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1.
Ethylene Oxide Gaseous Sterilization: I. Concentration and Temperature Effects 总被引:8,自引:6,他引:2 下载免费PDF全文
The relationships of reaction temperature and concentration of gaseous ethylene oxide to the time required for inactivation of air-dried Bacillus subtilis var. niger spores are more complex than previously reported. A plot of temperature vs. the logarithm of “thermochemical death time” (TCDT) resulted in a straight line between 18 and 57 C for systems of “high” ethylene oxide concentration. The TCDT values were independent of ethylene oxide concentrations above certain temperature-dependent limits. A given ethylene oxide concentration produced a TCDT curve identical in the upper temperature regions with that for higher concentrations. As the temperature was lowered beyond a critical point, this curve diverged from that for higher concentrations, as a straight line of lesser slope. Thus, a series of curves exists for a range of ethylene oxide concentrations. They are characterized by two segments, both logarithmic, intersecting at a critical temperature for each concentration. The intersecting point is at a temperature inversely related to the ethylene oxide gas concentration. The temperature quotient for the high temperature segments of all systems was 1.8. This value was characteristic for ethylene oxide concentrations of 440 and 880 mg/liter at temperatures above 40.6 and 33.4 C, respectively. Below these critical temperatures, the Q10 values for the respective systems were 3.2 and 2.3. 相似文献
2.
Ethylene Oxide Gaseous Sterilization: II. Influence of Method of Humidification 总被引:3,自引:2,他引:1 下载免费PDF全文
The duration of the equilibration period between admission of water vapor and subsequent introduction of gaseous ethylene oxide to an evacuated sterilizer chamber was studied with respect to its effect on the inactivation of spores of Bacillus subtilis var. niger under simulated practical conditions. Introduction of a water-adsorbing cotton barrier between the spores and an incoming gas mixture of water vapor and ethylene oxide caused a marked increase in the observed thermochemical death time of the spore populations. This effect was negated by admission of water vapor one or more minutes prior to introduction of ethylene oxide gas. Increases in temperature and relative humidity of the system promoted passage of water vapor through the cotton barriers and diminished their effect. 相似文献
3.
David J. Smith Dale W. Griffin Richard D. McPeters Peter D. Ward Andrew C. Schuerger 《Aerobiologia》2011,27(4):319-332
Spores of Bacillus subtilis were exposed to a series of stratosphere simulations. In total, five distinct treatments measured the effect of reduced pressure,
low temperature, high desiccation, and intense ultraviolet (UV) irradiation on stratosphere-isolated and ground-isolated B. subtilis strains. Environmental conditions were based on springtime data from a mid-latitude region of the lower stratosphere (20 km).
Experimentally, each treatment consisted of the following independent or combined conditions: −70°C, 56 mb, 10–12% relative
humidity and 0.00421, 5.11, and 54.64 W/m2 of UVC (200–280 nm), UVB (280–315 nm), UVA (315–400 nm), respectively. Bacteria were deposited on metal coupon surfaces in
monolayers of ~1 × 106 spores and prepared with palagonite (particle size < 20 μm). After 6 h of exposure to the stratosphere environment, 99.9%
of B. subtilis spores were killed due to UV irradiation. In contrast, temperature, desiccation, and pressure simulations without UV had
no effect on spore viability up through 96 h. There were no differences in survival between the stratosphere-isolated versus
ground-isolated B. subtilis strains. Inactivation of most bacteria in our simulation indicates that the stratosphere can be a critical barrier to long-distance
microbial dispersal and that survival in the upper atmosphere may be constrained by UV irradiation. 相似文献
4.
M. A. Ayude E. Okada J. F. González P. M. Haure S. E. Murialdo 《Journal of industrial microbiology & biotechnology》2009,36(5):765-768
Pentachlorophenol (PCP) and its sodium salt (Na-PCP) are extremely toxic chemicals responsible for important soil and groundwater
pollution, mainly caused by wastes from wood-treatment plants, because chlorinated phenols are widely used as wood preservatives.
