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1.
Margareth da Silva Copertino Thiago Tormena Ulrich Seeliger 《Journal of applied phycology》2009,21(1):31-45
The growth, biofiltering efficiency and uptake rates of Ulva clathrata were studied in a series of outdoor tanks, receiving waste water directly from a shrimp (Litopenaeus vannamei) aquaculture pond, under constant aeration and two different water regimes: (1) continuous flow, with 1 volume exchange a
day (VE day-1) and (2) static regime, with 1 VE after 4 days. Water temperature, salinity, pH, dissolved inorganic nitrogen (DIN), phosphate
(PO4), chlorophyll-a (chl-a), total suspended solids (TSS), macroalgal biomass (fresh weight) and tissue nutrient assimilation were monitored over 12 days.
Ulva clathrata was highly efficient in removing the main inorganic nutrients from effluent water, stripping 70–82% of the total ammonium
nitrogen (TAN) and 50% PO4 within 15 h. Reductions in control tanks were much lower (Tukey HSD, P < 0.05). After 3 days, the mean uptake rates by the seaweed biomass under continuous flow were 3.09 mg DIN g DW day−1 (383 mg DIN m−2 day−1) and 0.13 mg PO4 g DW day−1 (99 mg PO4 m−2 day−1), being significantly higher than in the static regime (Tukey HSD, P < 0.05). The chl-a decreased in seaweed tanks, suggesting that U. clathrata inhibited phytoplankton growth. Correlations between the cumulative values of DIN removed from the water and total nitrogen
assimilated into the seaweed biomass (r = 0.7 and 0.8, P < 0.05), suggest that nutrient removal by U. clathrata dominated over other processes such as phytoplankton and bacterial assimilation, ammonia volatilization and nutrient precipitation. 相似文献
2.
Kameshnee Naidoo Manimaran Ayyachamy Kugen Permaul Suren Singh 《Bioprocess and biosystems engineering》2009,32(5):689-695
Xanthomonas campestris pv phaseoli produced an extracellular endoinulinase (9.24 ± 0.03 U mL−1) in an optimized medium comprising of 3% sucrose and 2.5% tryptone. X. campestris pv. phaseoli was further subjected to ethylmethanesulfonate mutagenesis and the resulting mutant, X. campestris pv. phaseoli KM 24 demonstrated inulinase production of 22.09 ± 0.03 U mL−1 after 18 h, which was 2.4-fold higher than that of the wild type. Inulinase production by this mutant was scaled up using
sucrose as a carbon source in a 5-L fermenter yielding maximum volumetric (21,865 U L−1 h−1) and specific (119,025 U g−1 h−1) productivities of inulinase after 18 h with an inulinase/invertase ratio of 2.6. A maximum FOS production of 11.9 g L−1 h−1 and specific productivity of 72 g g−1 h−1 FOS from inulin were observed in a fermenter, when the mutant was grown on medium containing 3% inulin and 2.5% tryptone.
The detection of mono- and oligosaccharides in inulin hydrolysates by TLC analysis indicated the presence of an endoinulinase.
This mutant has potential for large-scale production of inulinase and fructooligosaccharides. 相似文献
3.
The green microalga Chlorella zofingiensis can produce the ketocarotenoid astaxanthin under heterotrophic culture conditions. Here we report the growth-associated biosynthesis
of astaxanthin in this biotechnologically important alga. With glucose as sole carbon and energy source, C. zofinginesis grew fast in the dark with rapid exhaustion of nitrogen and carbon sources from media, leading to a high specific growth
rate (0.034 h−1). Cultures started at a cell concentration of about 3.4 × 109 cells l−1 reached, after 6 days, standing biomass values of 1.6 × 1011 cells or 8.5 g dry weight l−1. Surprisingly, the biosynthesis of astaxanthin was found to start at early exponential phase, independent of cessation of
cell division. A general trend was observed that the culture conditions benefiting cell growth also benefited astaxanthin
accumulation, indicating that astaxanthin was a growth-associated product in this alga. The maximum cell dry biomass and astaxanthin
yield were 11.75 g l−1 and 11.14 mg l−1 (about 1 mg g−1), simultaneously obtained in the fed-batch culture with a combined glucose–nitrate mixture addition, which were the highest
ever reported in dark-heterotrophic algal cultures. The possible reasons why dark-heterotrophic C. zofingiensis could produce astaxanthin during the course of cell growth were discussed. 相似文献
4.
