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1.
The ability to produce several antibacterial agents greatly increases the chance of producer’s survival. In this study, red-pigmented
Vibrio sp. DSM 14379 and Bacillus sp., both isolated from the same sampling volume from estuarine waters of the Northern Adriatic Sea, were grown in a co-culture.
The antibacterial activity of the red pigment extract was tested on Bacillus sp. in microtiter plates. The MIC50 for Bacillus sp. was estimated to be around 10−5 mg/L. The extract prepared form the nonpigmented mutant of Vibrio sp. had no antibacterial effect. The pigment production of Vibrio sp. was studied under different physicochemical conditions. There was no pigment production at high or low temperatures,
high or low salt concentrations in peptone yeast extract (PYE) medium, low glucose concentration in mineral growth medium
or high glucose concentration in PYE medium. This indicates that the red pigment production is a luxurious good that Vibrio sp. makes only under favorable conditions. The Malthusian fitness of Bacillus sp. in a co-culture with Vibrio sp. under optimal environmental conditions dropped from 4.0 to −7.6, which corresponds to three orders of magnitude decrease
in the number of CFU relative to the monoculture. The nonpigmented mutant of Vibrio sp. in a co-culture with Bacillus sp. had a significant antibacterial activity. This result shows that studying antibacterial properties in isolation (i.e.
pigment extract only) may not reveal full antibacterial potential of the bacterial strain. The red pigment is a redundant
antibacterial agent of Vibrio sp. 相似文献
2.
The Vitreoscilla hemoglobin (VHb) gene (vgb) was integrated into the chromosome of Bacillus thuringiensis BMB171 using integrative vector pEG491. The production of VHb was confirmed by CO-difference spectra analysis. Fermentation
experiments results showed that with the production of VHb, the critical oxygen concentration (COC) of the host strain was
reduced from 18 to 12%. The maximum viable cell counts of the VHb+ strain in high, middle, and low aeration/agitation fermentations were 0.94-, 1.23-, and 1.59-fold of those of the VHb− strain, respectively. Under the same conditions, the yields of insecticidal crystal proteins (ICP) by VHb+ strain were 1.22-, 1.63-, and 3.13-fold of those of the VHb− strain. The production of VHb also accelerated the formation of ICP and spores. These results indicated that the production
of VHb could improve the cell density and ICP yield of B. thuringiensis, especially under low aeration/agitation condition. 相似文献
3.
Y-W Ryu C Y Park J B Park S-Y Kim J-H Seo 《Journal of industrial microbiology & biotechnology》2000,25(2):100-103
A two-stage fed-batch process was designed to enhance erythritol productivity by the mutant strain of Candida magnoliae. The first stage (or growth stage) was performed in the fed-batch mode where the growth medium was fed when the pH of the
culture broth dropped below 4.5. The second stage (or production stage) was started with addition of glucose powder into the
culture broth when the cell mass reached about 75 g dry cell weight l−1. When the initial glucose concentration was adjusted to 400 g l−1 in the production stage, 2.8 g l−1 h−1 of overall erythritol productivity and 41% of erythritol conversion yield were achieved, which represented a fivefold increase
in erythritol productivity compared with the simple batch fermentation process. A high glucose concentration in the production
phase resulted in formation of organic acids including citrate and butyrate. An increase in dissolved oxygen level caused
formation of gluconic acid instead of citric acid. Journal of Industrial Microbiology & Biotechnology (2000) 25, 100–103.
Received 25 February 2000/ Accepted in revised form 08 June 2000 相似文献
4.
Lakhal R Auria R Davidson S Ollivier B Durand MC Dolla A Hamdi M Combet-Blanc Y 《Archives of microbiology》2011,193(6):429-438
5.