The methods most commonly used for routine analysis of pesticides such as PCP and Na-PCP are high-performance liquid chromatography
(HPLC) and gas chromatography–mass spectroscopy (GC–MS). A variety of rapid biological screening tests using marine organisms,
bioluminescent bacteria, and enzymes have also been reported. In this study, rapid biological screening analysis using Bacillus subtilis was developed, to assess the biodegradation of PCP and its by-products in liquid samples. An empirical model is proposed
for spectrophotometric analysis of Na-PCP concentration after growth of Bacillus subtilis. 相似文献
5.
Santos LO Gonzales TA Ubeda BT Monte Alegre R 《Applied microbiology and biotechnology》2007,77(4):763-769
A strategy of experimental design using a fractional factorial design (FFD) and a central composite rotatable design (CCRD)
were carried out with the aim to obtain the best conditions of temperature (20–30°C), agitation rate (100–300 rpm), initial
pH (5.0–7.0), inoculum concentration (5–15%), and glucose concentration (30–70 g/l) for glutathione (GSH) production in shake-flask
culture by Saccharomyces cerevisiae ATCC 7754. By a FFD (25–2), the agitation rate, temperature, and pH were found to be significant factors for GSH production. In CCRD (22) was obtained a second-order model equation, and the percent of variation explained by the model was 95%. The results showed
that the optimal culture conditions were agitation rate, 300 rpm; temperature, 20°C; initial pH, 5; glucose, 54 g/l; and inoculum
concentration, 5%. The highest GSH concentration (154.5 mg/l) was obtained after 72 h of fermentation. 相似文献
6.
Experiments were designed to study chlorine dioxide (CD) gas sterilization under square-wave conditions. By using controlled humidity, gas concentration, and temperature at atmospheric pressure, standard biological indicators (BIs) and spore disks of environmental isolates were exposed to CD gas. The sporicidal activity of CD gas was found to be concentration dependent. Prehumidification enhanced the CD activity. The D values (time required for 90% inactivation) of Bacillus subtilis subsp. niger ATCC 9372 BIs were estimated to be 1.5, 2.5, and 4.2 min when exposed to CD concentrations of 30, 15, and 7 mg/liter, respectively, at 23°C and ambient (20 to 40%) relative humidity (RH). Survivor tailings were observed. Prehumidification of BIs to 70 to 75% RH in an environmental chamber for 30 min resulted in a D value of 1.6 min after exposure to a concentration of 6 to 7 mg of CD per liter at 23°C and eliminated survivor tailing. Prolonging prehumidification at 70 to 75% RH for up to 16 h did not further improve the inactivation rate. Prehumidification by ultrasonic nebulization was found to be more effective than prehumidification in the environmental chamber, improving the D value to 0.55 min at a CD concentration of 6 to 7 mg/liter. Based on the current observations, CD gas is estimated, on a molar concentration basis, to be 1,075 times more potent than ethylene oxide as a sterilant at 30°C. A comparative study showed B. subtilis var. niger BIs were more resistant than other types of BIs and most of the tested bacterial spores of environmental isolates. 相似文献
7.
A laboratory study was conducted to investigate the influence of four PGPR strains on the degradation of five soil applied
pesticides and their effects on bacterial growth. Interactions of Bacillus subtilis GB03, Bacillus subtilis FZB24, Bacillus amyloliquefaciens IN937a and Bacillus pumilus SE34 with two concentrations of acibenzolar-S-methyl, metribuzin, napropamide, propamocarb hydrochloride and thiamethoxam in liquid culture and soil microcosm were studied.
