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1.
S L Percival J S Knapp D S Wales R G J Edyvean 《Journal of industrial microbiology & biotechnology》1999,22(3):152-159
There is considerable interest in both Europe and the USA in the effects of microbiological fouling on stainless steels in
potable water. However, little is known about the formation and effects of biofilms, on stainless steel in potable water environments,
particularly in turbulent flow regimes. Results are presented on the development of biofilms on stainless steel grades 304
and 316 after exposure to potable water at velocities of 0.32, 0.96 and 1.75 m s−1. Cell counts on slides of stainless steel grades 304 and 316 with both 2B (smooth) and 2D (rough) finishes showed viable
and total cell counts were higher at the higher flow rates of 0.96 and 1.75 m s−1, compared to a flow rate of 0.32 m s−1. Extracellular polysaccharide levels were not significantly different (P< 0.05) between each flow rate on all stainless steel surfaces studied. higher levels were found at the higher water velocities.
the biofilm attached to stainless steel was comprised of a mixed bacterial flora including Acinetobacter sp, Pseudomonas spp, Methylobacterium sp, and Corynebacterium/Arthrobacter spp. Epifluorescence microscopy provided evidence of rod-shaped bacteria and the formation of stands, possibly of extracellular
material attached to stainless steel at high flow rates but not at low flow rates.
Received 04 February 1998/ Accepted in revised form 12 February 1999 相似文献
2.
3.
S L Percival 《Journal of industrial microbiology & biotechnology》1999,23(2):112-117
Little is known about the formation and effects of biofilms on stainless steel pipes in freshwater environments, particularly
as they are considered as a direct replacement for copper pipes for ‘problem’ water. There is some cause for concern especially
as stainless steel cannot claim the inherent biocidal potential of copper. As molybdenum is known to be leached out of stainless
steel grade 316, in very small amounts, a study was set up to see if molybdenum could retard the development of biofilms.
When a comparison of biofilm viable and total cell counts was made between pure molybdenum metal and stainless steel grade
304, it was found that cell counts were significantly higher (P < 0.05) on grade 304 stainless steel after 5 weeks exposure to flowing water (0.64 m s−1). Molybdenum (above a concentration of 1 g L−1) affected the growth rate of Acinetobacter sp, a pioneering bacterium of biofilms in potable water.
Received 18 February 1998/ Accepted in revised form 17 May 1999 相似文献
4.
Raulio M Pore V Areva S Ritala M Leskelä M Lindén M Rosenholm JB Lounatmaa K Salkinoja-Salonen M 《Journal of industrial microbiology & biotechnology》2006,33(4):261-268
The aim of the present work was to explore possibilities of photocatalytic TiO2 coating for reducing biofilms on non-living surfaces. The model organism, Deinococcus geothermalis, known to initiate growth of durable, colored biofilms on machine surfaces in the paper industry, was allowed to form biofilms
on stainless steel, glass and TiO2 film coated glass or titanium. Field emission electron microscopy revealed that the cells in the biofilm formed at 45°C under
vigorous shaking were connected to the surface by means of numerous adhesion threads of 0.1--0.3 μm in length. Adjacent cells
were connected to one another by threads of 0.5--1 μm in length. An ultrastructural analysis gave no indication for the involvement
of amorphous extracellular materials (e.g., slime) in the biofilm. When biofilms on photocatalytic TiO2 surfaces, submerged in water, were exposed to 20 W h m−2 of 360 nm light, both kinds of adhesion threads were completely destroyed and the D. geothermalis cells were extensively removed (from >107 down to below 106 cells cm−2). TiO2 films prepared by the sol-gel technique were slightly more effective than those prepared by the ALD technique. Doping of
the TiO2 with sulfur did not enhance its biofilm-destroying capacity. The results show that photocatalytic TiO2 surfaces have potential as a self-cleaning technology for warm water using industries. 相似文献
5.
