共查询到20条相似文献,搜索用时 31 毫秒
1.
Delta-endotoxin production by a strain of Bacillus thuringiensis subsp kurstakion complex media based on crude gruel and fish meal was investigated. High proteolytic activities were concomitantly produced
with the bioinsecticide. In such complex media, the repressive regulation due to readily consumed carbon sources was partially
overcome. In order to improve substrate assimilation, 0.5 g L−1 sodium chloride and 0.1% Tween-80 were supplemented to the production medium, increasing delta-endotoxin yields when using
gruel concentrations below 59 g L−1. At and beyond 75 g L−1 gruel, delta-endotoxin yields were not affected in the presence of 0.5 g L−1 NaCl and 0.1% Tween-80, but proteolytic activity yields were remarkably reduced. Thus, the use of sodium chloride and Tween-80
allowed reduction of the initial gruel concentration to 42 g L−1 for the production of 3350 mg L−1 delta-endotoxin, while it was only 3800 mg L−1 with 92 g L−1 gruel. Moreover, similar to 0.5 g L−1 NaCl and 0.1% Tween-80, the use of 10 g L−1 sodium acetate significantly improved delta-endotoxin production and also reduced the proteolytic activity to 250 U ml−1.
Received 05 November 1998/ Accepted in revised form 19 August 1999 相似文献
2.
Use of Acadian marine plant extract powder from Ascophyllum nodosum in tissue culture of Kappaphycus varieties 总被引:1,自引:0,他引:1
Anicia Q. Hurtado Dianne Aster Yunque Keneth Tibubos Alan T. Critchley 《Journal of applied phycology》2009,21(6):633-639
Three varieties of Kappaphycus alvarezii (Kapilaran, KAP), Tambalang purple (PUR), Adik-adik (AA), and one variety of Kappaphycus striatum var. sacol (green sacol (GS) were used to determine the efficiency of Acadian marine plant extract powder (AMPEP) as a culture medium
at different concentrations, for the regeneration of young plants of Kappaphycus varieties, using tissue culture techniques for the production of seed stock for nursery and outplanting purposes for the
commercial cultivation of carrageenophytes. A shorter duration for shoot formation was observed when the explant was treated
with AMPEP + Plant Growth Regulator (PGR = PAA + zeatin at 1 mg L−1) compared to AMPEP when used singly. However, four explants responded differently to the number of days required for shoot
formation. The KAP variety took 46 days to form shoots at 3–4 mg L−1 AMPEP + PGR; while PUR required 21 days at 3–5 mg L−1 AMPEP and 3–4 mg L−1 AMPEP + PGR. AA required 17 days at 3–5 mg L−1 AMPEP and AMPEP + PGR; and GS 25 days at 1 mg L−1 AMPEP + PGR. It was observed that among the four explants used, PUR and AA initiated shoot formation with the use of AMPEP
only at higher concentrations (3–5 mg L−1) after a shorter period. Only PUR responded positively to ESS/2 for shoot initiation. The use of AMPEP alone and/or in combination
with PGR as a culture medium in the propagation of microplantlets using tissue culture technique is highly encouraging. 相似文献
3.