The degradation of acibenzolar-S-methyl by all PGPR tested in low and high concentration, was 5.4 and 5.7 times, respectively, faster than that in non-inoculated
liquid culture medium. At the end of the 72-h liquid cultured experiments, 8–18, 9–11, 15–36 and 11–22% of metribuzin, napropamide,
propamocarb hydrochloride and thiamethoxam, respectively, had disappeared from PGPR inoculated medium. Under the soil microcosm
experimental conditions, the half-lives of acibenzolar-S-methyl incubated in the presence of PGPR strains spiked at 1.0 and 10.0 mg kg−1 were 10.3–16.4 and 9.2–15.9 days, respectively, markedly lower compared with >34.2 days in the control. From the rest pesticides
studied degradation of propamocarb hydrochloride and thiamethoxam was enhanced in the presence of B. amyloliquefaciens IN937a and B. pumilus SE34. Acibenzolar-S-methyl, propamocarb hydrochloride and thiamethoxam significantly increased the PGPR growth. However, the stimulatory effect
was related to the level of pesticide spiked. 相似文献
8.
In order to obtain the diversity and temporal–spatial distribution of Bacillus community during the swine manure composting, we utilized traditional culture methods and the modern molecular biology techniques
of polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) and –denaturing gradient gel electrophoresis
(PCR-DGGE). Bacillus species were firstly isolated from the composting. Based on temperature changes, the temporal–spatial characteristics of
total culturable Bacillus were remarkable that the number of the culturable Bacillus detected at the high-temperature stage was the highest in each layer of the pile and that detected in the middle layer was
the lowest at each stage of composting respectively. The diversity of cultivated Bacillus species isolated from different composting stages was low. A total of 540 isolates were classified by the RFLP method and
partial 16S rDNA sequences. They affiliated to eight species including Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, Bacillus anthracis, Bacillus megaterium, Bacillus licheniformis, Bacillus pumilus, and Bacillus circulans. The predominant species was B. subtilis, and the diversity of culturable Bacillus isolated in the middle-level samples at temperature rising and cooling stages was the highest. The DGGE profile and clone
library analysis revealed that the temporal–spatial distribution of Bacillus community was not obvious, species belonging to the Bacillus were dominant (67%) with unculturable bacteria and B. cereus was the second major culturable Bacillus species. This study indicated that a combination of culture and culture-independent approaches could be very useful for monitoring
the diversity and temporal–spatial distribution of Bacillus community during the composting process. 相似文献
9.
Douglas J. Kojetin Patrick D. McLaughlin Richele J. Thompson Ronald A. Venters Mark Rance John Cavanagh 《Biomolecular NMR assignments》2007,1(2):163-165
The HSP100/AAA+ superfamily protein ClpC is a key regulator of cell development in Bacillus subtilis. We present here the backbone and side-chain assignments of the N-terminal repeat domain (residues 1–145) of ClpC from Bacillus subtilis.
Douglas J. Kojetin and Patrick D. McLaughlin have equally contributed. 相似文献
10.
Bacillus subtilis fmbj can produce a lipopeptide antimicrobial substance, the main components of which are surfactin and fengycin. In this
paper, the sensitivity of Bacillus cereus to antimicrobial lipopeptides from B.
subtilis fmbj was observed, and the effect of the microstructure of antimicrobial lipopeptide on spores of B.
cereus was investigated. At the same time, the optimization of the inactivation of antimicrobial lipopeptides to spores of B.
cereus by a response surface methodology was studied. Results showed that B.
cereus had high sensitivity to it, whose minimal inhibitory concentration was 156.25 μg/ml. It could result in the death of spores
by destroying the structure of resting spores and sprouting spores, as was observed by transmission electron microscopy. The
optimization result indicated that spores of B.
cereus could be inactivated by 2 orders of magnitude when the temperature was 29.6°C, the action time was 7.6 h, and the concentration
was 3.46 mg·ml−1. 相似文献
11.
Natural wild-type strains of Bacillus subtilis spore is regarded as a non-pathogenic for both human and animal, and has been classified as a novel food which is currently
being used as probiotics added in the consumption. To identify B. subtilis spore proteins, we have accomplished a preliminary proteomic analysis of B. subtilis spore, with a combination of two-dimensional electrophoretic separations and matrix-assisted laser desorption ionization
tandem time of flight mass spectrometry (MALDI–TOF–MS). In this article, we presented a reference map of 158 B. subtilis spore proteins with an isoelectric point (pI) between 4 and 7. Followed by mass spectrometry (MS) analysis, we identified
71 B. subtilis spore proteins with high level of confidence. Database searches, combined with hydropathy analysis and GO analysis revealed
that most of the B. subtilis spore proteins were hydrophilic proteins related to catalytic function. These results should accelerate efforts to understand
the resistance of spore to harsh conditions. 相似文献
12.
