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1.
Wen Gu 《World journal of microbiology & biotechnology》2009,25(9):1677-1683
A total of 48 strains were isolated from the normal tissues of Malus halliana and the EtOAc extracts of their cultures were subjected to primary antimicrobial screening against four test bacteria and
three fungi. As a result, 22 strains exhibited antimicrobial activity against at least one test microbe. Among them, Alternaria brassicicola ML-P08 showing strong activity (MICs: 0.31–2.50 mg/ml) was selected for further investigation on its secondary metabolites.
Bioassay-guided fractionation of the EtOAc extract of its liquid culture afforded seven compounds, which were identified as
alternariol (1), alternariol 9-methyl ether (2), altechromone A (3), herbarin A (4), cerevisterol (5), 3β,5α-dihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (6) and 3β-hydroxy-(22E,24R)-ergosta-5,8,22-trien-7-one (7), respectively, by spectral means (MS, IR, 1H- and 13C-NMR). In vitro antimicrobial assay showed that compound 3 was substantially active against Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens and Candida albicans with the MICs of 3.9, 3.9, 1.8, and 3.9 μg/ml, respectively. Compound 4 also showed pronounced antifungal activity against Trichophyton rubrum and C. albicans with MICs of both 15.6 μg/ml. In addition, compound 1 exhibited strong xanthine oxidase inhibitory activity with the IC50 of 15.5 μM, comparable to that of positive control, allopurinol (IC50: 10.7 μM). 相似文献
2.
An endophytic Xylaria sp., having broad antimicrobial activity, was isolated and characterized from Ginkgo biloba L. From the culture extracts of this fungus, a bioactive compound P3 was isolated by bioactivity-guided fractionation and
identified as 7-amino-4-methylcoumarin by nuclear magnetic resonance, infrared, and mass spectrometry spectral data. The compound
showed strong antibacterial and antifungal activities in vitro against Staphylococcus aureus [minimal inhibitory concentrations (MIC) 16 μg·ml−1], Escherichia coli (MIC, 10 μg·ml−1), Salmonella typhia (MIC, 20 μg·ml−1), Salmonella typhimurium (MIC, 15 μg·ml−1), Salmonella enteritidis (MIC, 8.5 μg·ml−1), Aeromonas hydrophila (MIC, 4 μg·ml−1), Yersinia sp. (MIC, 12.5 μg·ml−1), Vibrio anguillarum (MIC, 25 μg·ml−1), Shigella sp. (MIC, 6.3 μg·ml−1), Vibrio parahaemolyticus (MIC, 12.5 μg·ml−1), Candida albicans (MIC, 15 μg·ml−1), Penicillium expansum (MIC, 40 μg·ml−1), and Aspergillus niger (MIC, 25 μg·ml−1). This is the first report of 7-amino-4-methylcoumarin in fungus and of the antimicrobial activity of this metabolite. The
obtained results provide promising baseline information for the potential use of this unusual endophytic fungus and its components
in the control of food spoilage and food-borne diseases. 相似文献
3.
Although resistance of microorganisms to Hg(II) salts has been widely investigated and resistant strains have been reported
from many eubacterial genera, there are few reports of mercuric ion resistance in extremophilic microorganisms. Moderately
thermophilic mercury resistant bacteria were selected by growth at 62 °C on Luria agar containing HgCl2. Sequence analysis of 16S rRNA genes of two isolates showed the closest matches to be with Bacillus pallidus and Ureibacillus thermosphaericus. Minimum inhibitory concentration (MIC) values for HgCl2 were 80 μg/ml and 30 μg/ml for these isolates, respectively, compared to 10 μg/ml for B. pallidus H12 DSM3670, a mercury-sensitive control. The best-characterised mercury-resistant Bacillus strain, B. cereus RC607, had an MIC of 60 μg/ml. The new isolates had negligible mercuric reductase activity but removed Hg from the medium
by the formation of a black precipitate, identified as HgS by X-ray powder diffraction analysis. No volatile H2S was detected in the headspace of cultures in the absence or presence of Hg2+, and it is suggested that a new mechanism of Hg tolerance, based on the production of non-volatile thiol species, may have
potential for decontamination of solutions containing Hg2+ without production of toxic volatile H2S. 相似文献
4.
