Molecular Cloning, Nucleotide Sequence, and Expression of the Structural Gene for Alkaline Serine Protease from AlkaliphilicBacillussp. 221

The gene encoding an alkaline serine protease from alkaliphilic Bacillus sp. 221 was cloned in Escherichia coli and expressed in Bacillus subtilis. An open reading frame of 1,140 bases, identified as the protease gene was preceded by a putative Shine-Dalgarno sequence (AGGAGG) with a spacing of 7 bases. The deduced amino acid sequence had a pre-pro-peptide of 111 residues followed by the mature protease comprising 269 residues. The alkaline protease from alkaliphilic Bacillus sp. 221 had higher homology to the protease from alkaliphilic bacilli (82.1% and 99.6%) than to those from neutrophilic bacilli (60.6-61.7%). Also Bacillus sp. 221 protease and other protease from alkaliphilic bacilli shared common amino acid changes and 4 amino acid deletions that seemed to be related to characteristics of the enzyme of alkaliphilic bacilli when compared to the proteases from neutrophilic bacilli.

The Rice Annotation Project Database (RAP-DB): 2008 update

The Rice Annotation Project Database (RAP-DB) was created to provide the genome sequence assembly of the International Rice Genome Sequencing Project (IRGSP), manually curated annotation of the sequence, and other genomics information that could be useful for comprehensive understanding of the rice biology. Since the last publication of the RAP-DB, the IRGSP genome has been revised and reassembled. In addition, a large number of rice-expressed sequence tags have been released, and functional genomics resources have been produced worldwide. Thus, we have thoroughly updated our genome annotation by manual curation of all the functional descriptions of rice genes. The latest version of the RAP-DB contains a variety of annotation data as follows: clone positions, structures and functions of 31 439 genes validated by cDNAs, RNA genes detected by massively parallel signature sequencing (MPSS) technology and sequence similarity, flanking sequences of mutant lines, transposable elements, etc. Other annotation data such as Gnomon can be displayed along with those of RAP for comparison. We have also developed a new keyword search system to allow the user to access useful information. The RAP-DB is available at: http://rapdb.dna.affrc.go.jp/ and http://rapdb.lab.nig.ac.jp/.

Indigo production by Escherichia coli carrying the phenol hydroxylase gene from Acinetobacter sp strain ST-550 in a water-organic solvent two-phase system

Acinetobacter sp. strain ST-550 produces indigo from indole in the presence of a large volume of diphenylmethane and a high level of indole. Particular proteins increased remarkably in strain ST-550 grown in the two-phase culture system for indigo production. One of the proteins showed a N-terminal amino acid sequence that was identical to that of the largest subunit of phenol hydroxylase (MopN) from A. calcoaceticus NCBI8250. The indigo-producing activity was strongly induced when ST-550 was grown with phenol as a sole carbon source. Genes coding for the multicomponent phenol hydroxylase were cloned, based on the homology with mopKLMOP from A. calcoaceticus NCBI8250. Escherichia coli carrying the genes produced indigo from indole. E. coli JA300 and its cyclohexane-resistant mutant, OST3410, carrying the hydroxylase genes and the NADH regeneration system were grown in the two-phase culture system for indigo production. The OST3410 recombinant produced 52 microg indigo ml(-1) of medium in the presence of diphenylmethane. This productivity was 4.3-fold higher than that of the JA300 recombinant.

Isolation of an Acinetobacter sp. ST-550 which produces a high level of indigo in a water-organic solvent two-phase system containing high levels of indole

Acinetobacter sp. strain ST-550 was isolated from fumus soil as an efficient indigo producer in the presence of organic solvent. The minimum inhibitory concentration of indole was 0.4 mg/ml for ST-550. ST-550 produced only a small amount of indigo (less than 0.01 microg/ml) when grown in the presence of indole at concentrations of 0.05 to 0.3 mg/ml without any organic solvent. However. ST-550 produced indigo effectively when grown in the presence of a large volume of diphenylmethane and a high level of indole: optimized conditions were 3 ml of a medium containing 0.3 ml diphenylmethane and 2.7 mg indole. Under these conditions, ST-550 produced 0.88 mg indigo (292 microg/mI medium).