Durban MA Silbersack J Schweder T Schauer F Bornscheuer UT 《Applied microbiology and biotechnology》2007,74(3):634-639
Twenty-two Bacillus cereus strains were screened for phospholipase C (PLC, EC 3.1.4.3) activity using p-nitrophenyl phosphorylcholine as a substrate. Two strains (B. cereus SBUG 318 and SBUG 516) showed high activity at elevated temperatures (>70°C) at acidic pH (pH 3.5–6) and were selected for
cloning and functional expression using Bacillus subtilis. The genes were amplified from B. cereus DNA using primers based on a known PLC sequence and cloned into the expression vector pMSE3 followed by transformation into
B. subtilis WB800. On the amino acid level, one protein (PLC318) was identical to a PLC described from B. cereus, whereas PLC516 contained an amino acid substitution (E173D). PLC production using the recombinant strains was performed
by an acetoin-controlled expression system. For PLC516, 13.7 U g−1 wet cell weight was determined in the culture supernatant after 30 h cultivation time. Three purification steps resulted
in pure PLC516 with a specific activity of 13,190 U mg−1 protein. 相似文献
13.
Vojcic L Despotovic D Martinez R Maurer KH Schwaneberg U 《Applied microbiology and biotechnology》2012,94(2):487-493
Bacillus subtilis strains are used for extracellular expression of enzymes (i.e., proteases, lipases, and cellulases) which are often engineered
by directed evolution for industrial applications. B. subtilis DB104 represents an attractive directed evolution host since it has a low proteolytic activity and efficient secretion. B. subtilis DB104 is hampered like many other Bacillus strains by insufficient transformation efficiencies (≤103 transformants/μg DNA). After investigating five physical and chemical transformation protocols, a novel natural competent
transformation protocol was established for B. subtilis DB104 by optimizing growth conditions and histidine concentration during competence development, implementing an additional
incubation step in the competence development phase and a recovery step during the transformation procedure. In addition,
the influence of the amount and size of the transformed plasmid DNA on transformation efficiency was investigated. The natural
competence protocol is “easy” in handling and allows for the first time to generate large libraries (1.5 × 105 transformants/μg plasmid DNA) in B. subtilis DB104 without requiring microgram amounts of DNA. 相似文献
14.
Md. Ashaduzzaman Siddikee Puneet S. Chauhan Tongmin Sa 《Journal of Plant Growth Regulation》2012,31(2):265-272
The present study was carried out to understand the mechanism of salt stress amelioration in red pepper plants by inoculation
of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing halotolerant bacteria. In general, ethylene production,
ACC concentration, ACC synthase (ACS), and ACC oxidase (ACO) enzyme activities increased with increasing levels of salt stress.
Treatment with halotolerant bacteria reduced ethylene production by 47–64%, ACC concentration by 47–55% and ACO activity by
18–19% in salt-stressed (150 mmol NaCl) red pepper seedlings compared to uninoculated controls. ACS activity was lower in
red pepper seedlings treated with Bacillus aryabhattai RS341 but higher in seedlings treated with Brevibacterium epidermidis RS15 (44%) and Micrococcus yunnanensis RS222 (23%) under salt-stressed conditions as compared to uninoculated controls. A significant increase was recorded in red
pepper plant growth under salt stress when treated with ACC deaminase-producing halotolerant bacteria as compared to uninoculated
controls. The results of this study collectively suggest that salt stress enhanced ethylene production by increasing enzyme
activities of the ethylene biosynthetic pathway. Inoculation with ACC deaminase-producing halotolerant bacteria plays an important
role in ethylene metabolism, particularly by reducing the ACC concentration, although a direct effect on reducing ACO activity
was also observed. It is suggested that growth promotion in inoculated red pepper plants under inhibitory levels of salt stress
is due to ACC deaminase activity present in the halotolerant bacteria. 相似文献
15.
