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1.
Anaerobic bacteria that reduce hexavalent chromium [Cr(VI)] to trivalent [Cr(III)] are common in soils and were used to develop
a bioprocess employing a selection strategy. Indigenous Cr(VI)-reducers were enriched from Cr(VI)-contaminated soil under
anaerobic conditions. The mixed culture was then tested for Cr(VI)-reducing activity in a chemostat, followed by transfer
to a 1-L packed-bed bioreactor operated at 30°C for additional study. The support material used in the reactor consisted
of 6-mm porcelain saddles. Cr(VI) concentrations in the liquid ranged from 140–750 mg L−1. Cr(VI)-reducing bacteria were the dominant population with Cr(VI)-reduction rates of approximately 0.71 mg g−1 dry cells h−1 achieved at Cr(VI) concentrations of 750 mg L−1. These results indicate a potential for selecting and maintaining indigenous Cr(VI)-reducers in a bioreactor for Cr(VI)-remediation
of groundwater or soil wash effluents.
Received 09 January 1996/ Accepted in revised form 15 November 1996 相似文献
2.
Torres R Ramón F de la Mata I Acebal C Castillón MP 《Applied microbiology and biotechnology》1999,53(1):81-84
At 28 °C, Streptomyces lavendulae produced high levels of penicillin V acylase (178 IU/l of culture) when grown on skim milk as the sole nutrient source for
275 h. The enzyme showed catabolite repression by glucose and was produced in the stationary phase of growth. Penicillin V
was a good inducer of penicillin V acylase formation, while phenoxyacetic acid, the side-chain moiety of penicillin V, did
not alter enzyme production significantly. The enzyme was stable between pH 6 and 11 and at temperatures from 20 °C to 55 °C.
This extracellular enzyme was able to hydrolyse natural penicillins and unable to hydrolyse penicillin G.
Received: 22 March 1999 / Received revision: 16 June 1999 / Accepted: 20 June 1999 相似文献
3.
J. P. Costanzo J. B. Moore R. E. Lee Jr. P. E. Kaufman J. A. Wyman 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(3):169-176
This investigation examined the influence of soil moisture and associated parameters on the cold hardiness of the Colorado
potato beetle (Leptinotarsa decemlineata Say), a temperate-zone species that overwinters in terrestrial burrows. The body mass and water content of adult beetles
kept in sand at 4 °C varied over a 16-week period of diapause according to the substratum's moisture content. Changes in body
water content, in turn, influenced the crystallization temperature (range −3.3 to −18.4 °C; n = 417), indicating that environmental moisture indirectly determined supercooling capacity, a measure of physiological cold
hardiness. Beetles held in dry sand readily tolerated a 24-h exposure to temperatures ranging from 0° to −5 °C, but those
chilled in sand containing as little as 1.7% water (dry mass) had elevated mortality. Thus, burrowing in dry soils not only
promotes supercooling via its effect on water balance, but may also inhibit inoculative freezing. Mortality of beetles exposed
to −5 °C for 24 h was lower in substrates composed of sand, clay and/or peat (36–52%) than in pure silica sand (78%) having
an identical water content (17.0% dry mass). In addition to moisture, the texture, structure, water potential, and other physico-chemical
attributes of soil may strongly influence the cold hardiness and overwintering survival of burrowing insects.
Accepted: 10 September 1996 相似文献
4.