Mineralization of pentachlorophenol in a contaminated soil by Pseudomonas sp UG30 cells encapsulated in κ-carrageenan 总被引:2,自引:0,他引:2
M B Cassidy H Mullineers H Lee J T Trevors 《Journal of industrial microbiology & biotechnology》1997,18(1):43-48
A fermentation process in Escherichia coli for production of supercoiled plasmid DNA for use as a DNA vaccine was developed using an automated feed-back control nutrient
feeding strategy based on dissolved oxygen (DO) and pH. The process was further automated through a computer-aided data
processing system to regulate the cell growth rate by controlling interactively both the nutrient feed rate and agitation
speed based on DO. The process increased the total yield of the plasmid DNA by approximately 10-fold as compared to a manual
fed-batch culture. The final cell yield from the automated process reached 60 g L−1 of dry cell weight (OD600 = 120) within 24 h. A plasmid DNA yield of 100 mg L−1 (1.7 mg g−1 cell weight) was achieved by using an alkaline cell lysis method. Plasmid yield was confirmed using High Performance Liquid
Chromatography (HPLC) analysis. Because cells had been grown under carbon-limiting conditions in the automated process,
acetic acid production was minimal (below 0.01 g L−1) throughout the fed-batch stage. In contrast, in the manual process, an acid accumulation rate as high as 0.36 g L−1 was observed, presumably due to the high nutrient feed rates used to maintain a maximum growth rate. The manual fed-batch
process produced a low cell density averaging 10–12 g L−1 (OD600 = 25–30) and plasmid yields of 5–8 mg L−1 (approximately 0.7 mg g−1 cells). The improved plasmid DNA yields in the DO- and pH-based feed-back controlled process were assumed to be a result
of a combination of increased cell density, reduced growth rate (μ) from 0.69 h−1 to 0.13 h−1 and the carbon/nitrogen limitation in the fed-batch stage. The DO- and pH-based feed-back control, fed-batch process has
proven itself to be advantageous in regulating cell growth rate to achieve both high cell density and plasmid yield without
having to use pure oxygen. The process was reproducible in triplicate fermentations at both 7-L and 80-L scales.
Received 22 March 1996/ Accepted in revised form 20 September 1996 相似文献
4.
A Pessoa Jr I M de Mancilha S Sato 《Journal of industrial microbiology & biotechnology》1997,18(6):360-363
Sugar cane bagasse hemicellulosic fraction submitted to hydrolytic treatment with 100 mg of sulfuric acid per gram of dry
mass, at 140°C for 20 min, was employed as a substrate for microbial protein production. Among the 22 species of microorganisms
evaluated, Candida tropicalis IZ 1824 showed TRS consumption rate of 89.8%, net cell mass of 11.8 g L−1 and yield coefficient (Yx/s) of 0.50 g g−1. The hydrolyzate supplemented with rice bran (20.0 g L−1), P2O5 (2.0 g L−1) and urea (2.0 g L−1) provided a TRS consumption rate of 86.3% and a cell mass of 8.4 g L−1. At pH 4.0 cellular metabolism was inhibited, whereas at pH 6.0 the highest yield was obtained. The presence of furfural
(2.0 g L−1) hydroxymethylfurfural (0.08 g L−1) and acetic acid (3.7 g L−1) in the hydrolyzate did not interfere with cultivation at pH 6.0.
Received 25 October 1996/ Accepted in revised form 10 March 1997 相似文献
5.
The biodegradation of phenol by a pure culture of Pseudomonas putida was investigated in a continuously fed stirred-tank reactor, under aerobic conditions. The dilution rate was varied between
0.0174 h−1 and 0.278 h−1, covering a wide range of dissolved oxygen and the inhibition region of phenol. Through non-linear analysis of the data,
a dual-substrate growth kinetics, Haldane kinetics for phenol and Monod kinetics for oxygen, was derived with high correlation
coefficients. Respective biokinetic parameters were evaluated as μm = 0.569 h−1, K
p = 18.539 mg/l, K
i = 99.374 mg/l, K
o = 0.048 mg/l, Y
x/p = 0.521 g microorganism/g phenol and Y
x/o = 0.338 g microorganism/g oxygen, being in good agreement with other studies in the literature. Maintenance factors for both
phenol and oxygen were calculated for the first time for P. putida while the saturation coefficient for oxygen, K
o, was genuinely evaluated from the constructed model, not imported or adapted from other studies as reported in the literature.
All pertinent biokinetic parameters for P. putida have been calculated from continuous system data, which are most appropriate for use in continuous bioprocess applications.
Received: 29 July 1996 / Received revision: 18 November 1996 / Accepted: 23 November 1996 相似文献
6.
D Di Simine C Finoli A Vecchio V Andreoni 《Journal of industrial microbiology & biotechnology》1998,20(2):116-120
This paper explores the use of an experimental system based on polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ for the removal of metal ions from solutions. Experiments were performed in columns filled with the immobilised
cells and challenged with influents containing 20 mg L−1 of lead and 10 mg L−1 of cadmium. The cells were able to accumulate lead (about 40 mg g−1 dry biomass) and, to a lesser extent, cadmium (about 13 mg g−1 dry biomass) from solutions. In the presence of 0.4 g L−1 of glucose, the cells removed up to 53% of lead. Lead competed with cadmium for attachment to the binding sites when a solution
containing both the metals was applied. Lead removal occurred by a combination of fast physico-chemical adsorption and prolonged
low rate accumulation mediated by cell metabolism. The biosorptive capacity of the cells was sensitive to pH. Desorption of
the metal with EDTA restored the binding capability of the cells.
