共查询到20条相似文献,搜索用时 46 毫秒
1.
Causative microorganisms for musty odor occurrence in the eutrophic Lake Kasumigaura 总被引:3,自引:0,他引:3
The musty odor phenomenon in Lake Kasumigaura, Japan (a eutrophic lake that is used for various purposes, including water supply source) was examined. The causative microorganisms responsible for the production of the odor compounds, geosmin and/or 2-methylisoborneol (MIB), and the odor release mechanism were studied in vitro and in situ. The numbers of the filamentous P. tenue in the lake water column were closely correlated with the concentration of MIB, but not geosmin. The isolated monoxenic P. tenue in culture produced only MIB. Geosmin concentration was well correlated with the number of actinomycetes in the sediment. Forty isolates of actinomycetes from the sediment around the water supply intake tower produced both geosmin and MIB in culture. Furthermore, the average ratio of production of geosmin to MIB was 1.40–1.0. Actinomycetes in the sediment played an important role in geosmin production. We concluded that geosmin and MIB from actinomycetes in the sediment, and MIB from P. tenue in the water column were jointly responsible for the severe musty odor occurrence of the waters supply source at Lake Kasumigaura. 相似文献
2.
Blue-green algal blooms formed by Microcystis and Oscillatoria often occur in shallow eutrophic lakes, such as Lake Taihu (China) and Lake Kasumigaura (Japan). Growth characteristics
and competitions between Microcystis aeruginosa and Oscillatoria mougeotii were investigated using lake simulator systems (microcosms) at various temperatures. Oscillatoria was the superior competitor, which suppressed Microcystis, when temperature was <20°C, whereas the opposite phenomenon occurred at 30°C. Oscillatoria had a long exponential phase (20 day) and a low growth rate of 0.22 day−1 and 0.20 day−1 at 15°C and 20°C, respectively, whereas Microcystis had a shorter exponential phase (2–3 days) at 30°C and a higher growth rate (0.86 day−1). Interactions between the algae were stronger and more complex in the lake simulator system than flask systems. Algal growth
in the lake simulator system was susceptible to light attenuation and pH change, and algae biomasses were lower than those
in flasks. The outcome of competition between Microcystis and Oscillatoria at different temperatures agrees with field observations of algal communities in Lake Taihu, indicating that temperature
is a significant factor affecting competition between Microcystis and Oscillatoria in shallow, eutrophic lakes. 相似文献
3.
An experiment was carried out to evaluate the effects of phosphorus concentration (1, 4 and 10 mg l−1) and temperature (15 and 25°C) on chlorophyll a (chl a) contents and cell size/volume of green alga Scenedesmus
obliquus and blue green alga Microcystis aeruginosa. Long-term field data from Lake Taihu, a large, shallow eutrophic lake between Jiangsu and Zhejiang Provinces, China, was
also used to evaluate the effect of temperature on the model between chl a and total phosphorus (TP). The chl a content of both algae increased with an increase in phosphorus concentration and temperature. Temperatures showed a significantly
different effect on chl a content of S. obliquus at a phosphorus concentration of 10 mg l−1, whereas there was no significant difference at the two lower phosphorus levels. For M. aeruginosa, temperatures presented significantly different effects on the chl a contents at three phosphorus concentrations. Chl a content of neither alga presented an interaction between the nutrient and the temperature. Long-term field data from Lake
Taihu also indicated that the addition of temperature to the model increased predictability of chl a by TP. The length/diameter and volume of both algae were greater at the lower temperature and phosphorus concentration. Moderate
negative correlations were observed between algal size, volume, and chl a content. Our results suggest that phosphorus concentration and temperature could change chl a contents and size in species-specific algal cells and that temperature should be considered when building the model of TP
and chl a concentration. 相似文献
4.
Thuy ML Kharel MK Lamichhane R Lee HC Suh JW Liou K Sohng JK 《Biotechnology letters》2005,27(7):465-470
An actinomycetes expression vector (pIBR25) was constructed and applied to express a gene from the kanamycin biosynthetic gene cluster encoding 2-deoxy-scyllo-inosose synthase (kanA) in Streptomyces lividans TK24. The expression of kanA in pIBR25 transformants reached a maximum after 72 h of culture. The plasmid pIBR25 showed better expression than pSET152, and resulted in the formation of insoluble KanA when it was expressed in Escherichia coli. This strategy thus provides a valuable tool for expressing aminoglycoside-aminocyclitols (AmAcs) biosynthetic genes in Streptomyces spp. 相似文献
5.