Cloning, sequence analysis and expression of a gene encoding an organic solvent- and detergent-tolerant cholesterol oxidase of Burkholderia cepacia strain ST-200

Burkholderia cepacia strain ST-200 produces an extracellular cholesterol oxidase which is stable and highly active in the presence of organic solvents. This cholesterol oxidase produces 6beta-hydroperoxycholest-4-en-3-one from cholesterol, with the consumption of two moles of O2 and the formation of one mole of H2O2. The structural gene encoding the cholesterol oxidase was cloned and sequenced. The primary translation product was predicted to be 582 amino acid residues. The mature product is composed of 539 amino acid residues and is preceded by a signal sequence of 43 residues. The cloned gene was expressed as an active product in Escherichia coli and the product was localized in the periplasmic space. The cholesterol oxidase produced from E. coli was purified to homogeneity from the periplasmic fraction. The purified enzyme was highly stable in the presence of various organic solvents or detergents, as compared with the commercially available cholesterol oxidases tested.

Synthesis of oligosaccharide with controlled sequence

A simple method for the synthesis of alternate heteropolysaccharide was investigated. Two types of modified glucose were combined into a cellobiose-type disaccharide monomer having only acetyl groups except a free hydroxyl group at C-3'. Polycondensation of this monomer, using stannic tetrachloride as catalyst, easily gave a novel copolysaccharide having regularly alternating 1,3-beta and 1,4-beta linkages.

Suppression of hypersensitivity of Escherichia coli acrB mutant to organic solvents by integrational activation of the acrEF operon with the IS1 or IS2 element

The AcrAB-TolC efflux pump plays an intrinsic role in resistance to hydrophobic solvents in Escherichia coli. E. coli OST5500 is hypersensitive to solvents due to inactivation of the acrB gene by insertion of IS30. Suppressor mutants showing high solvent resistance were isolated from OST5500. These mutants produced high levels of AcrE and AcrF proteins, which were not produced in OST5500, and in each mutant an insertion sequence (IS1 or IS2) was found integrated upstream of the acrEF operon, coding for the two proteins. The suppressor mutants lost solvent resistance on inactivation of the acrEF operon. The solvent hypersensitivity of OST5500 was suppressed by introduction of the acrEF operon with IS1 or IS2 integrated upstream but not by introduction of the operon lacking the integrated IS. It was concluded that IS integration activated acrEF, resulting in functional complementation of the acrB mutation. The acrB mutation was also complemented by a plasmid containing acrF or acrEF under the control of Plac. The wild-type tolC gene was found to be essential for complementation of the acrB mutation by acrEF. Thus, it is concluded that in these cells a combination of the proteins AcrA, AcrF, and TolC or the proteins AcrE, AcrF, and TolC is functional in solvent efflux instead of the AcrAB-TolC efflux pump.

Evaluation of the growth and inhibition strength of hydrocarbon solvents against Escherichia coli and Pseudomonas putida grown in a two-liquid phase culture system consisting of a medium and organic solvent

The growth of microorganisms is often inhibited in a two-liquid phase culture system consisting of an aqueous medium and a large volume of hydrophobic solvent. Escherichia coli and Pseudomonas putida were cultured in a two-phase system containing a solvent with a log Pow value in a range of 2.1 to 6.0. The increase in the cell mass was monitored by increase in turbidity of the medium phase. We devised a semiquantitative method to evaluate the growth inhibition strength of solvents based on the relative amount of bacterial growth occurring in the two-phase system. Analyses of growth of the bacteria by this method showed that the growth inhibition strength of a given solvent was usually but not always correlated inversely with its polarity. It is clear that growth inhibition strength is not determined simply by polarity of the solvent.

Entry into and release of solvents by Escherichia coli in an organic-aqueous two-liquid-phase system and substrate specificity of the AcrAB-TolC solvent-extruding pump

Growth of Escherichia coli is inhibited upon exposure to a large volume of a harmful solvent, and there is an inverse correlation between the degree of inhibition and the log P(OW) of the solvent, where P(OW) is the partition coefficient measured for the partition equilibrium established between the n-octanol and water phases. The AcrAB-TolC efflux pump system is involved in maintaining intrinsic solvent resistance. We inspected the solvent resistance of delta acrAB and/or delta tolC mutants in the presence of a large volume of solvent. Both mutants were hypersensitive to weakly harmful solvents, such as nonane (log P(OW) = 5.5). The delta tolC mutant was more sensitive to nonane than the delta acrAB mutant. The solvent entered the E. coli cells rapidly. Entry of solvents with a log P(OW) higher than 4.4 was retarded in the parent cells, and the intracellular levels of these solvents were maintained at low levels. The delta tolC mutant accumulated n-nonane or decane (log P(OW) = 6. 0) more abundantly than the parent or the delta acrAB mutant. The AcrAB-TolC complex likely extrudes solvents with a log P(OW) in the range of 3.4 to 6.0 through a first-order reaction. The most favorable substrates for the efflux system were considered to be octane, heptane, and n-hexane.

