共查询到20条相似文献,搜索用时 31 毫秒
1.
Sreyashi Sarkar Debashis Roy Joydeep Mukherjee 《Bioprocess and biosystems engineering》2010,33(2):207-217
After initial small-scale experiments, a 25.0 l rotating disk bioreactor (RDBR) was investigated for the cultivation of a
biofilm-forming salt-tolerant Streptomyces sp. MS1/7, producing an antimicrobial compound. Peak activity attainment rate, PAAR (ratio of the peak antimicrobial activity,
PAMA and the time taken to attain PAMA) was determined. Of the three pH values examined (8.0, 9.0 and 10.0) maximum PAAR (1.82 mm/h)
was attained at pH 9.0. Three aeration rates (9.0, 6.0 and 3.0 l/min) were considered at three levels (25, 50 and 75%) of
disk submergence. At the highest aeration rate and 50% submergence level, PAMA (41 mm), PAAR (1.86 mm/h) and biofilm density
(BD, 0.91 g/ml) attained their highest values. At any given aeration rate, PAMA was always higher at 50% submergence level.
This supports our earlier premise that ideal intertidal conditions, 12 h periods of immersion and emersion, promote maximum
BD and antimicrobial production in the niche-mimic RDBR. 相似文献
2.
Sarkar S Saha M Roy D Jaisankar P Das S Gauri Roy L Gachhui R Sen T Mukherjee J 《Marine biotechnology (New York, N.Y.)》2008,10(5):518-526
A novel reactor system, the rotating disk bioreactor (RDBR), was used to mimic the niche environmental conditions of three salt-tolerant estuarine actinobacteria isolated from the Sundarbans region off the Bay of Bengal, designated MS310 (99% similar in its 16S rRNA gene sequence to Streptomyces parvallus), MS3/20 and MS1/7. The RDBR, operated at a rotational speed of one revolution per day, 50% submergence of discs, aeration rate of 1.0 vvm, and with a sucrose-containing medium, faithfully mimicked the intertidal estuarine habitat of these marine isolates, and supported biofilm formation and production of antimicrobial metabolites-in particular, actinomycin D by MS310. Onset of antibiotic production by MS310 occurs at 20 h in the RDBR compared to 55 h in a conventional stirred-tank bioreactor (STBR). Furthermore, peak antimicrobial activity is attained much earlier in the RDBR with MS310 (at 45 h) than that reported with a terrestrial strain of S. parvallus grown in a STBR (at 144 h). Peak antimicrobial activity of metabolites produced by MS1/7 and MS3/20 were also attained earlier in the RDBR (at 25 and 12 h, respectively) than in a STBR (at 80 and 28 h, respectively). Antibiotic synthesis in the three isolates, in general, appears to be associated with their growth. Overall, the RDBR may be considered the preferred alternative to the STBR for production of antimicrobials by biofilm-forming estuarine bacteria for its much higher surface/volume ratio, lower costs, and easy operability. 相似文献
3.
The marine phage ϕHSIC has been previously reported to enter into a pseudolysogenic-like interaction with its host Listonella pelagia. This phage–host system displays behaviors that are characteristic of both pseudolysogeny and lysogeny including a high rate of spontaneous induction and chromosomal integration of the prophage. To determine what parameters may influence the transition from lysogenic to lytic existence in the ϕHSIC/L. pelagia phage–host system, cultures of this organism were incubated under different environmental conditions, while host cell growth and bacteriophage production were monitored. The environmental parameters tested included salinity, temperature, a rapid temperature shift, and degree of culture aeration. The highest titers of phage were produced by HSIC-1a cells grown in high-salinity nutrient artificial seawater media (67 ppt with a natural salinity equivalent of 57 ppt) or those cultured in highly aerated nutrient artificial seawater media (cultures shaken at 300 rpm). Conversely, the lowest titers of phage were produced under low salinity or rate of aeration. In general, conditions that stimulated growth resulted in greater lytic phage production, whereas slow growth favored lysogeny. These results indicate that elevated salinity and aeration influenced the switch from lysogenic to lytic existence for the phage ϕHSIC. These results may have implications for environmental controls of the lysogenic switch in natural populations of marine bacteria. 相似文献
4.
