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1.
The paper reports a study involving the use of Halomonas boliviensis, a moderate halophile, for co-production of compatible solute ectoine and biopolyester poly(3-hydroxybutyrate) (PHB) in a
process comprising two fed-batch cultures. Initial investigations on the growth of the organism in a medium with varying NaCl
concentrations showed the highest level of intracellular accumulation of ectoine (0.74 g L −1) at 10–15% ( w/ v) NaCl, while at 15% ( w/ v) NaCl, the presence of hydroxyectoine (50 mg L −1) was also noted. On the other hand, the maximum cell dry weight and PHB concentration of 10 and 5.8 g L −1, respectively, were obtained at 5–7.5% ( w/ v) NaCl. A process comprising two fed-batch cultivations was developed—the first culture aimed at obtaining high cell mass
and the second for achieving high yields of ectoine and PHB. In the first fed-batch culture, H. boliviensis was grown in a medium with 4.5% ( w/ v) NaCl and sufficient levels of monosodium glutamate, NH 4+, and PO 43−. In the second fed-batch culture, the NaCl concentration was increased to 7.5% ( w/ v) to trigger ectoine synthesis, while nitrogen and phosphorus sources were fed only during the first 3 h and then stopped
to favor PHB accumulation. The process resulted in PHB yield of 68.5 wt.% of cell dry weight and volumetric productivity of
about 1 g L −1 h −1 and ectoine concentration, content, and volumetric productivity of 4.3 g L −1, 7.2 wt.%, and 2.8 g L −1 day −1, respectively. At salt concentration of 12.5% ( w/ v) during the second cultivation, the ectoine content was increased to 17 wt.% and productivity to 3.4 g L −1 day −1. 相似文献
2.
Compared with steady state, oscillation in continuous very-high-gravity ethanol fermentation with Saccharomyces cerevisiae improved process productivity, which was thus introduced for the fermentation system composed of a tank fermentor followed
by four-stage packed tubular bioreactors. When the very-high-gravity medium containing 280 g l −1 glucose was fed at the dilution rate of 0.04 h −1, the average ethanol of 15.8% ( v/ v) and residual glucose of 1.5 g l −1 were achieved under the oscillatory state, with an average ethanol productivity of 2.14 g h −1 l −1. By contrast, only 14.8% ( v/ v) ethanol was achieved under the steady state at the same dilution rate, and the residual glucose was as high as 17.1 g l −1, with an ethanol productivity of 2.00 g h −1 l −1, indicating a 7% improvement under the oscillatory state. When the fermentation system was operated under the steady state
at the dilution rate of 0.027 h −1 to extend the average fermentation time to 88 h from 59 h, the ethanol concentration increased slightly to 15.4% ( v/ v) and residual glucose decreased to 7.3 g l −1, correspondingly, but the ethanol productivity was decreased drastically to 1.43 g h −1 l −1, indicating a 48% improvement under the oscillatory state at the dilution rate of 0.04 h −1. 相似文献
3.
We isolated and characterized novel insoluble phosphate (P)-solubilizing bacteria tolerant to environmental factors like high
salt, low and high pHs, and low temperature. A bacterium M6 was isolated from a ginseng rhizospheric soil and confirmed to
belong to Burkholderia vietnamiensis by BIOLOG system and 16S rRNA gene analysis. The optimal cultural conditions for the solubilization of P were 2.5% ( w/ v) glucose, 0.015% ( w/ v) urea, and 0.4% ( w/ v) MgCl 2·6H 2O along with initial pH 7.0 at 35°C. High-performance liquid chromatography analysis showed that B. vietnamiensis M6 produced gluconic and 2-ketogluconic acids. During the culture, the pH was reduced with increase in gluconic acid concentration
and was inversely correlated with P solubilization. Insoluble P solubilization in the optimal medium was about 902 mg l −1, which was approximately 1.6-fold higher than the yield in NBRIP medium (580 mg l −1). B. vietnamiensis M6 showed resistance against different environmental stresses like 10–45°C, 1–5% ( w/ v) salt, and 2–11 pH range. The maximal concentration of soluble P produced by B. vietnamiensis M6 from Ca 3(PO 4) 2, CaHPO 4, and hydroxyapatite was 1,039, 2,132, and 1,754 mg l −1, respectively. However, the strain M6 produced soluble P with 20 mg l −1 from FePO 4 after 2 days and 100 mg l −1 from AlPO 4 after 6 days, respectively. Our results indicate that B. vietnamiensis M6 could be a potential candidate for the development of biofertilizer applicable to environmentally stressed soil. 相似文献
4.
