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1.
Electricity from microorganisms 总被引:1,自引:0,他引:1
V. G. Debabov 《Microbiology》2008,77(2):123-131
Over the last ten years, the recently discovered process of direct electron transfer from anaerobically grown microorganisms to an electrode of a fuel cell has been the object of intense study. The microorganisms responsible for such electron transport were termed electrogenic; the devices using them to generate electric current, microbial fuel cells (MFCs). The review discussed the molecular mechanisms of electron transfer to the environment in the case of the two best studied microorganisms, Shewanella oneidensis and Geobacter sulfurreducens. The discovery of bacterial conducting pili (nanowires) used for electron transfer to the electrode and between bacterial cells was sensational. In the real MFCs, which use complex substrates (industrial liquid waste), microbial associations are active, often as biofilms. The progress in MFCs design and the prospects of their practical application are considered. 相似文献
2.
Electricity generation from cellulose by rumen microorganisms in microbial fuel cells 总被引:3,自引:0,他引:3
Rismani-Yazdi H Christy AD Dehority BA Morrison M Yu Z Tuovinen OH 《Biotechnology and bioengineering》2007,97(6):1398-1407
In microbial fuel cells (MFCs) bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. The anode and cathode chambers were separated by a proton exchange membrane and graphite plates were used as electrodes. The medium in the anode chamber was inoculated with rumen microorganisms, and the catholyte in the cathode compartment was ferricyanide solution. Maximum power density reached 55 mW/m(2) (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over 2 months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. Denaturing gradient gel electrophoresis (DGGE) of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and sequencing analysis of 16S rRNA genes indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. abounded in the suspended consortia. The results demonstrated that electricity can be generated from cellulose by exploiting rumen microorganisms as biocatalysts, but both technical and biological optimization is needed to maximize power output. 相似文献
3.
Cellulases from microorganisms 总被引:3,自引:0,他引:3
Compositions of cellulase-hemicellulase systems of aerobic fungi (hyphomycetes, ascomycetes, and basidiomycetes), aerobic bacteria, actinomycetes, as well as anaerobic fungi and bacteria, are considered in the context of modern structural classification of glycosyl hydrolases. A new nomenclature of cellulases and relative enzymes based on their structural classification is reviewed. Some opportunities of cellulase improvement by means of protein engineering are discussed. 相似文献
4.
Bioplastics from microorganisms 总被引:7,自引:0,他引:7
Luengo JM García B Sandoval A Naharro G Olivera ER 《Current opinion in microbiology》2003,6(3):251-260
The term 'biomaterials' includes chemically unrelated products that are synthesised by microorganisms (or part of them) under different environmental conditions. One important family of biomaterials is bioplastics. These are polyesters that are widely distributed in nature and accumulate intracellularly in microorganisms in the form of storage granules, with physico-chemical properties resembling petrochemical plastics. These polymers are usually built from hydroxy-acyl-CoA derivatives via different metabolic pathways. Depending on their microbial origin, bioplastics differ in their monomer composition, macromolecular structure and physical properties. Most of them are biodegradable and biocompatible, which makes them extremely interesting from the biotechnological point of view. 相似文献
5.
García-Mu?oz J Amils R Fernández VM De Lacey AL Malki M 《International microbiology》2011,14(2):73-81
The attachment of microorganisms to electrodes is of great interest for electricity generation in microbial fuel cells (MFC) or other applications in bioelectrochemical systems (BES). In this work, a microcosm of the acidic ecosystem of Río Tinto was built and graphite electrodes were introduced at different points. This allowed the study of electricity generation in the sediment/water interface and the involvement of acidophilic microorganisms as biocatalysts of the anodic and cathodic reactions in a fuel-cell configuration. Current densities and power outputs of up to 3.5 A/m2 and 0.3 W/m2, respectively, were measured at pH 3. Microbial analyses of the electrode surfaces showed that Acidiphilium spp., which uses organic compounds as electron donors, were the predominant biocatalysts of the anodic reactions, whereas the aerobic iron oxidizers Acidithiobacillus ferrooxidans and Leptospirillum spp. were detected mainly on the cathode surface. 相似文献
6.