Summary The role of mechanical impedance, poor aeration and water availability in restricting pea (Pisum sativum L.) seedling root growth in sandy loam soil at three bulk densities and six matric potentials was studied. Mechanical impedance
increased both with bulk density and —matric potential. In certain treatments the roots were shorter and thicker as impedance
increased but in others shorter, thicker roots were found as impedance decreased and this was attributed to poor aeration.
An aeration deficiency index was defined to separate the impedance and aeration effects when the two acted in combination.
An aeration effect was found in soils having less than 30, 22, and 11 per cent gas-filled pore space at low, medium and high
bulk densities respectively and the distribution and area of the gas/liquid interface probably influenced diffusion resistance.
Effects due to restricted water availability were found only at potentials greater than –3.5 bars, the roots being shorter
and thinner as moisture stress increased. 相似文献
5.
The effect of agitation and aeration on the growth and antibiotic production by Xenorhabdus nematophila YL001 grown in batch cultures were investigated. Efficiency of aeration and agitation was evaluated through the oxygen mass
transfer coefficient (K
L
a). With increase in K
L
a, the biomass and antibiotic activity increased. Activity units of antibiotic and dry cell weight were increased to 232 U ml−1 and 19.58 g l−1, respectively, productivity in cell and antibiotic was up more than 30% when K
L
a increased from 115.9 h−1 to 185.7 h−1. During the exponential growth phase, DO concentration was zero, the oxygen supply was not sufficient. So, based on process
analysis, a three-stage oxygen supply control strategy was used to improved the DO concentration above 30% by controlling
the agitation speed and aeration rate. The dry cell weight and activity units of antibiotic were further increased to 24.22 g l−1 and 249 U ml−1, and were improved by 24.0% and 7.0%, compared with fermentation at a constant agitation speed and a constant aeration rate
(300 rev min−1, 2.5 l min−1). 相似文献
6.
G. D. García de Fernando P. E. Hernández J. Burgos B. Sanz J. A. Ordóňez 《Folia microbiologica》1991,36(5):423-428
Growth and extracellular proteinase production byEnterococcus faecalis subsp.liquefaciens was studied on several culture media and under different incubation conditions. The organisms grew well and developed extracellular
proteinase activity on proteinaceous media, but when it grew on Collins basal medium (lacking of protein), growth was poor
and proteinase activity was not detected. The activation energy for growth was estimated to be 116 kJ/mol, the optimum being
at 37°C. Proteinase production was not affected by temperature in the range studied (7–45°C). Growth rate was not affected
by aeration although a higher amount of microorganisms was observed on shaking the culture during incubation. Likewise, extracellular
proteolytic activity was about twice higher in cultures shaken at 2.3 or 3.3 Hz than in those shaken at 0 or 1.3 Hz. 相似文献
7.
Alfenore S Cameleyre X Benbadis L Bideaux C Uribelarrea JL Goma G Molina-Jouve C Guillouet SE 《Applied microbiology and biotechnology》2004,63(5):537-542
In order to identify an optimal aeration strategy for intensifying bio-fuel ethanol production in fermentation processes where growth and production have to be managed simultaneously, we quantified the effect of aeration conditions—oxygen limited vs non limited culture (micro-aerobic vs aerobic culture)—on the dynamic behaviour of Saccharomyces cerevisiae cultivated in very high ethanol performance fed-batch cultures. Fermentation parameters and kinetics were established within a range of ethanol concentrations (up to 147 g l–1), which very few studies have addressed. Higher ethanol titres (147 vs 131 g l–1 in 45 h) and average productivity (3.3 vs 2.6 g l–1
h–1) were obtained in cultures without oxygen limitation. Compared to micro-aerobic culture, full aeration led to a 23% increase in the viable cell mass as a result of the concomitant increase in growth rate and yield, with lower ethanol inhibition. The second beneficial effect of aeration was better management of by-product production, with production of glycerol, the main by-product, being strongly reduced from 12 to 4 g l–1. We demonstrate that aeration strategy is as much a determining factor as vitamin feeding (Alfenore et al. 2002) in very high ethanol performance (147 g l–1 in 45 h) in order to achieve a highly competitive dynamic process. 相似文献
8.