Contribution of the cell wall component teichuronopeptide to pH homeostasis and alkaliphily in the alkaliphile Bacillus lentus C-125

A teichuronopeptide (TUP) is one of major structural components of the cell wall of the facultative alkaliphilic strain Bacillus lentus C-125. A mutant defective in TUP synthesis grows slowly at alkaline pH. An upper limit of pH for growth of the mutant was 10.4, while that of the parental strain C-125 was 10.8. Gene tupA, directing synthesis of TUP, was cloned from C-125 chromosomal DNA. The primary translation product of this gene is likely a cytoplasmic protein (57. 3 kDa) consisting of 489 amino acid residues. Introduction of the tupA gene into the TUP-defective mutant complemented the mutation responsible for the pleiotropic phenotypes of the mutant, leading to simultaneous disappearance of the defect in TUP synthesis, the diminished ability for cytoplasmic pH homeostasis, and the low tolerance for alkaline conditions. These results demonstrate that the acidic polymer TUP in the cell wall plays a role in pH homeostasis in this alkaliphile.

Two moles of O2 consumption and one mole of H2O2 formation during cholesterol peroxidation with cholesterol oxidase from Pseudomonas sp. strain ST-200

Cholesterol oxidase from Pseudomonas sp. strain ST-200 oxidized cholesterol and cholestanol to 6beta-hydroperoxycholest-4-en-3-one and 5alpha-cholestan-3-one respectively. The former was converted spontaneously to several oxysteroids such as 6-hydroxycholest-4-en-3-one and cholest-4-ene-3,6-dione, with the consumption of 2 mol of O(2) and the formation of 1 mol of H(2)O(2) for each mole of cholesterol oxidized. An oxidized form of the cholesterol oxidase dehydrogenates cholesterol, probably to the 5-en-3-one derivative. A reduced form of the enzyme, yielded from the cholesterol dehydrogenation reaction, dioxygenated cholest-5-en-3-one to 6beta-hydroperoxycholest-4-en-3-one.

Organic solvent tolerance of Escherichia coli is independent of OmpF levels in the membrane

The organic solvent tolerance of Escherichia coli was measured under conditions in which OmpF levels were controlled by various means as follows: alteration of NaCl concentration in the medium, transformation with a stress-responsive gene (marA, robA, or soxS), or disruption of the ompF gene. It was shown that solvent tolerance of E. coli did not depend upon OmpF levels in the membrane.

Lithocholic acid side-chain cleavage to produce 17-keto or 22-aldehyde steroids by Pseudomonas putida strain ST-491 grown in the presence of an organic solvent, diphenyl ether

We devised a method to screen for microorganisms capable of growing on bile acids in the presence of organic solvents and producing organic solvent-soluble derivatives. Pseudomonas putida biovar A strain ST-491 isolated in this study produced decarboxylated derivatives from the bile acids. Strain ST-491 grown on 0.5% lithocholic acid catabolized approximately 30% of the substrate as a carbon source, and transiently accumulated in the medium androsta-1,4-diene-3,17-dione in an amount of corresponding to 5% of the substrate added. When 20% (v/v) diphenyl ether was added to the medium, 60% of the substrate was converted to 17-keto steroids (androst-4-ene-3,17-dione-like steroid, androsta-1,4-diene-3,17-dione) or a 22-aldehyde steroid (pregna-1,4-dien-3-on-20-al). Amounts of the products were responsible for 45, 10, and 5% of the substrate, respectively. In the presence of the surfactant Triton X-100 instead of diphenyl ether, 40% of the substrate was converted exclusively to androsta-1,4-diene-3,17-dione.