Micheline Cristiane Rocha de Souza Cybelle Teixeira Marques Celina Maria Guerra Dore Fernando Roberto Ferreira da Silva Hugo Alexandre Oliveira Rocha Edda Lisboa Leite 《Journal of applied phycology》2007,19(2):153-160
The in vitro antioxidant activities of the following six sulfated polysaccharides were investigated: iota, kappa and lambda carrageenans,
which are widely used in the food industry, fucoidan (homofucan) from the edible seaweed Fucus vesiculosus and fucans (heterofucans) F0.5 and F1.1 from the seaweed Padina gymnospora. With respect to the inhibition of superoxide radical formation, fucoidan had an IC50 (the half maximal inhibitory concentration) of 0.058 mg·mL−1, while the IC50 for the kappa, iota and lambda carrageenans were 0.112, 0.332 and 0.046 mg·mL−1, respectively. All of the samples had an inhibitory effect on the formation of hydroxyl radicals. The results of peroxidation
tests showed that fucoidan had an IC50 of 1.250 mg·mL−1 and that the kappa, iota and lambda carrageenans had an IC50 of 2.753 and 2.338 and 0.323 mg·mL−1, respectively. Fucan fractions showed low antioxidant activity relative to fucoidan. These results clearly indicate the beneficial
effect of algal polysaccharides as antioxidants. 相似文献
5.
Biomass and lipid productivities of Chlorella vulgaris under different growth conditions were investigated. While autotrophic growth did provide higher cellular lipid content (38%),
the lipid productivity was much lower compared with those from heterotrophic growth with acetate, glucose, or glycerol. Optimal
cell growth (2 g l−1) and lipid productivity (54 mg l−1 day−1) were attained using glucose at 1% (w/v) whereas higher concentrations were inhibitory. Growth of C. vulgaris on glycerol had a similar dose effects as those from glucose. Overall, C. vulgaris is mixotrophic. 相似文献
6.
Cyclodextrin glycosyltransferase (CGTase; E.C. 2.4.1.19) is an industrially important enzyme, which is used to produce cyclodextrins
(CDs). In this research, we report the use of experimental factorial design to find the best conditions of pH and temperature
for CGTase production by Bacillus circulans var. alkalophilus. The optimized calculated values for the tested variables were, respectively, pH 9.7 and temperature 36oC, with a CGTase activity of 615 U mL−1. The CGTase production was further studied with the optimized process parameters on submerged cultivations (SC) and solid-state
cultivations (SSC) using soybean industrial fibrous residue (SIFR). The maximum CGTase activity obtained on SC was 1,155 U mL−1 under aerobic conditions. Cell growth and CGTase synthesis in SSC using SIFR as substrate was excellent, with CGTase activity
of 32,776 U g(SIFR) −1. These results strongly support the use of SIFR for CGTase production since it is a non-expensive residue. 相似文献
7.