Received 07 July 1997/ Accepted in revised form 26 November 1997 相似文献
7.
Kinetic models for astaxanthin production by high cell density mixotrophic culture of the microalga Haematococcus pluvialis 总被引:3,自引:0,他引:3
High cell density cultivation of Haematococcus pluvialis for astaxanthin production was carried out in batch and fed-batch modes in 3.7-L bioreactors with stepwise increased light
intensity control mode. A high cell density of 2.65 g L−1 (batch culture) or 2.74 g L−1 (fed-batch culture) was obtained, and total astaxanthin production in the fed-batch culture (64.36 mg L−1) was about 20.5% higher than in the batch culture (53.43 mg L−1). An unstructured kinetic model to describe the microalga culture system including cell growth, astaxanthin formation, as
well as sodium acetate consumption was proposed. Good agreement was found between the model predictions and experimental data.
The models demonstrated that the optimal light intensity for mixotrophic growth of H. pluvialis in batch or fed-batch cultures in a 3.7-L bioreactor was 90–360 μmol m−2 s−1, and that the stepwise increased light intensity mode could be replaced by a constant light intensity mode.
Received 24 December 1998/ Accepted in revised form 23 April 1999 相似文献
8.
N Kiran Sree M Sridhar K Suresh I M Banat L Venkateswar Rao 《Journal of industrial microbiology & biotechnology》2000,24(3):222-226
A repeated batch fermentation system was used to produce ethanol using an osmotolerant Saccharomyces cerevisiae (VS3) immobilized in calcium alginate beads. For comparison free cells were also used to produce ethanol by repeated batch fermentation.
Fermentation was carried for six cycles with 125, 250 or 500 beads using 150, 200 or 250 g glucose L−1 at 30°C. The maximum amount of ethanol produced by immobilized VS3 using 150 g L−1 glucose was only 44 g L−1 after 48 h, while the amount of ethanol produced by free cells in the first cycle was 72 g L−1. However in subsequent fed batch cultures more ethanol was produced by immobilized cells compared to free cells. The amount
of ethanol produced by free cells decreased from 72 g L−1 to 25 g L−1 after the fourth cycle, while that of immobilized cells increased from 44 to 72 g L−1. The maximum amount of ethanol produced by immobilized VS3 cells using 150, 200 and 250 g glucose L−1 was 72.5, 93 and 87 g ethanol L−1 at 30°C. Journal of Industrial Microbiology & Biotechnology (2000) 24, 222–226.
Received 16 September 1999/ Accepted in revised form 22 December 1999 相似文献
9.
Dianne Aster T. Yunque Keneth R. Tibubos Anicia Q. Hurtado Alan T. Critchley 《Journal of applied phycology》2011,23(3):433-438
To improve the production of Kappaphycus plantlets in tissue culture, optimum media concentrations of an Ascophyllum nodosum extract (Acadian Marine Plant Extract Powder, AMPEP), plant growth regulators (PGR), pH–temperature combinations, and explant
density were determined. Kappaphycus alvarezii var. tambalang purple (PUR), kapilaran brown (KAP), vanguard brown (VAN), adik-adik (AA), tungawan green (TGR), and K. striatum var. sacol green (GS) were used as explants. Based on the shortest period for shoot emergence and the economical use of AMPEP, the optimum
enriched media was 3.0 mg L−1 AMPEP and 0.1 mg L−1 AMPEP + PGR 1 mg L−1 each phenylacetic acid (PAA) and zeatin for PUR, 1.0 mg L−1 AMPEP + PGR for KAP and GS, 0.1 mg L−1 AMPEP + PGR for VAN, and 3.0 mg L−1 AMPEP and 0.001 mg L−1 AMPEP + PGR for AA and TGR. Results showed that the addition of PGR to low concentrations of AMPEP hastened shoot formation.