Antimicrobial Butyrolactone I Derivatives from the Ecuadorian Soil Fungus Aspergillus terreus Thorn. var terreus 总被引:1,自引:0,他引:1
M. E. Cazar G. Schmeda-Hirschmann L. Astudillo 《World journal of microbiology & biotechnology》2005,21(6-7):1067-1075
Summary The fungus Aspergillus terreus Thorn var. terreus isolated from an Ecuador soil sample was cultured in liquid and solid media and yielded three main metabolites identified
as terreic acid (1), butyrolactone I (2) and lovastatin (3). The natural products as well as three synthetic butyrolactone I derivatives were assessed for antimicrobial activity against
Gram-positive and Gram-negative bacteria and fungi as well as for seed germination and seedling growth. Furthermore, the compounds
were assessed as inhibitors towards the enzymes acetylcholinesterase, β-glucosidase, and β-glucuronidase. Terreic acid, butyrolactone I, butyrolactone 4′,4′′-diacetate (2.1), and 3′-(3-methylbutyl)-butyrolactone II (2.2) were active towards the phytopathogenic bacteria Erwinia carotovora with IC50 of 5 and 4–18 μg/ml, respectively. Under the same experimental conditions, the IC50 of streptomycin was 1.9 μg/ml. 3′-(3-Methylbutyl)-butyrolactone II was moderately active against Pseudomonas syringae and Botrytis cinerea with IC50 of 21μg/ml and MIC of 15.6 μg/ml, respectively. Butyrolactone I also inhibited germination of the dicot Lactuca sativa with an IC50 of 5 × 10−5 M. The IC50 of reference herbicide acetochlor was 1 × 10−5 M. The effect of 2.2 and 2.3, known as butyrolactone III on Panicum millaceum germination and growth was stronger than that of 2 and 2.1. Reduction of the double bond in the isoprenyl side chain of butyrolactone I increased the antibacterial effect against E. carotovora as well as acetylation. To our best knowledge, this is the first report on the antibacterial effect of butyrolactone derivatives
towards Erwinia carotovora and the phytopathogenic fungus Botrytis cinerea. The butyrolactone I derivative 2.2 presented a moderate inhibitory effect against the enzyme acetylcholinesterase with an IC50 of 47 μg/ml. Under the same experimental conditions, the reference inhibitor galanthamine had an IC50 of 3 μg/ml. 相似文献
5.
Arthrospira
platensis SAG 21.99 and the isolated bacteria (Halomonas spp., Staphylococcus sp., etc.) from the culture of A. platensis SAG 21.99 were treated with five antibiotics to determine the minimal lethal concentrations. The combination of a washing
step and a consecutive treatment with antibiotics, imipenem (100 μg ml−1), neomycin (100 μg ml−1) and cycloheximide (20 μg ml−1), treatment step was highly effective in eliminating bacteria. An axenic culture of A. platensis SAG 21.99 could be induced within 3 days using this method. This technique is a simple and rapid method for obtaining axenic
cultures of filamentous cyanobacteria. 相似文献
6.
Dae-Sung Lee Min-Seung Kang Hye-Jin Hwang Sung-Hwan Eom Ji-Young Yang Myung-Suk Lee Won-Jae Lee You-Jin Jeon Jae-Sue Choi Young-Mog Kim 《Biotechnology and Bioprocess Engineering》2008,13(6):758-764
We have been attempting for some time to discover a compound evidencing antibacterial activity against methicillin-resistant
Staphylococcus aureus (MRSA). The dieckol isolated from Ecklonia stolonifera has been shown to exhibit antibacterial activity against methicillin-susceptible S. aureus (MSSA) and MRSA. The minimum inhibitory concentrations (MICs) of dieckol were determined in a range of 32 to 64 μg/mL against
standard MSSA and MRSA strains. Furthermore, dieckol clearly reversed the high-level ampicillin and penicillin resistance
of MRSA. The MICs of ampicillin against two standard strains of MRSA were dramatically reduced from 512 to 0.5 μg/mL in combination
with 1/4 MIC of dieckol (16 μg/mL). The fractional inhibitory concentration (FIC) indices of ampicillin and penicillin were
measured from 0.066 to 0.266 in combination with 8 or 16 μg/mL of dieckol against all tested MRSA strains, thereby suggesting
that dieckol-ampicillin or dieckol-penicillin combinations exert a synergistic effect against MRSA. The results of this study
indicate that dieckol, administered in combination with β-lactams, may prove effective in the treatment of MRSA infections.