The bacteriostatic potency of the cerium-humic acid complex was evaluated by experimental measurement of this complex interaction
with E. coli, Bacillus pyocyaneus, Staphylococcus aureus, Leuconostoc and Streptococcus faecalis, and by comparison bacteriostatic effects with the cerium-citrate complex. The experimental results indicated that the cerium-humic
acid complex strongly inhibited growth of all five bacterial strains, and its diameter of bacteriostatic circles were more
than 30 mm. The minimal bacteria-inhibiting concentration were 1×10−3, 2×10−3 and 1×10−2 mol/L for E. coli and Bacillus pyocyaneus, Staphylococcus aureus, and Leuconostoc and Streptococcus faecalis individually, and the measured minimal bactericidal concentrations were 2×10−3 and 1×10−2 mol/L for Bacillus pyocyaneus, E. coli, and Leuconostoc. To kill Staphylococcus aureus and Streptococcus faecalis, the concentration had to be more than 1×10−2 mol/L. On the contrary, we found that cerium-citrate complex did not inhibit the growth of the above five bacteria, but stimulated
bacterial growth. The completely different bacteriostatic results of two cerium complexes may hint that the association and
chemical properties of the two complexes were different. 相似文献
6.
The effects of initial culture pH ranging from 5.0 to 7.5 on biomass content, precursor 3-hydroxy-2-butanone (HB) accumulation,
and 2,3,5,6-tetramethylpyrazine (TTMP) formation by Bacillus subtilis CCTCC M 208157 were investigated in shake flask fermentation. Weak acidic conditions were found to favor cell growth and
precursor HB accumulation, while TTMP could be synthesized more efficiently in conditions with initial pH towards neutrality.
Batch bioprocess of TTMP fermentation by Bacillus subtilis CCTCC M 208157 at various controlled pH values ranging from 5.5 to 7.0 was then examined in 7.5-l fermentor. The results
suggested that optimum pH for cell growth and precursor HB accumulation was 5.5 with maximum cell growth rate (Q
x) and precursor HB accumulation rate (Q
HB) of 0.833 g l−1 h−1 and 1.118 g l−1 h−1, respectively, while optimum pH for TTMP formation was 7.0 with maximum TTMP formation rate (Q
TTMP) of 0.095 g l−1 h−1. A pH-shifted strategy was accordingly developed to improve TTMP production in bioreactor fermentation by shifting the culture
pH from 5.5 to 7.0 after 48 h of cultivation. By applying the strategy, final TTMP concentration of 7.43 g l−1 was obtained, being 22.2% greater than that of constant-pH fermentation. 相似文献
7.
H D Paik S S Bae S H Park J G Pan 《Journal of industrial microbiology & biotechnology》1997,19(4):294-298
Bacillus thuringiensis subsp tochigiensis HD868 was identified as a bacteriocin producer which exhibited a bactericidal effect against closely related species. This
bacteriocin designated as tochicin, was partially purified by 75% ammonium sulfate precipitation followed by subsequent
dialysis. This partially purified tochicin showed a narrow antibacterial spectrum of activity against most of 20 typical
B. thuringiensis strains and a strain of B. cereus, but not against other bacteria and yeasts tested. The antibacterial activity of tochicin on sensitive indicator cells disappeared
completely by proteinase K treatment (1 mg ml−1), which indicates its proteinaceous nature. Tochicin was very stable throughout the range of pH 3.0–9.0 and was relatively
heat-stable at 90°C, but bacteriocin activity was not detected after boiling for 30 min. The relationship between cell growth
and bacteriocin production was studied in a semi-defined medium. Tochicin activity was detected at the mid-log growth phase,
reached the maximum at the early stationary phase, but decreased after the stationary phase. Direct detection of tochicin
activity on sodium dodecyl sulfate-polyacrylamide gel suggested it has an apparent molecular mass of about 10.5 kDa. Tochicin
exhibited a bactericidal activity against B. thuringiensis subsp thompsoni HD522 in phosphate buffer (pH 7.0).
Received 02 December 1996/ Accepted in revised form 25 August 1997 相似文献
8.
N. M. Rosas-García A. Sánchez-Varela J. M. Villegas-Mendoza 《Folia microbiologica》2009,54(6):487-492
The δ-endotoxins (δ-ETX) of four native strains (RT7, RT19, RT25, and RT25), and one reference strain (4L1) of Bacillus thuringiensis were biochemically and molecularly characterized to determine their potential toxic activity against lepidopteran larvae.
