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1.
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
2.
Qu Yuanyuan Zhang Ruijie Ma Fang Zhou Jiti Yan Bin 《World journal of microbiology & biotechnology》2011,27(8):1919-1926
A novel alkali-tolerant strain JY-2, which could utilize phenol as sole source of carbon and energy, was isolated from activated
sludge. It was identified as Pseudomonas sp. by 16S rDNA sequencing analysis. The appropriate conditions for strain growth and phenol biodegradation were as follows:
pH 8.0–10.0 and temperature 23–30°C. With initial phenol concentrations of 225, 400, 550 and 750 mg/l, the degradation efficiencies
were 94.9, 93.3, 89.3 and 48.2% within 40 h at pH 10.0 and 30°C, respectively. The alkaline phenol-containing wastewater treatment
augmented with strain JY-2 in sequencing batch reactor (SBR) system was investigated, which suggested that the bioaugmented
(BA) system exhibited the better performance for adjusting high pH to neutral value than the non-bioaugmented (non-BA) one.
Also, the BA system showed strong abilities for phenol degradation and maintaining good sedimentation coefficient (SV30). The microbial community dynamics of both sequencing batch reactor (SBR) systems were analyzed by Denaturing Gradient Gel
Electrophoresis (DGGE) technique, which showed substantial changes between the two systems. This study suggests that it is
feasible to treat alkaline phenol-containing wastewater augmented with strain JY-2. 相似文献
3.
Autolytic degradation of yeast RNA occurs in many foods and beverages and can impact on the sensory quality of the product,
but the resulting complex mixture of nucleotides, nucleosides and nucleobases has not been properly characterised. In this
study, yeast autolysis was induced by incubating cell suspensions of Saccharomyces cerevisiae at 30–60 °C (pH 7.0), and at pH 4.0–7.0 (40 °C) for 10–14 days, and the RNA degradation products formed during the process
were determined by reversed-phase HPLC. Up to 95% of cell RNA was degraded, with consequent leakage into the extracellular
environment of mainly 3′-, 5′- and 2′-ribonucleotides, and lesser amounts of polynucleotides, ribonucleosides and nucleobases.
The rate of RNA degradation and the composition of the breakdown products varied with temperature and pH. RNA degradation
was fastest at 50 °C (pH 7.0). Autolysis at lower temperatures (30 °C and 40 °C) and at pH 5.0 and 6.0 favoured the formation
of 3′-nucleotides, whereas autolysis at 40 °C and 50 °C (pH 7.0) favoured 5′- and 2′-nucleotides. The best conditions for
the formation of the two flavour-enhancing nucleotides, 5′-AMP and 5′-GMP, were 50 °C (pH 7.0) and pH 4.0 (40 °C), respectively. 相似文献
4.
The autolysis of yeast cells has practical implications in the production of fermented foods and beverages and flavourants
for food processing. Protein and RNA degradation during yeast autolysis are well described but the fate of DNA is unclear.
Yeast cells (Saccharomyces cerevisiae) were autolysed by incubating suspensions at 30–60°C (pH 7.0), and at pH 4.0–7.0 (40°C) for 10–14 days. Up to 55% of total
DNA was degraded, with consequent leakage into the extracellular environment of mainly 3′- and 5′-deoxyribonucleotides, and
lesser amounts of polynucleotides. The rate and extent of DNA degradation, composition of the DNA degradation products and
DNase activity were affected by temperature and pH. The highest amount of DNA degradation occurred at 40°C and pH 7.0, where
the highest DNase activity was recorded. DNase activity was lowest at 60°C and pH 4.0, where the proportion of polynucleotides
in the degradation products was higher.
Electronic Publication 相似文献
5.
A number of substrates were tested for the cultivation of microorganisms to produce a host of enzymes. The effect of different
substrates (wheat and rice straw, sugar cane waste, wood waste), incubation temperatures (20–40°C), initial pH levels (3.5–9.0),
incubation periods (0–72 hours) and nitrogen sources (ammonium sulfate, urea, peptone, yeast extract, sodium nitrate) on growth
and α-amylase activity was studied for the native and mutant strains. Maximum enzyme activity was observed at 1.5% wheat straw
for Aspergillus niger FCBP-198 and An-Ch-4.7 and at 2% wheat straw for An-UV-5.6, with sodium nitrate as a principle nitrogen source. The optimum
temperature for maximum enzyme activity was 30°C for the parental strain, while An-UV-5.6 and An-Ch-4.7 thrived well at 32.5°C.
The best conditions of pH and incubation duration were 4.5 and 48 hours, respectively, for all the strains. Mass production
under preoptimized growth conditions demonstrated the suitability of wheat straw for swift mycelial colonization and viability. 相似文献
6.
Bioaugmentation of Bromoamine Acid Degradation with Sphingomonas xenophaga QYY and DNA Fingerprint Analysis of Augmented Systems 总被引:1,自引:0,他引:1
One high-effective bromoamine acid (1-amino-4-bromoanthraquinone-2-sulfonic acid, BAA) degrading strain was isolated previously
with the ability to use BAA as sole source of carbon and nitrogen. It was identified as Sphingomonas xenophaga QYY by 16S rDNA sequence analysis and physio-biochemical tests. In this study, bioaugmentation of BAA degradation with suspended
and immobilized cells of strain QYY was investigated. The optimal degradation conditions were as follows: temperature 30 °C,
pH 6.0–7.0, 150 rev min−1 and the immobilized cells maintained degradation activity to BAA after 60 days storage at 4 °C. The structure of BAA was
evidently changed according to the analysis of total organic carbon removal of BAA (about 50%) and the UV–VIS spectra changes
during the biodegradation. Bioaugmented systems exhibited stronger abilities degrading BAA than the non-bioaugmented control
ones. And microbial community dynamics of augmented systems was revealed by amplified ribosomal DNA restriction analysis (ARDRA),
a modern DNA fingerprint technique. The results indicated that the microbial community dynamics was substantially changed
throughout the augmentation process. This study suggests that it is feasible and potentially useful to enhance BAA degradation
using bioaugmentation with the immobilized cells of BAA-degrading bacterium. 相似文献
7.
