Two strains of an undescribed species belonging to the anamorphic genus Myxozyma were recovered from frass of a Ips typographus f. japonicus larvae. The strains differ from the accepted species of the genus in their utilization of carbon sources, mol% G+C and low percentage of DNA-DNA homology. A description of the new species Myxozymanipponensis is given and a key to the genus is provided.
This study compared the growth, photosynthesis, electron transport, ATP content, NO3- and NH4+ uptake, Na+ and K+ loss, nitrate reductase and ATPase activities of an acid-tolerant strain and a wild-type strain of Chlorella vulgaris exposed to Cu at varied pHs (pH 6.8, 5.0, 4.0 and 3.5). A general reduction in growth, NH4+ uptake, photosynthesis and nitrate reductase activity of both the strains was noticed at decreasing pH. In contrast, the acid-tolerant strain depicted an increased NO3- uptake, insignificant Na+, K+ loss and superactive ATPase at decreasing pH. Both pH and Cu produced a non-competitive inhibition of NO3- uptake. An increase in Vmax of ATPase of acid-tolerant Chlorella and inhibition of the Vmax of its wild-type strain at decreasing pH was noticed. Though the magnitude of Cu toxicity was significantly low in tolerant strain, a significant negative correlation (r=-0.99, p<0.01) of Cu uptake with acid pH was noticed. The acid-tolerant Chlorella was less sensitive to Cu and physiologically more efficient than the wild type. Presence of a superactive ATPase and change in membrane permeability are considered responsible for acid tolerance in Chlorella.
Thirty-nine Rhizopus isolates and 9 authentic Rhizopus strains were grown on wheat bran solid culture and assayed for their soluble starch digestive glucoamylase (GA) and raw-starch digestive glucoamylase (GARS). Results showed that the Rhizopus strains tested can be classified into 4 groups based on their GA and GARS production and ratio of GARS to GA. Four Rhizopus isolates and 2 authentic Rhizopus strains produced reasonable amount of GA and GARS activities (GA>100 units/ml and GARS>10 units/ml) in the solid culture extracts, having ratios of GARS to GA activity>0.10. The strain with the highest ratio of GARS to GA (F75) was selected for medium optimization. The highest GA- and GARS-producing Rhizopus strain (IFO 4697), Rhizopus F75 and a good glucoamylase-producing Aspergillus niger (K-20) were cultured using the optimum medium and the glucoamylase enzymes produced were further characterized based on saccharification rate on various raw starches and rates of simultaneous saccharification and fermentation in combination with baker's yeast.
Lipopolysaccharides (LPSs), isolated from four Aquaspirillum species, i.e. the type strains of A. itersonii subsp. nipponicum, A. polymorphum, A. aquaticum and A. metamorphum together with A. metamorphum mutant strain 12-3 were characterized onto their chemical composition. A. itersonii subsp. nipponicum IFO 13615 and A. polymorphum IFO 13961, both belonging to the α-1 subgroup of Proteobacteria, possess L-glycero-D- manno-heptose, glucuronic acid and galacturonic acid in their LPS and both have 3-hydroxy-tetradecanoic acid as hydroxylated fatty acid. A. itersonii subsp. nipponicum has additionally 3-hydroxy-hexadecanoic acid and a small amount of 3-hydroxy-octadecanoic acid. In the LPSs of A. aquaticum IFO 14918 and both A. metamorphum IFO 13960 strains, which belong to the β-1 subgroup of Proteobacteria, neither heptoses nor uronic acids could be detected. The main sugar components were rhamnose and glucose and both possess the same three major fatty acid constituents dodecanoic acid, tetradecanoic acid and 3-hydroxydecanoic acid. From the DOC-PAGE pattern it was evident that A. itersonii subsp. nipponicum and A. polymorphum have a similar LPS-type as revealed for two Rhodospirillum strains, R. fulvum DSM 117 and R. molischianum NTHC 131. These strains being members of the α-1 group of Proteobacteria possess LPSs which show distinct gaps between the band of R-type LPS and other slower-moving bands. In the case of A. metamorphum such gap was also visible. The LPS of A. aquaticum showed R-type character on DOC-PAGE.
