FeCl₃. One mM of EDTA, 2-mercaptoethanol, and PMSF did not affect the xylanase activity. TLC analysis of the catalyzed products after reaction with birchwood xylan revealed that xylobiose was the major product with smaller amounts of xylotriose and xylose. A similarity analysis of the amino acids in KRICT PX1 resulted 72% identity with xylanase from Geobacillus stearothermophilus (GB: ZP_03040360), 70% identity with intracellular xylanase from an uncultured bacterium (GB: AAP51133), 68% identity with endo-1-4-xylanse from Paenibacillus sp. (GB: ZP_02847150). In addition, the amino acid alignment of KRICT PX1 with glycosyl hydralase (GH) family 10 xylanases revealed a high degree of homology in highly conserved regions including the catalytic sites, and this was confirmed through PROSITE scan. These results imply that KRICT PX1 is a new xylanase gene, and this alkaline xylanase belongs to GH family 10.     

Purification and characterization of a thermophilic alkaline xylanase from thermoalkaliphilic Bacillus sp. strain TAR-1

Thermoalkaliphilic Bacillus sp. strain TAR-1 isolated from soil produced an extracellular xylanase. The enzyme (xylanase R) was purified to homogeneity by ammonium sulfate fractionation and anion-exchange chromatography. The molecular mass of xylanase R was 40 kDa and the isoelectric point was 4.1. The enzyme was most active over the range of pH 5.0 to 10.0 at 50°C. The optimum temperatures for activity were 75°C at pH 7.0 and 70°C at pH 9.0. Xylanase R was stable up to 65°C at pH 9.0 for 30 min in the presence of xylan. Mercury(ll) ion at 1 mM concentration abolished all the xylanase activity. The predominant products of xylan-hydrolysate were xylobiose, xylotriose, and higher oligosaccharides, indicating that xylanase R was an endo-acting enzyme. Xylanase R had a K_m of 0.82 mg/ml and a V_max of 280 μmol min⁻¹ mg⁻¹ for xylan at 50°C and pH 9.0.     

Classification of novel soil streptomycetes as Streptomyces aureus sp. nov., Streptomyces laceyi sp. nov. and Streptomyces sanglieri sp. nov

The taxonomic positions of soil isolates known as Streptomyces groups A, B and C were clarified. Comparative 16S rDNA sequence studies indicated that representatives of all three taxa formed distinct phyletic lines within the Streptomyces tree though the group A strains were shown to be related to Streptomyces griseus and associated validly described species. The taxonomic integrity of all three groups was highlighted by DNA:DNA relatedness and ribotype data though the group A strains encompassed a higher degree of genetic variation than the group B and C strains. In light of these and earlier phenotypic data it is proposed that Streptomyces groups A, B and C be given species status as Streptomyces sanglieri sp. nov., Streptomyces aureus sp. nov. and Streptomyces laceyi sp. nov., respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Cloning, expression, and characterization of a new deoxyribose 5-phosphate aldolase from Yersinia sp. EA015

A new deoC gene encoding deoxyribose 5-phosphate aldolase (DERA) was identified in Yersinia sp. EA015 isolated from soil. The DERA gene had an open reading frame (ORF) of 672 base pairs encoding 223 amino acids to yield a protein of molecular mass 24.8 kDa. The amino acid sequence was 94% identical to that of DERA from Yersinia intermedia ATCC 29909. DERA was over-expressed in Escherichia coli and purified using Ni–NTA affinity chromatography. The specific activity was 137 μmol/min/mg. The Michaelis constant (k_m value) of DERA was 9.1 mM. DERA was optimally active at pH 6.0 and 50 °C. DERA was tolerant to a high concentration (300 mM) of acetaldehyde.     

Production and characterization of xylanase from a Streptomyces species grown on agricultural wastes

Alkali-treated corn stalk gave maximum xylanase production at supporting growth of Streptomyces HM-15. Xylanase was stable for 24 h over a pH range of 5.0 to 7.0, had optimal activity between 50 and 60°C and a halflife of 5 h at 60°C. Xylanase production and activity were inhibited by xylose.The authors are with Department of Biosciences, Sardar Patel University. Vallabh Vidyanagar-388120, Gujarat, India.     