Polymer production by two newly isolated extremely halophilic archaea: application of a novel corrosion-resistant bioreactor 总被引:3,自引:0,他引:3
Hezayen FF Rehm BH Eberhardt R Steinbüchel A 《Applied microbiology and biotechnology》2000,54(3):319-325
A novel corrosion-resistant bioreactor composed of polyetherether ketone (PEEK), tech glass and silicium nitrite ceramics
was constructed and applied for the cultivation of two newly isolated, extremely halophilic archaea producing poly(γ-glutamic
acid) (PGA), or poly(β-hydroxy butyric acid) (PHB), respectively. These bacteria were isolated from hypersaline soil close
to Aswan (Egypt). The isolate strain 40, which is related to the genus Natrialba, produced large amounts of PGA when cultivated on solid medium. Culture conditions were optimised applying the corrosion-resistant
bioreactor. PGA production was dependent on NaCl concentration and occurred about at 20% (w/v) NaCl in the medium. A maximum
cell density of about 1.6 g cell dry matter/l was obtained when the bioreactor was stirred and aerated in a batch fermentation
process using proteose-peptone medium. The supernatant was monitored with respect to PGA formation, and after 90 h a maximum
of 470 mg/l culture volume was detected by HPLC analysis. Culture conditions were optimized for the isolate 56, which accumulated
PHB as intracellular granules. Batch fermentations in the stirred and aerated bioreactor applying acetate and n-butyric acid as carbon sources led to cell density of 2.28 g cell dry matter/l and a maximum PHB accumulation contributing
to about 53% of cellular dry weight. About 4.6 g PHB were isolated from 10.6 g dried cells of strain 56, which exhibited a
weight average molar mass of 2.3 × 105 g mol−1 and a polydispersity of about 1.4.
Received: 3 December 1999 / Received revision: 22 February 2000 / Accepted: 25 February 2000 相似文献
5.
R Rech C F Cassini A Secchi M A Z Ayub 《Journal of industrial microbiology & biotechnology》1999,23(2):91-96
We studied the utilization of protein-hydrolyzed sweet cheese whey as a medium for the production of β-galactosidase by the
yeasts Kluyveromyces marxianus CBS 712 and CBS 6556. The conditions for growth were determined in shake cultures. The best growth occurred at pH 5.5 and
37°C. Strain CBS 6556 grew in cheese whey in natura, while strain CBS 712 needed cheese whey supplemented with yeast extract. Each yeast was grown in a bioreactor under these
conditions. The strains produced equivalent amounts of β-galactosidase. To optimize the process, strain CBS 6556 was grown
in concentrated cheese whey, resulting in a higher β-galactosidase production. The β-galactosidase produced by strain CBS
6556 produced maximum activity at 37°C, and had low stability at room temperature (30°C) as well as at a storage temperature
of 4°C. At −4°C and −18°C, the enzyme maintained its activity for over 9 weeks.
Received 20 January 1999/ Accepted in revised form 30 April 1999 相似文献
6.
Misawa N Nodate M Otomatsu T Shimizu K Kaido C Kikuta M Ideno A Ikenaga H Ogawa J Shimizu S Shindo K 《Applied microbiology and biotechnology》2011,92(1):147-157
Deposit of useful microorganisms in culture collections requires long-term preservation and successful reactivation techniques.
The goal of this study was to develop a simple preservation protocol for the long-term storage and reactivation of the anammox
biomass. To achieve this, anammox biomass was frozen or lyophilized at two different freezing temperatures (−60°C and in liquid
nitrogen (−200°C)) in skim milk media (with and without glycerol), and the reactivation of anammox activity was monitored
after a 4-month storage period. Of the different preservation treatments tested, only anammox biomass preserved via freezing
in liquid nitrogen followed by lyophilization in skim milk media without glycerol achieved stoichiometric ratios for the anammox
reaction similar to the biomass in both the parent bioreactor and in the freshly harvested control treatment. A freezing temperature
of −60°C alone, or in conjunction with lyophilization, resulted in the partial recovery of the anammox bacteria, with an equal
mixture of anammox and nitrifying bacteria in the reactivated biomass. To our knowledge, this is the first report of the successful
reactivation of anammox biomass preserved via sub-zero freezing and/or lyophilization. The simple preservation protocol developed
from this study could be beneficial to accelerate the integration of anammox-based processes into current treatment systems
through a highly efficient starting anammox biomass. 相似文献
7.
The thermophilic bacterium, Thermus species ATCC 27978, which is capable of aerobically degrading benzene, toluene, ethylbenzene, and the xylenes (BTEX), was
cultured in 5-1 fermentors on a Castenholz salts-tryptone medium. This bacterium can be cultivated more conveniently at 45 °C,
a temperature substantially lower than its optimal growth temperature (approx. 60 °C). Yet, the washed harvested cells from
such cultures display the same initial BTEX-degrading activity as those when Thermus sp. is grown at its higher optimal temperature. Two bioreactor cultivation modes, batch and fed batch, were investigated.