Crystals of δ-ETX were purified through a two-phase system to determine their morphology, molar mass, solubility, and resistance
to proteinases. Toxic activity and cry gene content were also determined. Crystals from native strains exhibited polyhedral, irregular and cuboidal shapes, while
those from 4L1 were bipyramidal. Seven proteins with estimated molar mass ≈30–134 kDa were detected as the main components
of the native δ-ETX. Only crystals from 4L1, RT24, and RT25 underwend complete solubilization at pH >12.0. Crystals from all
strains produced trypsinresistant peptides. None of the cry genes associated with toxicity in lepidopterans (cry1, cry2, cry9) was found in the native strains; however, 4L1 strain harbors cry1 and cry2 genes. Strains RT19 and RT25 caused significant mortality against Trichoplusia ni larvae with partial solubilization at pH 10, strain 4L1 caused 100 % mortality. Toxicity of native strains may come from
a novel cry gene. 相似文献
9.
This report describes the optimization of culture conditions for vancomycin production by Amycolatopsis orientalis KCCM-10836P, an identified high-vancomycin-producing strain (US11/712,494). Among the conditions tested, pH and the dissolved
oxygen tension (DOT) were key factors affecting vancomycin production. When the pH and DOT were controlled at 7.0 and 20–30%,
respectively, a dry-cell weight (DCW) of 62.0 g l−1 and a vancomycin production of 11.5 g l−1 were obtained after 120 h of batch culture, corresponding to a specific vancomycin content of 185.4 mg g-DCW−1. Vancomycin production was scaled up from a laboratory scale (7-l fermentor) to a pilot scale (300 l) and a plant scale (5,000 l)
using the impeller tip velocity (V
tip) as a scale-up parameter. Vancomycin production at the laboratory scale was similar to those at the pilot and plant scales. 相似文献
10.
Streptococcus bovis HC5 inhibits a variety of S. bovis strains and other Gram-positive bacteria, but factors affecting this activity had not been defined. Batch culture studies
indicated that S. bovis HC5 did not inhibit S. bovis JB1 (a non-bacteriocin-producing strain) until glucose was depleted and cells were entering stationary phase, but slow-dilution-rate,
continuous cultures (0.2 h−1) had as much antibacterial activity as stationary-phase batch cultures. Because the activity of continuous cultures (0.2–1.2
h−1) was inversely related to the glucose consumption rate, it appeared that the antibacterial activity was being catabolite
repressed by glucose. When the pH of continuous cultures (0.2 h−1) was decreased from 6.7 to 5.4, antibacterial activity doubled, but this activity declined at pH values less than 5.0. Continuous
cultures (0.2 h−1) that had only ammonia as a nitrogen source had antibacterial activity, and large amounts of Trypticase (10 mg ml−1) caused only a 2.0-fold decline in the amount of HC5 cell-associated protein that was needed to prevent S. bovis JB1 growth. Because S. bovis HC5 was able to produce antibacterial activity over a wide range of culture conditions, there is an increased likelihood
that this activity could have commercial application.
Received: 6 February 2002 / Accepted: 27 March 2002 相似文献
11.
Ringel AK Wilkens E Hortig D Willke T Vorlop KD 《Applied microbiology and biotechnology》2012,93(3):1049-1056
A new screening method was developed and established to find high-performance bacteria for the conversion of crude glycerol
to 1,3-propanediol. Three soil samples from palm oil-rich habitats were investigated using crude glycerol of a German biodiesel
plant. Nine promising 1,3-propanediol producers could be found. Because of a special pH buffer system, a fast evaluation on
microscale and high 1,3-propanediol concentrations up to 40 g L−1 could be achieved. Three strains demonstrated very high product tolerance and were identified as Clostridium butyricum. Two strains, AKR91b and AKR102a, grew and produced 1,3-propanediol in the presence of 60 g L−1 initial 1,3-propanediol, the strain AKR92a even in the presence of 77 g L−1 1,3-propanediol. The strains AKR91b and AKR102a tolerated up to 150 g L−1 crude glycerol and produced 80% of the 1,3-propanediol attained from pure glycerol of the same concentration. Further criteria
for the choice of a production strain were the pathogenicity (risk class), ability to grow on low-cost media, e.g., with less
yeast extract, and robustness, e.g., process stability after several bioconversions. Overall, the strain C. butyricum AKR102a was chosen for further process optimization and scale-up due to its high productivity and high final concentration
in a pH-regulated bioreactor. 相似文献
12.