Thermophilic Bacillus species readily attached and grew on stainless steel surfaces, forming mature biofilms of >106.0 cells/cm2 in 6 h on a surface inoculated with the bacteria. Clean stainless steel exposed only to pasteurized skim milk at 55 °C developed a mature biofilm of >106.0 cells/cm2 within 18 h. When bacilli were inoculated onto the steel coupons, 18-h biofilms were 30 m thick. Biofilm growth followed a repeatable pattern, with a reduction in the numbers of bacteria on the surface occurring after 30 h, followed by a recovery. This reduction in numbers was associated with the production of a substance that inhibited the growth of the bacteria. Variations in the environment, including pH and molarity, affected the viability of the cells. Chemicals that attack the polysaccharide matrix of the biofilm were particularly effective in killing and removing cells from the biofilm, demonstrating the importance of polysaccharides in the persistence of these biofilms. Treatment of either the biofilm or a clean stainless steel surface with lysozyme killed biofilm cells and prevented the attachment of any bacteria exposed to the surface. This suggests that lysozyme may have potential as an alternative control method for biofilms of these bacteria. 相似文献
6.
Species and material considerations in the formation and development of microalgal biofilms 总被引:2,自引:0,他引:2
The development of microalgal biofilms has received very limited study despite its relevance in the design of photobioreactors
where film growth may be advantageous for biomass separation or disadvantageous in fouling surfaces. Here, the effects of
species selection, species control, and substrate properties on biofilms of Scenedesmus obliquus and Chlorella vulgaris were investigated. Experiments were conducted in batch culture and in continuous culture modes in a flow cell. Cell growth
was monitored using confocal laser scanning microscopy and gravimetrically. Species selection and species control had significant
effects on biofilm development. On non-sterile wastewater, C. vulgaris shifted from primarily planktonic (23.7% attachment) to primarily sessile (79.8% attachment) growth. The biofilms that developed
in non-sterile conditions were thicker (52 ± 19 μm) than those grown in sterile conditions (7 ± 6 μm). By contrast, S. obliquus attained similar thicknesses (54 ± 31 and 53 ± 38 μm) in both sterile and non-sterile conditions. Neither species was able
to dominate a non-sterile biofilm. The effect of substrate surface properties was minimal. Both species grew films of similar
thickness (∼30 μm for S. obliquus, <10 μm for C. vulgaris) on materials ranging from hydrophilic (glass) to hydrophobic (polytetrafluoroethylene). Surface roughness created by micropatterning
the surface with 10 μm grooves did not translate into long-term increases in biofilm thickness. The results indicate that
species selection and control are more important than surface properties in the development of microalgal biofilms. 相似文献
7.
Francesca Di Pippo Neil Tomas William Ellwood Antonella Guzzon Luisa Siliato Ernesto Micheletti Roberto De Philippis Patrizia B. Albertano 《Journal of applied phycology》2012,24(2):211-220
Phototrophic biofilms seem to be suitable candidates for tertiary wastewater treatment due to their high uptake capacity for
nutrients and other pollutants, also taking into account the time and cost savings derived from easy procedures for biomass
harvesting. Biomass accrual, structure, and physiology of biofilms affect the efficiency of nutrient removal by its microbial
community. Here, we construct a biofilm consisting of a cyanobacterium Synechocystis sp. and the green alga Chlorococcum sp. and determine the effect of combined variations of irradiance and temperature on the biofilm structure and function.
The two species were isolated from phototrophic biofilms naturally developing in an Italian wastewater treatment plant and
grown in a microcosm designed for biofilm investigations. Phototrophic biomass accumulation, percent species composition,
photosynthetic response and the amount and composition of capsular polysaccharides (CPS), including anionic residues, are
reported. The results showed that biofilm development required relatively moderate irradiances (60 μmol photons m−2 s−1) below which development was arrested. Both light and temperature had a strong effect on the composition of each species
to the biofilm. The CPS compositions also changed with temperature, light and species composition. The CPS of the green-algal-dominated
biofilm had the higher uronic acid content indicating a potential to exploit green algae in the treatment of waste contaminated
with heavy metals. Given the knowledge of the response of certain species to light and temperature combinations, it may be
possible to construct biofilms of known species and CPS composition to use them for specific applications. 相似文献
8.
