Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 63 , Issue 6
Showing 1-36 articles out of 36 articles from the selected issue
Review
  • Masahiro KAMEKURA, Morris KATES
    1999 Volume 63 Issue 6 Pages 969-972
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      This minireview gives an updated and consolidated summary of taxonomic classification correlated with membrane phospholipid, glycolipid, and core lipid structural diversity within the family Halobacteriaceae. We also point out that the recently reported diversity in the membrane core lipid structure of a putative strain of Halobacterium (Halobacterium halobium strain IAM 13167) (Morita et al., Biosci. Biotechnol. Biochem., 62, 596-598, 1998) is not correct since the strain used by the authors has for some time been recognized not to be a member of the genus Halobacterium but a member of halobacteria group 2 (Grant and Larsen, Bergey’s Manual of Systematic Bacteriology, Vol.3, pp.2216-2233, 1989), which has recently been designated as a new genus, Natrinema (McGenity et al., Int. J. Syst. Bacteriol. 48, 1187-1196, 1998).
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Analytical Chemistry Regular Paper
  • Hitoshi AOSHIMA, Kiyoshi KADOYA, Hitoshi TANIGUCHI, Takumi SATOH, Hiro ...
    1999 Volume 63 Issue 6 Pages 1025-1031
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      The exposure of Saccharomyces cerevisiae cells to 13-L-hydroperoxylinoleic acid (LOOH) caused their death, the degree of which was dependent on the growth phase of the cells. Pre-application of ethanol, hydrogen peroxide (H2O2) and LOOH to S. cerevisiae cells reduced the effect of LOOH on the cells, showing the transient cross adaptation to LOOH. Antioxidants such as N,N′,-diphenyl-p-phenylenediamine (DPPD), melatonin and vitamin E, and inhibitors of permeability transition of mitochondria, cyclosporin A and trifluoperazine, inhibited the LOOH-triggered cell death, while an inhibitor of glutathione synthetase, buthionine sulfoximine (BSO), enhanced the cell death by LOOH. Reactive oxygen species (ROS) were detected by flow cytometry, using the ROS-specific fluorescent indicator. A ferric iron chelator, deferoxamine, inhibited the LOOH-triggered cell death, and peroxyl radicals (LOO•) were detected by a spin trapping method. These reactive radicals possibly induced the death of S. cerevisiae cells. However, the DNA fragmentation characteristic of apoptosis was not observed in S. cerevisiae cells after exposure to LOOH, staurosporine, dexamethasone or etoposide, which have been reported to cause apoptosis in mammalian cells.
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Organic Chemistry Notes
Organic Chemistry Preliminary Communication
Biochemistry & Molecular Biology Regular Papers
  • Masamichi IKEDA, Kazuya HAMADA, Naomi SUMITOMO, Hiroshi OKAMOTO, Bunsa ...
    1999 Volume 63 Issue 6 Pages 1006-1010
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      To determine why germfree mice are less susceptible to lipopolysaccharide (LPS) than conventional mice, we studied serum levels of serum amyloid A (SAA), tumor necrosis factor (TNF), interleukin 1 (IL-1), IL-6, and corticosterone in mice after treatment with LPS. A single injection of LPS caused an elevation of SAA, an acute-phase protein in the mouse, in both conventional and germfree IQI mice, and the response was significantly less in germfree mice. LPS-induced elevations of serum TNF, IL-1, and IL-6 levels were also significantly less in germfree mice, while serum corticosterone levels were greater in germfree mice than in conventional mice. These results suggest that the lower susceptibility to LPS and a smaller response of SAA elevation by LPS in germfree mice may result from less elevation in serum of these cytokines in these mice, which are known to mediate the acute phase response of SAA. High levels of serum corticosterone in germfree mice may be partly responsible for the lower responsiveness of these inflammatory cytokines to LPS in these mice.
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  • Nobuyo TSUBOYAMA-KASAOKA, Yu HOSOKAWA, Hiroyuki KODAMA, Akiyo MATSUMOT ...