Demulsification of oil-in-water emulsions by aerial spores of a Streptomyces sp.

Of a number of actinomycetes isolated from Antarctica and coastal regions of Korea, one isolate, identified as a Streptomycessp., demulsified an emulsion of kerosene/0.2% Triton X-100 (2:1, v/v) within 1 min. The aerial spores broke emulsions of low viscosity hydrocarbons such as kerosene and gasoline within 1 min, but after 3 min of contact they could demulsify less than 50% of emulsions of high viscosity hydrocarbons diluted with kerosene.     

New isolate of Streptomyces sp. with novel thermoalkalotolerant cellulases

A Streptomyces sp. was isolated that produced novel thermoalkalotolerant cellulase activity after growth on crystalline cellulose at 50°C. Three major components of the cellulases (CMCase, Avicelase and cellobiase) were produced with maximal activities (11.8, 7.8 and 3.9 IU/ml) and maximum specific activities 357, 276 and 118 IU/mg protein, respectively, after 120 h growth. Maximum CMCase activity was between 50 and 60°C measured over 3 h. The enzyme also retained 88% of its maximum activity at 70°C and pH 5, and 80% of the activity at pH 10 and 50°C when assayed after 1 h. After incubation at 40°C for 1 h with commercial detergent (Tide) at pH 11, 95% activity was retained. The enzyme mixture produced glucose from crystalline cellulose.     

Cloning, Expression, and Biological Function of a dTDP-Deoxyglucose Epimerase (gerF) Gene from Streptomyces sp. GERI-155

GERI-155 is a macrolide antibiotic containing two deoxyhexose molecules which has antimicrobial activities against gram-positive bacteria. The deoxyhexose biosynthetic gene cluster of GERI-155 from Streptomyces sp. GERI-155 genome has now been isolated. Four orf were identified and a putative orf, supposed to code for the dTDP-deoxyglucose epimerase gene, was designated as gerF. gerF was expressed in E. coli using recombinant expression vector pHJ3. The recombinant protein expressed in a soluble form. The enzyme was purified by Ni-affinity column using imidazole buffer as eluents. The molecular mass of the expressed protein correlated with the predicted mass (36,000 Da) deduced from the cloned gene sequence data. The purified enzyme produced maltol from dTDP-4-keto-6-deoxyglucose and it was confirmed that the expressed protein was dTDP-deoxyglucose epimerase catalyzing epimerization of C-3 and C-5 or C-3 of dTDP-4-keto-6-deoxyglucose.     

Streptomyces daliensis sp. nov. from soil

A novel actinomycete strain YIM 31724^T was isolated from a soil sample collected from Dali, Yunnan Province, People’s Republic of China. The strain is characterized by white to yellow white aerial mycelia, spiral spore chains and smooth spore surface. The cell wall of strain YIM 31724^T contained LL-diaminopimelic acid (A₂pm) and traces of meso-A₂pm. Whole-cell hydrolysates contained mainly glucose and small amounts of galactose and xylose. The menaquinones were MK-9(H₆) (31%) and MK-9(H₈) (69%). Phosphatidylethanolamine was the diagnostic phospholipid. The DNA G+C content of strain YIM 31724^T was 67.2 mol%. Phylogenetic analysis indicated that the strain belongs to the genus Streptomyces, with highest similarity to Streptomyces rimosus subsp. rimosus JCM 4667^T (rRNA gene sequence similarity value of 98.9%) and Streptomyces erumpens DSM 40941^T (rRNA gene sequence similarity value of 98.7%). Based on its phenotypic and genotypic characteristics, including low DNA–DNA hybridization results, strain is proposed as the type strain of a novel species, Streptomyces daliensis sp. nov.     