Dunsmore BC Jacobsen A Hall-Stoodley L Bass CJ Lappin-Scott HM Stoodley P 《Journal of industrial microbiology & biotechnology》2002,29(6):347-353
Biofilms of sulphate-reducing Desulfovibrio sp. EX265 were grown in square section glass capillary flow cells under a range of fluid flow velocities from 0.01 to 0.4
m/s (wall shear stress, τw, from 0.027 to 1.0 N/m2). In situ image analysis and confocal scanning laser microscopy revealed biofilm characteristics similar to those reported for aerobic
biofilms. Biofilms in both flow cells were patchy and consisted of cell clusters separated by voids. Length-to-width ratio
measurements (l
c:w
c) of biofilm clusters demonstrated the formation of more “streamlined” biofilm clusters (l
c:w
c=3.03) at high-flow velocity (Reynolds number, Re, 1200), whereas at low-flow velocity (Re 120), the l
c:w
c of the clusters was approximately 1 (l
c:w
c of 1 indicates no elongation in the flow direction). Cell clusters grown under high flow were more rigid and had a higher
yield point (the point at which the biofilm began to flow like a fluid) than those established at low flow and some biofilm
cell aggregates were able to relocate within a cluster, by travelling in the direction of flow, before attaching more firmly
downstream.
Received 01 February 2002/ Accepted in revised form 16 July 2002 相似文献
9.
Various measurements of microbial productivity in streambed pebble biofilms were analyzed almost monthly for 1 year to quantify the importance of primary production as an autochthonous source of organic matter utilized to support heterotrophic bacterial production in the dynamic food web within this natural microbial habitat. Bacterial density varied from 0.3 × 108 to 1.4 × 108 cells cm−2, and chlorophyll a concentration ranged from 0.7 to 25.9 μg cm−2, with no coupled oscillation between seasonal changes in these two parameters. In bottle incubation experiments, the instantaneous bacterial growth rate of bacteria was significantly correlated with their production rate [measured by frequency of dividing cells (FDC)] as follows: ln μ = 0.138FDC − 3.003 (n = 15, r
2 = 0.445, p < 0.001). FDC values in the pebble biofilms increased with fluctuations during the study period, ranging from 3.6% to 9.2%. Bacterial production rates largely fluctuated between 0.15 to 0.92 μg C cm−2 h−1, and its seasonal pattern was similar to that of bacterial density. Net primary production measured between May 2002 to November 2002 attained minimum level (0.5 μg C cm−2 h−1) in June and maximum level (1.9 μg C cm−2 h−1) in August. Percentages of bacterial production to net primary production ranged between 21% and 120%. Because this ratio extends both below and above 100% for these parameters, it is likely that both autochthonous and allochthonous supplies of organic matter are important for production of bacteria in the pebble biofilms that develop in rapidly flowing fresh water streams. 相似文献
10.
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
11.
Whereas the transfer of Listeria from surfaces to foods and vice versa has been well documented, little is known about the mechanism of bacterial transfer.
The objective of this work is to gain a better understanding of the forces involved in listerial biofilms adhesion using atomic
force microscopy (AFM). L. monocytogenes Scott A was grown as biofilms on stainless steel surfaces by inoculating stainless steel coupons with Listeria and incubating the coupons for 48 h at 32 °C with a diluted 1:20 tryptic soy broth. After growth, biofilms were equilibrated
over saturated salt solutions at a constant relative humidity (%RH) before measurement of adhesion forces using AFM. The effects
of contact time, loading force, and biofilm relative humidity (%RH) suggested that neither contact time, loading force nor
biofilm %RH had a significant effect on biofilm adhesiveness at a cellular level (P > 0.05). In a second set of experiments, the influence of material type on biofilm adhesiveness was evaluated using two different
colloidal probes (SiO2 and polyethylene). Results showed that the maximum pull-off force and retraction work needed to retract the cantilever for
glass (−85.42 nN and 1.610−15 J, respectively) were significantly lower than those of polyethylene (−113.38 nN and 2.7 × 10–15 J, respectively; P < 0.001). The results of this study suggest that Listeria biofilms adhere more strongly to hydrophobic surfaces than hydrophilic surfaces when measured at a cellular level. These
results provide important insights that could lead to new ways to remediate and avoid listerial biofilm formation in the food
industry. 相似文献
12.
Yun Hee Kang Jong Ahm Shin Myung Sook Kim Ik Kyo Chung 《Journal of applied phycology》2008,20(2):183-190
In integrated multi-trophic aquaculture (IMTA), seaweeds have the capacity to reduce the environmental impact of nitrogen-rich
effluents in coastal ecosystems. To establish such bioremediation systems, selection of suitable seaweed species is important.