16.
Jin-Ha Jeong Young-Dong Jeon O-Mi Lee Jeong-Do Kim Na-Ri Lee Geun-Tae Park Hong-Joo Son 《Biodegradation》2010,21(6):1029-1040
In this study, we isolated and characterized a novel feather-degrading bacterium that shows keratinolytic, antifungal and
plant growth-promoting activities. A bacterium S8 was isolated from forest soil and confirmed to belong to Bacillus subtilis by BIOLOG system and 16S rRNA gene analysis. The improved culture conditions for the production of keratinolytic protease
were 0.1% (w/v) sorbitol, 0.3% (w/v) KNO3, 0.1% (w/v) K2HPO4, 0.06% (w/v) KH2PO4 and 0.04% (w/v) MgCl2·6H2O (pH 8.0 and 30°C), respectively. In the improved medium containing 0.1% (w/v) feather, keratinolytic protease production
was around 53.3 ± 0.3 U/ml at 4 day; this value was 10-fold higher than the yield in the basal feather medium (5.3 ± 0.1 U/ml).
After cultivation for 5 days in the improved medium, intact feather was completely degraded. Feather degradation resulted
in free –SH group, soluble protein and amino acids production. The concentration of free –SH group in the culture medium was
15.5 ± 0.2 μM at 4 days. Nineteen amino acids including all essential amino acids were produced in the culture medium; the
concentration of total amino acid produced was 3360.4 μM. Proline (2809.9 μM), histidine (371.3 μM) and phenylalanine (172.0 μM)
were the major amino acids released in the culture medium. B. subtilis S8 showed the properties related to plant growth promotion: hydrolytic enzymes, ammonification, indoleacetic acid (IAA),
phosphate solubilization, and broad-spectrum antimicrobial activity. Interestingly, the strain S8 grown in the improved medium
produced IAA and antifungal activity, indicating simultaneous production of keratinolytic and antifungal activities and IAA
by B. subtilis S8. These results suggest that B. subtilis S8 could be not only used to improve the nutritional value of feather wastes but also is useful in situ biodegradation of
feather wastes. Furthermore, it could also be a potential biofertilizer or biocontrol agent applicable to crop plant soil. 相似文献
17.
Fukushima T Yao Y Kitajima T Yamamoto H Sekiguchi J 《Molecular genetics and genomics : MGG》2007,278(4):371-383
Bacillus subtilis has various cell wall hydrolases, however, the functions and hydrolase activities of some enzymes are still unknown. B. subtilis CwlK (YcdD) exhibits high sequence similarity with the peptidoglycan hydrolytic l,d-endopeptidase (PLY500) of Listeria monocytogenes phage and CwlK has the VanY motif which is a d-alanyl-d-alanine carboxypeptidase (Pfam: http://www.sanger.ac.uk/Software/Pfam/). The β-galactosidase activity observed on cwlK-lacZ fusion indicated that the cwlK gene was expressed during the vegetative growth phase, and Western blotting suggested that CwlK seems to be localized in
the membrane. Truncated CwlK fused with a histidine-tag (h-ΔCwlK) was produced in Escherichia coli and purified on a nickel column. The h-ΔCwlK protein hydrolyzed the peptidoglycan of B. subtilis, and the optimal pH, temperature and NaCl concentration for h-ΔCwlK were pH 6.5, 37°C, and 0 M, respectively. Interestingly,
h-ΔCwlK could hydrolyze the linkage of l-alanine-d-glutamic acid in the stem of the peptidoglycan, however, this enzyme could not hydrolyze the linkage of d-alanine-d-alanine, suggesting that CwlK is an l,d-endopeptidase not a d,d-carboxypeptidase. CwlK could not hydrolyze polyglutamate from B. natto or peptidoglycan of Staphylococcus aureus. This is the first report describing the characterization of an l,d-endopeptidase in B. subtilis and also the first report in bacteria of the characterization of a PLY500 family protein encoded in chromosomal DNA.