<Emphasis Type="Italic">Streptomyces tritolerans</Emphasis> sp. nov., a novel actinomycete isolated from soil in Karnataka,India

A Gram-positive, nonmotile, moderately halophilic, alkali and thermotolerant strain designated DAS 165(T), was isolated from a dry land soil sample from the Gulbarga region, Karnataka province, India. The isolate produced yellow substrate mycelia and gray aerial mycelia on most tested media. Strain DAS 165(T) showed growth in the presence of 5 to 7% NaCl and at 45 degrees C. The DNA G + C content was 69.7%. 16S rRNA gene sequence analysis together with these characteristics consistently assigned strain DAS 165(T) to the genus Streptomyces. The 16S rRNA gene sequence analysis revealed that strain DAS 165(T) was most closely related to S. tendae ATCC 19812(T) (D 63873) with a sequence similarity of 99.6% (three nucleotide differences out of 1,517). Strain DAS 165(T) formed a distinct clade based on analysis of the almost complete sequence and 120-nucleotide variable gamma region of the 16S rRNA gene. Despite the high sequence similarity, strain DAS 165(T) was phenotypically different from S. tendae ATCC 19812(T). DNA-DNA hybridization between these strains was 47% showing that strain DAS 165(T) is a distinct genomic species. Phenetic and genetic results support the classification of strain DAS 165(T) as a new species, for which the name S. tritolerans is proposed, with strain DAS 165(T) as the type strain (=DSM 41899(T )= CCTCCAA 206013(T)).     

Effect of amino acids on production of xylanase and pectinase from Streptomyces sp. QG-11-3

Xylanase and pectinase production by Streptomyces sp. QG-11-3 was stimulated by DL-norleucine, L-leucine, DL-isoleucine, L-lysine monohydrochloride and DL--phenylalanine by up to 3.72- and 2.78-fold, respectively, whereas the combination of DL-norleucine, L-leucine and DL-isoleucine synergistically stimulated the xylanase and pectinase production by up to 6.72- and 5.62-fold, respectively. Glycine, DL-norvaline, DL-methionine, and DL-aspartic acid showed no significant stimulatory effect on enzyme production.     

Molecular cloning, expression and characterization of a chitosanase from Microbacterium sp.

A gene encoding a chitosanase (mschito) was cloned from Microbacterium sp. OU01. The ORF consists of 801 bp which encoded a polypeptide of 266 amino acid residues. The deduced amino acid sequence shows 98% identity to that of the chitosanase reported in Pseudomonas sp. A-01. In addition, the fusion protein containing MSCHITO was expressed in E. coli and purified using Ni-NTA affinity chromatography. The purified rMSCHITO protein degraded the chitosan (the degree of deacetylation of 99%) and produced a mixture of chitooligosaccharides. The MSCHITO is thus an endo-chitosanase.     

Streptomyces sp. Z-11-6, a novel producer of extracellular L-glutamate oxidase

Glutamate oxidase activity was studied in 1254Streptomyces strains isolated from the zonal soils of various regions of Russia and other countries. Seven strains proved to be producers of extracellular L-glutamate oxidase. The most active producer strain was identified, and the conditions of enzyme biosynthesis were optimized. A multistep mutagenesis-selection procedure allowed a genetically stable strain,Streptomyces sp. Z-11-6, to be obtained, whose glutamate oxidase activity was 40 times higher than that of the original natural isolate.     

Bioconversion of compactin into pravastatin by Streptomyces sp.

Streptomyces sp. Y-110, isolated from soil, modified compactin to pravastatin, a therapeutic agent for hypercholesterolemia. In a batch culture, the highest production of pravastatin was 340 mg l^–1 from 750 mg compactin l^–1 in 24 h. By intermittent feeding of compactin into the culture medium, both the compactin concentration and its conversion increased to 2000 mg l^–1 and 1000 mg pravastatin l^–1, respectively, with the conversion rate of 10 mg l^–1 h^–1. Continuous feeding of compactin increased production of pravastatin to 15 mg l^–1 h^–1.