The effects of three selected agrochemicals on bacterial diversity in cultivated soil have been studied. The selected agrochemicals
are Cerox (an insecticide), Ceresate and Paraquat (both herbicides). The effect on bacterial population was studied by looking
at the total heterotrophic bacteria presence and the effect of the agrochemicals on some selected soil microbes. The soil
type used was loamy with pH of 6.0–7.0. The soil was placed in opaque pots and bambara bean (Vigna subterranean) seeds cultivated in them. The agrochemicals were applied two weeks after germination of seeds at concentrations based on
manufacturer’s recommendation. Plant growth was assessed by weekly measurement of plant height, foliage appearance and number
of nodules formed after one month. The results indicated that the diversity index (Di) among the bacteria populations in untreated
soil and that of Cerox-treated soils were high with mean diversity index above 0.95. Mean Di for Ceresate-treated soil was
0.88, and that for Paraquattreated soil was 0.85 indicating low bacterial populations in these treatment-type soils. The study
also showed that application of the agrochemicals caused reduction in the number of total heterotrophic bacteria population
sizes in the soil. Ceresate caused 82.50% reduction in bacteria number from a mean of 40 × 105 cfu g−1 of soil sample to 70 × 104 cfu g−1. Paraquat-treated soil showed 92.86% reduction, from a mean of 56 × 105 cfu g−1 to 40 × 104 cfu g−1. Application of Cerox to the soil did not have any remarkable reduction in bacterial population number. Total viable cell
count studies using Congo red yeast-extract mannitol agar indicated reduction in the number of Rhizobium spp. after application of the agrochemicals. Mean number of Rhizobium population numbers per gram of soil was 180 × 104 for the untreated soil. Cerox-treated soil recorded mean number of 138 × 104 rhizobial cfu g−1 of soil, a 23.33% reduction. Ceresate- and Paraquat-treated soils recorded 20 × 104 and 12 × 104 cfu g−1 of soil, respectively, representing 88.89% and 93.33% reduction in Rhizobium population numbers. Correspondingly, the mean number of nodules per plant was 44 for the growth in untreated soil, 30 for
the plant in the Cerox-treated soil, 8 for the plant in Paraquat-treated soil and 3 for the plant in Ceresate-treated soil.
The study has confirmed detrimental effect of insecticide on bacterial populations in the soil. Total heterotrophic counts,
rhizobial counts as well as the number of nodules of all samples taken from the chemically treated soils were all low as compared
to values obtained for the untreated soil. However, the effect of the insecticide was minimal in all cases as compared to
the effects of the herbicides on the soil fauna. Indiscriminate use of agrochemicals on farms can therefore affect soil flora
and subsequently food production. 相似文献
8.
Malaysia is the world’s leading producer of palm oil products that contribute US$ 7.5 billion in export revenues. Like any
other agro-based industries, it generates waste that could be utilized as a source of organic nutrients for microalgae culture.
Present investigation delves upon Isochrysis sp. culture in POME modified medium and its utilization as a supplement to Nanochloropsis sp. in rotifer cultures. The culture conditions were optimized using a 1 L photobioreactor (Temp: 23°C, illumination: 180 ∼ 200 μmol
photons m−2s−1, n = 6) and scaled up to 10 L outdoor system (Temp: 26–29°C, illumination: 50 ∼ 180 μmol photons m−2s−1, n = 3). Algal growth rate in photobioreactor (μ = 0.0363 h−1) was 55% higher compared to outdoor culture (μ = 0.0163 h−1), but biomass production was 1.3 times higher in outdoor culture (Outdoor = 91.7 mg m−2d−1; Photobioreactor = 69 mg m−2d−1). Outdoor culture produced 18% higher lipid; while total fatty acids (FA) was not significantly affected by the change in
culture systems as both cultures yield almost similar concentrations of fatty acids per gram of sample (photobioreactor = 119.17 mg
g−1; outdoor culture = 104.50 mg g−1); however, outdoor cultured Isochrysis sp. had 26% more polyunsaturated fatty acids (PUFAs). Rotifers cultured in Isochrysis sp./ Nanochloropsis sp. (1:1, v/v) mixture gave similar growth rate as 100% Nanochoropsis sp. culture (μ = 0.40 d−1), but had 45% higher counts of rotifers with eggs (t = 7, maximum). The Isochrysis sp. culture successfully lowered the nitrate (46%) and orthophosphate (83%) during outdoor culture. 相似文献
9.