More biomass and more BTEX-degrading activity (assayed at 60 °C) were generated in fed-batch cultures than in the growth-limited
batch cultures. The former yielded a biomass concentration of 2.5 g dry cell weight (DCW) l−1 and whole-cell degrading specific activities of 7.6 ± 1.3, 10.1 ± 1.9, 9.8 ± 2.1, 2.3 ± 0.5, and 4.6 ± 0.9 nmol degraded
(mg DCW)−1 min−1 for benzene, toluene, ethylbenzene, m-xylene, and the o- plus p-xylenes (unresolved mixture), respectively. Although the formation of cellular BTEX-degrading activity is growth-associated,
a slow to moderate specific growth rate of 0.02–0.07 h−1 favors the production of BTEX-degrading activity, while a high growth rate, of the order of 0.16 h−1, is detrimental to its production. The washed harvested Thermus sp. cells were capable of degrading BTEX over a broad range of thermophilic incubation temperatures, 45–77 °C.
Received: 28 June 1996 / Received revision: 31 December 1996 / Accepted: 31 January 1997 相似文献
8.
Bioremediation of two diesel-oil-contaminated alpine subsoils, differing in soil type and bedrock, was investigated in laboratory
experiments at 10 °C after supplementation with an inorganic fertilizer. Initial diesel oil contamination of 4000 mg kg−1 soil dry matter (dm) was reduced to 380–400 mg kg−1 dm after 155 days of incubation. In both soils, about 30 % of the diesel oil contamination (1200 mg kg−1 dm) was eliminated by abiotic processes. The residual decontamination (60 %–65 %) could be attributed to microbial degradation
activities. In both soils, the addition of a cold-adapted diesel-oil-degrading inoculum enhanced biodegradation rates only
slightly and temporarily. From C/N and N/P ratios (determined by measuring the contents of total hydrocarbons, NH4
+ N, NO3
− N and PO4
3− P) of soils␣it could be deduced that there was no nutrient deficiency during the whole incubation period. Soil biological
activities (basal respiration and dehydrogenase activity) corresponded to the course of biodegradation activities in the soils.
Received: 9 September 1996 / Accepted: 7 December 1996 相似文献
9.
Production of high yields of arachidonic acid in a fed-batch system by Mortierella alpina ATCC 32222
Of six strains of Mortierella tested, Mortierella alpina ATCC 32222 produced the highest yields of arachidonic acid. Supplementation of soy flour (1% w/v) and vegetable oils (1%
v/v) significantly increased the biomass, lipid content and arachidonic acid level. Replacement of NaNO3 with corn steep liquor (1% w/v) also improved arachidonic acid production. A fed-batch culture system at 25 °C, producing
a high biomass (52.4 g/l) and arachidonic acid content (9.1 g/l) in 8␣days, was developed. A fed-batch system at low temperature
(15 °C) gave even higher arachidonic acid levels (11.1 g/l) in 11 days.
Received: 28 October 1996 / Received revision: 3 March 1997 / Accepted: 7 March 1997 相似文献
10.
The properties of 21 isolates ofPenicillium roqueforti from just as many commercial blue-veined cheeses, purchased from the Argentinean market (domestic and imported products)
were comparatively examined. Isolates were investigated for their ability to grow at different temperatures, pH values and
concentration of NaCl, as well as for their proteolytic and lipolytic activities, respectively. The potential of these strains
to produce roquefortin in vitro, and the actual levels of roquefortin in 10 of these cheeses were analysed by TLC. All strains
showed similar growth properties in aspects of salt concentration and pH-value of the medium, and all grew well at 10 °C.