    1999 Volume 63 Issue 6 Pages 1017-1024
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      The organization of the human cysteine dioxygenase (CDO) gene was found to be similar to its rat counterpart, and the location of the introns in the protein structure was identical to the rat CDO gene. The major transcription start site, identified by primer extension, was located 260 bp upstream from the ATG codon. The sequence of the 5′-immediate upstream region was highly conserved between the human and rat CDO genes. The putative promoter region contained a TATA-box-like sequence, and many putative cis-acting elements including HNF5, GRE, TRE, CRE, CArG box, ARE, MBS, and NF-kB. A Northern blot analysis revealed that CDO mRNA was strongly expressed in the liver and placenta, and weakly in the heart, brain and pancreas. CDO mRNA was also detected in human hepatoblastoma HepG2 cells. The CDO mRNA level in HepG2 cells was decreased after 2 h and reached a minimum 6 h-8 h after a phorbol 12-myristate 13-acetate (PMA) treatment, and then gradually returned to the basal level.
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  • Kazumi HIRAGA, Suzuko HAYASHI, Mitsunori KITAZAWA, Kohei ODA
    1999 Volume 63 Issue 6 Pages 1037-1044
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      A killer toxin-like protein was found in the culture supernatant of a strain isolated from soil. The strain was classified and designated as Streptomyces sp. F-287. The molecular weight of the purified killer toxin-like protein was estimated to be 9,500 by SDS-PAGE. The purified protein was heat stable (100°C, 5 min), pH stable (pH 6.0-9.0, 60°C, for 30 min), and had a relatively wide action spectra. The SKLP showed a cytocidal effect on both budding yeast, Saccharomyces cerevisiae W303 (IC50=15.6 μg/ml) and on fission yeast, Schizosaccharomyces pombe SP870 (IC50=20.0 μg/ml). The SKLP also caused morphological changes on some sensitive yeasts and filamentous fungi. These characteristics are apparently different from known killer toxins. These results suggest that this is a novel killer toxin-like protein from Streptomyces sp. strain F-287.
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  • Hiroyuki SHIMIZU, Hiroshi UENO, Rikimaru HAYASHI
    1999 Volume 63 Issue 6 Pages 1045-1050
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      To study the roles of the carbohydrate moiety in the function of carboxypeptidase Y, asparagine residues at 13, 87, 168, and 368, the four-consensus N-linked glycosylation sites, were altered to alanine with site-directed mutagenesis. The mutant enzyme of 51 kDa completely lost the carbohydrate moiety which was present in the 61-kDa wild-type enzyme. Structural studies of the mutant enzyme showed that it maintained the native-like structure; hydrolytic activity, and substrate specificity of the mutant enzyme analogous to those of the wild-type enzyme. Susceptibility of the mutant enzyme toward proteolysis and pressure denaturation was reduced by 10-20%. It is concluded that the carbohydrate moiety functions to maintain the structural integrity of the enzyme under stressed.
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  • Yumiko TAKATSUKA, Motoko ONODA, Takeyoshi SUGIYAMA, Koji MURAMOTO, Tos ...
    1999 Volume 63 Issue 6 Pages 1063-1069
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Lysine decarboxylase (LDC; EC 4.1.1.18) of Selenomonas ruminantium is a constitutive enzyme and is involved in the synthesis of cadaverine, which is an essential constituent of the peptidoglycan for normal cell growth. We purified the S. ruminantium LDC by an improved method including hydrophobic chromatography and studied the fine characteristics of the enzyme. Kinetic study of LDC showed that S. ruminanitum LDC decarboxylated both L-lysine and L-ornithine with similar Km and the decarboxylase activities towards both substrates were competitively and irreversibly inhibited by DL-α-difluoromethylornithine, which is a specific inhibitor of ornithine decarboxylase (EC 4.1.1.17). We also showed a drastic descent of LDC activity owing to the degradation of LDC at entry into the stationary phase of cell growth.
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Biochemistry & Molecular Biology Notes
Food & Nutrition Science Regular Papers
  • Masami HARADA, Yukiko KAN, Hideo NAOKI, Yuko FUKUI, Norihiko KAGEYAMA, ...