The distribution and productivity of seaweeds vary seasonally based on water temperature and photoperiod. In Korea, candidate
genera such as Pophyra, Laminaria, and Undaria grow from autumn to spring. In contrast, Codium grows well at relatively high water temperatures in summer. Thus, aquaculture systems potentially could capitalize on Codium’s capacity for rapid growth in the warm temperatures of late summer and early fall. In this study, we investigated ammonium
uptake and removal efficiency by Codium fragile. In laboratory experiments, we grew C. fragile under various water temperatures (10, 15, 20, and 25°C), irradiances (dark, 10, and 100 μmol photons m−2 s−1), and initial ammonium concentrations (150 and 300 μM); in all cases, C. fragile exhausted the ammonium supply for 6 h. At 150 μM of , ammonium removal efficiency was greatest (99.5 ± 2.6%) when C. fragile was incubated at 20°C under 100 μmol photons m−2 s−1. At 300 μM of , removal efficiency was greatest (86.3 ± 2.1%) at 25°C under 100 μmol photons m−2 s−1. Ammonium removal efficiency was significantly greater at 20 and 25°C under irradiance of 100 μmol photons m−2 s−1 than under other conditions tested. 相似文献
13.
Summary The effects were studied of light intensity, culture method and cytokinins on plant formation from callus-derived rhizomes
of Cymbidium ensifolium var. misericors. The results demonstrated that one piece of rhizome produced seven shoot buds in 45 d when cultured in 1/2 MS basal liquid
medium supplemented with 0.17 μM N6-(2-isopentenyl) adenine, 0.17 μM thidiazuron, 33 μM 6-aminopurine adenine and 1.5 μM naphthaleneacetic acid under 10 μmol m−2 s−1 artificial light and agitated at 60 rpm on a rotary shaker. These shoot-cm plantlets in 5 mo. when transferred to the same
Gelrite-gel basal medium supplemented with 50 g l−1 banana pulp. Plantlets were acclimated and grew well when potted in the greenhouse. 相似文献
14.
Merja R. Häkkinen Mervi T. Hyvönen Seppo Auriola Robert A. Casero Jr Jouko Vepsäläinen Alex R. Khomutov Leena Alhonen Tuomo A. Keinänen 《Amino acids》2010,38(2):369-381
N-alkylated polyamine analogues have potential as anticancer and antiparasitic drugs. However, their metabolism in the host
has remained incompletely defined thus potentially limiting their utility. Here, we have studied the degradation of three
different spermine analogues N,N′-bis-(3-ethylaminopropyl)butane-1,4-diamine (DESPM), N-(3-benzyl-aminopropyl)-N′-(3-ethylaminopropyl)butane-1,4-diamine (BnEtSPM) and N,N′-bis-(3-benzylaminopropyl)butane-1,4-diamine (DBSPM) and related mono-alkylated derivatives as substrates of recombinant
human polyamine oxidase (APAO) and spermine oxidase (SMO). APAO and SMO metabolized DESPM to EtSPD [K
m(APAO) = 10 μM, k
cat(APAO) = 1.1 s−1 and K
m(SMO) = 28 μM, k
cat(SMO) = 0.8 s−1, respectively], metabolized BnEtSPM to EtSPD [K
m(APAO) = 0.9 μM, k
cat(APAO) = 1.1 s−1 and K
m(SMO) = 51 μM, k
cat(SMO) = 0.4 s−1, respectively], and metabolized DBSPM to BnSPD [K
m(APAO) = 5.4 μM, k
cat(APAO) = 2.0 s−1 and K
m(SMO) = 33 μM, k
cat(SMO) = 0.3 s−1, respectively]. Interestingly, mono-alkylated spermine derivatives were metabolized by APAO and SMO to SPD [EtSPM K
m(APAO) = 16 μM, k
cat(APAO) = 1.5 s−1; K
m(SMO) = 25 μM, k
cat(SMO) = 8.2 s−1; BnSPM K
m(APAO) = 6.0 μM, k
cat(APAO) = 2.8 s−1; K
m(SMO) = 19 μM, k
cat(SMO) = 0.8 s−1, respectively]. Surprisingly, EtSPD [K
m(APAO) = 37 μM, k
cat(APAO) = 0.1 s−1; K
m(SMO) = 48 μM, k
cat(SMO) = 0.05 s−1] and BnSPD [K
m(APAO) = 2.5 μM, k
cat(APAO) = 3.5 s−1; K
m(SMO) = 60 μM, k
cat(SMO) = 0.54 s−1] were metabolized to SPD by both the oxidases. Furthermore, we studied the degradation of DESPM, BnEtSPM or DBSPM in the
DU145 prostate carcinoma cell line. The same major metabolites EtSPD and/or BnSPD were detected both in the culture medium
and intracellularly after 48 h of culture. Moreover, EtSPM and BnSPM were detected from cell samples. Present data shows that
inducible SMO parallel with APAO could play an important role in polyamine based drug action, i.e. degradation of parent drug
and its metabolites, having significant impact on efficiency of these drugs, and hence for the development of novel N-alkylated polyamine analogues. 相似文献
15.