Only four strains showed proteolytic activity on casein agar, while all strains were lipolytic on trybutirin agar. After incubation
at 25 °C for 16 days, all strains produced roquefortin in Yeast Extract Sucrose (25.6–426.7 μg/g) and in reconstituted (10%)
sterile skim milk (26.9–488 μg/g). Roquefortin at >0.1 μg/g was also found in 9 out of 10 analysed samples of blue-veined
cheeses (8 from Argentine, 1 from Spain), with a maximum value 3.6 μg/g. During the ripening process of blueveined cheese,
production of roquefortin seems to be unavoidable. Care should be taken to select strains with low toxin production characteristics,
to minimize potential health risks. Roquefortin C production byP. roqueforti in vitro was not correlated with roquefortin C levels found in cheese.
Financial support: Research grants from the National University of Quilmes, Argentina 相似文献
11.
M. Graf A. Brunella M. Kittelmann K. Laumen O. Ghisalba 《Applied microbiology and biotechnology》1997,47(6):650-657
A new amidohydrolase deacetylating several N-acetyl-1-phenylethylamine derivatives (R)-specifically was found in Arthrobacter aurescens AcR5b. The strain was isolated from a wet haystack by enrichment culture with (R)-N-acetyl-1-phenylethylamine as the sole carbon source. (R) and (S )-N-acetyl-1-phenylethylamine do not serve as inducers for acylase formation. By improving the growth conditions the enzyme production
was increased 47-fold. The amidohydrolase was purified to homogeneity leading to a 5.2-fold increase of the specific activity
with a recovery of 67%. A molecular mass of 220 kDa was estimated by gel filtration. Sodium dodecyl sulfate/polyacrylamide
gel electrophorosis shows two subunits with molecular masses of 16 kDa and 89 kDa. The optimum pH and temperature were pH 8
and 50 °C, respectively. The enzyme was stable in the range of pH 7–9 and at temperatures up to 30 °C. The enzyme activity
was inhibited by Cu2+, Co2+, Ni2+, and Zn2+, and this inhibition was reversed by EDTA.M
Received: 20 September 1996 / Received version: 23 December 1996 / Accepted: 30 December 1996 相似文献
12.
A number of nutritional factors influencing growth and glucose oxidase (EC 1.1.3.4) production by a newly isolated strain
of Penicillium pinophilum were investigated. The most important factors for glucose oxidase production were the use of sucrose as the carbon source,
and growth of the fungus at non-optimal pH 6.5. The enzyme was purified to apparent homogeneity with a yield of 74%, including
an efficient extraction step of the mycelium mass at pH 3.0, cation-exchange chromatography and gel filtration. The relative
molecular mass (M
r) of native glucose oxidase was determined to be 154 700 ± 4970, and 77 700 for the denatured subunit. Electron-microscopic
examinations revealed a sandwich-shaped dimeric molecule with subunit dimensions of 5.0 × 8.0 nm. Glucose oxidase is a glycoprotein
that contains tightly bound FAD with an estimated stoichiometry of 1.76 mol/mol enzyme. The enzyme is specific for d-glucose, for which a K
m value of 6.2 mM was determined. The pH optimum was determined in the range pH 4.0–6.0. Glucose oxidase showed high stability
on storage in sodium citrate (pH 5.0) and in potassium phosphate (pH 6.0), each 100 mM. The half-life of the activity was
considerably more than 305 days at 4 °C and 30 °C, and 213 days at 40 °C. The enzyme was unstable at temperatures above 40 °C
in the range pH 2.0–4.0 and at a pH above 7.0.
Received: 18 November 1996 / Received revision: 3 March 1997 / Accepted: 7 March 1997 相似文献
13.