    1999 Volume 63 Issue 6 Pages 973-977
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      (+)-Catechin and (-)-epicatechin are known to be biologically effective antioxidants present in the human diet, particularly in wine and tea. We studied the metabolism of these compounds to elucidate the truly active structures in biological fluids by their oral administration to rats. Without any treatment with β-glucuronidase and sulfatase, a pair of metabolites were detected at much higher concentrations in the plasma, bile, and urine than the originally ingested compounds. Each major metabolite found in the plasma at the highest concentration was excreted in both the bile and urine, and was purified from urine. Their chemical structures were established to be (+)-catechin 5-O-β-glucuronide and (-)-epicatechin 5-O-β-glucuronide by MS and NMR analyses. These glucuronide conjugates exhibited high antioxidative activities as superoxide anion radical scavengers like their parent compounds. It is concluded that (+)-catechin 5-O-β-glucuronide and (-)-epicatechin 5-O-β-glucuronide are the biologically active in vivo structures of the ingested polyphenolic antioxidants.
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  • Jian-Jun GAO, Kiharu IGALASHI, Manabu NUKINA
    1999 Volume 63 Issue 6 Pages 983-988
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      In our screening program for antioxidants from traditional drugs and foodstuffs, one new phenylpropanoid glycoside, incanoside, was isolated together with four known phenylpropanoid glycosides, verbascoside, isoverbascoside, phlinoside A, and 6-O-caffeoyl-β-D-glucose from the whole plant of Caryopteris incana (Thunb.) Miq. On the basis of chemical evidence and spectral analysis data, the structure of incanoside was determined to be 1-O-(3,4-dihydroxyphenyl)ethyl-O-β-D-glucopyranosyl (1→2)-α-L-rhamnopyranosyl(1→3)-6-O-caffeoyl-β-D-glucopyranoside. The four phenylpropanoid glycosides exhibited potent radical scavenging activity against DPPH, hydroxyl (•OH), and superoxide anion (O2-) radicals.
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  • Masako TOKITA, Jyunko IWAHARA, Makio MORITA
    1999 Volume 63 Issue 6 Pages 993-997
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Methyl linoleate hydroperoxide produced by autoxidation was refluxed with 10-4 M Cu-naphthenate in benzene. Two new geometrical isomers of oxooctadecadienoate (compounds I and II) were found in addition to the four known isomers. They were isolated by a Sephadex LH-20 column chromatography with chloroform-hexane (2:1) and purified by HPLC on Nucleosil ®100-5 and Zorbax ODS columns. UV, IR, MS, and 1H-NMR spectra were measured. The geometry of conjugated dienes were assigned from the coupling constants of the olefinic protons. Compounds I and II were identified as 13-oxo-trans-9, cis-11- and 9-oxo-cis-10, trans-12-octadecadienoate, respectively. Each of them had a cis double bond adjacent to the oxo group. The hydroperoxides of the same geometry as compounds I and II were also detected in autoxidation products.
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  • Hirofumi YAJIMA, Kazuo WATANABE, Tetsuo TAKEMURA, Tadahiro ISHII
    1999 Volume 63 Issue 6 Pages 1011-1016
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      In order to gain a better understanding of the adaptability of glucoamylase to the conformational change in the substrate related with the specificity of the enzyme action, the effect of the solution conformation of amylose (the substrate) as a function of the I2 concentration on enzyme activity was studied in the initial state by using amyloses with a wide range of average degree of polymerization (DP) in the presence of excess KI. The enzyme activity for the amylose oligomers in the DP range of 20 to 100 decreased monotonically with increasing I2 concentration. This inhibition of the enzyme activity is ascribed to the effect of the conformational change in amylose of the random coil or worm-like chain to a helix that is induced by the binding of I3- ions responsible for inclusion complexation in combination with direct effect of free I3- ions. In a rapidly mixed complex system for amylose with a large DP of 1,000, however, a significant two-step form of the inhibition of enzyme activity appeared with increasing I2 concentration, corresponding to the two-step conformational change of amylose in a random coil or worm-like chain to a helix and then to a rod-like compact structure.