Hai-Nan Su Bin-Bin Xie Xiu-Lan Chen Jin-Xia Wang Xi-Ying Zhang Bai-Cheng Zhou Yu-Zhong Zhang 《Journal of applied phycology》2010,22(1):65-70
Allophycocyanin (APC) is a minor component of phycobiliproteins in cyanobacteria and red algae. This paper describes a simple
and inexpensive extracting method for isolating APC from Spirulina (Arthrospira) platensis with high efficiency. The crude phycobiliprotein extract was pretreated by ammonium sulfate fractionation. Then, by adding
hydroxylapatite into crude phycobiliprotein extract dissolved in 20 mM phosphate buffer (pH 7.0), APC was selectively adsorbed
by hydroxylapatite but C-phycocyanin (C-PC) was not. The hydroxylapatite was collected and APC was extracted from the crude
phycobiliprotein extract. Then, the enriched APC was washed off from the hydroxylapatite using 100 mM phosphate buffer (pH 7.0).
In this simple extracting method it was easy to remove C-PC and isolate APC in large amounts. The absorbance ratio A
650/A
280 of extracted APC reached 2.0. The recovery yield was 70%, representing 4.61 mg · g−1 wet weight. The extracted APC could be further purified by a simple anion-exchange chromatography with a pH gradient from
5.6 to 4.0. The absorbance ratio A
650/A
280 of the purified APC reached 5.0, and the overall recovery yield was 43%, representing 2.83 mg · g−1 wet weight. Its purity was confirmed by native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE. 相似文献
6.
Contrary to an expectation from the size-efficiency hypothesis, small herbivore zooplankton such as Ceriodaphnia often competitively predominate against large species such as Daphnia. However, little is known about critical feeding conditions favoring Ceriodaphnia over Daphnia. To elucidate these conditions, a series of growth experiments was performed with various types of foods in terms of phosphorus
(P) contents and composition (algae and bacteria). An experiment with P-rich algae showed that the threshold food level, at
which an individual’s growth rate equals zero, was not significantly different between the two species. However, the food
P:C ratio, at which the growth rate becomes zero, was lower for Daphnia than for Ceriodaphnia, suggesting that the latter species is rather disfavored by P-poor algae. Ceriodaphnia showed a higher growth rate than Daphnia only when a substantial amount of bacteria was supplied together with a low amount of P-poor algae as food. These results
suggest that an abundance of bacteria relative to algae plays a crucial role in favoring Ceriodaphnia over Daphnia because these are an important food resource for the former species but not for the latter. 相似文献
7.
Maria José Ruiz Chancho José Fermín López Sánchez Roser Rubio 《Journal of applied phycology》2010,22(4):465-472
The seagrass Posidonia oceanica from the Mediterranean coast and the brown algae Durvillaea antarctica and Lessonia nigrescens from the Chilean coast were analysed for total arsenic and for arsenic species. Arsenic species were extracted with water
and measured by high-performance liquid chromatography–inductive coupled plasma mass spectrometry. Arsenite, arsenate, methylarsonate,
dimethylarsinate, sulfonate sugar, sulphate sugar and phosphate sugar were analysed with an anion exchange column. Arsenobetaine,
arsenocholine and glycerol sugar were separated with a cation exchange column. An extract of Fucus serratus was used to assign the arsenosugar peaks in the chromatograms from the sample extracts. In addition to the four common arsenosugars
found in algae, inorganic arsenic was also measured in some samples, with the highest content found in L. nigrescens. The certified reference material (CRM) NIES no. 9 Sargassum fullvellum was analysed for quality assessment of total arsenic, and moreover, arsenosugars were also determined in this CRM. 相似文献
8.
First year ontogenetic diet patterns and size-dependent diet partitioning of two coexisting piscivorous percids, pikeperch and Volga pikeperch were analysed in Lake Balaton. Diet patterns of the two pikeperches followed a common trend, catching larger preys at larger sizes, but in details they were different. Until 20–30 mm size age-0 pikeperch fed on planktonic microcrustaceans and were found only in the pelagic zone. After this size, from the end of May, a part of the stock shifted habitat and moved to the littoral zone to feed on Limnomysis benedeni. Majority of the stock stayed in the pelagic zone and shifted to Leptodora kindtii. In the pelagic group early piscivory, mainly cannibalism, occurred only sporadically. However, the few individuals that reached 100 mm size during the first year were typically piscivorous. Volga pikeperch stayed in the pelagic zone during the first year and shifted from planktonic microcrustaceans to benthic macroinvertebrates. General patterns of the first year diet ontogeny were similar in the different areas of Lake Balaton in both pikeperches with only some differences in the secondary food resources, especially in the share of chironomids. Chironomids were eaten at highest ratio by the two fish species in the Keszthely basin in accordance with their abundance pattern. Maximum prey sizes increased significantly with predator size in both pikeperch and Volga pikeperch. However, pikeperch ate much larger prey than did Volga pikeperch at the same size although they have a similar mouth gape to length ratio. These two, closely related pikeperches, although occur in the same habitat and have similar patterns of diet ontogeny, effectively partition food resources in Lake Balaton during the first growing season, except in the very beginning of their ontogeny at L = 5–10 mm size. It appears that age-0 Volga pikeperch is not a significant competitor for the economically highly rated pikeperch in Lake Balaton. On the other hand, it is age-0 pikeperch that might affect Volga pikeperch during its early ontogeny, in the planktivorous stage. 相似文献
9.