pH–temperature combinations for the most rapid shoot formation were determined for the brown (KAP) and purple (PUR) color
morphotypes of K. alvarezii var. tambalang and the green morphotype of K. striatum var. sacol (GS) cultured in 1.0 mg L−1 AMPEP + PGR. The brown morphotype produced the most number of shoots at pH 7.7 at 20°C after as little as 20 days. Purple
K. alvarezii showed an increased shoot formation at pH 6.7 at 25°C and the green K. striatum morphotype at pH 8.7 at 25°C. The optimum number of explants added to the culture media was also determined for tungawan
green (TGR), brown (KAP), and tambalang purple (PUR) varieties of K. alvarezii in 1.0 mg L−1 AMPEP + PGR. The number of explants and the volume of the culture media combination were also tested. The highest average
number of shoots formed occurred in two explants:1 mL culture media (2:1) for KAP and PUR (35.00% and 16.67%, respectively)
and 1 explant: 2 mL culture media for the TGR (100.00%) with a range of 0.5–3.0 mm shoot length after 40 days in culture.
The earliest shoot formation was observed after 21 days for the brown and 9 days for both the green and purple color morphotypes
of Kappaphycus, in all densities investigated. This indicated that within the range tested, the density of explants did not have a significant
effect on the rate of shoot formation but did influence the average number generated from the culture. The rate of production
of new and improved Kappaphycus explants for a commercial nursery stock was improved through the use of AMPEP with optimized culture media pH, temperature,
and density conditions. 相似文献
10.
M G A Felipe M Vitolo I M Mancilha S S Silva 《Journal of industrial microbiology & biotechnology》1997,18(4):251-254
The bioconversion of xylose to xylitol by Candida guilliermondii FTI 20037 cultivated in sugar cane bagasse hemicellulosic hydrolyzate was influenced by cell inoculum level, age of inoculum
and hydrolyzate concentration. The maximum xylitol productivity (0.75 g L−1 h−1) occurred in tests carried out with hydrolyzate containing 54.5 g L−1 of xylose, using 3.0 g L−1 of a 24-h-old inoculum. Xylitol productivity and cell concentration decreased with hydrolyzate containing 74.2 g L−1 of xylose.
Received 02 February 1996/ Accepted in revised form 15 November 1996 相似文献
11.
A two-phase aqueous/organic partitioning bioreactor scheme was used to degrade mixtures of toluene and benzene, and toluene
and p-xylene, using simultaneous and sequential feeding strategies. The aqueous phase of the partitioning bioreactor contained
Pseudomonas sp. ATCC 55595, an organism able to degrade benzene, toluene and p-xylene simultaneously. An industrial grade of oleyl alcohol served as the organic phase. In each experiment, the organic
phase of the bioreactor was loaded with 10.15 g toluene, and either 2.0 g benzene or 2.1 g p-xylene. The resulting aqueous phase concentrations were 50 mg/l, 25 mg/l and 8 mg/l toluene, benzene and p-xylene respectively. The simultaneous fermentation of benzene and toluene consumed these compounds at volumetric rates of
0.024 g l−1 h−1 and 0.067 g l−1 h−1, respectively. The simultaneous fermentation of toluene and p-xylene consumed these xenobiotics at volumetric rates of 0.066 g l−1 h−1 and 0.018 g l−1 h−1, respectively. A sequential feeding strategy was employed in which toluene was added initially, but the benzene or p-xylene aliquot was added only after the cells had consumed half of the initial toluene concentration. This strategy was shown
to improve overall degradation rates, and to reduce the stress on the microorganisms. In the sequential fermentation of benzene
and toluene, the volumetric degradation rates were 0.056 g l−1 h−1 and 0.079 g l−1 h−1, respectively. In the toluene/p-xylene sequential fermentation, the initial toluene load was consumed before the p-xylene aliquot was consumed. After 12 h in which no p-xylene degradation was observed, a 4.0-g toluene aliquot was added, and p-xylene degradation resumed. Excluding that 12-h period, the microbes consumed toluene and p-xylene at volumetric rates of 0.074 g l−1 h−1 and 0.025 g l−1 h−1, respectively. Oxygen limitation occurred in all fermentations during the rapid growth phase.