Our finding may also contribute to the development of an alternative phytotherapeutic anti-MRSA agent. 相似文献
7.
In this study, using a bioassay-guided isolation and purification procedure, we obtained 3-chloro-2,5-dihydroxybenzyl alcohol
from a marine-derived Ampelomyces species that effectively inhibited larval settlement of the tubeworm Hydroides elegans and of cyprids of the barnacle Balanus amphitrite. The inhibitive effect on larval settlement was nontoxic and the EC50 of 3-chloro-2,5-dihydroxybenzyl alcohol ranged from 3.19 μg ml−1 to 3.81 μg ml−1 while the LC50 was 266.68 μg ml−1 for B. amphitrite cyprids; EC50 ranged from 0.67 μg ml−1 to 0.78 μg ml−1, and LC50 was 2.64 μg ml−1 for competent larvae of H. elegans, indicating that inhibitive effect of this compound was nontoxic. At a concentration of 50 μg per disc, this compound showed
strong inhibitive effects on the growth of 13 out of 15 marine bacterial species tested in disc diffusion bioassay. Overall,
the high inhibitory activities against bacteria and larval settlement as well as the non- or low-toxic nature of this compound
to the barnacle and polychaete larvae suggest this compound could be a potent antifoulant and/or antibiotic. 相似文献
8.
Of 23 strains of halotolerant (up to 12% w/v NaCl) photosynthetic bacteria isolated from various sources, one isolate, SH5,
accumulated intracellular 5-aminolevulinic acid (ALA) at 0.45 μg/g dry cell wt (DCW) growing aerobically in the dark. The
strain was identified as Rhodobacter sphaeroides using 16S rDNA sequencing. Biosynthesis of ALA was enhanced to 14 μg/g DCW using modified glutamate/glucose (50 mM) medium
with the addition of 10 mM levulinic acid after 24 h cultivation. Addition of 30 μM Fe2+ to this medium increased the yield to 226 μg/g DCW. 相似文献
9.
F. W. Wang Z. M. Hou C. R. Wang P. Li D. H. Shi 《World journal of microbiology & biotechnology》2008,24(10):2143-2147
The metabolites of endophytic fungus Penicillium sp. from the leaf of Hopea hainanensis were reported for the first time. By bioassay-guided fractionation, the EtOAc extract of a solid-matrix steady culture of
this fungus afforded six compounds, which were identified through a combination of spectral and chemical methods (IR, MS,
1H- and 13C-NMR) to be monomethylsulochrin (1), rhizoctonic acid (2), asperfumoid (3), physcion (4), 7,8-dimethyl-iso-alloxazine (5) and 3,5-dichloro-p-anisic acid (6). Compounds 2, 3 and 6 were obtained from Penicillium sp. for the first time. All of the six isolates were subjected to in vitro bioactive assays including antifungal action against
three human pathogenic fungi Candida albicans, Trichophyton rubrum and Aspergillus niger and cytotoxic activity against the human nasopharyngeal epidermoid tumor KB cell line and human liver cancer HepG2 cell line.
As a result, compounds 2–4 and 6 inhibited the growth of C. albicans with MICs of 40.0, 20.0, 50.0 and 15.0 μg/ml, respectively and the compound 6 showed growth inhibition against A. niger with MICs of 40.0 μg/ml. In addition, compounds 1–3 and 6 exhibited cytotoxic activity against KB cell line with IC50 value of 30.0, 20.0, 20.0, 5.0 μg/ml, respectively and against HepG2 cell line with IC50 value of 30.0, 25.0, 15.0, 10.0 μg/ml, respectively. 相似文献
10.