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
10.
Luo H Wang Y Wang H Yang J Yang Y Huang H Yang P Bai Y Shi P Fan Y Yao B 《Applied microbiology and biotechnology》2009,82(3):453-461
Using degenerate polymerase chain reaction (PCR) and thermal asymmetric interlaced PCR, a 1,347-bp full-length complementary
DNA fragment encompassing the gene man5A, which encodes a 429-amino acid β-mannanase with a calculated mass of 46.8 kDa, was cloned from acidophilic Bispora sp. MEY-1. The deduced amino acid sequence (catalytic domain) displayed highest identity (54.1%) with the Emericella nidulans endo-β-1,4-d-mannanase, a member of the glycoside hydrolase family 5. Recombinant MAN5A was overexpressed in Pichia pastoris, and its activity in the culture medium reached 500 U ml−1. The enzyme was acidophilic, with highest activity at pH 1.0–1.5, lower than any known mannanases, and optimal temperature
for activity was 65°C. MAN5A had good pH adaptability, excellent thermal and pH stability, and high resistance to both pepsin
and trypsin. The specific activity, K
m, and V
max for locust bean gum substrate was 3,373 U mg−1, 1.56 mg ml−1, and 6,587.6 μmol min−1 mg−1, respectively. The enzymatic activity was not significantly affected by ions such as Ca2+, Cr3+, Co2+, Zn2+, Na+, K+, and Mg2+ and enhanced by Ni2+, Fe3+, Mn2+ and Ag+. These favorable properties make MAN5A a potential candidate for use in various industrial applications. 相似文献
11.
Cui Fengjie Li Yin Liu Zhiqiang Zhao Hui Ping Lifeng Ping Liying Yang Yinan Xue Yaping Yan Lijiao 《World journal of microbiology & biotechnology》2009,25(4):721-725
The objective of this study was to maximize production of xylanase by a newly isolated strain Penicillium thiersii ZH-19. Response surface methodology was employed to study the effects of significant factors such as pH, temperature, xylan
concentration, and cultivation time, on the production of xylanase by Penicillium thiersii ZH-19. The optimal fermentation parameters for enhanced xylanase production were found to be pH 7.72, temperature 24.8°C, xylan
13.2 g l−1 and the fermentation time 125.8 h. The model predicted a xylanase activity of 75.24 U ml−1. Verification of the optimization showed that the maximum xylanase production reached 73.50 U mL−1 in the flask experiments and 80.23 U mL−1 in the scale of 15-L fermenter under the optimal condition. 相似文献
12.
Kaarel Adamberg Petri-Jaan Lahtvee Kaspar Valgepea Kristo Abner Raivo Vilu 《Antonie van Leeuwenhoek》2009,95(3):219-226
Quasi steady state growth of Lactococcus
lactis IL 1403 was studied in glucose-limited A-stat cultivation experiments with acceleration rates (a) from 0.003 to 0.06 h−2 after initial stabilization of the cultures in chemostat at D = 0.2–0.3 h−1. It was shown that the high limit of quasi steady state growth rate depended on the acceleration rate used—at an acceleration
rate 0.003 h−2 the quasi steady state growth was observed until μ
crit = 0.59 h−1, which is also the μ
max value for the culture. Lower values of μ
crit were observed at higher acceleration rates. The steady state growth of bacteria stabilized at dilution rate 0.2 h−1 was immediately disrupted after initiating acceleration at the highest acceleration rate studied—0.06 h−2. Observation was made that differences [Δ(μ − D)] of the specific growth rates from pre-programmed dilution rates were the lowest using an acceleration rate of 0.003 h−2 (< 4% of preset changing growth rate). The adaptability of cells to follow preprogrammed growth rate was found to decrease
with increasing dilution rate—it was shown that lower acceleration rates should be applied at higher growth rates to maintain
the culture in the quasi steady state. The critical specific growth rate and the biomass yields based on glucose consumption
were higher if the medium contained S
0 = 5 g L−1 glucose instead of S
0 = 10 g L−1. It was assumed that this was due to the inhibitory effect of lactate accumulating at higher concentrations in the latter
cultures. Parallel A-stat experiments at the same acceleration and dilution rates showed good reproducibility—Δ(μ − D) was less than 5%, standard deviations of biomass yields per ATP produced (Y
ATP), and biomass yields per glucose consumed (Y
XS) were less than 15%. 相似文献
13.