Received: 16 November 1998 / Received revision: 29 March 1999 / Accepted: 9 April 1999 相似文献
12.
Development of a cost-effective glucose-corn steep medium for production of butanol by Clostridium beijerinckii 总被引:1,自引:0,他引:1
M Parekh J Formanek H P Blaschek 《Journal of industrial microbiology & biotechnology》1998,21(4-5):187-191
Corn steep water (CSW) medium (1.6% solids plus 6% glucose) was evaluated for growth and butanol production by Clostridium beijerinckii NCIMB 8052 wild-type and hyper-amylolytic, hyper-butanol-producing mutant strain BA101. CSW alone was not a suitable substrate,
whereas addition of glucose supported growth and butanol production by both strains. In a batch-scale fermentation using an
optimized 6% glucose-1.6% solids CSW medium, C. beijerinckii NCIMB 8052 and strain BA101 produced 10.7 g L−1 and 14.5 g L−1 of butanol, respectively. The total solvents (acetone, butanol, and ethanol) produced by C. beijerinckii NCIMB 8052 and strain BA101 were 14 g L−1 and 20 g L−1, respectively. Initial fermentation in small-scale flasks containing 6% maltodextrin-1.6% solids concentration CSW medium
resulted in 6 g L−1 and 12.6 g L−1 of butanol production by C. beijerinckii NCIMB 8052 and strain BA101, respectively. CSW can serve as an economic source of nitrogen, vitamins, amino acids, minerals,
and other nutrients. Thus, it is feasible to use 6% glucose-1.6% solids CSW medium in place of semi-defined P2 medium.
Received 9 February 1998/ Accepted in revised form 1 September 1998 相似文献
13.
Xue-Song Shen Qi Su Zhuang-ping Qiu Jing-yi Xu Yan-xia Xie Han-fu Liu Yi Liu 《Biological trace element research》2010,136(1):117-125
The toxic effects of artesunate and dihydroartemisinin on the growth metabolism of Tetrahymena thermophila BF5 were studied by microcalorimetry. The results showed that: (1) low concentrations of artesunate (≤1 mg L−1) and dihydroartemisinin (≤ 2 mg L−1) promoted the growth metabolism of T. thermophila BF5, whereas high concentrations of artesunate (1–60 mg L−1) and dihydroartemisinin (2–60 mg L−1) inhibited its growth; (2) the half inhibition concentrations IC50 of artesunate and dihydroartemisinin were 17.5817 and 9.5089 mg L−1, respectively. It was concluded that the inhibition of dihydroartemisinin was stronger than that of artesunate. 相似文献
14.
Production of hexanoic acid from d-galactitol by a newly isolated Clostridium sp. BS-1 总被引:1,自引:0,他引:1
Byoung Seung Jeon Byung-Chun Kim Youngsoon Um Byoung-In Sang 《Applied microbiology and biotechnology》2010,88(5):1161-1167
In a study screening anaerobic microbes utilizing d-galactitol as a fermentable carbon source, four bacterial strains were isolated from an enrichment culture producing H2, ethanol, butanol, acetic acid, butyric acid, and hexanoic acid. Among these isolates, strain BS-1 produced hexanoic acid
as a major metabolic product of anaerobic fermentation with d-galactitol. Strain BS-1 belonged to the genus Clostridium based on phylogenetic analysis using 16S rRNA gene sequences, and the most closely related strain was Clostridium sporosphaeroides DSM 1294T, with 94.4% 16S rRNA gene similarity. In batch cultures, Clostridium sp. BS-1 produced 550 ± 31 mL L−1 of H2, 0.36 ± 0.01 g L−1 of acetic acid, 0.44 ± 0.01 g L−1 of butyric acid, and 0.98 ± 0.03 g L−1 of hexanoic acid in a 4-day cultivation. The production of hexanoic acid increased to 1.22 and 1.73 g L−1 with the addition of 1.5 g L−1 of sodium acetate and 100 mM 2-(N-morpholino)ethanesulfonic acid (MES), respectively. Especially when 1.5 g L−1 of sodium acetate and 100 mM MES were added simultaneously, the production of hexanoic acid increased up to 2.99 g L−1. Without adding sodium acetate, 2.75 g L−1 of hexanoic acid production from d-galactitol was achieved using a coculture of Clostridium sp. BS-1 and one of the isolates, Clostridium sp. BS-7, in the presence of 100 mM MES. In addition, volatile fatty acid (VFA) production by Clostridium sp. BS-1 from d-galactitol and d-glucose was enhanced when a more reduced culture redox potential (CRP) was applied via addition of Na2S·9H2O. 相似文献
15.