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  • Takashi NISHI, Hiroshi HARA, Yoritaka AOYAMA
    1999 Volume 63 Issue 6 Pages 1070-1074
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      We had demonstrated that a peptic hydrolysate of guanidinated casein that is made from casein by the conversion of lysine to homoarginine stimulated pancreatic exocrine secretion in rats with chronic bile-pancreatic juice (BPJ) diversion from the proximal small intestine. This modified protein also stimulated cholecystokinin (CCK) release from dispersed rat intestinal cells. In this study, we found that guanidinated casein hydrolysate stimulates CCK release in chronic BPJ-diverted rats with cholinergic control blocked by atropine. Intraduodenal guanidinated casein hydrolysate increased portal plasma CCK concentration and pancreatic secretion in atropine-treated BPJ-diverted rats. In contrast, the portal plasma CCK concentration was not increased by intact casein hydrolysate. We conclude that guanidinated casein hydrolysate directly stimulates CCK release from the intestine via some cholinergic-independent mechanism, and an increase of the pancreatic exocrine secretion is regulated by CCK released by guanidinated casein hydrolysate. A guanidyl residue is likely to be involved in this control.
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Food & Nutrition Science Notes
  • Masao YAMASAKI, Keiko MANSHO, Hiroko MISHIMA, Masaaki KASAI, Michihiro ...
    1999 Volume 63 Issue 6 Pages 1104-1106
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      We examined the effect of dietary conjugated linoleic acid (CLA) on lipid parameters in the liver, white adipose tissue (WAT) and brown adipose tissue (BAT) of Sprague-Dawley rats and found that it reduced the levels of triglycerides and non-esterified fatty acid in the liver and WAT without significant change in the BAT lipid levels. These results suggest that CLA has an obesity-preventing action.
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  • Seok-In HONG, Wan-Soo PARK
    1999 Volume 63 Issue 6 Pages 1119-1121
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Baechu (Chinese cabbage) kimchi was treated with high-pressure carbon dioxide at 70 kg/cm2 for 24 h. The effect of this treatment on kimchi fermentation during storage at 10°C was investigated in terms of pH value, titratable acidity, lactic acid bacterial count, and sensory properties. Kimchi samples treated with pressurized CO2 had relatively a higher pH value, lower titratable acidity, and smaller lactic acid bacterial population than the untreated sample. A sensory evaluation showed that the sourness and overall acceptability of treated kimchi were better than those of the control. The color, flavor and texture were not significantly affected by the treatment. The results indicate that high-pressure CO2 treatment could be used as one of the applicable nonthermal processes for baechu kimchi preservation.
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Microbiology & Fermentation Technology Regular Papers
  • Manabu OHTAKE, Hirotaka YAMAMOTO, Takeo UCHIYAMA
    1999 Volume 63 Issue 6 Pages 978-982
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      For discovering the components that contributed to the bonding strength of the glue substances produced by appressoria of Pyricularia oryzae on wax-coated cover-glasses, the influences of metabolic inhibitors and hydrolytic enzymes were investigated. The bonding strength of appressoria was assessed by the ratio of the remaining appressoria after sonication to the appressoria formed before sonication. Remaining appressoria decreased with increasing concentrations of cerulenin, an inhibitor of lipid synthesis, but isoprothiolane and compactin showed no influence on bonding strength. Tunicamycin, an inhibitor of glycoprotein synthesis, weakened the bonding strength of appressoria, but castanospermin had no effect. Of the hydrolytic enzymes tested, protease particularly weakened the bonding strength of appressoria. On the surfaces of substrata, the appressoria’s bonding strength was higher on the hydrophobic surfaces than on the hydrophilic. These results suggest that lipid components and glycoprotein were closely associated with appressoria bonding strength to the surface of wax-coated cover-glass.