A novel cellulolytic bacterium was isolated from the forest soil of KNU University campus. Through 16S rRNA sequence matching
and morphological observation it was identified as Nocardiopsis sp. KNU. This strain can utilize a broad range of cellulosic substrates including: carboxymethyl cellulose (CMC), avicel,
xylan, cellobiose, filter paper and rice straw by producing a large amount of thermoalkalotolerant endoglucanase, exoglucanase,
xylanase and glucoamylase. Optimal culture conditions (Dubos medium, 37°C, pH 6.5 and static condition) for the maximal production
of the cellulolytic enzymes were determined. The activity of cellulolytic and hemicelluloytic enzymes produced by this strain
was mainly present extracellularly and the enzyme production was dependent on the cellulosic substrates used for the growth.
Effect of physicochemical conditions and metal additives on the cellulolytic enzymes production were systematically investigated.
The cellulases produced by Nocardiopsis sp. KNU have an optimal temperature of 40°C and pH of 5.0. These cellulases also have high thermotolerance as evidenced by
retaining 55–70% activity at 80°C and pH of 5.0 and alkalotolerance by retaining >55% of the activity at pH 10 and 40°C after
1 h. The efficiency of fermentative conversion of the hydrolyzed rice straw by Saccharomyces cerevisiae (KCTC-7296) resulted in 64% of theoretical ethanol yield. 相似文献
8.
I. A. Tsaplina A. E. Zhuravleva N. V. Grigor’eva A. V. Belyi T. A. Pivovarova A. G. Bulaev V. S. Melamud T. F. Kondrat’eva 《Microbiology》2012,81(3):288-298
The growth of a microbial community and the oxidation of iron- and sulfur-containing substrates in batch culture during the leaching/oxidation of the flotation concentrate of refractory gold-arsenic sulfide ore were optimized with respect to the following medium parameters: temperature, pH, and requirement in organic substances. It was revealed that the optimum mode is (i) to maintain the pH at 1.6–1.7 and the temperature at 34–35 and 38°C and (ii) to add Corg in the form of yeast extract (0.02%). Mutually beneficial or competitive relationships among groups of microorganisms of the community were established, depending on the cultivation conditions. 相似文献
9.
Identification and characterization of fermentation inhibitors formed during hydrothermal treatment and following SSF of wheat straw 总被引:1,自引:0,他引:1
Mette Hedegaard Thomsen Anders Thygesen Anne Belinda Thomsen 《Applied microbiology and biotechnology》2009,83(3):447-455
A pilot plant for hydrothermal treatment of wheat straw was compared in reactor systems of two steps (first, 80°C; second,
190–205°C) and of three steps (first, 80°C; second, 170–180°C; third, 195°C). Fermentation (SSF) with Sacharomyces cerevisiae of the pretreated fibers and hydrolysate from the two-step system gave higher ethanol yield (64–75%) than that obtained from
the three-step system (61–65%), due to higher enzymatic cellulose convertibility. At the optimal conditions (two steps, 195°C
for 6 min), 69% of available C6-sugar could be fermented into ethanol with a high hemicellulose recovery (65%). The concentration
of furfural obtained during the pretreatment process increased versus temperature from 50 mg/l at 190°C to 1,200 mg/l at 205°C
as a result of xylose degradation. S. cerevisiae detoxified the hydrolysates by degradation of several toxic compounds such as 90–99% furfural and 80–100% phenolic aldehydes,
which extended the lag phase to 5 h. Acetic acid concentration increased by 0.2–1 g/l during enzymatic hydrolysis and 0–3.4 g/l
during fermentation due to hydrolysis of acetyl groups and minor xylose degradation. Formic acid concentration increased by
0.5–1.5 g/l probably due to degradation of furfural. Phenolic aldehydes were oxidized to the corresponding acids during fermentation
reducing the inhibition level. 相似文献
10.
A psychrotolerant microbial consortium from a low-temperature anaerobic EGSB bioreactor was grown separately on acetate, propionate,
butyrate, and H2/CO2 at 30 and 10°C in glass flasks. In the course of the experiments, the cultivation temperature was changed at different time
intervals. The initial rates of substrate utilization were higher at 30 than at 10°C. However, the microbial consortium was
found to be well adapted to low temperatures; when grown at 10°C for 1.5–5 months, the rates of butyrate, propionate, and
H2/CO2 utilization increased steadily. When grown at 30°C for 1.5–2.5 months, this consortium retained its ability to degrade VFA
and H2/CO2 at 10°C. However, after long-term (150 days) cultivation at 10°C, its ability to utilize the substrates at 30°C decreased.
In the consortium grown in the acetate-containing medium, a Methanosaeta-like methanogen was predominant; in media with propionate and butyrate, besides VFA-degrading bacteria, acetoclastic Methanosaeta-like and hydrogenotrophic Methanospirillum-like methanogenic archaea prevailed. A Methanospirillum-like strain predominated in the H2/CO2-containing medium. The Methanospirillum strain of this microbial community was presumably psychrotolerant. A method based on changes in the cultivation temperature
is of practical interest and can be used to start up new bioreactors. 相似文献