The continuous production of citric acid from dairy wastewater was investigated using calcium-alginate immobilizedAspergillus niger ATCC 9142. The citric acid productivity and yield were strongly affected by the culture conditions. The optimal pH, temperature,
and dilution rate were 3.0, 30°C, and 0.025 h−1, respectively. Under optimal culture conditions, the maximum productivity, concentration, and yield of citric acid produced
by the calcium-alginate immobilizedAspergillus niger were 160 mg L−1 h−1, 4.5 g/L, and 70.3% respectively. The culture was continuously perfored for 20 days without any apparent loss in citric acid
productivity. Conversely, under the same conditions with a batch shake-flask culture, the maximum productivity, citric acid
concentration, and yield were only 63.3 mg L−1 h−1, 4.7 g/L and 51.4%, respectively. Therefore, the results suggest that the bioreactor used in this study could be potentially
used for continuous citric acid production from dairy wastewater by applying calcium-alginate immobilizedAspergillus niger. 相似文献
13.
Nitrate reduction by Citrobacter diversus under aerobic environment 总被引:17,自引:0,他引:17
A new aerobic denitrifier, Citrobacter diversus, was isolated from both nitrification and denitrification sludge. To monitor the variation in the concentration of nitrogen
oxides, aerobic denitrification by C. diversus was carried out in a batch reactor. When the nitrate concentration was greater than 180 mg N l−1, the nitrate reduction rate became stable. The effect of the C/N ratio on the denitrification activity was also investigated.
The results showed that the optimum denitrification activity was obtained when the C/N ratio was 4–5. The range of the C/N
ratio was higher than that for traditional anoxic denitrification. The effect of the dissolved oxygen concentration was further
studied; and it was found that the range of dissolved oxygen concentrations, both for specific growth rates and for specific
denitrification rates, was 2–6 mg−1. From these results, it can be concluded that both the concentration of dissolved oxygen and the C/N ratio are key factors
in the aerobic denitrification by C. diversus.
Received: 23 November 1999 / Received revision: 4 February 2000 / Accepted: 13 February 2000 相似文献
14.
Bum-Kyu Lee No-Hwan Park Hai Yon Piao Wook-Jin Chung 《Biotechnology and Bioprocess Engineering》2001,6(5):341-346
For the purpose of mass producingMonascus red pigments optimum medium composition and environmental conditions were investigated in submerged flask cultures. The optimum
carbon and nitrogen sources were determined to be 30 g/L of glucose and 1.5 g/L of monosodium glutamate (MSG). Of the three
metals examined, Fe2+ showed the stronges stimulatory effect on pigment production and some stimulatory effect was also found in Mn2+. Optimum pH and agitation speed were determined to be 6.5 and 700 rpm, respectively. Under the optimum culture conditions
batch fermentation showed that the maximum biomass yield and specific productivity of red pigments were 0.20 g DCW/g glucose
and, 32.5 OD500 g DCW−1 h−1, respectively. 相似文献
15.
Laura Pinilla Rodrigo Torres Claudia Ortiz 《World journal of microbiology & biotechnology》2011,27(11):2521-2528
Two wild strains of Zymomonas mobilis were isolated (named as ML1 and ML2) from sugar cane molasses obtained from different farms of Santander, Colombia. Initially,
selection of the best ethanol-producer strains was carried out using ethanol production parameters obtained with a commercial
strain Z. mobilis DSM 3580. Three isolated strains were cultivated in a culture medium containing yeast extract, peptone, glucose and salts,
at pH 6 and 32°C with stirring rate of 65 rpm during 62 h. The best results of ethanol production were obtained with the native
strain ML1, reaching a maximum ethanol concentration of 79.78 g l−1. ML1 and ML2 strains were identified as Z.