Significant amelioration of Cr and Pb toxicity was observed in Nostocmuscorum at high concentrations of phosphate. The effect of Cr and Pb on growth, photosynthetic oxygen evolution, carbon and nitrogen fixation of N. muscorum was less in cultures pre- and post-treated with high (80 μM) phosphate concentration than in those treated with a lower (20μM) orthophosphate concentration. The uptake of Cr and Pb in the cyanobacterial cells was not affected by phosphate concentration. Likewise phosphate uptake was not disturbed either by Cr or Pb. A rapid accumulation of polyphosphate bodies in the cells treated with Cr and Pb indicates that uptake and accumulation of phosphate was not inhibited. N. muscorum cells exposed to both the metals registered a notable decrease in the breakdown of polyphosphate bodies and acid and alkaline phosphatase activities. Cr and Pb competitively inhibited the activity of partially purified acid and alkaline phosphatases. It is concluded that Cr and Pb affect intracellular phosphate metabolism rather than the uptake and incorporation of phosphate in N. muscorum.
A new genus, Prasinococcus, and a new species, P. capsulatus, are described on the basis of specimen that appeared in enriched cultures inoculated from water samples in the western Pacific Ocean. Cells of this unicellular alga are spherical and surrounded with a large amount of gelatinous matrix. The pigment composition, which includes chlorophylls a and b, prasinoxanthin, Mg 2, 4-diviriylphaeoporphyrin a5 monomethyl ester (Mg 2, 4-D) and 5, 6-epoxy-3, 3′-dihydroxy-5, 6, 7′, 8′-tetrahydro-β-ε-caroten-11′, 19-olide (uriolide), is close to that observed in the Mamiellales (Prasinophyceae). The cell is non-flagellate and has a firm cell wall, but no scales on the cell body. The pyrenoid has a characteristic structure in which a mitochondrial lobe and chloroplast outer membranes protrude into the pyrenoid matrix. The cell wall has a projecting appendage like a circle collar surrounded by distinctive holes penetrating the cell wall. Since the cell contains no 3-deoxy-manno-octulosonic acid (KDO), the wall is considered to have a different origin from the cell coverings which consist of fused scales in Tetraselmis species. It has a characteristic way of asexual reproduction in which, after cell division, one cell remains within the parent cell wall while the other is extruded. This suggests that this alga be placed tentatively in the Pycnococcaceae (Order Mamiellales) on the basis of the pigment composition and morphological characteristics, but the taxonomic position of coccoid prasinophytes may need to be reconsidered.
Bacillus subtilis secA341 mutant cells sporulate at 32°C but not at 39°C. Temperature shift-up and -down experiments indicated that the cells were sensitive to the high-temperature treatment from an early stage of sporulation to relatively late stages. Within this temperature-sensitive duration, three discontinuous periods were discriminated by means of pulse-treatment with the nonpermissive temperature. These periods were T-0.5-T0.5, T1-T2 and T3-T5; T0 indicates the end of exponential growth and subscript numbers represent hourly periods after T0. When the mutant cells harboring the spo0A-lacZ fusion with the sporulation specific promoter, Ps, were incubated at 39°C from T-0.5 to T0.5, the subsequent expression of lacZ gene at 32°C was almost completely abolished. Although the sporulation frequency of these temperature-treated cells was around 1/10 of the control culture, the remaining vegetative cells exhibited the so-called Spo0 phenotypes. Electron microscopic analysis with cells incubated at 39°C after developing to some stages of sporulation at 32°C, suggested that the second temperature-sensitive period, T1-T2, corresponded to a SecA-dependent stage for the initiation of asymmetric septation which occurred at around T3 in the control culture. The third period, T3-T5, dependent on the SecA function was shown to correspond to a stage of septum engulfment; the control culture at 32°C completed the engulfment process and forespore formation at T7.
Differential scanning calorimetry (DSC) was carried out for the study on the effect of various anions on the melting of plasmid pJL3-TB5 DNA (5, 277 base pairs in length). In the presence of halide ions such as Cl-, Br-, or I- in citrate buffer solutions, seven separate peaks caused by the stepwise melting of the DNA molecule were found in the DSC curve. Similar profile of the DSC curve was also found in the presence of SCN-. Such a characteristic melting profile was not observed, when some other buffer solutions such as phosphate, borate, and acetate buffers were used. These ions affected significantly the melting profile of DNA; the height of the peaks seen in the high temperature range decreased and broadened. The presence of the anions such as NO3-, ClO4-, SO42- and IO3- instead of Cl- in the saline-sodium citrate (SSC) buffer solution also affected the DSC curves in the high temperature range in the similar manner to phosphate, borate, and acetate buffers. These results indicate that the type of anions in the solution as well as that of cations is very important for the melting of DNA. Since anions are known to alter the structure of water, it is suggested that these results are closely related to alteration of the structure of water caused by the interaction between anions and water, rather than the direct interaction between anions and DNA. The borate buffer solutions also showed not only clearly separated peaks, but also excellent reversibility for the melting of the DNA.