David A. Lipson Russell K. Monson Steven K. Schmidt Michael N. Weintraub 《Biogeochemistry》2009,95(1):23-35
Soil microbial respiration is a critical component of the global carbon cycle, but it is uncertain how properties of microbes
affect this process. Previous studies have noted a thermodynamic trade-off between the rate and efficiency of growth in heterotrophic
organisms. Growth rate and yield determine the biomass-specific respiration rate of growing microbial populations, but these
traits have not previously been used to scale from microbial communities to ecosystems. Here we report seasonal variation
in microbial growth kinetics and temperature responses (Q10) in a coniferous forest soil, relate these properties to cultured and uncultured soil microbes, and model the effects of
shifting growth kinetics on soil heterotrophic respiration (Rh). Soil microbial communities from under-snow had higher growth rates and lower growth yields than the summer and fall communities
from exposed soils, causing higher biomass-specific respiration rates. Growth rate and yield were strongly negatively correlated.
Based on experiments using specific growth inhibitors, bacteria had higher growth rates and lower yields than fungi, overall,
suggesting a more important role for bacteria in determining Rh. The dominant bacteria from laboratory-incubated soil differed seasonally: faster-growing, cold-adapted Janthinobacterium species dominated in winter and slower-growing, mesophilic Burkholderia and Variovorax species dominated in summer. Modeled Rh was sensitive to microbial kinetics and Q10: a sixfold lower annual Rh resulted from using kinetic parameters from summer versus winter communities. Under the most realistic scenario using seasonally
changing communities, the model estimated Rh at 22.67 mol m−2 year−1, or 47.0% of annual total ecosystem respiration (Re) for this forest. 相似文献
14.
The effect of the fungicide, chlorothalonil, on vesicular-arbuscular mycorrhizal (VAM) symbiosis was studied in a greenhouse
using Leucaena leucocephala as test plant. Chlorothalonil was applied to soil at 0, 50, 100 and 200 μg g−1. The initial soil solution P levels were 0.003 μg mL−1 (sub-optimal) and 0.026 μg mL−1 (optimal). After 4 weeks, the sub-optimal P level was raised to 0.6 μg mL−1 (high). The soil was either uninoculated or inoculated with the VAM fungus, Glomus aggregatum. The fungicide reduced mycorrhizal colonization of roots, development of mycorrhizal effectiveness, shoot P concentration
and uptake and dry matter yields at all concentrations tested, although the highest inhibitory effect was noted as the concentration
of the fungicide was increased from 50 to 100 μg g−1. Phosphorus applied after four weeks tended to partially offset the deleterious effects of chlorothalonil in plants grown
in the inoculated and uninoculated soil which suggests that the fungicide was interfering with plant P uptake. The results
suggest that the use of chlorothalonil should be restricted to levels below 50 μg g−1 if the benefits of mycorrhizal symbiosis are to be expected.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464. 相似文献
15.
A. Q. Hurtado A. T. Critchley A. Trespoey G. Bleicher-Lhonneur 《Journal of applied phycology》2008,20(5):551-555
Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different
durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan
content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly
(P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower
stocking density (500 g m−1line−1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise,
decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period
produced the highest molecular weight at both stocking densities (500 g m−1line−1 = 1,079.5 ± 31.8 kDa, 1,000 g m−1line−1 = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values
of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m−1line−1, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content
and molecular weight. 相似文献
16.