Richard H. Baltz 《Journal of industrial microbiology & biotechnology》2010,37(8):759-772
Natural products discovery from actinomycetes has been on the decline in recent years, and has suffered from a lack of innovative
ways to discover new secondary metabolites within a background of the thousands of known compounds. Recent advances in whole
genome sequencing have revealed that actinomycetes with large genomes encode multiple secondary metabolite pathways, most
of which remain cryptic. One approach to address the expression of cryptic pathways is to first identify novel pathways by
bioinformatics, then clone and express them in well-characterized hosts with known secondary metabolomes. This process should
eliminate the tedious dereplication process that has hampered natural products discovery. Several laboratory and industrial
production strains have been used for heterologous production of secondary metabolite pathways. This review discusses the
results of these studies, and the pros and cons of using various Streptomyces and one Saccharopolyspora strain for heterologous expression. This information should provide an experimental basis to help researchers choose hosts
for current application and future development to express heterologous secondary metabolite pathways in yields sufficient
for rapid scale-up, biological testing, and commercial production. 相似文献
10.
A. V. Krylov D. B. Kosolapov N. G. Kosolapova A. A. Hovsepyan Yu. V. Gerasimov 《Biology Bulletin》2018,45(5):505-511
The appearance of Daphnia (Ctenodaphnia) magna Straus, 1820 in the pelagial of Sevan Lake caused significant changes in the communities of planktonic algae, bacteria, and heterotrophic nanoflagellates. Phytoplankton and nanoflagellates were the most affected by the direct impact of D. magna, and the number and biomass of bacteria increased due to the reduction in the trophic pressure of the protists. It was also facilitated by the increased supply of phosphorus as a result of the activity of the cladocerans, as well as the decrease in the number and biomass of phytoplankton, which competes with heterotrophic bacteria for the nutrients. 相似文献
11.
Karseno Kazuo Harada Takeshi Bamba Susilaningsih Dwi Aparat Mahakhant Tomoaki Yoshikawa Kazumasa Hirata 《Biotechnology letters》2009,31(7):999-1003
During growth of the freshwater cyanobacteria, Oscillatoria sp. BTCC/A0004, and Scytonema sp. TISTR 8208, a pink pigment is released into the growth medium. The pigment from each source had a molecular weight of
approximately 250 kDa and had adsorption maxima at 560 and 620 nm. These results suggest that pink pigment is a phycoerythrin-like
protein. It inhibited the growth of green algae, Chlorella fusca and Chlamydomonas reinhardtii, but not other cyanobacteria or true bacteria. The concentration at which growth inhibition 50% occurred was 0.5, 6 and more
than 10 mg ml−1, respectively. 相似文献
12.
Recently, the prenyltransferase SirD was found to be responsible for the O-prenylation of tyrosine in the biosynthesis of sirodesmin PL in Leptosphaeria maculans. In this study, the behavior of SirD towards phenylalanine/tyrosine and tryptophan derivatives was investigated. Product
formation has been observed with 12 of 19 phenylalanine/tyrosine derivatives. It was shown that the alanine structure attached
to the benzene ring and an electron donor, e.g., OH or NH2, at its para-position are essential for the enzyme activity. Modifications were possible both at the side chain and the benzene ring.
Enzyme products from seven phenylalanine/tyrosine derivatives were isolated and characterized by MS and NMR analyses including
HSQC and HMBC and proven to be O- or N-prenylated derivatives at position C4 of the benzene rings. K
M
values of six selected derivatives were found in the range of 0.10–0.68 mM. Catalytic efficiencies (K
cat/K
M
) were determined in the range of 430–1,110 s−1·M−1 with l-tyrosine as the best substrate. In addition, 7 of 14 tested tryptophan analogs were also accepted by SirD and converted to
C7-prenylated derivatives, which was confirmed by comparison with products obtained from enzyme assays using a 7-dimethylallyltryptophan
synthase 7-DMATS from Aspergillus fumigatus. 相似文献
13.