Xiang-Jing Wang Xiao-Chong Wang Wen-Sheng Xiang 《World journal of microbiology & biotechnology》2009,25(6):1051-1056
Milbemycin antibiotics are produced by Streptomyces
hygroscopicus subsp. aureolacrimosus and a newly isolated Streptomyces bingchenggensis, respectively. According to the biosynthetic pathway of milbemycins generated by S.
hygroscopicus subsp. aureolacrimosus, a rational screening procedure with UV irradiation and N-methyl-N′-nitroso-N-nitrosoguanidine (NTG) mutation was performed to obtain high milbemycin-producing S. bingchenggensis. Aminoacetic acid (Glycine)-resistant mutants (AAr), propionate-resistant mutants (PRPr), streptomycin-resistant mutants (STRr) and 2-deoxy-d-glucose-resistant mutants (DOGr) were selected successively. A strain S. bingchenggensis BC-109-6 with AAr, PRPr, STRr and DOGr was obtained and its production of milbemycin A3 and A4 reached 1,450 μg/ml, which was 80% higher than that of the ancestral
strain S. bingchenggensis BC-101-4. The subculture experiments indicated that the hereditary characteristic of high productivity of S. bingchenggensis BC-109-6 was stable. The production of milbemycin A3 and A4 by S. bingchenggensis BC-109-6 in a 50-l fermentor could reach 1,380 μg/ml after 360 h batch fermentation. 相似文献
11.
In this study, the effects of inositol addition on expression of the MAL gene encoding maltase and phosphatidylinositol (PI) biosynthesis in Schizosaccharomyces pombe (a naturally inositol-requiring strain) were examined. We found that specific maltase activity was at its maximum when the concentration of added inositol reached 6 μg ml−1 in a synthetic medium containing 2.0% (w/v) glucose. When the concentration of added inositol was 1 μg ml−1 in the medium, repression of MAL gene expression occurred at glucose concentration higher than 0.2% (w/v). However, when S. pombe was cultured in the synthetic medium containing 6 μg ml−1, repression of maltase gene expression occurred only at initial glucose concentration above 1.0% (w/v). More mRNA encoding maltase was detected in the cells grown in the medium with 6 μg ml−1 inositol than in those grown in the same medium with 1 μg ml−1 inositol. These results demonstrate that higher inositol concentrations in the synthetic medium could derepress MAL gene expression in S. pombe. PI content of the yeast cells grown in the synthetic medium with 6 μg ml−1 of inositol was higher than that of the yeast cells grown in the same medium with 1 μg ml−1 of inositol. This means that PI may be involved in the derepression of MAL gene expression in S. pombe. 相似文献
12.
Cell suspension cultures of Commiphora wightii, grown in modified MS medium containing 2,4-dichlorophenoxyacetic acid (0.5 mg l−1) and kinetin (0.25 mg l−1), produced ∼5 μg guggulsterone g−1 dry wt. In a 2 l stirred tank bioreactor, the biomass was 5.5 g l−1 and total guggulsterone was 36 μg l−1. 相似文献
13.
Domínguez-Bocanegra AR Ponce-Noyola T Torres-Muñoz JA 《Applied microbiology and biotechnology》2007,75(4):783-791
Phaffia rhodozyma (now Xanthophyllomyces dendrorhous) and Haematococcus pluvialis are known as the major prominent microorganisms able to synthesize astaxanthin natural pigment. Important research efforts
have been made to determine optimal conditions for astaxanthin synthesis. When the focus is on astaxanthin production, the
maximal reported value of 9.2 mg/g cell is obtained within H. pluvialis grown on BAR medium, under continuous illumination (345 μmol photon m−2 s−1) and without aeration. Whereas fermentation by mutated R1 yeast grown on coconut milk produced 1,850 μg/g yeast. However,
when looking at astaxanthin productivity, the picture is slightly different. The figures obtained with P. rhodozyma are rather similar to those of H. pluvialis. Maximal reported values are 170 μg/g yeast per day with a wild yeast strain and 370 μg/g yeast per day with mutated R1 yeast.
In the case of H. pluvialis, maximal values ranged from 290 to 428 μg/g cell per day depending on the media (BG-11 or BAR), light intensity (177 μmol
photon m−2 s−1), aeration, etc. The main aim of this work was to examine how astaxanthin synthesis, by P. rhodozyma and H. pluvialis, could be compared. The study is based on previous works by the authors where pigment productions have been reported. 相似文献
14.