A flue gas originating from a municipal waste incinerator was used as a source of CO 2 for the cultivation of the microalga Chlorella vulgaris, in order to decrease the biomass production costs and to bioremediate CO 2 simultaneously. The utilization of the flue gas containing 10–13% ( v/ v) CO 2 and 8–10% ( v/ v) O 2 for the photobioreactor agitation and CO 2 supply was proven to be convenient. The growth rate of algal cultures on the flue gas was even higher when compared with
the control culture supplied by a mixture of pure CO 2 and air (11% ( v/ v) CO 2). Correspondingly, the CO 2 fixation rate was also higher when using the flue gas (4.4 g CO 2 l −1 24 h −1) than using the control gas (3.0 g CO 2 l −1 24 h −1). The toxicological analysis of the biomass produced using untreated flue gas showed only a slight excess of mercury while
all the other compounds (other heavy metals, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and dibenzofurans,
and polychlorinated biphenyls) were below the limits required by the European Union foodstuff legislation. Fortunately, extending
the flue gas treatment prior to the cultivation unit by a simple granulated activated carbon column led to an efficient absorption
of gaseous mercury and to the algal biomass composition compliant with all the foodstuff legislation requirements. 相似文献
5.
Bambusa balcooa is one of the most commercially important bamboo species. Regeneration of this species by sexual means is impossible because
no seeds are set after flowering. Vegetative propagation is hindered due to bulky propagules, low rooting ability of the culm
and branch cuttings, and seasonal specificity. This makes in vitro-based methods of regeneration important. This paper describes an efficient micropropagation protocol for multiplication of
B. balcooa from nodal explants. Nodal segments were surface sterilized with 0.1% mercuric chloride for 10 min, and cultured on Murashige
and Skoog (MS) medium supplemented with 4.4 μM 6-benzylaminopurine (BAP), 2.32 μM kinetin (Kn), and gelled with 0.2% w/ v gelrite. Eighty-five percent of explants could be established in vitro with 90% of these achieving bud break. In vitro-formed shoots were successfully multiplied in MS liquid medium supplemented with 6.6 μM BAP, 2.32 μM Kn, 2.5% v/ v coconut water, and 100 mg l −1
myo-inositol. Subculturing shoots every 3 wk yielded a consistent proliferation rate of 4.11-fold without decline in vigor. Shoot
clusters, containing 5 to 8 shoots, were rooted with 87.5% success in 1/2 MS supplemented with 5.71 μM indole-3-acetic acid
(IAA), 4.9 μM indole-3-butyric acid (IBA), and 5.37 μM naphthaleneacetic acid (NAA) within 3 wk. Plants regenerated in this
manner were acclimatized in the greenhouse and under a shade net with 88% success. 相似文献
6.
A novel low-cost medium was developed from by-products and wastes from the ethanol agro-industry to replace commercial media
in the production of a steam sterilization biological indicator (BI). Various recovery media were developed using soybean
or sugarcane molasses and vinasse to prepare a self-contained BI. Media performance was evaluated by viability and heat resistance
( D
121 °C value) according to regulatory standards. A medium produced with a soybean vinasse ratio of 1:70 (1.4%) ( w/ v) produced the results, with D
121 °C = 2.9 ± 0.5 min and Usk = 12.7 ± 2.1 min. The addition of 0.8% ( w/ v) yeast extract improved the germination of heat-damaged spores. The pH variation from 6.0 to 7.3 resulted in a gradual increase
in the D
121 °C value. The absence of calcium chloride resulted in a decrease in germination, while no significant differences were observed
with starch addition. Soybean vinasses may thus be used as the main component of a culture medium to substitute for commercial
media in the production of self-contained biological indicators. The use of ethanol production waste in this biotechnological
process realized a reliable performance, minimized the environmental impact, and decreased BI production costs while producing
a high quality product. 相似文献
7.