Phenylacetic acid improves bud elongation and in vitro plant regeneration efficiency in Capsicum annuum L. 总被引:1,自引:0,他引:1
A highly efficient three-stage protocol for the regeneration of chilli pepper (Capsicum annuum L.) from cotyledon explants was developed. This protocol used PAA in both the shoot-bud induction medium and the medium for
elongation of the shoot buds. A superior medium for the induction of buds from the cotyledons was MS medium supplemented with
BA (5 or 7 mg/l) + PAA (2 mg/l). Buds were elongated during the second stage on medium containing BA (2 or 5 mg/l) + PAA (2 mg/l).
On this medium most of the buds elongated, and their number also increased due to the formation of new buds; bud elongation
was achieved in 100% of the cultures provided the buds were induced in the primary stage on a medium supplemented with BA+PAA.
The shoots that elongated in the second-stage rooted at 100% frequency on a medium supplemented with NAA (1 mg/l). The complete
plantlets with well-developed root and shoot systems were transferred to field conditions where they grew to maturity, flowered
and fruited normally. While shoot-bud induction from the cultured cotyledons was also observed on media supplemented with
BA (5 or 7 mg/l) alone or in combination with IAA (0.2–2 mg/l), buds induced on these media were often distorted, with most
not developing into normal shoots in the second-stage subculturing; a rosette of buds was seen in the second stage subculturing.
On the other hand, PAA in combination with BA in the primary induction medium and second-stage medium promoted normal development
and the elongation of shoot buds.
Received: 28 July 1998 / Revision received: 22 December 1998 / Accepted: 19 February 1999 相似文献
9.
A 700 ml membrane-aerated, stirred glass reactor equipped with four vertical baffles was constructed. Biodesulfurization of
model oil (n-dodecane containing dibenzothiophene—DBT) and hydrodesulfurized diesel was carried out using Pseudomonas delafieldii strain R-8. Microbubble aeration gave an activity of 1.3 mg DBT removed g−1 h−1 and 277 μg sulfur g−1 h−1 for model oil and hydrodesulfurized diesel, respectively. These values were 1.9- and 1.6-times higher than using a traditional
bubble aeration process. This is a promising method for the biodesulfurization of petroleum feedstocks. 相似文献
10.
The effect of fulvic acids (FA) on arbuscular mycorrhizal (AM) fungi and on the toxicity of lead and manganese toward these
symbionts were demonstatedin vitro. Incubation of root segments colonized with the AM fungusGlomus intraradices in undiluted fraction of FA (813 mg/L carbon) decreased an outgrowth of intraradical hyphae. Diluted FA solutions (<271 mg/L
C) did not influence the proportion of root segments bearing proliferating hyphae; solution containing 27.1 mg/L C even increased
the proliferation. A decrease of heavy metal toxicity toward the fungus was observed when FA (81.3 mg/L C) were added to the
solutions containing higher concentrations (≤100 μmol/L) of Mn and Pb; the positive effect of FA was not significant at higher
concentrations of metals (0.5 mmol/L). A short-term cultivation of six different saprophytic microorganisms — three actinomycetes
and three filamentous fungi — on the FA media (81.3 mg/L C) did not result in a modification of hyphal proliferation from
the root segments subsequently incubated in these media. 相似文献
11.
Magdalena Wegiera Urszula Kosikowska Anna Malm Helena D. Smolarz 《Central European Journal of Biology》2011,6(6):1036-1043
This study was designed primarily to investigate the antibacterial and antifungal activity of the extracts from fruits of
six Rumex L. species: R. acetosa L., R. acetosella L., R. confertus Willd., R. crispus L., R. hydrolapathum Huds. and R. obtusifolius L. The 7 Grampositive and 7 Gram-negative bacteria strains and 5 fungal ones were tested by agar and broth dilution method.