People adapt to thermal environments, such as the changing seasons, predominantly by controlling the amount of clothing insulation, usually in the form of the clothing that they wear. The aim of this study was to determine the actual daily clothing insulation on sedentary human subjects across the seasons. Thirteen females and seven males participated in experiments from January to December in a thermal chamber. Adjacent months were grouped in pairs to give six environmental conditions: (1) January/February = 5°C; (2) March/April = 14°C; (3) May/June = 25°C; (4) July/August = 29°C; (5) September/October = 23°C; (6) November/December = 8°C. Humidity(45 ± 5%) and air velocity(0.14 ± 0.01 m/s) were constant across all six experimental conditions. Participants put on their own clothing that allowed them to achieve thermal comfort for each air temperature, and sat for 60 min (1Met). The clothing insulation (clo) required by these participants had a significant relationship with air temperature: insulation was reduced as air temperature increased. The range of clothing insulation for each condition was 1.87–3.14 clo at 5°C(Jan/Feb), 1.62–2.63 clo at 14°C(Mar/Apr), 0.87–1.59 clo at 25°C(May/Jun), 0.4–1.01 clo at 29°C(Jul/Aug), 0.92–1.81 clo at 23°C (Sept/Oct), and 2.12–3.09 clo at 8°C(Nov/Dec) for females, and 1.84–2.90 clo at 5°C, 1.52–1.98 clo at 14°C, 1.04–1.23 clo at 25°C, 0.51–1.30 clo at 29°C, 0.82–1.45 clo at 23°C and 1.96–3.53 clo at 8°C for males. The hypothesis was that thermal insulation of free living clothing worn by sedentary Korean people would vary across seasons. For Korean people, a comfortable air temperature with clothing insulation of 1 clo was approximately 27°C. This is greater than the typical comfort temperature for 1 clo. It was also found that women clearly increased their clothing insulation level of their clothing as winter approached but did not decrease it by the same amount when spring came. 相似文献
14.
Effects of hypothermic hypoxia on anaerobic energy metabolism in isolated anuran livers 总被引:1,自引:0,他引:1
C. A. Fedorow T. A. Churchill N. M. Kneteman 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(8):555-561
Many lower vertebrates (reptilian and amphibian species) are capable of surviving natural episodes of hypoxia and hypothermia.
It is by specific metabolic adaptations that anurans are able to tolerate prolonged exposure to harsh environmental stresses.
In this study, it was hypothesized that livers from an aquatic frog would possess an inherent metabolic ability to sustain
high levels of ATP in an isolated organ system, providing insight into a metabolic system that is well-adapted for low temperature
in vitro organ storage. Frogs of the species, R. pipiens were acclimated at 20 °C and at 5 °C. Livers were preserved using a clinical preservation solution after flushing. Livers
from 20 °C-acclimated frogs were stored at 20 °C and 5 °C and livers from 5 °C-acclimated frogs were stored at 5 °C. The results
indicated that hepatic adenylate status was maintained for 96 h during 5 °C storage, but not longer than 4–10 h during 20 °C
storage. In livers from 5 °C-acclimated animals subjected to 5 °C storage, ATP was maintained at 100% throughout the 96-h
period. Warm acclimation (20 °C) and 20 °C storage resulted in poorer maintenance of ATP; energy charge values dropped to
0.50 within 2 h and by 24 h, only 24% of control ATP remained. Lactate levels remained less than 25 μ mol/g dry weight in
all 5 °C-stored livers; 20 °C-stored livers exhibited greater accumulation of this anaerobic end-product (lactate reached
45–50 μ mol/g by 10 h). The data imply that hepatic adenylate status is largely dependent on exposure to hypothermic hypoxia
and although small amounts of ATP were accounted for by anaerobic glycolysis, there must have been either a substantial reduction
in cellular energy-utilization or an efficient use of low oxygen tensions.
Accepted: 24 August 1998 相似文献
15.
The influence of low temperature (5–29 °C) on the methanogenic activity of non-adapted digested sewage sludge and on temperature/leachate-adapted
biomass was assayed by using municipal landfill leachate, intermediates of anaerobic degradation (propionate) and methane
precursors (acetate, H2/CO2) as substrates. The temperature dependence of methanogenic activity could be described by Arrhenius-derived models. However,
both substrate and adaptation affected the temperature dependence. The adaptation of biomass in a leachate-fed upflow anaerobic
sludge-blanket reactor at approximately 20 °C for 4 months resulted in a sevenfold and fivefold increase of methanogenic activity
at 11 °C and 22 °C respectively. Both acetate and H2/CO2 were methanized even at 5 °C. At 22 °C, methanogenic activities (acetate 4.8–84 mM) were 1.6–5.2 times higher than those
at 11 °C. The half-velocity constant (K
s) of acetate utilization at 11 °C was one-third of that at 22 °C while a similar K
i was obtained at both temperatures. With propionate (1.1–5.5 mM) as substrate, meth‐anogenic activities at 11 °C were half
those at 22 °C. Furthermore, the residual concentration of the substrates was not dependent on temperature. The results suggest
that the adaptation of biomass enables the achievement of a high treatment capacity in the anaerobic process even under psychrophilic
conditions.