The effects of pH (6.7 or 5.8), protein concentration and the heat treatment conditions (70 or 90 °C) on the physical properties
of heat-induced milk protein gels were studied using uniaxial compression, scanning electron microscopy, differential scanning
calorimetry, and water-holding capacity measurements. The systems were formed from whey protein isolate (10–15% w/ v) with (5% w/ v) or without the addition of caseinate. The reduction in pH from 6.7 to 5.8 increased the denaturation temperature of the
whey proteins, which directly affected the gel structure and mechanical properties. Due to this increase in the denaturation
temperature of the β-lactoglobulin and α-lactalbumin, a heat treatment of 70 °C/30 min did not provide sufficient protein
unfolding to form self-supporting gels. However, the presence of 5% ( w/ v) sodium caseinate decreased the whey protein thermo stability and was essential for the formation of self-supporting gels
at pH 6.7 with heat treatment at 70 °C/30 min. The gels formed at pH 6.7 showed a fine-stranded structure, with great rigidity
and deformability as compared to those formed at pH 5.8. The latter had a particulate structure and exuded water, which did
not occur with the gels formed at pH 6.7. The addition of sodium caseinate led to less porous networks with increased gel
deformability and strength but decreased water exudation. The same tendencies were observed with increasing whey protein concentration. 相似文献
8.
Chile is an important producer of brown seaweeds representing 10% of world supply. Landings of Chilean kelp fluctuated between
40,000 t.year −1 in the early ‘80s to 250,000 t.year −1 more recently. Commercialized algae come from natural populations and no mass-cultures of involved species have been established.
Four species of brown algae are commercially collected in the country: Lessonia trabeculata, L. nigrescens, Macrocystis pyrifera and M. integrifolia. Since 2000, the demand of alginate sources and food for cultivated abalones dramatically raised the harvesting of these
species. Direct evaluations of Lessonia spp. and Macrocystis standing-stocks were made along 700 km of coast in northern Chile. Lessonia spp. estimated populations exceed 900,000 t, whereas M. integrifolia does not exceed 300 t. The insights provided indicate that sustainability of Chilean kelp subjected to intense harvesting
would require management programs including the following bio-ecological recommendations: (1) to harvest the entire plant
including the holdfast; (2) to harvest plants larger than 20 cm in diameter; (3) to harvest plants sparsely, selecting mayor
specimens; (4) rotation of harvesting areas; and (5) for Macrocystis, to cut the canopy 1–2 m from the surface. They must be implemented in a National Program of Kelp Management, elaborated
by government, scientists, fisherman, and industry. 相似文献
9.
In vitro propagation has played a key role for obtaining large numbers of virus free, homogenous plants, and for breeding of plantains
and bananas ( Musa spp.). Explant sources utilized for banana micropropagation include suckers, shoot tips, and floral buds. The present study
employed male floral meristems as explant material for micropropagation of hill banana ecotypes (AAB) ‘Virupakshi’ and ‘Sirumalai.’
Immature male floral buds were collected from healthy plants from hill banana growing areas. Exposure of explants to ethyl
alcohol (70%, v/v) for 30 s, then mercuric chloride (0.1%, w/v) for 30 s, followed by three independent rinses of 5 min each in autoclaved, double-distilled water satisfactorily reduced
the contamination. Male floral bud explants were cultured on Murashige and Skoog (MS) basal medium supplemented with different
combinations of 6-benzylaminopurine (BAP), coconut water, naphthaleneacetic acid, gibberellic acid, and additional supplements.