Pseudomonas putida KT2440 grew on glucose at a specific rate of 0.48 h−1 but accumulated almost no poly-3-hydroxyalkanoates (PHA). Subsequent nitrogen limitation on nonanoic acid resulted in the
accumulation of only 27% medium-chain-length PHA (MCL-PHA). In contrast, exponential nonanoic acid-limited growth (μ = 0.15 h−1) produced 70 g l−1 biomass containing 75% PHA. At a higher exponential feed rate (μ = 0.25 h−1), the overall productivity was increased but less biomass (56 g l−1) was produced due to higher oxygen demand, and the biomass contained less PHA (67%). It was concluded that carbon-limited
exponential feeding of nonanoic acid or related substrates to cultures of P. putida KT2440 is a simple and highly effective method of producing MCL-PHA. Nitrogen limitation is unnecessary. 相似文献
15.
Ilkay Orhan Berrin Özçelik Sinem Aslan Murat Kartal Taner Karaoglu Bilge Şener Salih Terzioglu M. Iqbal Choudhary 《Phytochemistry Reviews》2007,6(1):189-196
Purpose of the present study was to evaluate antioxidant, antibacterial, antifungal, and antiviral activities of the petroleum
ether, chloroform, ethyl acetate and methanol extracts as well as the alkaloid fraction of Lycopodium clavatum L. (LC) from Lycopodiaceae growing in Turkey. Antioxidant activity of the LC extracts was evaluated by 1,1-diphenyl-2-picrylhydrazyl
(DPPH) radical-scavenging method at 0.2 mg/ml using microplate-reader assay. Antiviral assessment of LC extracts was evaluated
towards the DNA virus Herpes simplex (HSV) and the RNA virus Parainfluenza (PI-3) using Madin-Darby Bovine Kidney (MDBK) and Vero cell lines. Antibacterial and antifungal activities of the extracts
were tested against standard and isolated strains of the following bacteria; Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Acinobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis as well as the fungi; Candida albicans and C. parapsilosis. All of the extracts possessed noteworthy activity against ATCC strain of S. aureus (4 μg/ml), while the LC extracts showed reasonable antifungal effect. On the other hand, we found that only the chloroform
extract was active against HSV (16–8 μg/ml), while petroleum ether and alkaloid extracts inhibited potently PI-3 (16–4 μg/ml
and 32–4 μg/ml, respectively). However, all of the extracts had insignificant antiradical effect on DPPH. In addition, we
also analyzed the content of the alkaloid fraction of the plant by capillary gas chromatography-mass spectrometry (GC-MS)
and identified lycopodine as the major alkaloid. 相似文献
16.
Ping Su Anders Henriksson Christina Nilsson Hazel Mitchell 《World journal of microbiology & biotechnology》2008,24(9):1837-1842
The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three
probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against
Staphylococcus aureus and Streptococcus pyogenes (100 μg ml−1) were considerably lower than those against the probiotic strains tested (>800 μg ml−1) and Escherichia coli (800 μg ml−1). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both
Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by
24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately.
These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections
caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important
adjuncts to, or alternatives to, conventional antibiotic therapy. 相似文献
17.
Summary Totipotent callus of Cypripedium formosanum, an endangered slipper orchid species, was induced from seed-derived protocorm segments on a quarter-strength Murashige and
Skoog medium containing 4.52 μM 2,4-dichlorophenoxyacetic acid and 4.54 μM 1-phenyl-3-(1,2,3-thiadiazol-5-yl)-urea (thidiazuron). This callus proliferated well and was maintained by subculturing on
the same medium. On average, 13 protocorm-like bodies could be obtained from a piece of 4 mm callus after being transferred
to the medium with 4.44 μM N6-benzyladenine after 8 wk of culture. The regenerated protocorm-like bodies formed shoots and roots on medium containing 1
g l−1 activated charcoal and 20 g l−1 potato homogenate. After 24 wk of culture on this medium, well-developed plantlets ready for potting were established. 相似文献
18.