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  • Machiko TANAKA, Shuichiro MURAKAMI, Ryu SHINKE, Kenji AOKI
    1999 Volume 63 Issue 6 Pages 989-992
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Three species, Gluconobacter cerinus, G. asaii, and G. frateurii are reported to show lower G+C contents than G. oxydans. Isolate 145 also showed a similar G+C content to those of the three species. We try to reclassify the three species. G. frateurii including a type strain, isolate 145, G. cerinus IFO 3262, 3263, 3269, and G. asaii IFO 3265 formed acid from D-arabitol, ribitol, and L-arabitol. DNAs from G. cerinus IFO 3262, 3263, 3269, and G. asaii IFO 3265 showed 100-53% sequence similarity with that from the type strain of G. frateurii, but showed 31-39% and 34-42% similarity with those from the type strains of G. cerinus and G. asaii, respectively. On the basis of these observations, G. cerinus IFO 3262, 3263, 3269 and G. asaii IFO 3265 were identified as G. frateurii. The type strains of G. cerinus and G. asaii formed acid from D-arabitol, but did not form acid from ribitol and L-arabitol. DNAs from the type strains of G. cerinus and G. asaii showed species-level similarity (95 and 88%) with each other. From these results, we concluded that G. asaii is conspesific and synonymous with G. cerinus.
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  • Yuji HATADA, Norihiko HIGAKI, Kazuhiro SAITO, Akinori OGAWA, Kazuhisa ...
    1999 Volume 63 Issue 6 Pages 998-1005
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Alkaliphilic Bacillus sp. strain KSM-P103 was found to exoproduce a high-alkaline pectate lyase (pectate transeliminase, EC 4.2.2.2). The gene for this enzyme from the alkaliphile was cloned and sequenced for the first time. The structural gene contained a 1,038-bp open reading frame encoding 345 amino acids. The deduced amino acid sequence of the mature enzyme (302 amino acids, 33,312 Da), designated Pel-103, showed very low similarity to those of known pectate lyases with 28-36% identity: the loop regions were very short and the amino acid usage in the parallel β-helix core structure was considerably different. Moreover, physicochemical and catalytic properties of Pel-103 were different from those of other enzymes reported so far. Pel-103 was a very basic protein with an isoelectric point close to pH 10.5 and had optimal activity at 60-65°C and at pH as high as 10.5. However, Pel-103 appeared to have a similar core and active site topology to the enzymes of known structure from Erwinia chrysanthemi and Bacillus subtilis. Expression of the gene for Pel-103 in B. subtilis resulted in high pectate lyase activity in the culture broth, concomitant with the appearance of a main protein band on an SDS gel at 33 kDa.
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  • Hideyuki AOKI, Koshi NISHIOKA, Mitsumasa MANKURA, Yasushi ENDO, Kenshi ...
    1999 Volume 63 Issue 6 Pages 1032-1036
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Accumulation of free unsaturated fatty acids, added individually to the medium, into cellular triacylglycerol (TG) were examined using a fungus, Mucor hiemalis HA-30, which could produce the eicosapentaenoic acid (20:5n-3)-enriched TG. Linoleic (18:2n-6), γ-linolenic (18:3n-6), arachidonic acids (20:4n-6), and 20:5n-3 were favored for accumulation in TG and each fatty acid accumulated in TG at about 80% purity. However, docosahexaenoic acid (22:6n-3) was not efficiently accumulated in TG and its content was about 60%.
      Incorporation and accumulation of various fatty acids added to the cultivation medium were investigated using a model fatty acids mixture. Generally, unsaturated fatty acids were efficiently incorporated into cells more than saturated fatty acids. Fatty acids with odd-numbered double bonds such as 18:3n-3, 18:3n-6, and 20:5n-3 showed the higher incorporation efficiency compared with those with even-numbered double bonds such as 18:2n-6, 20:4n-6, and 22:6n-3. On the other hand, saturated and monounsaturated fatty acids of 16:0, 18:0, and 18:1 were preferentially accumulated in microbial cells over other fatty acids.
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  • Hiroaki YAMAMOTO, Naoki KAWADA, Akinobu MATSUYAMA, Yoshinori KOBAYASHI
    1999 Volume 63 Issue 6 Pages 1051-1055
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      A gene encoding a stereo-specific secondary alcohol dehydrogenase (CpSADH) that catalyzed the oxidation of (S)-1,3-BDO to 4-hydroxy-2-butanone was cloned from Candida parapsilosis. This CpSADH-gene consisted of 1,009 nucleotides coding for a protein with Mr 35,964. A recombinant Escherichia coli JM109 strain harboring the expression plasmid, pKK-CPA1, produced (R)-1,3-BDO (93.5% ee, 94.7% yield) from the racemate without any additive to regenerate NAD+ from NADH.