Photosynthetic Response of Carrots to Varying Irradiances 总被引:7,自引:3,他引:4
Response to irradiance of leaf net photosynthetic rates (P
N) of four carrot cultivars: Cascade, Caro Choice (CC), Oranza, and Red Core Chantenay (RCC) were examined in a controlled
environment. Gas exchange measurements were conducted at photosynthetic active radiation (PAR) from 100 to 1 000 μmol m−2 s−1 at 20 °C and 350 μmol (CO2) mol−1(air). The values of P
N were fitted to a rectangular hyperbolic nonlinear regression model. P
N for all cultivars increased similarly with increasing PAR but Cascade and Oranza generally had higher P
N than CC. None of the cultivars reached saturation at 1 000 μmol m−2 s−1. The predicted P
N at saturation (P
Nmax) for Cascade, CC, Oranza, and RCC were 19.78, 16.40, 19.79, and 18.11 μmol (CO2) m−2 s−1, respectively. The compensation irradiance (I
c) occurred at 54 μmol m−2 s−1 for Cascade, 36 μmol m−2 s−1 for CC, 45 μmol m−2 s−1 for Oranza, and 25 μmol m−2 s−1 for RCC. The quantum yield among the cultivars ranged between 0.057–0.033 mol(CO2) mol−1(PAR) and did not differ. Dark respiration varied from 2.66 μmol m−2 s−1 for Cascade to 0.85 μmol m−2 s−1 for RCC. As P
N increased with PAR, intercellular CO2 decreased in a non-linear manner. Increasing PAR increased stomatal conductance and transpiration rate to a peak between
600 and 800 μmol m−2 s−1 followed by a steep decline resulting in sharp increases in water use efficiency.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Bacterial biofilms are associated with chronic infections due to their resistance to antimicrobial agents. Staphylococcus
aureus is a versatile human pathogen and can form biofilms on human tissues and diverse medical devices. To identify novel biofilm
inhibitors of S. aureus, the supernatants from a library of 458 Actinomycetes strains were screened. The culture supernatants (1% v/v) of more than 10 Actinomycetes strains inhibited S. aureus biofilm formation by more than 80% without affecting the growth. The culture supernatants of these biofilm-reducing Actinomycetes strains contained a protease (equivalent to 0.1 μg proteinase K ml−1), which both inhibited S. aureus biofilm formation and detached pre-existing S. aureus biofilms. This study suggests that protease treatment could be a feasible tool to reduce and eradicate S. aureus biofilms. 相似文献
17.
Christophe Sandt Truis Smith-Palmer Jonathan Comeau David Pink 《Applied microbiology and biotechnology》2009,83(6):1171-1182
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 × 1010 cfu mL−1 for SCV, while the maximum cell density for NCIMB biofilms was 2.8 × 1010 cfu mL−1. 相似文献
18.