C-terminal domain of beta-1,3-glucanase H in Bacillus circulans IAM1165 has a role in binding to insoluble beta-1,3-glucan

The deduced amino acid sequences of 72-kDa beta-1,3-glucanase from Bacillus circulans WL-12 (GIcA) and 91-kDa enzyme from B. circulans IAM1165 (BglH) are highly homologous, except that the latter has an additional long C-terminal region composed of 192 amino acid residues. Two mutant enzymes (BgIH deprived of the C-terminal region and GIcA with the C-terminal region added) were constructed. The enzymes possessing the C-terminal region bound more abundantly to pachyman (insoluble beta-1,3-glucan) and A.spergillus oryzae cell wall than those not possessing the region. This indicates that the C-terminal region participated in binding of the enzymes to insoluble beta-1,3-glucan.

Improvement of organic solvent tolerance level of Escherichia coli by overexpression of stress-responsive genes

Water-immiscible organic solvents can be toxic to microorganisms. The tolerance levels differ among strains of Escherichia coli, suggesting that the organic solvent tolerance level is strain specific and determined genetically. We constructed several mutants from E. coli, of which the organic solvent tolerance levels were improved. The mutants were defective in the marR gene encoding a repressor protein for the mar operon that is responsible for environmental stress factors. High expression of stress-responsive genes, soxS, marA, and robA, elevated organic solvent tolerance levels of several strains of E. coli. These genes code for DNA-binding proteins that are transcriptional activators belonging to the AraC subfamily with the helix-turn-helix motif. It was shown that expression of the AcrAB-TolC system, a major efflux pump in E. coli, was positively regulated by the proteins. This system was highly expressed in the organic solvent-tolerant mutants. Strains defective in one of the genes, acrA, acrB, or tolC, were remarkably sensitive to organic solvents.

Effect of magnetite on the hematocrit value in exsanguinated rats

Magnetite prepared by an enzyme-dependent reaction gradually released iron ion into the acidic-to-neutral buffer solution. A preparatory experiment was performed to examine the efficiency of magnetite as an iron supplement. Feeding exsanguinated rats with being magnetite resulted in the hematocrit value being recovered without any serious adverse effect on the digestive organs.

Involvement of outer membrane protein TolC, a possible member of the mar-sox regulon, in maintenance and improvement of organic solvent tolerance of Escherichia coli K-12

Escherichia coli mutants with improved organic solvent tolerance levels showed high levels of outer membrane protein TolC and inner membrane protein AcrA. The TolC level was regulated positively by MarA, Rob, or SoxS. A possible mar-rob-sox box sequence was found upstream of the tolC gene. These findings suggest that tolC is a member of the mar-sox regulon responsive to stress conditions. When a defective tolC gene was transferred to n-hexane- or cyclohexane-tolerant strains by P1 transduction, the organic solvent tolerance level was lowered dramatically to the decane-tolerant and nonane-sensitive level. The tolerance level was restored by transformation of the transductants with a wild-type tolC gene. Therefore, it is evident that TolC is essential for E. coli to maintain organic solvent tolerance.

Effects of oxygen and nitrate on growth of Escherichia coli and Pseudomonas aeruginosa in the presence of organic solvents

Escherichia coli and Pseudomonas aeruginosa grown in the presence of certain harmful organic solvents become susceptible to these solvents during the cultivation. This susceptibility is conspicuous in the stationary phase of growth. The organic solvent tolerance levels of these microorganisms were maintained when the oxygen concentration was kept high. The tolerance levels were maintained also when these organisms were grown with nitrate present under anaerobic respiratory conditions.

Cell surface properties of organic solvent-tolerant mutants of Escherichia coli K-12

In this study, we examined cell surface properties of mutants of Escherichia coli for which organic solvent tolerance levels were elevated. The cell surface of each mutant was less hydrophobic than that of the parent, probably due to an increase in lipopolysaccharide content. OmpF synthesis was repressed in the mutants. Organic solvent bound readily to viable E. coli cells in response to the polarity of the solvent. The mutants were bound less abundantly with the organic solvent than was the parent.

Biodegradation of indole at high concentration by persolvent fermentation with Pseudomonas sp. ST-200

Pseudomonas sp. strain ST-200 grew on indole as a sole carbon source. The minimal inhibitory concentration of indole was 0.3 mg/ml for ST-200. However, ST-200 grew in a persolvent fermentation system containing a large amount of indole (a medium containing 20% by vol. diphenylmethane and 4 mg/ml indole), because most of the indole was partitioned in the organic solvent layer. When the organism was grown in the medium containing indole at 1 mg/ml in the presence of diphenylmethane, more than 98% of the indole was consumed after 48h. Isatic acid (0.4 mg/ml) and isatin (0.03 mg/ml) were produced as the metabolites in the aqueous medium layer.