Okeke BC 《Journal of industrial microbiology & biotechnology》2008,35(12):1571-1579
Pollution of terrestrial surfaces and aquatic systems by hexavalent chromium, Cr(VI), is a worldwide public health problem.
A chromium resistant bacterial isolate identified as Exiguobacterium sp. GS1 by 16S rRNA gene sequencing displayed high rate of removal of Cr(VI) from water. Exiguobacterium sp. GS1 is 99% identical to Exiguobacterium acetylicum. The isolate significantly removed Cr(VI) at both high and low concentrations (1–200 μg mL−1) within 12 h. The Michaelis–Menten K
m
and V
max for Cr(VI) bioremoval were calculated to be 141.92 μg mL−1 and 13.22 μg mL−1 h−1, respectively. Growth of Exiguobacterium sp. GS1 was indifferent at 1–75 μg mL−1 Cr(VI) in 12 h. At initial concentration of 8,000 μg L−1, Exiguobacterium sp. GS1 displayed rapid bioremoval of Cr(VI) with over 50% bioremoval in 3 h and 91% bioremoval in 8 h. Kinetic analysis
of Cr(VI) bioremoval rate revealed zero-order in 8 h. Exiguobacterium sp. GS1 grew and significantly reduced Cr(VI) in cultures containing 1–9% salt indicating high salt tolerance. Similarly
the isolate substantially reduced Cr(VI) over a wide range of temperature (18–45 °C) and initial pH (6.0–9.0). The T
opt and initial pHopt were 35–40 °C and 7–8, respectively. Exiguobacterium sp. GS1 displayed a great potential for bioremediation of Cr(VI) in diverse complex environments. 相似文献
17.
Yoon-Kyung Kang Soo-Yeon Cho Yoon-Ho Kang Toshiya Katano Eon-Seon Jin Dong-Soo Kong Myung-Soo Han 《Journal of applied phycology》2008,20(4):375-386
Five strains (HYY0510-SK04, HYY0511-SK09, HYK0512-SK12, HYK0512-PK04 and HYY0512-PK05) of algicidal bacteria against the harmful
bloom forming diatom Stephanodiscus hantzschii and dinoflagellate Peridinium bipes, were isolated. Among these strains, HYY0510-SK04, HYY0511-SK09 and HYK0512-SK12 have an effective algicidal activity for
S. hantzschii, while HYK0512-PK04 and HYY0512-PK05 have an algicidal effect against P. bipes. Sequence analysis of 16S rDNA showed that HYY0510-SK04 and HYY0511-SK09 were closely related to Acidovorax delafieldii ATCC 17505T. HYK0512-SK12, HYK0512-PK04 and HYY0512-PK05 showed high homology with Variovorax paradoxus IAM 12373T (98.9%), Hydrogenophaga palleronii ATCC 49743T (98.8%) and Pseudomonas plecoglossicida ATCC 700383T (98.3%), respectively. HYY0510-SK04, HYY0511-SK09 and HYK0512-SK12 degraded S. hantzschii cells within two weeks when those bacteria were inoculated at densities of ≥107cells mL−1 to the lag or logarithmic growth phase of the algal culture. HYK0512-PK04 and HYY0512-PK05 degraded more than 90% of P. bipes cells within 14 and 8 days, respectively, when these bacteria were inoculated at densities of ≥107cells mL−1. Among the five bacterial strains, HYK0512-SK12 and HYY0512-PK05 showed the most effective growth inhibition of all the algae
and cyanobacteria tested. Biochemical assays revealed that the main algicidal substance from all isolates were likely to be
extracellular substances. These results indicate that the bacterial strains isolated for this study are potential agents for
the control of harmful algal blooms in eutrophic reservoirs. 相似文献
18.