Determination of minimal inhibitory concentration (MIC) revealed that the extracts from R. confertus, R. crispus, R. hydrolapathum and R. obtusifolius exerted differential inhibitory effect on the growth of Gram-positive bacteria — staphylococci (MIC=62.5–125 μg/mL) and Gramnegative
bacteria — Escherichia coli ATCC 3521, Proteus mirabilis, Pseudomonas aeruginosa (MIC=125→500 μg/mL); MIC values determined by agar dilution method were somewhat higher. The same extracts inhibited also
the growth of fungi — Candida spp. or Trichophyton mentagrophytes ATCC 9533 (MIC=250–500 μg/mL), as found by agar dilution method. The total content of polyphenols (11.66–78.36 mg/g), anthracene
derivatives (0.26–12.93 mg/g) and tannins (4.00–11.16%) was also determined. 相似文献
12.
Despite its ubiquity in fermented dairy products, the safety of lactic acid enterococcal bacteria remains controversial. In
this study, five Enterococcus durans strains — A1, A2, B1, B2, and C1 — were isolated from traditional fermented yak milk from Tibet. To evaluate the strains’
safety, biogenic amine production, antibiotic resistance and presence of known virulence determinants were investigated. Strain
A1 can produce biogenic amines for histamine, spermine, and spermidine (mean values: 8.64, 8.31, and 0.30 mg/L, respectively).
Polymerase chain reaction amplification for Strain A1 found genes involved in expression of gelatinase (gleE), cytolysin (cylA, cylB, and cylM), sex pheromones (ccf and cpd) and cell wall adhesion (efaA). Strain A2 showed sensitivity or intermediate resistance to all tested antibiotics, and no virulence determinants except
gelE and ccf, but did produce tyramine at a relatively high level (912.02 mg/L). Both strains B1 and B2 could produce histamine (10.43
and 10.56 mg/L, respectively), and showed vancomycin resistance; B1 also produced tyramine (504.02 mg/L). Strain C1 could
produce all five biogenic amines tested in the study -putrescine, histamine, tyramine, spermine, and spermidine; concentrations
were 6.51, 9.59, 205.85, 5.55, and 5.39 mg/L, respectively. All E. durans strains found in Tibetan traditional fermented yak milk thus offer potential risk. 相似文献
13.
The cell wall loosening enzymes viz. glycosidases, polygalacturonase and xylanase were analyzed in cytoplasmic and wall bound fractions extracted from control
and hormone (GA3 NAA, PAA) treated internodes, as they are known to play a key role in cell wall metabolism. Among the glycosidases, wall
bound β-glucosidase and α-galactosidase activities were significantly correlated with age of control internodes. Cytoplasmic
α-galactosidase showed significant correlation in hormone treated internodes. Maximum correlation was observed in GA3, followed by PAA and NAA. Wall bound xylanase activity was well correlated with length only in NAA treated internodes and
less after GA3 treatment while cytoplasmic xylanase showed correlation with intrnode length only in control and after NAA treatment. Cytoplasmic
polygalacturonase showed correlation with internode length only after GA3 treatment while wall bound polygalacturonase showed correlation with internode length after NAA treatment. The possible role
of these enzymes in internode development is discussed. 相似文献
14.
You-Jung Lee Hye-Jin Kim Wa Gao Chung-Han Chung Jin-Woo Lee 《Biotechnology and Bioprocess Engineering》2012,17(2):227-235
The optimal conditions for production of carboxymethylcellulase (CMCase) of Bacillus amyloliquefaciens DL-3 by a recombinant Escherichia coli JM109/DL-3 were established at a flask scale using the response surface method (RSM). The optimal conditions of rice bran,
tryptone, and initial pH of the medium for cell growth extracted by Design Expert Software were 66.1 g/L, 6.2 g/L, and 7.2,
respectively, whereas those for production of CMCase were 58.0 g/L, 5.0 g/L, and 7.1. The analysis of variance (ANOVA) of
results from central composite design (CCD) indicated that significant factor (“probe > F” less than 0.0500) for cell growth was rice bran, whereas those for production of CMCase were rice bran and initial pH of
the medium. The optimal temperatures for cell growth and the production of CMCase by E. coli JM109/DL-3 were found to be 37°C. The optimal agitation speed and aeration rate of 7 L bioreactors for cell growth were 498
rpm and 1.4 vvm, whereas those for production of CMCase were 395 rpm and 1.1 vvm. The ANOVA of results indicated that the
aeration rate was more significant factor (“probe > F” less than 0.0001) than the agitation speed for cell growth and production of CMCase. The optimal inner pressure for cell
growth was 0.08 MPa, whereas that for the production of CMCase was 0.06 MPa. The maximal production of CMCase by E. coli JM109/DL-3 under optimized conditions was 871.0 U/mL, which was 3.0 times higher than the initial production of CMCase before
optimization. 相似文献
15.