Organic solvent tolerance and antibiotic resistance increased by overexpression of marA in Escherichia coli

We previously reported that overexpression of the soxS or robA gene causes in several Escherichia coli strains the acquisition of higher organic solvent tolerance and also increased resistance to a number of antibiotics (H. Nakajima, K. Kobayashi, M. Kobayashi, H. Asako, and R. Aono, Appl. Environ. Microbiol. 61:2302-2307, 1995). Most E. coli strains cannot grow in the presence of cyclohexane. We isolated the marRAB genes from a Kohara lambda phage clone and cyclohexane-tolerant mutant strain OST3408. We found a substitution of serine for arginine at position 73 in the coding region of marR of OST3408 and designated the gene marR08. Our genetic analysis revealed that marR08 is responsible for the cyclohexane-tolerant phenotype. We observed that the marA gene on high-copy-number plasmids increased the organic solvent tolerance of E. coli strains. Furthermore, exposure of E. coli cells to salicylate, which activates the mar regulon genes, also raised organic solvent tolerance. Overexpression of the marA, soxS, or robA gene increased resistance to numerous antibiotics but not to hydrophilic aminoglycosides.

Cloning and sequencing of the gene encoding the cell surface glycoprotein of Haloarcula japonica strain TR-1

The triangular disk-shaped halophilic archaeon Haloarcula japonica strain TR-1 has a glycoprotein on its cell surface. The complete gene encoding the cell surface glycoprotein (CSG) was cloned and sequenced. The gene has an open reading frame of 2586 bp, and a potential archaeal promoter sequence approximately 150 bp upstream of the ATG initiation codon. The mature CSG is composed of 828 amino acids and is preceded by a signal sequence of 34 amino acid residues. A hydropathy analysis showed a hydrophobic stretch at the C-terminus, that probably serves as a transmembrane domain. The amino acid sequence of the Ha. japonica CSG showed 52.1% and 43.2% identities to those from the Halobacterium halobium and Haloferax volcanii CSGs, respectively. Five potential N-glycosylation sites were found in the mature Ha. japonica CSG, sites that were distinctly different from those in Hb. halobium and Hf. volcanii. The Ha. japonica CSG gene was expressed in Escherichia coli.

Natronococcus amylolyticus sp. nov., a haloalkaliphilic archaeon

The alpha-amylase-producing haloalkaliphilic archaeon Natronococcus sp. strain Ah-36T (T = type strain) was isolated previously from a Kenyan soda lake, Lake Magadi. Most cells of strain Ah-36T occurred in irregular clusters, and the colonies were orange-red. The polar lipids of this organism were composed of C20, C20 and C20, C25 derivatives of phosphatidylglycerol and phosphatidylglycerophosphate. Phosphatidylglycero-(cyclo-) phosphate, which is characteristic of Natronococcus occultus, was not detected. The complete nucleotide sequence of the 16S rRNA gene revealed that the closest relative of strain Ah-36T is N. occultus ATCC43101T (level of similarity, 96.4%), an extremely halophilic archaeon. However, strain Ah-36T did not exhibit a significant level of DNA homology to N. occultus ATCC43101T, which represents the only previously described species in the genus Natronococcus. We describe a new species for strain Ah-36T, for which we propose the name Natronococcus amylolyticus.

soxRS gene increased the level of organic solvent tolerance in Escherichia coli

Escherichia coli strain JA300 grows in the presence of n-hexane, but not in the presence of cyclohexane. We isolated a 10.5-kb DNA fragment that provided cyclohexane tolerance on a multi-copy plasmid, from the chromosomal DNA of JA300. In this fragment, there were found C-terminal 10-amino acids truncated soxR (soxR') and soxS which control the superoxide response regulon genes. Characterization of subclones found that both the soxR' and overexpression of the soxS increased the levels of organic solvent tolerance in several E. coli strains.