Tatsuya Fukushima and Yang Yao contributed equally to this work. 相似文献
18.
In this study, the effects of citrate addition on d-ribose production were investigated in batch culture of a transketolase-deficient strain, Bacillus subtilis EC2, in shake flasks and bioreactors. Batch cultures in shake flasks and a 5-l reactor indicated that supplementation with
0.2–0.5 g l−1 of citrate enhanced d-ribose production. When B. subtilis EC2 was cultivated in a 15-l reactor in a complex medium, the d-ribose concentration was 70.9 g l−1 with a ribose yield of 0.497 mol mol−1. When this strain was grown in the same medium supplemented with 0.3 g l−1 of citrate, 83.4 g l−1 of d-ribose were obtained, and the ribose yield was increased to 0.587 mol mol−1. Addition of citrate reduced the activities of pyruvate kinase and phosphofructokinase, while it increased those of glucose-6-phosphate
dehydrogenase and 6-phosphogluconate dehydrogenase. Metabolic flux distribution in the stationary phase indicated that citrate
addition resulted in increased fluxes in the pentose phosphate pathway and TCA cycle, and decreased fluxes in the glycolysis
and acetate pathways. 相似文献
19.
G. M. Streshinskaya A. S. Shashkov N. V. Potekhina Yu. I. Kozlova E. M. Tul’skaya S. N. Senchenkova E. B. Kudryashova L. N. Anan’ina 《Microbiology》2011,80(1):21-29
A comparative study of the structures of carbohydrate-containing cell wall polymers isolated from the strains of the Bacillus subtilis group was performed by means of chemical and NMR spectroscopic meth ods. Polymers of different structure were revealed, namely,
1,3-poly(glycerol phosphates) with β-glucopyranose in Bacillus subtilis strains VKM B-520, VKM B-723, and VKM B-763 (= VKM B-911); 1,5-poly(ribitol phosphate) with α-glucopyranose in B. subtilis strains VKM B-722 and VKM B-922 (the structure is reported for the first time); and simultaneously two polymers in B. subtilis VKM B-761, 1,5-poly(ribitol phosphate) with β-glucopyranose and the disaccharide 1-phosphate polymer with the following repeating
unit: -6)-α-D-Galp-(1-P-4)-gB-D-GlcpNAc-(1-, in which the hydroxyls at C3 and C6 of glucosamine residues are partially O-acetylated (the structure is reported
for the first time). Heterogeneity of the B. subtilis group is con firmed by variations in the structure and composition of the cell wall polymers. The cell surface polymers are
useful for discrimination of closely related bacilli strains and are cell wall marker components that may be an indispensable
element of the Bacillus subtilis group taxonomy along with the genomosystematic methods. 相似文献
20.
Bacterial strains with ability to suppress Colletotrichum falcatum were isolated from the rhizosphere of sugarcane. Thirty nine candidates, chosen on the basis of in vitro antagonism, inhibited
C. falcatum growth by 15–65% on test plates. Twenty two isolates causing 50% or more in vitro inhibition were screened for their root
colonization ability and biocontrol activity on micropropagated sugarcane plants under greenhouse conditions. Twelve strains
suppressed red rot infection in plantlets, but no significant correlation was observed between in vitro pathogen inhibition
and in vivo disease suppression. However, isolates showing root colonization over 5.2 log10 CFU g−1 of soil showed highest suppression of C. falcatum and reduction of red rot disease. Six strains with the capability to maintain a significant population in the sugarcane rhizosphere
and with a high potential to control red rot were identified by 16S rDNA as Ochrobacterum intermedium NH-5, Pseudomonas putida NH-50, Bacillus subtilis NH-100, Bacillus subtilis NH-160, Bacillus sp NH-217 and Stenotrophomonas maltophilia NH-300. 相似文献