MS medium supplemented with 5 mg l −1 BAP and coconut water (15%) was the most efficient media for shoot initiation and multiple shoot formation (15 shoots from
a single part of a floral bud). The best response for shoot elongation was obtained using the combination of basal MS, 5 mg l −1 BAP, 1 mg l −1 naphthaleneacetic acid and 1.5 mg l −1 gibberellic acid. Regenerated shoots were rooted in basal MS medium within 15–20 d. The rooted plantlets were transferred
to a soil mixture and maintained at a temperature of 25 ± 2°C for 10 d and then at room temperature (30–32°C) for 2 wk, before
transferring to a greenhouse. The regenerated plantlets showed 100% survival. 相似文献
10.
Chromosomes of 228 captive specimens of the family Bovidae have been investigated. The examined animals were classified into
the subfamilies Aepycerotinae, Reduncinae, Antilopinae, Alcelaphinae, Hippotraginae and Bovinae. Polymorphism for one fusion
was identified in the species: Aepyceros melampus, 2 n = 59–60; Redunca fulvorufula, 2 n = 56–57; Kobus e. ellipsiprymnus, 2 n = 50–52; Kobus e. defassa, 2 n = 52–54 and Syncerus c. nanus, 2 n = 54–55. This is the first study to reveal fusion 7;29 in Kobus e. defassa and simultaneously the respective polymorphism. Variation in the diploid number of chromosomes is also known in species:
Oryx g. dammah and Oryx g. leucoryx but in this study only fusion 1;25 was identified in both karyotyped species. Our study showed that 13% of investigated individuals
were polymorphic for the centric fusion and demonstrated the important role of cytogenetic screening in captive animals at
zoological gardens. 相似文献
11.
The inhibitory effect of antimicrobial zeolite coated concrete specimens (Z2) against Acidithiobacillus thiooxidans was studied by measuring biomass dry cell weight (DCW), biological sulphate generation, and oxygen uptake rates (OURs). Uncoated
(UC), and blank zeolite coated without antimicrobial agent (ZC) concrete specimens were used as controls. The study was undertaken
by exposing inoculated basal nutrient medium (BNM) to the various specimens. The coating material was prepared by mixing zeolite,
epoxy and cure with ratios, by weight of 2:2:1. Concrete specimens were characterized before and after exposure to inoculated
or sterile BNM by field emission-scanning electron microscopy (FE-SEM). Gypsum, which was absent in the other test concrete
specimens, was detected in uncoated specimens exposed to the bacterium. In UC and ZC, the growth of the bacteria increased
throughout the duration of the experiment. However, significant biomass inhibition was observed in experiments where Z2 was
used. The overall biomass growth rate in suspension before the specimens were placed ranged from 3.18 to 3.5 mg DCW day −1. After the bacterium was exposed to UC and ZC, growth continued with a corresponding value of 4 ± 0.4 and 5.5 ± 0.6 mg DCW day −1, respectively. No biomass growth was observed upon exposure of the bacterium to Z2. Similarly, while biological sulphur oxidation
rates in UC and ZC were 88 ± 13 and 238 ± 25 mg SO 4
2− day −1, respectively, no sulphate production was observed in experiments where Z2 concrete specimens were used. Peak OURs for UC
and ZC ranged from 2.6 to 5.2 mg l −1 h −1, and there was no oxygen uptake in those experiments where Z2 was used. The present study revealed that the antimicrobial
zeolite inhibits the growth of both planktonic as well as biofilm populations of Acidithiobacillus thiooxidans. 相似文献
12.
Phosphoglucose isomerase-deficient ( pgi1) strains of Saccharomyces cerevisiae were studied for the production of D-ribose and ribitol from D-glucose via the intermediates of the pentose phosphate pathway.