J. O. Nacorda M. R. Martinez-Goss N. K. Torreta F. E. Merca 《Journal of applied phycology》2007,19(6):701-710
Two strains of Chlorella vulgaris Beijerinck isolated from two different sites in Laguna de Bay, Philippines, were studied for their resistance and ability
to remove four metal ions, i.e., Cu2+, Cr6+, Pb2+, and Cd2+ added separately in BG-11 growth medium. The growth of the two strains was severely inhibited at 2 mg.L−1 of Cu2+, 5 mg.L−1 of Cr6+, 8 mg.L−1 of Pb2+, and 10 mg.L−1 of Cd2+. However, the two strains exhibited different EC50 values for the same metal ion. The WB strain had a significantly higher resistance (p < 0.01) for Cd2+ and Cr6+ compared with the SB strain, while the SB strain had significantly higher resistance (p < 0.01) for Cu2+ compared with the WB strain. On the other hand, the two strains behaved differently in their capacity to remove the metal
ions in BG-11 medium containing 1.0 mg.L−1 of the three metal ions, except for Cu2+, which was added at 0.1 mg.L−1. The WB strain showed the highest removal of Cd2+ at 70.3% of total, followed by Pb2+ at 32%, while the SB strain exhibited the highest removal of Pb2+ at 48.7% followed by Cd2+ at 40.7% of the total. Both strains showed the least removal of Cr6+ at 28% and 20.8% of the total for the WB and SB strains respectively. The percentage removal for Cu2+ was 50.7% and 60.8% for the WB and SB strains respectively. After 12 days of incubation, both strains showed that a greater
percentage of the metal ions removed were accumulated intracellularly than adsorbed at a ratio of at least 2:1. Both strains
manifested the same cytological deformities, like a loss of pyrenoids at 10 mg.L−1 in all four metal ions. Discoloration and disintegration of chloroplasts were observed at 1.0 mg.L−1 in Cu2+ and 5 mg.L−1 in Cr6+. The nonrelease of autospores from the mother cells was observed at 10 mg.L−1 in Cu2+ and Cr6+.
Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
16.
I-Y Lee W T Seo G J Kim M K Kim C S Park Y H Park 《Journal of industrial microbiology & biotechnology》1997,18(4):255-259
Maltose and sucrose were efficient carbon sources for the production of curdlan by a strain of Agrobacterium sp. A two-step, fed-batch operation was designed in which biomass was first produced, followed by curdlan production which
was stimulated by nitrogen limitation. There exists an optimal timing for nitrogen limitation for curdlan production in the
two-step, fed-batch operation. Maximum curdlan production (60 g L−1) was obtained from sucrose with a productivity of 0.2 g L−1 h−1 when nitrogen was limited at a cell concentration of 16.0 g L−1. It was also noted that the curdlan yield from sucrose was as high as 0.45 g curdlan g−1 sucrose, and the highest specific production rate was 1.0 g curdlan g−1 cells h−1 right after nitrogen limitation. Of particular importance was the use of molasses as a cheap carbon source to produce curdlan
in the two-step, fed-batch cultivation. As high as 42 g L−1 of curdlan with a yield of 0.35 g curdlan g−1 total sugar was obtained after 120 h of fed-batch cultivation.
Received 20 August 1996/ Accepted in revised form 26 November 1996 相似文献
17.
Phycocyanin production by high cell density cultivation of Spirulina platensis in batch and fed-batch modes in 3.7-L bioreactors with a programmed stepwise increase in light intensity program was investigated.