André Morin Jean-Pierre Touzel Alain Lafond Danielle Leblanc 《Applied microbiology and biotechnology》1991,35(4):536-540
Summary Of 373 anaerobic microbial isolates screened for the enzymatic conversion of dihydrouracil to N-carbamyl--alanine, several strains of Clostridium spp., C. glycolicum, C. subterminale and Peptococcus anaerobius were positive. These Clostridium and Peptococcus strains produced also N-carbamyl-d-amino acids from the respective 5-monosubstituted hydantoins. The d-hydantoinase activity from whole cell suspensions of P. anaerobius strain CRDA 303 was characterized with regard to pH and temperature stability and activity by using dihydrouracil (DHU) and isopropylhydantoin (IPH) as substrates. The d-hydantoinase from P. anaerobius was optimal at 60°C and at pH 6.5–9.5 for the substrate DHU. It was stable up to 55°C and at pH 5.0–9.5 and could be stored at 4°C under an aerobic atmosphere for at least 14 days.
Offprint requests to: A. Morin 相似文献
7.
Microbial products are surveyed that have an immunoregulatory activity, both from the realm of low-molar-mass compounds and
from the group of naturally occurring polymers. The data include in most cases the producer organism or source, a brief chemical
characteristic and biological activity. Various groups of substances are compared, the drawbacks attendant on their acquisition
and application are pointed out and their advantageous properties are specified.
Translated by K. Sigler 相似文献
8.
Michael A. Wright Ian N. Taylor Michael J. Lenn David R. Kelly Jasem G. Mahdi Christopher J. Knowles 《FEMS microbiology letters》1994,116(1):67-72
Abstract The oxidation of bicyclo[3.2.0]hept-2-en-6-one and 7- endo propylbicyclo[3.2.0]hept-2-en-one was investigated using whole cells of Pseudomonas putida NCIMB 10007 and Xanthobacter autotrophicus NCIMB 10811. The bacteria demonstrated both regio- and enantioselective oxidation of the substrates. P. putida gave 'mirror image' with both substrates when the products of these oxidations were compared with cells grown on the different enantiomers of camphor. The regio- and enantioselectivity of the oxidation of the substrates by X. autotrophicus were enhanced by the 7- endo propyl substitution of bicyclo[3.2.0]hept-2-en-6-one. 相似文献
9.
Proteins from thermophilic microorganisms 总被引:14,自引:0,他引:14
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13.
Emission of microorganisms from biofilters 总被引:2,自引:0,他引:2
Experiments are reported on the discharge of microbial germs by biofilter systems used for the treatment of waste gases containing volatile organic compounds. The systems investigated concern six full-scale filter installations located in the Netherlands in several branches of industry, as well as a laboratory-scale installation used for modelling the discharge process. It is concluded that the number of microbial germs (mainly bacteria and to a much smaller extent moulds) in the outlet gas of the different full scale biofilters varies between 103 and 104 m–3, a number which is only slightly higher than the number encountered in open air and of the same order of magnitude encountered in indoor air. It is furthermore concluded that the concentration of microorganisms of a highly contaminated inlet gas is considerably reduced by the filtration process. On the basis of the experiments performed in the laboratory-scale filter bed, it is shown that the effect of the gas velocity on the discharge process results from two distinctive mechanisms: capture and emission. A theoretical model is presented describing the rate processes of both mechanisms. The model presented and the experimentally determined data agree rather well.List of Symbols
a
s
m–1
specific area of the packing material
-
C m–3
microbial gas phase concentration
-
C
e
, C
i
m–3
microbial concentration in the exit and inlet gas resp.
- CFU
colony-forming-units
-
d
c
, d
m
m
diameter of collecting and captured particle resp.