Overexpression of the genes coding for NAD +-specific glutamate dehydrogenase ( GDH2) of S. cerevisiae or NADPH-utilising glyceraldehyde-3-phosphate dehydrogenase ( gapB) of Bacillus subtilis enabled growth of the pgi1 mutant strains on D-glucose. Overexpression of the gene encoding sugar phosphate phosphatase ( DOG1) of S. cerevisiae was needed for the production of D-ribose and ribitol; however, it reduced the growth of the pgi1 strains expressing GDH2 or gapB in the presence of higher D-glucose concentrations. The CEN.PK2-1D laboratory strain expressing both gapB and DOG1 produced approximately 0.4 g l −1 of D-ribose and ribitol when grown on 20 g l −1 ( w/ v) D-fructose with 4 g l −1 ( w/ v) D-glucose. Nuclear magnetic resonance measurements of the cells grown with 13C-labelled D-glucose showed that about 60% of the D-ribose produced was derived from D-glucose. Strains deficient in both
phosphoglucose isomerase and transketolase activities, and expressing DOG1 and GDH2 tolerated only low D-glucose concentrations (≤2 g l −1 ( w/ v)), but produced 1 g l −1 ( w/ v) D-ribose and ribitol when grown on 20 g l −1 ( w/ v) D-fructose with 2 g l −1 ( w/ v) D-glucose. 相似文献
13.
An efficient system to regenerate shoots on excised leaves of greenhouse-grown wild lowbush blueberry ( Vaccinium angustifolium Ait.) was developed in vitro. The effect of thidiazuron (TDZ) on adventitious bud and shoot formation from apical, medial, and basal segments of the leaves
was tested. Leaf cultures produced multiple buds and shoots with or without an intermediary callus phase on 2.3–4.5 μM TDZ
within 6 wk of culture initiation. The greatest shoot regeneration came from young expanding basal leaf segments positioned
with the adaxial side touching the culture medium and maintained for 2 wk in darkness. Callus development and shoot regeneration
depended not only on the polarity of the explants but also on the genotype of the clone that supplied the explant material.
TDZ-initiated cultures were transferred to medium containing 2.3–4.6 μM zeatin and produced usable shoots after one additional
subculture. Elongated shoots were dipped in 39.4 mM indole-3-butyric acid powder and planted on a peat:perlite soilless medium
at a ratio of 3:2 ( v/ v), which yielded an 80–90% rooting efficiency. The plantlets were acclimatized and eventually established in the greenhouse
with 75–85% survival. 相似文献
14.
In this study, an effective root-based cryopreservation method was developed for Hypericum perforatum L., an important medicinal species, using in vitro plants. A systematic approach was applied to determine effective combinations of protocol steps such as preculture, osmoprotection, vitrification solution treatment, and unloading, followed by protocol optimization using a single-factor approach. The effects of root section type (root tips, middle sections, or basal sections), duration of root section culture after excision, and donor plant age were also investigated. In a wild genotype, middle and basal root sections excised from 8-wk-old plants and cryopreserved at the age of 10 d after excision showed the highest plant regrowth after cryopreservation. In the optimized protocol, root sections were precultured in 10% (w/v) sucrose for 17 h, osmoprotected with a solution composed of 17.5% (w/v) glycerol and 17.5% (w/v) sucrose for 20 min, followed by a vitrification solution of 40% (w/v) glycerol and 40% (w/v) sucrose for 30 min, and cryopreserved using aluminum foil strips (droplet-vitrification). After rewarming in preheated 25% (w/v) sucrose solution and 30-min unloading, root segments were recovered on medium supplemented with 1.0 mg L−1 gibberellic acid and showed 78% plant regrowth. This cryopreservation method was successfully adapted for five elite lines of H. perforatum with a 45 to 87% regrowth rate after cryopreservation. These results suggest that root cryopreservation may be an effective method for medicinal plant conservation and should be tested with a broader range of species. 相似文献
15.