Inhibiting sulfate-reducing bacteria in biofilms by expressing the antimicrobial peptides indolicidin and bactenecin 总被引:3,自引:0,他引:3
A Jayaraman F B Mansfeld T K Wood 《Journal of industrial microbiology & biotechnology》1999,22(3):167-175
To identify novel, less-toxic compounds capable of inhibiting sulfate-reducing bacteria (SRB), Desulfovibrio vulgaris and Desulfovibrio gigas in suspension cultures were exposed to several antimicrobial peptides. The bacterial peptide antimicrobials gramicidin S,
gramicidin D, and polymyxin B as well as the cationic peptides indolicidin and bactenecin from bovine neutrophils decreased
the viability of both SRB by 90% after a 1-h exposure at concentrations of 25–100 μg ml−1. To reduce corrosion by inhibiting SRB in biofilms, the genes for indolicidin and bactenecin were expressed in Bacillus subtilisBE1500 and B. subtilis WB600 under the control of the constitutive alkaline protease (apr) promoter, and the antimicrobials were secreted into the culture medium using the apr signal sequence. Bactenecin was also synthesized and expressed as a fusion to the pro-region of barnase from Bacillus amyloliquefaciens. Concentrated culture supernatants of B. subtilis BE1500 expressing bactenecin at 3 μg ml−1 decreased the viability of Escherichia coli BK6 by 90% and the reference SRB D. vulgaris by 83% in suspension cultures. B. subtilis BE1500 and B. subtilis WB600 expressing bactenecin in biofilms also inhibited the SRB-induced corrosion of 304 stainless steel six to 12-fold in
continuous reactors as evidenced by the lack of change in the impedance spectra (resistance polarization) upon addition of
SRB and by the reduction in hydrogen sulfide and iron sulfide in batch fermentations with mild steel. A 36-fold decrease in
the population of D. vulgaris in a B. subtilis BE1500 biofilm expressing bactenecin was also observed. This is the first report of an antimicrobial produced in a biofilm
for in vivo applications and represents the first application of a beneficial, genetically-engineered biofilm for combating corrosion.
Received 27 October 1998/ Accepted in revised form 21 February 1999 相似文献
19.
The activity of 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (DS-Mn, DS-Co), phenylalanine ammonia-lyase (PAL),
and chalcone synthase (CHS) was monitored at various light intensities (dark, 8.88 μmol m−2 s−1, 88.8 μmol m−2 s−1) using a strawberry cell suspension culture. DS-Mn, PAL, and CHS were found to increase significantly (p>0.05) under light intensitie of 88.8 μmol m−2 s−1 compared to those of 8.88 μmol m−2 s−1 and dark. The activity of DS-Mn, PAL, and CHS were maximum at 88.8 μmol m−2 s−1. Anthocyanin content reached a maximum after 48–60 h of culturing at 88.8 μmol m−2 s−1. DS-Co showed greater activity than DS-Mn during cell culturing, but showed no correlation with anthocyanin production and
light intensity. The CHS gene expression was continuous at a light intensity of 88.8 μmol m−2 s−1.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
Xuemei Tang Steve H. Flint Rod J. Bennett John D. Brooks R. Hugh Morton 《Journal of industrial microbiology & biotechnology》2009,36(12):1491-1497
Formation of biofilms in dairy membrane plants causes membrane pore blocking, product contamination and subsequent economic
loss. To investigate the biofilm growth, two Klebsiella
oxytoca strains, K. B006 and TR002, previously isolated from New Zealand dairy membrane plants, were grown both individually and combined on
three types of ultrafiltration (UF) membranes in different concentrations of whey medium in biofilm reactors (CBR 90, BioSurface
Technologies, Bozeman, USA). Biofilms of both the individual and combined strains grew on the membrane surfaces to levels
of 4.9–7.99 log colony-forming units (CFU) cm−2 measured by standard plate counting after removing the cells by sonication. More biofilm grew on used polyethersulfone (PES)
membranes than on new PES and polyvinylidene fluoride (PVDF) membranes. Both strains formed good biofilms, although K. B006 formed a denser biofilm than TR002. This corresponded to our previous study on the attachment of these organisms, where
K. B006 attached in greater numbers than K. TR002. The dual strains produced a higher biofilm density than single strains on the new membranes. Biofilm density tended
to increase with increased whey concentration. The saturated biofilm was approximately 108 CFU cm−2. PES membranes appeared to support biofilm growth less readily than did PVDF membranes and therefore may be the preferred
material for UF membranes to reduce problems with microbial colonisation. Used membranes were more readily colonised with
biofilm than were new membranes. Therefore, selecting a membrane type and monitoring membrane age will help manage biofilm
development during UF. 相似文献