Received: 23 December 1996 / Received last revision: 18 June 1997 / Accepted: 23 June 1997 相似文献
16.
The use of molasses as a substrate for ethanol production by the thermotolerant yeast Kluyveromyces marxianus var. marxianus was investigated at 45°C. A maximum ethanol concentration of 7.4% (v/v) was produced from unsupplemented molasses at a concentration
of 23% (v/v). The effect on ethanol production of increasing the sucrose concentration in 23% (v/v) molasses was determined.
Increased sucrose concentration had a similar detrimental effect on the final ethanol produced as the increase in molasses
concentration. This indicated that the effect may be due to increased osmotic activity as opposed to other components in the
molasses. The optimum concentration of the supplements nitrogen, magnesium, potassium and fatty acid for maximum ethanol production
rate was determined using the Nelder and Mead (Computer J 7:308–313, 1965) simplex optimisation method. The optimum concentrations
of the supplements were 0.576 g l-1 magnesium sulphate, 0.288 g l-1 potassium dihydrogen phosphate and 0.36% (v/v) linseed oil. Added nitrogen in the form of ammonium sulphate did not affect
the ethanol production rate.
Received: 29 January 1996/Received revision: 23 April 1996/Accepted: 29 April 1996 相似文献
17.
Purification and properties of a novel raw starch degrading cyclomaltodextrin glucanotransferase from Bacillus firmus 总被引:3,自引:0,他引:3
B. N. Gawande A. Goel A. Y. Patkar S. N. Nene 《Applied microbiology and biotechnology》1999,51(4):504-509
A novel raw starch degrading cyclomaltodextrin glucanotransferase (CGTase; E.C. 2.4.1.19), produced by Bacillus firmus, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The molecular weight of the
pure protein was estimated to be 78 000 and 82 000 Da, by SDS-PAGE and gel filtration, respectively. The pure enzyme had a
pH optimum in the range 5.5–8.5. It was stable over the pH range 7–11 at 10 °C, and at pH 7.0 at 60 °C. The optimum temperature
for enzyme activity was 65 °C. In the absence of substrate, the enzyme rapidly lost its activity above 30 °C. K
m and k
cat for the pure enzyme were 1.21 mg/ml and 145.17 μM/mg per minute respectively, with soluble starch as the substrate. For cyclodextrin
production, tapioca starch was the best substrate used when gelatinized, while wheat starch was the best substrate used when
raw. This CGTase could degrade raw wheat starch very efficiently; up to 50% conversion to cyclodextrins was obtained from
150 g/l starch without using any additives. The enzyme produced α-, β- and γ-cyclodextrins in the ratio of 0.2:9.2:0.6 and
0.2:8.6:1.2 from gelatinized tapioca starch and raw wheat starch with 150 g/l concentration respectively, after 18 h incubation.
Received: 25 September 1998 / Received revision: 15 December 1998 / Accepted: 21 December 1998 相似文献
18.
Two thermophilic anaerobic bacterial consortia (ALK-1 and LLNL-1), capable of degrading the aromatic fuel hydrocarbons, benzene,
toluene, ethylbenzene, and the xylenes (BTEX compounds), were developed at 60 °C from the produced water of ARCO'S Kuparuk
oil field at Alaska and the subsurface water at the Lawrence Livermore National Laboratory gasoline-spill site, respectively.