Mariana Solans Gernot Vobis Luis Gabriel Wall 《Journal of Plant Growth Regulation》2009,28(2):106-114
Saprophytic rhizoactinomycetes isolated from the root nodule surface of the nitrogen-fixing actinorhizal plant Discaria trinervis, Streptomyces MM40, Actinoplanes ME3, and Micromonospora MM18, previously shown to stimulate nodulation in Frankia-Discaria trinervis symbiosis, were assayed as co-inoculants with Sinorhizobium meliloti 2011 on Medicago sativa. When plants were fertilized with a low level of N (0.07 mM), the inoculation of the actinomycetes alone did not show any
effect on plant growth. Meanwhile, when actinomycetes were co-inoculated with S. meliloti, nodulation and plant growth were significantly stimulated compared to plants inoculated with only S. meliloti. The analysis of nodulation kinetics of simultaneously or delayed co-inoculations suggests that the effect of the actinomycetes
operates in early infection and nodule development counteracting the autoregulation of nodulation by the plant. Because the
actinomycete effect was found in the symbiotic nitrogen-fixing state of the plant, we investigated the effects of the actinomycetes,
in single inoculation or co-inoculation with S. meliloti, on plants grown under a high level of N (7 mM) that was inhibitory for nodulation by S. meliloti. The inoculation of the actinomycetes alone did not show any effect on plant growth although high N was available. Unexpectedly,
the co-inoculation of actinomycetes with S. meliloti on plants grown with high N (7 mM) significantly stimulates nodulation, clearly counteracting the inhibition of nodulation
by high N. These results corroborate that the interaction of rhizoactinomycetes would interfere with the autoregulation of
nodulation in alfalfa mediated by high N, opening new research lines of potential agronomical applications. 相似文献
14.
Phylogenetic diversity among filamentous sulfur-oxidizing bacteria of the genus Thioploca inhabiting freshwater/brackish environments was analyzed in detail. The 16S rRNA gene sequence of Thioploca found in a freshwater lake in Japan, Lake Okotanpe, was identical to that of Thioploca from Lake Ogawara, a brackish lake. The samples of the two lakes could be differentiated by the sequences of their 23S rRNA
genes and 16S–23S rRNA internal transcribed spacer (ITS) regions. The 23S rRNA-based phylogenetic relationships between Thioploca samples from four lakes (Lake Okotanpe, Lake Ogawara, Lake Biwa, and Lake Constance) were similar to those based on the 16S
rRNA gene sequences. In addition, multiple types of the ITS sequences were obtained from Thioploca inhabiting Lake Okotanpe and Lake Constance. Variations within respective Thioploca populations were also observed in the analysis of the soxB gene, involved in sulfur oxidation. As major members of the sheath-associated microbial community, bacteria of the phylum
Chloroflexi were consistently detected in the samples from different lakes. Fluorescence in situ hybridization revealed that they were
filamentous and abundantly distributed within the sheaths of Thioploca. 相似文献
15.
Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner.
The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate
larvae Galleria
mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host. 相似文献
16.
An increasing number of recent studies indicate that multiple interacting factors can affect the invasion of plants. However,
few studies have focused on asexual propagation and the interaction of propagation with environmental factors that regulate
the invasive potential of introduced exotic species in aquatic habitats. This study was designed to investigate the differences
in asexual propagation between introduced exotic and non-invasive native aquatic macrophytes in nutrient-poor and nutrient-rich
sediments and to test the hypothesis that differences in asexual propagation (stem fragment production) and propagule establishment
between introduced exotic and non-invasive native macrophytes are driven by sediment nutrient levels. Three exotic aquatic
macrophytes (Elodea nuttallii, Myriophyllum aquaticum, and M. propinquum) recently introduced to China and their non-invasive native counterparts (Hydrilla
verticillata, M. oguraense, and M. ussuriense) were used for comparison in nutrient-poor (TN 0.59 and TP 0.03 mg g−1) and nutrient-rich (TN 2.35 and TP 0.10 mg g−1) sediments. After 8 weeks of growth, the exotic species tended to produce more total biomass, branch biomass and apical shoots
and have higher relative growth rate (RGR) than their native counterparts in nutrient-rich sediment. Rooting efficiency and
root growth of exotic fragments were higher than that of native counterparts in nutrient-rich sediment, although the survival
rates of fragments did not differ between native and exotic species. In addition, superior traits (rooting efficiency and
root growth) of exotic species were also observed in nutrient-poor sediment, but to a lesser degree than in nutrient-rich
sediment. These results suggest that asexual propagation of these three introduced exotic macrophytes is more effective in
nutrient-rich sediment than in nutrient-poor sediment in China. 相似文献
17.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
18.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
19.
Stefanie Kimbacher Ingrid Gerstl Branko Velimirov Sylvia Hagemann 《Molecular genetics and genomics : MGG》2009,282(2):165-172
P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding
region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.