JACKSON M. B.; WATERS I.; SETTER T.; GREENWAY H. 《Journal of experimental botany》1987,38(11):1826-1838
Complete submergence of rice plants (Oryza sativa L. cv. IR42)in dilute nutrient solution for 36 d almost stopped theaccumulation of dry matter, depressed soluble carbohydrate concentrationby over 75% and promoted chlorosis in fully expanded leaves.Increase in fresh weight by the shoots was not impaired. Extensionby the youngest visible leaf was stimulated. Extension by thenext leaf to appear was retarded by submergence. These growthresponses to submergence were associated with a 1-5-fold increasein the partial pressure of endogenous ethylene (ethene). Applying ethylene (0.30.35 Pa) in the gas-phase to non-submergedplants reproduced some, but not all, of these effects of submergence.Thus, greater leaf extension and chlorosis of submerged plantscould be attributable to accumulated ethylene but neither theslow relative growth rate nor the decreased extension of leavesemerging after the start of submergence could be so attributed. Two cultivars (FR13A and Kurkaruppan)already known to tolerate submergence, differed little fromsubmergence-intolerant IR42 in their relativegrowth rate and soluble carbohydrate concentration during submergence.However, their underwater leaf extension was less than in IR42and chlorosis was much less prevalent, especially in FR13A.Similarly, ethylene supplied to non-submerged plants was a lesseffective promotor of leaf extension and chlorosis in the twosubmergence tolerant cultivars. Application of 1.0 kPa carbondioxide in the gas-phase prevented the chlorosis response toethylene. The results indicate that accumulated ethylene is a likely causeof fast leaf extension and chlorosis in submergence intolerantforms of rice, particularly when amounts of dissolved carbondioxide are minimal. Key words: Oryza sativa L., aeration, ethylene (ethene), stress-tolerance 相似文献
16.
The glycerol fermentation by Klebsiella pneumoniae occurs by receiving more than five liquid products—organic acids, diols, and ethanol. Aiming to direct the glycerol conversion
towards predominant production of 2,3-butanediol (2,3-BD), the main influencing parameters (the aeration and the pH) were
investigated during fed-batch processes. The regime of intensive aeration (2.2 vvm air supply) was evaluated as most favorable
for 2,3-BD synthesis and ensured the decrease of all other metabolites. Thus, without pH control, 52.5 g/l 2,3-BD were produced,
as the carbon conversion of glycerol into 2,3-BD reached 60.6%. Additional enhancement in 2,3-BD production (by significant
increase of glycerol utilization) was achieved by the development of a new method of “forced pH fluctuations”. It was realized
by consecutive raisings of pH using definite ΔpH value, at exact time intervals, allowing multiple variations. Thus, the optimal
conditions for maximal glycerol consumption were defined, and 70 g/l 2,3-BD were produced, which is the highest amount obtained
from glycerol as a sole carbon source until now. The forced pH fluctuations emphasized pH as a governing factor in microbial
conversion processes. 相似文献
17.