An innovative consecutive batch fermentation process was developed for very high gravity (VHG) ethanol fermentation with the
self-flocculating yeast under high biomass concentration conditions. On the one hand, the high biomass concentration significantly
shortened the time required to complete the VHG fermentation and the duration of yeast cells suffering from strong ethanol
inhibition, preventing them from losing viability and making them suitable for being repeatedly used in the process. On the
other hand, the separation of yeast cells from the fermentation broth by sedimentation instead of centrifugation, making the
process economically more competitive. The VHG medium composed of 255 g L −1 glucose and 6.75 g L −1 each of yeast extract and peptone was fed into the fermentation system for nine consecutive batch fermentations, which were
completed within 8–14 h with an average ethanol concentration of 15% ( v/ v) and ethanol yield of 0.464, 90.8% of its theoretical value of 0.511. The average ethanol productivity that was calculated
with the inclusion of the downstream time for the yeast flocs to settle from the fermentation broth and the supernatant to
be removed from the fermentation system was 8.2 g L −1 h −1, much higher than those previously reported for VHG ethanol fermentation and regular ethanol fermentation with ethanol concentration
around 12% ( v/ v) as well. 相似文献
16.
We investigated the relationships of photosynthetic capacity ( P
nsat, near light-saturated net photosynthetic rate measured at 1,200 μmol m −2 s −1 PPFD) to photosystem II efficiency ( F
v/ F
m) and to photochemical reflectance index [PRI = ( R
531 − R
570)/( R
531 + R
570)] of Pinus taiwanensis Hay. needles at high (2,600 m a.s.l) and low-elevation (800 m a.s.l) sites through different seasons. Results indicate that
at high-elevation site, P
nsat, F
v/ F
m and PRI (both measured at predawn) paralleled in general with the air temperature. On the coolest measuring day with the
minimum air temperature dropping to −2°C, P
nsat could decrease to ca. 15% of its highest value, which was measured in autumn. At low-elevation site, with the minimum air
temperature of 10–12°C in cooler season and almost no seasonal variation of F
v/ F
m, P
nsat dropped to ca. 65% of its highest value and PRI decreased ca. 0.02 in winter. Even though seasonal variation of P
nsat was affected by many factors, it was still closely related to PRI based on statistical analyses using data from both sites,
through different seasons. On the contrary, seasonal variation of F
v/ F
m of P. taiwanensis needles was influenced mainly by low temperature at high elevation. Therefore, the correlation of P
nsat − F
v/ F
m was lower than that of P
nsat − PRI when data combined from both high- and low-elevation sites were analyzed. It is concluded that predawn PRI could be
used as an indicator to estimate the seasonal potential of photosynthetic capacity of P. taiwanensis grown at low- and high-elevations of sub-tropical Taiwan. 相似文献
17.
Abies faxoniana is a key species in reforestation processes in the southeast of the Qinghai-Tibetan Plateau of China. The changes in growth,
photosynthesis and nutrient status of A. faxoniana seedlings exposed to enhanced ultraviolet-B (UV-B), nitrogen supply and their combination were investigated. The experimental
design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m −2 day −1; enhanced UV-B, 14.33 KJ m −2 day −1) and two nitrogen levels (0; 20 g N m −2). The results indicated that: (1) enhanced UV-B significantly caused a marked decline in growth parameters, net photosynthetic
rate (Pn), photosynthetic pigments and F
v/ F
m, (2) supplemental nitrogen supply increased the accumulation of total biomass, Pn, photosynthetic pigments and F
v/ F
m under ambient UV-B, whereas supplemental nitrogen supply reduced Pn, and not affect biomass under enhanced UV-B, (3) enhanced
UV-B or nitrogen supply changed the concentration of nutrient elements of various organs. 相似文献
18.