Food and growth relations of the marine microzooplankter,Synchaeta cecilia (Rotifera) 总被引:2,自引:2,他引:0
David A. Egloff 《Hydrobiologia》1988,157(2):129-141
The trophic interactions of the marine rotifer Synchaeta cecilia were investigated by determining its feeding and growth rates on a wide variety of marine phytoplankton and by determining
its susceptibility to predation by the calanoid copepod, Acartia tonsa. Reproduction of S. cecilia was sustained in four-day feeding trails by 13 of 37 algal species tested. Growth-supporting species included species of
Cryptophyceae, Dinophyceae, Chlorophyceae and Haptophyceae in sizes from 4 to 47 μm. Within these taxa, other species in the
acceptable size range failed to support growth. No species of Cyanophyceae, Bacillariophyceae, or Chrysophyceae supported
growth of the rotifer. S. cecilia can be maintained on unialgal cultures of Cryptophyceae but growth is enhanced by a combination of two or three species;
a mixture of Chroomonas salina (Cryptophyceae), Heterocapsa pygmaea (Dinophyceae), and Isochrysis galbana (Haptophyceae) has sustained laboratory stocks of S. cecilia for over four years. The expected response of S. cecilia to food quantity was observed: as food concentration was increased from 58 to 1154 μg C 1−1, the population growth constant increased from 0.17 to 0.60 d−1 at 20°C. This is equivalent to population doubling times of 4.0 and 1.1 days at H. pygmaea densities of 500 and 104 cells ml−1, respectively. The susceptibility of S. cecilia to predation was investigated by determining its rate of capture by the omnivorous marine copepod Acartia tonsa. At prey densities of 5 to 35 μg C 1−1 (0.3 to 1.9 individuals 1−1), A. tonsa readily ingested S. cecilia at rates up to 3 μg C copepod−1 day−1. 相似文献
19.
Summary
Hydrastis canadensis L. (Goldenseal) is an endangered medicinal plant used in the treatment of many ailments, such as gastrointestinal disturbances,
urinary disorders, hemorrhage, skin, mouth and eye infections, and inflammation. Commercial preparations of wild-harvested
goldenseal were found to contain heavy metal contaminants including aluminum (848 μgg−1), cadmium (0.4μgg−1), lead (18.7μgg−1), and mercury (0.1 μgg−1). As well, goldenseal is an endangered species listed in the Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES) Appendix II. Therefore, the practice of wild-harvest is actually decimating natural populations of
goldenseal and endangering its genetic diversity. In vitro propagation protocol by tissue culture was developed for producing high-quality tissues of goldenseal. Significantly more
de novo regeneration was induced on stem explants of 3-mo.-old plants cultured on a medium containing 10 μM 6-benzylaminopurine (BA) (22 regenerants per explant) than any other treatment. Subculture of the regenerants on a medium
devoid of growth regulators resulted in the development of complete plants that were acclimatized and thrived in standard
greenhouse conditions. The plants regenerated in vitro contained the lowest levels of heavy metals. The findings of this study provide the first evidence that heavy metal contaminants
bioaccumulate in goldenseal tissues and also provide a method for germplasm conservation, mass multiplication, and production
of goldenseal tissues free from abiotic contamination. 相似文献
20.
Han Gil Choi Ki Hoon Lee Hyun Il Yoo Pil Jun Kang Young Sik Kim Ki Wan Nam 《Journal of applied phycology》2008,20(5):729-735
The effects of temperature, irradiance, and daylength on Sargassum horneri growth were examined at the germling and adult stages to discern their physiological differences. Temperature–irradiance
(10, 15, 20, 25, 30°C × 20, 40, 80 μmol photons m−2s−1) and daylength (8, 12, 16, 24 h) experiments were carried out. The germlings and blades of S. horneri grew over a wide range of temperatures (10–25°C), irradiances (20–80 μmol photons m−2s−1), and daylengths (8–24 h). At the optimal growth conditions, the relative growth rates (RGR) of the germlings were 21% day−1 (25°C, 20 μmol photons m−2s−1) and 13% day−1 (8 h daylength). In contrast, the RGRs of the blade weights were 4% day−1 (15°C, 20 μmol photons m−2s−1) and 5% day−1 (12 h daylength). Negative growth rates were found at 20 μmol photons m−2s−1 of 20°C and 25°C treatments after 12 days. This phenomenon coincides with the necrosis of S. horneri blades in field populations. In conclusion, we found physiological differences between S. horneri germlings and adults with respect to daylength and temperature optima. The growth of S. horneri germlings could be enhanced at 25°C, 20 μmol photons m−2s−1, and 8 h daylength for construction of Sargassum beds and restoration of barren areas. 相似文献