Bolibok H Gruszczyńska A Hromada-Judycka A Rakoczy-Trojanowska M 《Cellular & molecular biology letters》2007,12(4):523-535
This study was conducted in order to identify quantitative trait loci (QTLs) for the in vitro culture response of winter rye (Secale cereale L.) immature embryos and immature inflorescences. A genetic linkage map comprising 67 SSRs, 9 ISSRs, 13 SAMPLs, 7 RAPDs,
2 SCARs and one EST marker was created based on the analyses of 102 recombinant inbred lines from the cross between lines
L318 (which has a good response in tissue cultures) and L9 (which is unable to regenerate plants from somatic tissues and
anthers). The map spans 979.2 cM, and the average distance between markers is 9.9 cM. Two characteristics were evaluated:
callus induction (CI) and somatic embryogenesis ability (SE). They were expressed as the percentage of immature embryos/inflorescences
producing callus (designated ECI/ICI) and the percentage of explants producing somatic embryos (ESE/ISE). All the analysed
traits showed continuous variation in the mapping population but a non-normal frequency distribution. We identified nine putative
QTLs controlling the tissue culture response of rye, explaining up to 41.6% of the total phenotypic variation: two QTLs for
ECI — eci-1, eci-2; 4 for ESE — ece-1, ese-2, ese-3, ese-4; 2 for ICI — ici-1, ici2; and 1 for ISE — ise-1. They were detected on chromosomes 1R, 4R, 5R, 6R and 7R. 相似文献
18.
Human kringle domains (KDs) are ubiquitously expressed binding modulators that fold into seven flexible loops and it has been
previously demonstrated that KDs can be engineered toward target-specific binding proteins as a non-antibody protein scaffold.
Here, we report a method for efficient expression of a KD derivative (KD548)—a promising anti-cancer agent—by high-cell-density
culture of Escherichia coli at a preparative scale production. The correct folding of KD548 requires three disulfide bonds. Nevertheless, cytoplasmic
expression of KD548 in E. coli led to good yields of highly soluble proteins with high activity. For efficient expression, four sets of expression systems
consisting of different promoters (lac or T7) and fusion tags (His or FLAG) were examined. Of these, the expression system using a combination of the T7 promoter
with the FLAG tag resulted in the highest production in shake flask cultivation as well as in high-cell-density cultivation
performed in a 6.6-L jar bioreactor. When protein expression was induced at high-cell density (optical density [OD] = 100)
and when complex feeding solutions were supplemented, cell density (maximum OD = 184) and production yield (∼5.4 g/L) were
significantly enhanced to values that were much higher than those found previously with Pichia cultivation (<8 mg/L). 相似文献
19.
Aeration alleviates ethanol inhibition and glycerol production during fed-batch ethanol fermentation
Hyeon-Beom Seo Ji-Hyeon Yeon Myung Hoon Jeong Do Hyung Kang Hyeon-Yong Lee Kyung-Hwan Jung 《Biotechnology and Bioprocess Engineering》2009,14(5):599-605
In this study, we investigated the effects of aeration on ethanol inhibition and glycerol production during fed-batch ethanol
fermentation. When aeration was conducted at 0.13, 0.33, and 0.8 vvm, the ethanol productivity, specific ethanol production
rate, and ethanol yield in the presence of greater than 100 g/L of ethanol were higher than when aeration was not conducted.
In addition, estimation of the parameters (α and β) in a model equation of ethanol inhibition kinetics indicated that aeration alleviated ethanol inhibition against the specific
growth rate and the specific ethanol production rate. Specifically, when aeration was conducted, the glycerol yield and specific
glycerol production rate decreased approximately 50 and 70%, respectively. Finally, the results of this study indicated that
aeration during fed-batch ethanol fermentation may improve the ethanol concentration in the final culture broth, as well as
the ethanol productivity. 相似文献
20.
A bacterial strain producing a -lactam antibiotic acylase, able to hydrolyze ampicillin to 6-aminopenicillanic acid more efficiently than penicillin G, was isolated from soil and characterized. The isolate was identified as Achromobacter sp. using the phenotypic characteristics, composition of cellular fatty acids and 16S rRNA gene sequence. The enzyme synthesis was fully induced by phenylacetic acid (PAA) at a concentration of 2 g l–1. PAA at concentrations up to 12 g l–1 had no negative effect on the specific activity of acylase and biomass production, but slowed down the specific growth rate. Benzoic or 4-hydroxyphenylacetic acids can also induce synthesis of the enzyme. The inducers were metabolized in all cases. Acylase activity in cell-free extracts was determined with various substrates; ampicillin, cephalexin and amoxicillin were hydrolyzed 1.5- and 2-times faster than penicillin G. A high stability of acylase activity was observed over a wide range of pH (5.0–8.5) and at temperatures above 55°C. 相似文献