In Brazil, the use of cashew apple ( Anacardium occidentale L .) to obtain new products by biotechnological process represents an important alternative to avoid wastage of a large quantity
of this fruit, which reaches about 85% of the annual production of 1 million tons. This work focuses on the development of
an alcoholic product obtained by the fermentation of cashew apple juice. The inoculation with two different strains of yeast
Saccharomyces cerevisiae viz. SCP and SCT, were standardized to a concentration of 10 7 cells ml −1. Each inoculum was added to 1,500 ml of cashew must. Fermentation was performed at 28 ± 3°C and aliquots were withdrawn every
24 h to monitor soluble sugar concentrations, pH, and dry matter contents. The volatile compounds in fermented products were
analyzed using the gas chromatography/mass spectrometry (GC/MS) system. After 6 days, the fermentation process was completed,
cells removed by filtration and centrifugation, and the products were stabilized under refrigeration for a period of 20 days.
The stabilized products were stored in glass bottles and pasteurized at 60 ± 5°C/30 min. Both fermented products contained
ethanol concentration above 6% (v v −1) while methanol was not detected and total acidity was below 90 mEq l −1, representing a pH of 3.8–3.9. The volatile compounds were characterized by the presence of aldehyde (butyl aldehyde diethyl
acetal, 2,4-dimethyl-hepta-2,4-dienal, and 2-methyl-2-pentenal) and ester (ethyl α-methylbutyrate) representing fruity aroma.
The strain SCT was found to be better and efficient and this produced 10% more alcohol over that of strain SCP. 相似文献
19.
Experimental ecology methods and chlorophyll fluorescence technology were used to study the effects of different concentrations
of manganese (10 −12– 10 −4 mol L −1) on the growth, photosystem II and superoxide dismutase (SOD) activity of Amphidinium sp. MACC/D31. The results showed that manganese had a significant effect on the growth rate, fluorescence parameters (maximal
photochemical efficiency of PSII ( F
v
/F
m
), photochemical quenching (qP) and non-photochemical quenching (NPQ)) in the exponential stage (days 1–3) and SOD activity
of Amphidinium sp. ( P < 0.05). F
v/ F
m in the exponential stage in 10 −12 mol L −1 manganese concentration was significantly lower whilst qP and NPQ significantly higher than those in the other concentrations.
F
v
/F
m
(days 6–9) in 10 −4 mol L −1 manganese was significantly higher than those in the other concentrations. F
v
/F
m
(days 3–6) increased with increased concentration of manganese from 10 −12 to 10 −4 mol L −1. The values of qP and NPQ decreased with decreased concentrations of manganese, except for those in days 4–6. F
v
/F
m
under each concentration increased earlier and decreased later with culture stage whilst NPQ decreased earlier and increased
later. The SOD activity increased with increased concentration of manganese from 10 −12 to 10 −8 mol L −1. The SOD activity in 10 −4 mol L −1 manganese was significantly higher than those in the other concentrations and in 10 −12 mol L −1 manganese, it was significantly lower than those in the other concentrations. 相似文献
20.
The Raman spectra, water content, and biomass density of wild-type (WT) Pseudomonas aeruginosa PAO1, small colony variant (SCV) PAO1, and Pseudoalteromonas sp. NCIMB 2021 biofilms were compared in order to determine their variation with strain and species. Living, fully submerged
biofilms were analyzed in situ by confocal Raman microspectroscopy for up to 2 weeks. Water to biomass ratios (W/BRs), which
are the ratios of the O–H stretching vibration of water at 3,450 cm −1 to the C–H stretching band characteristic of biomass at 2,950 cm −1, were used to estimate the biomass density and cell density by comparison with W/BRs of protein solutions and bacterial suspensions,
respectively, on calibration curves. The hydration within SCV biofilm colonies was extremely heterogeneous whereas W/BRs were
generally constant in young WT biofilm colonies. The mean biomass in biofilm colonies of WT or colony cores of SCV was typically
equivalent to 16% to 27% protein ( w/ v), but was 10% or less for NCIMB 2021. The corresponding cell densities were 7.5 to >10 × 10 10 cfu mL −1 for SCV, while the maximum cell density for NCIMB biofilms was 2.8 × 10 10 cfu mL −1. 相似文献
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