Growth characteristics of the cyanobacterium Nostoc flagelliforme in photoautotrophic, mixotrophic and heterotrophic cultivation 总被引:1,自引:0,他引:1
Nostoc flagelliforme is a terrestrial cyanobacterium with high economic value. Dissociated cells separated from a natural colony of N. flagelliforme were cultivated for 7 days under either phototrophic, mixotrophic or heterotrophic culture conditions. The highest biomass,
1.67 g L−1 cell concentration, was obtained under mixotrophic culture, representing 4.98 and 2.28 times the biomass obtained in phototrophic
and heterotrophic cultures, respectively. The biomass in mixotrophic culture was not the sum as that in photoautotrophic and
heterotrophic cultures. During the first 4 days of culture, the cell concentration in mixotrophic culture was lower than the
sum of those in photoautotrophic and heterotrophic cultures. However, from the 5th day, the cell concentration in mixotrophic
culture surpassed the sum of those obtained from the other two trophic modes. Although the inhibitor of photosynthetic electron
transport DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea] efficiently inhibited autotrophic growth of N. flagelliforme cells, under mixotrophic culture they could grow by using glucose. The addition of glucose changed the response of N.flagelliforme cells to light. The maximal photosynthetic rate, dark respiration rate and light compensation point in mixotrophic culture
were higher than those in photoautotrophic cultures. These results suggest that photoautotrophic (photosynthesis) and heterotrophic
(oxidative metabolism of glucose) growth interact in mixotrophic growth of N. flagelliforme cells. 相似文献
19.
Ling-hua Zhang Ya-jun Lang Shinichi Nagata 《Extremophiles : life under extreme conditions》2009,13(4):717-724
Halophilic bacteria strain Halomonas salina DSM 5928 was found to excrete ectoine, suggesting its potential in the development of a new method of ectoine production.
We performed HPLC and LC–MS analyses that showed that Halomonas salina DSM 5928 excreted ectoine under constant extracellular osmolarity. Medium adopting monosodium glutamate as a sole source
of carbon and nitrogen was beneficial for ectoine synthesis. The total concentration of ectoine was not affected by NaCl concentration
in the range 0.5–2 mol l−1. The total concentration of ectoine and productivity in a 10-l fermentor with 0.5 mol l−1 NaCl were 6.9 g l−1 and 7.9 g l−1 d−1, respectively. These findings show that Halomonas salina DSM 5928 efficiently produces ectoine at relatively low NaCl concentration. This research also indicates the potential application
of free or immobilized cells for continuous culture to produce ectoine. 相似文献
20.
Bettin F Montanari Q Calloni R Gaio TA Silveira MM Dillon AJ 《Journal of industrial microbiology & biotechnology》2009,36(1):1-9
Some conditions in media composition for laccases production, such as different sources of carbon and organic nitrogen, antifoams
and a surfactant, were studied in liquid cultures of Pleurotus sajor-caju strain PS-2001. Cultivation with fructose or glucose as carbon sources produced maximum enzyme activities of 37 and 36 U mL−1, respectively. When sucrose was present in the medium, the best results were obtained using 5 g L−1 of this carbohydrate, on the 11th day of the process, attaining laccase titres of 13 U mL−1. In a medium without casein, practically no enzyme was produced during the experiments; among the sources of nitrogen studied,
pure casein led to the highest titres of laccase activity. Different concentrations of pure casein and sucrose were also tested.
As to the different concentrations of casein, the addition of 1.5 g L−1 resulted in the highest titres of laccase activity. Negligible levels of manganese peroxidase activity were also detected
in the culture medium. In low concentrations, polypropylene glycol or silicon-based antifoams and the surfactant Tween 80
have no significant influence on the formation of laccases by P. sajor-caju. However, enhanced concentration of polypropylene glycol negatively affected the production of laccases but favored the titres
in total peroxidases, lignin peroxidase and veratryl alcohol oxidase. 相似文献