-
D m
diameter of the filter bed
-
E
single particle target efficiency
-
H m
bed height
-
k
c
s–1
first order capture rate constant per unit of bedvolume
-
k
e
m–3
emission rate constant per unit of bedvolume
-
n
number of observations
-
r
c
, r
e
m–3 s–1
capture and emission rate per unit of bed-volume
- Re =
Reynolds number
-
S
t
=
Stokes number
-
u m s–1
superficial gas velocity
-
u
m
m s–1
superficial gas velocity at which C
e
= C
i
Greek Symbols
void fraction of the filter bed
- kg m–3
density of the gas phase
-
m
kg m–3
density of captured particle
- Pa s
dynamic gas phase viscosity
- =
filter bed efficiency 相似文献
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Microorganisms are but a few micrometers in diameter and are not visible to the naked eye. Yet, the large numbers of microorganisms
present in the oceans and the global impact of their activities make it possible to observe them from space. Here a few examples
of how microorganisms can be studied from satellites are presented. The first case is the best known: the main pigment used
in photosynthesis (chlorophyll a) can be determined from satellites. These kinds of studies have contributed a tremendous amount of understanding about the
distribution and dynamics of primary production in the oceans. Two other examples will concern analysis of heterotrophic prokaryotic
production and estimates of dimethyl sulfide (DMS) concentration and flux to the atmosphere. These three processes are of
fundamental importance for the functioning of the biosphere. Marine microbes carry out about half of the total primary production
in the planet. A substantial fraction of the respiration in the oceans is due to the activity of heterotrophic prokaryotes.
Finally, the flux of DMS to the atmosphere is believed to constitute one of the mechanisms by which the biota can regulate
climate. The global implications of microbial processes in the oceans can only be addressed with the help of satellites.
Electronic Publication 相似文献
16.
Selected strains of alkalophilicbacillus organisms showed a remarkable ability for reducing redox mediator reagents, and were used as biocatalysts in the anode compartment of a redox-mediated microbial fuel cell. Substantial generation of electricity from oxidation of glucose as the fuel-substrate was demonstrated, particularly at the optimum growth pH. 相似文献
17.
Thiobacillus denitrificans was grown anaerobically with nitrate as an acceptor in both sterile and nonsterile media. Ribulose diphosphate carboxylase was stable throughout the exponential growth phase and declined slowly only after cells reached the stationary phase. Reversible inactivation of the carboxylase occurred in extracts as a result of bicarbonate omission. The enzyme was purified 32-fold with excellent recovery of a preparation which was 50 to 60% pure by the criterion of polyacrylamide gel electrophoresis. This purified preparation catalyzed the fixation of 1.25 mumoles of CO(2) per min per mg of protein at pH 8.1 and 30 C, and the molecular weight of ribulose diphosphate carboxylase was approximately 350,000 daltons. A striking biphasic time course of CO(2) fixation that was independent of protein and ribulose diphosphate concentration was observed. The optimal pH of the enzyme assay was fairly broad, ranging from 7 to 8.2. Kinetic dependence upon bicarbonate, ribulose diphosphate, and Mg(2+) was characterized and indicated that bicarbonate and Mg(2+) must combine with enzyme prior to addition of ribulose diphosphate. Antiserum to ribulose diphosphate carboxylase from Hydrogenomonas eutropha was only slightly inhibitory when added to the enzyme from T. denitrificans, and the mixture did not precipitate. Cyanide (4 x 10(-5)m) gave 61% inhibition of the enzyme from T. denitrificans. Ribulose diphosphate carboxylase in extracts of H. eutropha, H. facilis, Chromatium D, Rhodospirillum rubrum, and Chlorella pyrenoidosa were also inhibited to varying extents by cyanide and antiserum to the H. eutropha enzyme. 相似文献
18.
CHEKAN LI 《Mikrobiologiia》1951,20(5):452-453
19.
Isolation of polyacrylamide-degrading microorganisms from soil 总被引:1,自引:0,他引:1
H. Matsuoka F. Ishimura T. Takeda M. Hikuma 《Biotechnology and Bioprocess Engineering》2002,7(5):327-330
Two polyacrylamide-degrading bacterial strains, No. 2 and No. 11, were isolated from soil, and identified asBacillus sphaericus No. 2 andAcinetobacter sp. No. 11, respectively. Both strains grew on medium containing polyacrylamide as sole carbon and nitrogen sources.B. sphaericus No. 2 andA. sp. No. 11 reduced by 16% and 19% of the initial polyacrylamide concentration, respectively. Optimal pH and temperature in
growth ofAcinetobacter sp. No. 11 were 8.0 and 37°C, respectively. After 14-day cultivation ofA. sp. No. 11, the average molecular weight of polyacrylamide has been shifted from 2.3×106 to 0.5×106. 相似文献