The results showed that the cell density in fed-batch culture (10.2 g L−1) was 4.29-fold that in batch culture (2.38 g L−1), and the total phycocyanin production in the fed-batch culture (0.795 g L−1) was 3.05-fold that in the batch culture (0.261 g L−1). An unstructured kinetic model to describe the microalga culture system including cell growth, phycocyanin formation, as
well as glucose consumption was proposed. The data fitted the models well (r
2 > 0.99). Furthermore, based on the kinetic models, the potential effects of light limitation and photoinhibition on cell
growth and phycocyanin formation can be examined in depth. The models demonstrated that the optimal light intensity for mixotrophic
growth of Spirulina platensis in batch or fed-batch cultures using a 3.7-L bioreactor was 80160 μE m−2 s−1, and the stepwise increase in light intensity can be replaced by a constant light intensity mode.
Received 28 July 1998/ Accepted in revised form 8 October 1998 相似文献
18.
Biodegradation of BTEX by a microbial consortium isolated from a closed municipal landfill was studied using respirometric
techniques. The kinetics of biodegradation were estimated from experimental oxygen uptake data using a nonlinear parameter
estimation technique. All of the six compounds were rapidly degraded by the microbial culture and no substrate inhibition
was observed at the concentration levels examined (200 mg L−1 as COD). Microbial growth and contaminant degradation were adequately described by the Monod equation. Considerable differences
were observed in the rates of BTEX biodegradation as seen from the estimates of the kinetic parameters. A three-fold variation
was seen in the values of the maximum specific growth rate, μmax. The highest value of μmax was 0.389 h−1 for p-xylene while o-xylene was characterized by a μmax value of 0.14 h−1, the lowest observed in this study. The half saturation coefficient, K
s, and the yield coefficient, Y, varied between 1.288–4.681 mg L−1 and 0.272–0.645 mg mg−1, respectively. Benzene and o-xylene exhibited higher resistance to biodegradation while toluene and p-xylene were rapidly degraded. Ethylbenzene and m-xylene were degraded at intermediate rates. In biodegradation experiments with a multiple substrate matrix, substrate depletion
was slower than in single substrate experiments, suggesting an inhibitory nature of substrate interaction.
Received 15 February 1998/ Accepted in revised form 5 July 1998 相似文献
19.
Water pollution by toxic heavy metals is a burning environmental problem and has presented a challenge to humans. Removal
of heavy metals using non-living biomass of seaweeds could be a potential solution to this problem. In the present investigation,
biomass of three color forms of Kappaphycus alvarezii, viz. brown, green and pale yellow, were studied in the laboratory for their heavy metal chelating capacity using cadmium,
cobalt, chromium and copper. Amongst the four concentrations used (25, 50, 75 and 100 mg L−1) maximum chelation of Cd, Co and Cu was recorded at 25 mg L−1 concentration. The highest amount of Cr was chelated at 100 mg L−1 by all the three color forms. The pale yellow form showed maximum chelation for all four metals studied. Further, chelation
in all the color forms was found to be: Cd 5.37 ± 0.59–15.84 ± 0.32 %, Co 21.19 ± 0.13–32.32 ± 0.62 %, Cr 65.38 ± 0.27–88.09 ± 0.51
% and Cu 59.53 ± 0.37–90.28 ± 0.89 %. All the three color forms of K. alvarezii serve as an excellent biodetoxifier as they all chelated considerable amounts of heavy metals. 相似文献
20.
E Parente C Brienza A Ricciardi G Addario 《Journal of industrial microbiology & biotechnology》1997,18(1):62-67
Production of the bacteriocin enterocin 1146 (E1146) by Enterococcus faecium DPC1146 was studied in batch and continuous fermentation. Growth was strongly inhibited by lactic acid. In batch fermentations
maximum E1146 activity (2.8 MBU L−1) was obtained in 9 h with 20 g L−1 glucose. Increase in initial glucose concentration did not lead to a proportional increase in E1146 activity. A simple linear
model was found to be adequate to explain the relationship between specific bacteriocin production rate and specific growth
rate in batch fermentations with initial glucose concentration higher than 20 g L−1. Maximum bacteriocin activity (2.9–3.2 MBU L−1) was obtained in continuous fermentations at dilution rates between 0.12 and 0.17 h−1 and specific bacteriocin production rate increased linearly with dilution rate.
Received 31 July 1996/ Accepted in revised form 01 November 1996 相似文献