Both consortia were found to grow at 45–75 °C on BTEX compounds as their sole carbon and energy sources with 50 °C being the
optimal temperature. With 3.5 mg total BTEX added to sealed 50-ml serum bottles, which contained 30 ml mineral salts medium
and the consortium, benzene, toluene, ethylbenze, m-xylene, and an unresolved mixture of o- and p-xylenes were biodegraded by 22%, 38%, 42%, 40%, and 38%, respectively, by ALK-1 after 14 days of incubation at 50 °C. Somewhat
lower, but significant, percentages of the BTEX compounds also were biodegraded at 60 °C and 70 °C. The extent of biodegradation
of these BTEX compounds by LLNL-1 at each of these three temperatures was slightly less than that achieved by ALK-1. Use of
[ring-14C]toluene in the BTEX mixture incubated at 50 °C verified that 41% and 31% of the biodegraded toluene was metabolized within
14 days to water-soluble products by ALK-1 and LLNL-1, respectively. A small fraction of it was mineralized to 14CO2. The use of [U-14C]benzene revealed that 2.6%–4.3% of the biodegraded benzene was metabolized at 50 °C to water-soluble products by the two
consortia; however, no mineralization of the degraded [U-14C]benzene to 14CO2 was observed. The biodegradation of BTEX at all three temperatures by both consortia was tightly coupled to sulfate reduction
as well as H2S generation. None was observed when sulfate was omitted from the serum bottles. This suggests that sulfate-reducing bacteria
are most likely responsible for the observed thermophilic biodegradation of BTEX in both consortial cultures.
Received: 12 July 1996 / Received revision: 31 December 1996 / Accepted: 31 January 1997 相似文献
19.
Effects of elevated temperature on bacterial community structure and function in bioreactors treating a synthetic wastewater 总被引:1,自引:0,他引:1
T M LaPara A Konopka C H Nakatsu J E Alleman 《Journal of industrial microbiology & biotechnology》2000,24(2):140-145
The impact of elevated temperature on bacterial community structure and function during aerobic biological wastewater treatment
was investigated. Continuous cultures, fed a complex growth medium containing gelatin and α-lactose as the principal carbon
and energy sources, supported mixed bacterial consortia at temperatures ranging from 25–65°C. These temperature- and substrate-acclimated
organisms were then used as inocula for batch growth experiments in which the kinetics of microbial growth and substrate utilization,
efficiency of substrate removal, and mechanism of substrate removal were compared as functions of temperature. Bacterial community
analysis by denaturing gradient gel electrophoresis (DGGE) revealed that distinct bacterial consortia were supported at each
temperature. The efficiency of substrate removal declined at elevated temperatures. Maximum specific growth rates and the
growth yield increased with temperature from 25–45°C, but then decreased with further elevations in temperature. Thus, maximum
specific substrate utilization rates did not vary significantly over the 40°C temperature range (0.64 ± 0.04 mg COD mg−1 dry cell mass h−1). A comparison of the degradation of the protein and carbohydrate portions of the feed medium revealed a lag in α-lactose
uptake at 55°C, whereas both components were utilized simultaneously at 25°C. Journal of Industrial Microbiology & Biotechnology (2000) 24, 140–145.
Received 09 August 1999/ Accepted in revised form 12 November 1999 相似文献
20.
E Selmer-Olsen T Sørhaug S-E Birkeland R Pehrson 《Journal of industrial microbiology & biotechnology》1999,23(2):79-85
Lactobacillus helveticus CNRZ 303 entrapped in Ca-alginate gel beads was investigated for improved survival and stability during fluidized-bed drying,
storage and rehydration. Addition of protective solutes was very important. Studies of the conditions showed that inactivation
of entrapped L. helveticus started when the water content exceeded 0.3–0.4 g H2O (g dry wt)−1 for adonitol, glycerol and reconstituted non fat milk solids (NFSM). With Ringer’s solution (control) and betaine, the fall
in viability was evident above 1 g H2O (g dry wt)−1. Drying down to 0.2 g H2O (g dry wt)−1 required the removal of 98.5–98.9% of the water. The best survival rate with the least injured cells among survivors was
experienced with adonitol and NFMS, respectively, 71% and 57% (compared to the initial) immediately after dehydration. Adonitol
and NFMS were also best for survival during storage. The highest cell recovery was obtained by rehydrating the cells in cheese
whey permeate between 20–30°C done at pH 6.0–7.0, satisfying the demands for cell survival, repair and slow swelling (adaptions).
Received 04 January 1999/ Accepted in revised form 29 April 1999 相似文献