Overexpression of the robA gene increases organic solvent tolerance and multiple antibiotic and heavy metal ion resistance in Escherichia coli

Escherichia coli K-12 OST3410 was isolated previously as a stable cyclohexane-tolerant mutant derived from cyclohexane-sensitive strain JA300. A plasmid which provides cyclohexane tolerance to strain JA300 was isolated from the OST3410 genomic library. Subcloning and sequence analysis showed that the plasmid contained the robA gene, whose gene product was reported to bind specifically to the right border of oriC. We observed that the robA gene on the multicopy plasmid generally increased the organic solvent tolerance of several E. coli strains. We also observed an increase in the organic solvent tolerance of JA300 carrying the lac-robA fusion gene on a low-copy plasmid by isopropyl-beta-D-thiogalactopyranoside induction. Strain JA300 carrying the multicopy robA plasmid also showed an increase in resistance to a number of unrelated antibiotics and heavy metal ions, and the spectrum of resistance was significantly similar to that of the soxS-overexpressing strain.

A close correlation between improvement of organic solvent tolerance levels and alteration of resistance toward low levels of multiple antibiotics in Escherichia coli

We have isolated cyclohexane-tolerant mutants from Escherichi coli strain JA300, which is cyclohexane-sensitive and n-hexane-tolerant. These mutants were resistant to low levels of ampicillin, chloramphenicol, nalidixic acid, and tetracycline, and were sensitive to a low level of kanamycin. Spontaneous clones resistant to low levels of the antibiotics, isolated from JA300, showed altered levels of organic solvent tolerance. The clones resistant to ampicillin and chloramphenicol had cyclohexane tolerance. Some of the resistant clones had cyclohexane and n-pentane tolerances. On the other hand, some kanamycin resistant clones became sensitive to n-hexane. Therefore, mechanisms to improve tolerance levels toward organic solvents are closely correlated with some antibiotic resistant system to low levels of antiobiotics.

Structure-function relationship of the xylanase from alkaliphilic Bacillus sp. strain 41M-1

Xylanase J from alkaliphilic Bacillus sp. strain 41M-1 contains a family G catalytic domain at the N-terminus, followed by a linker sequence and a functionally-unknown C-terminal domain. The mutational analysis of xylanase J indicated that Glu-93, Glu-183, Trp-18, Trp-86, Tyr-84 and Tyr-95 play an important role in the catalytic activity. A deletion derivative of xylanase J lacking the C-terminal domain retained its activity, suggesting that the C-terminal domain does not directly involved in catalysis.

Isolation of extracellular 28- and 42-kilodalton beta-1,3-glucanases and comparison of three beta-1,3-glucanases produced by Bacillus circulans IAM1165

Bacillus circulans IAM1165 produces three major extracellular beta-1,3-glucanases (molecular masses, 28, 42, and 91 kDa) during the stationary phase of growth. The 28- and 42-kDa enzymes were purified to homogeneity from the culture supernatant in this study. The properties of these two enzymes were examined, together with those of the 91-kDa enzyme previously isolated. The enzymatic properties of the 28- and 42-kDa beta-1,3-glucanases closely resemble each other. The enzymes belong to a category of endo type 1,3-beta-D-glucan glucanohydrolases. The enzymes were active at pH 4.0 to 7.0. The optimum temperature of the reactions was 60 degrees C when laminarin (a soluble beta-1,3-glucan) was used as the substrate at pH 7.0. The enzymes hydrolyzed barley glucan and lichenan (beta-1,3-1,4-glucans) more effectively than laminarin. Of the three enzymes, the 42-kDa enzyme lysed fungal cell walls the most effectively.

Construction of a new teichuronopeptide-defective derivative from alkaliphilic Bacillus sp. C-125 by cell fusion

Cell walls of facultative alkaliphilic Bacillus sp. C-125 are composed of peptidoglycan, teichuronic acid, and teichuronopeptide. A mutant lacking teichuronic acid, or defective in both teichuronic acid and teichuronopeptide has been isolated from the organism. We now constructed another type of a cell-wall defective mutant that was defective in teichuronopeptide but had teichuronic acid, by cell fusion using protoplasts prepared from a wild-type strain and a mutant defective in teichuronopeptide and teichuronic acid. This mutant grew more poorly than wild type or a teichuronic acid-defective strain of C-125. The growth, however, was faster than that of the parental strain defective in both teichuronic acid and teichuronopeptide.

Cloning of organic solvent tolerance gene ostA that determines n-hexane tolerance level in Escherichia coli

A variety of genes are involved in determining the level of organic solvent tolerance of Escherichia coli K-12. Gene ostA is one of the genes contributing to the level of organic solvent tolerance. This gene was cloned from an n-hexane-tolerant strain of E. coli, JA300. A JA300-based n-hexane-sensitive strain, OST4251, was converted to the n-hexane-tolerant phenotype by transformation with DNA containing the ostA gene derived from JA300. Thus, the cloned ostA gene complemented the n-hexane-sensitive phenotype of OST4251.