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  • Yuji YAMAMOTO, Yoshiyuki KAMIO, Masako HIGUCHI
    1999 Volume 63 Issue 6 Pages 1056-1062
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      We cloned and sequenced the glutathione reductase gene (gor) of an oxygen-tolerant Streptococcus mutans, and constructed a gor-disruption mutant by homologous recombination. The gor gene consisted of 1,350 bp, coding for a protein of 450 amino acid residues. The deduced amino acid sequence of the S. mutans gor gene product showed extensive similarity with those of glutathione reductases from prokaryotes and eukaryotes. Although the mutant could grow aerobically, it showed no growth in the presence of 2 mM diamide, a thiol-specific oxidant. In contrast, growth of the wild-type strain was not significantly inhibited by 2 mM diamide, and glutathione reductase activity was increased 2.2-fold under these conditions. In addition, the level of glutathione reductase activity in the wild-type strain was increased 3.6-fold upon exposure to air, and the elevated level of the enzyme was retained throughout the aerobic growth. Thus, glutathione reductase may be important in protection of S. mutans against oxidative stress.
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  • M. Shah Alam BHUIYAN, Yuji ITO, Atsuko NAKAMURA, Naotaka TANAKA, Kiyot ...
    1999 Volume 63 Issue 6 Pages 1075-1082
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      The effects of nystatin, a polyene antibiotic, was studied in Saccharomyces cerevisiae by isolating and characterizing nystatin-sensitive mutants. We isolated a number of nystatin-sensitive mutants by ethylmethane sulfonate mutagenesis. One of these mutants, the nss1 mutant, was characterized in detail. The mutant was sensitive to stresses such as high temperature or high concentrations of monovalent and divalent cations. The nss1 mutants showed severe vacuolar protein sorting and vacuolar morphology defects. The nss1 mutant was demonstrated to have a mutational lesion in the known VPS16 gene, which is essential for vacuolar protein sorting in S. cerevisiae. All of the vacuolar deficient mutants (vps11, vps16, vps18, and vps33) were sensitive to nystatin. Nystatin was found to cause extensive enlargement of the vacuole in wild-type S. cerevisiae cells. These results are discussed with special reference to the vacuolar function of S. cerevisiae.
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  • Michiyo OHNO, Itsuho OKANO, Tomo-o WATSUJI, Teruhito KAKINUMA, Kenji U ...
    1999 Volume 63 Issue 6 Pages 1083-1090
    Published: 1999
    Released: March 12, 2005
    JOURNALS FREE ACCESS
      Symbiobacterium thermophilum is a strictly symbiotic thermophile, the growth of which is dependent on the coexistence of an associating thermophilic Bacillus sp., strain S. S. thermophilum grows only in mixed culture with the Bacillus strain in liquid media, and does not form visible colonies on solid media. To measure the growth of this symbiotic bacterium and to analyze its growth requirements, we developed a quantitative PCR method by using its specific sequences in a putative membrane translocator gene tnaT as primers. According to this method, independent growth of S. thermophilum was first confirmed in a dialyzing culture physically separated from Bacillus strain S with a cellulose membrane. Independent growth of S. thermophilum was also managed by adding conditioned medium prepared from the culture filtrate of the Bacillus strain, but the growth in the conditioned medium stopped at a very limited extent with appearance of filamentous cells, suggesting the uncoupling of cellular growth and cell division. Formation of micro-colonies of S. thermophilum was observed on the conditioned agar medium under both aerobic and anaerobic conditions, but the colony-forming efficiencies remained below 1%. Several other bacterial species, such as Bacillus stearothermophilus, Bacillus subtilis, Thermus thermophilus, and even Escherichia coli, were also found to support the growth of S. thermophilum. These results indicate that S. thermophilum essentially requires some ubiquitous metabolite(s) of low molecular weight produced by various bacterial species as growth factor(s) but coexistence of the living partner cells is still required, probably to maintain an effective level of the putative factor(s) in the medium.
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Microbiology & Fermentation Technology Notes
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