Cloning, expression, and nucleotide sequence of the alpha-amylase gene from the haloalkaliphilic archaeon Natronococcus sp. strain Ah-36

The alpha-amylase gene of a Natronococcus sp. (1,512 bp) contained a signal peptide of 43 amino acids. Haloferax volcanii expressed the gene and cleaved the signal peptide accurately. The signal peptide shared an extremely high amino acid sequence identity with that of a protease from the halophilic archaeon 172P1.

Oxidative Bioconversion of Cholesterol by Pseudomonas sp. Strain ST-200 in a Water-Organic Solvent Two-Phase System

Pseudomonas sp. strain ST-200, which is capable of conversion of cholesterol, was isolated from humus soil. This organism effectively modified cholesterol dissolved in an organic solvent by dehydrogenation and oxygenation. When the organism was grown in a medium overlaid with a 10% volume of a mixed organic solvent ( p -xylene and diphenylmethane; 3:7, vol/vol) containing cholesterol (20 mg/ml), the cholesterol concentration in the organic solvent was reduced to only 0.4 mg/ml after 8 days. Although the organism did not assimilate cholesterol, 98% of the cholesterol initially present disappeared. The organic solvent layer contained two major and three minor compounds converted from cholesterol. The major compounds were 6β-hydroxycholest-4-en-3-one (8.9 mg/ml) and cholest-4-ene-3,6-dione (7.6 mg/ml). The concentrations of these compounds were equivalent to 43 and 37% of the cholesterol initially present. This organism would provide an effective and convenient system to oxidize the C-3 and -6 positions of cholesterol by introduction of a hydroxyl or ketone group.

Mapping of organic solvent tolerance gene ostA in Escherichia coli K-12

The extent of organic solvent tolerance was variable among strains of Escherichia coli K-12. Genetic analyses of n-hexane-tolerant strains indicated that a number of genes were involved in the solvent-tolerance phenotype. One such gene, designated ostA, was mapped at 1.2 min, close to pdxA. Transduction of ostA from a n-hexane-sensitive strain to a n-hexane-tolerant strain generated n-hexane-sensitive transductants. The sensitive transductant restored n-hexane-tolerance by transduction of ostA from a tolerant strain. Thus, the gene ostA is one of the genes that contributes to deciding the level of organic solvent tolerance in E. coli.

Cloning and expression of the gene encoding the 7Fe type ferredoxin from a thermophilic hydrogen oxidizing bacterium, Bacillus schlegelii

The structural gene (fdxA) coding for a 7Fe type ferredoxin of a thermophilic hydrogen oxidizing bacterium Bacillus schlegelii has been cloned and sequenced. The fdxA coding region is 231 nucleotides which codes for a 77 amino acids protein with the molecular weight of 8,744 except for iron-sulfur clusters. The fdxA gene has been expressed in E. coli to obtain the recombinant ferredoxin. The recombinant ferredoxin have shown the identical properties to the native one for absorption spectra, and SDS-PAGE.

Expression of an 87-kD-beta-1,3-glucanase of Bacillus circulans IAM1165 in Saccharomyces cerevisiae by low-temperature incubation

A DNA segment encoding a signal peptide from yeast invertase was fused in frame to bglH gene encoding 87-kD-beta-1,3-glucanase from Bacillus circulans IAM1165 and was expressed in the yeast Saccharomyces cerevisiae under the control of the GAL1 gene promoter. Yeast cells containing this fused gene produced active beta-1,3-glucanase in the medium after a long period of incubation at low temperature. The enzyme produced by yeast was heterogeneous in size, and larger than the enzyme produced by Escherichia coli.

Structure of the 87-kDa beta-1,3-glucanase gene of Bacillus circulans IAM1165 and properties of the enzyme accumulated in the periplasm of Escherichia coli carrying the gene

The nucleotides of a gene for the extracellular 87-kDa beta-1,3-glucanase of Bacillus circulans IAM1165 and its flanking regions were sequenced. The sequence showed an open reading frame for 877 amino acids, which corresponds to a precursor of the beta-1,3-glucanase. The coding region of 2631 bp is flanked by putative promoter and transcription terminator sequences. The signal peptide was considered to be consisted of 38 amino acids. The amino acid sequence of the mature enzyme composed of 839 amino acids showed high homology to that of the enzyme from B. circulans WL-12, although these enzymes are different in their sizes. A catalytic domain of the enzyme was estimated central region of the sequence on the basis of comparison of amono acid sequences of beta-1,3- or beta-1,3:1,4-glucanases. Properties of the periplasmic enzyme produced in Escherichia coli carrying the gene were identical with those of the extracellular enzyme produced by B. circulans IAM1165.

Purification and some properties of an alkaline xylanase from alkaliphilic Bacillus sp. strain 41M-1

An alkaliphilic Bacillus sp. strain, 41M-1, isolated from soil produced multiple xylanases extracellularly. One of these xylanases was purified to homogeneity by ammonium sulfate fractionation and anion-exchange chromatography. The moleculr mass of this enzyme (xylanase J) was 36 kDa, and the isoelectric point was pH 5.3. Xylanase J was most active at pH 9.0. The optimum temperature for the activity at pH 9.0 was around 50 degrees C. The enzyme was stable up to 55 degrees C at pH 9.0 for 30 min. Xylanase J was completely inhibited by the Hg2+ion and N-bromosuccinimide. The predominant products of xylan hydrolysate were xylobiose, xylotriose, and higher oligosaccharides, indicating that the enzyme was an endoxylanase. The apparent Km and Vmax values on xylan were 3.3 mg/ml and 1,100 micromol-1 mg-1, respectively. Xylanase J showed high sequence homology with the xylanases from Bacillus pumilus and Clostridium acetobutylicum in the N-terminal region. Xylanase J acted on neither crystalline cellulose nor carboxymethyl cellulose, indicating a possible application of the enzyme in biobleaching processes.

Identification of 2-amino-2,6-dideoxy-D-glucose (D-quinovosamine), isolated from the cell walls of the alkaliphilic Bacillus sp. Y-25, by 500-MHz 1H NMR spectroscopy

Cell walls of alkaliphilic Bacillus strain Y-25 are composed of gamma-peptidoglycan and two acidic polymers. An amino sugar, which was a min component of one acidic polymer, did not correspond to any of the commercially available hexosamines. The amino sugar was isolated from the hydrolysate of the acidic polymer, purified, and identified as D-quinovosamine (2-amino-2,6- dideoxy-D-glucose) by 500-MHz NMR spectroscopic analysis and polarimetry.

Molecular cloning, nucleotide sequence and expression of the structural gene for a thermostable alkaline protease from Bacillus sp. no. AH-101

Alkaliphilic Bacillus sp. no. AH-101 produces an extremely thermostable alkaline serine protease that has a high optimum pH (pH 12-13) and shows keratinolytic activity. The gene encoding this protease was cloned in Escherichia coli and expressed in B. subtilis. The cloned protease was identical to the AH-101 protease in its optimum pH and thermostability at high alkaline pH. An open reading frame of 1083 bases, identified as the protease gene, was preceded by a putative Shine-Dalgarno sequence (AAAGGAGG) with a spacing of 11 bases. The deduced amino acid sequence revealed a pre-pro-peptide of 93 residues followed by the mature protease comprising 268 residues. AH-101 protease showed slightly higher homology to alkaline proteases from alkaliphilic bacilli (61.2% and 65.3%) than to those from neutrophilic bacilli (54.9-56.7%). Also AH-101 protease and other proteases from alkaliphilic bacilli shared common amino acid changes and a four amino acid deletion when compared to the proteases from neutrophilic bacilli. AH-101 protease, however, was distinct among the proteases from alkaliphilic bacilli in showing the lowest homology to the others.

Accumulation of alkaliphilic Bacillus penicillinase cleaved within the signal sequence in cytoplasm of Escherichia coli

Alkaliphilic Bacillus penicillinase produced by Escherichia coli is distributed in several subcellular compartments according to cultivation conditions. The penicillinase that accumulated in particular subcellular fractions of E. coli grown under different conditions was purified and characterized. Periplasmic or extracellular penicillinase (24 kDa) was mature protein, indicating that the putative precursor (27 kDa) was processed at the correct amino acid residue, probably by signal peptidase I. Cytoplasmic penicillinase contained two unusual proteins (25 kDa) that are produced by proteolytic cleavage of the precursor within its signal sequence.