mobilis, according to the morphology, biochemical tests and molecular characterization by PCR of specific DNA sequences from Z. mobilis. Subsequently, the effect of different nitrogen sources on production of ethanol was evaluated. The best results were obtained
using urea at a 0.73 g/l. In this case, maximum concentration of ethanol was 83.81 g l−1, with kinetic parameters of yield of ethanol on biomass (YP/X) = 69.01(g g−1), maximum volumetric productivity of ethanol (Qpmax) = 2.28 (g l−1 h−1), specific productivity of ethanol (qP) = 3.54 (h−1) and specific growth rate (μ) = 0.12 h−1. Finally, we studied the effect of different culture conditions (pH, temperature, stirring, C/N ratio) with a Placket-Burman′s
experimental design. This optimization indicated that the most significant variables were temperature and stirring. In the
best culture conditions a significant increase in all variables of response was achieved, reaching a maximum ethanol concentration
of 93.55 g l−1. 相似文献
16.
Ki Moon Park Min Woo Song Jae Heung Lee 《Biotechnology and Bioprocess Engineering》2009,14(4):414-418
Glucose-limited continuous culture experiments with Xanthophyllomyces dendrorhous ATCC 24202 were carried out in a 2.5 L jar fermentor at 20°C and pH 4.5. A reciprocal plot of the steady-state data at a
dilution rate of 0.037∼0.096 h−1 was used to estimate a maximum specific growth rate constant of 0.11 h−1 and a Monod constant of 260 mg/L. The degree of carotenogenesis in X. dendrorhous was also investigated in terms of the residence time, which is the reciprocal of the dilution rate. The carotenoid content
related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content for
the strain was estimated to be 0.6 μg/mg dry cell weight. The saturation constant, which was tentatively defined in this work,
was found to be 7.2 h. 相似文献
17.
Interpretation of photosynthetic pigment data using iterative programs such as CHEMTAX are widely used to examine algal community
structure in the surface ocean. The accuracy of such programs relies on understanding the effects of environmental parameters
on the pigment composition of taxonomically diverse algal groups. Phaeocystis antarctica is an important contributor to total autotrophic production and the biogeochemical cycling of carbon and sulfur in the Southern
Ocean. Here we report the results of a laboratory culture experiment in which we examined the effects of ambient dissolved
iron concentration on the pigment composition of colonial P. antarctica, using a new P. antarctica strain isolated from the southern Ross Sea in December 2003. Low-iron (<0.2 nM dissolved Fe) filtered Ross Sea seawater was
used to prepare the growth media, thus allowing sub-nanomolar iron additions without the use of EDTA to control dissolved
iron concentrations. The experiment was conducted at relatively low irradiance (∼20 μE m−2 s−1), with P. antarctica primarily present in the colonial form—conditions that are typical of the southern Ross Sea during austral spring. Relative
to the iron-limited control treatments (0.22 nM dissolved Fe), iron addition mediated a decrease in the ratio of 19′-hexanoyloxyfucoxanthin
to chlorophyll a, and an increase in the ratio of fucoxanthin to chlorophyll a. Our results also suggest that the ratio of 19′-hexanoyloxyfucoxanthin to chlorophyll c3 (Hex:Chl c3 ratio) may be a characteristic physiological indicator for the iron-nutritional status of colonial P. antarctica, with higher Hex:Chl c3 ratios (>3) indicative of Fe stress. We also observed that the ratio of fucoxanthin to 19′-hexanoyloxyfucoxanthin (Fuco:Hex
ratio) was highly correlated (r
2 = 0.82) with initial dissolved Fe concentration, with Fuco:Hex ratios <0.05 measured under iron-limited conditions (dissolved
Fe <0.45 nM). Our results corroborate and extend the results of previous experimental studies, and, combined with pigment
measurements from the southern Ross Sea, are consistent with the hypothesis that the interconversion of fucoxanthin and 19′-hexanoyloxyfucoxanthin
by colonial P. antarctica is used as a photo-protective or light-harvesting mechanism, according to the availability of dissolved iron. 相似文献
18.
M. Sharari A. Jahan Latibari A. Guillet M. Aurousseau B. Mouhamadou Gh. Rafeiee A. Mirshokraei D. Parsapaghouh 《Biodegradation》2011,22(2):421-430
Biotreatment of bagasse effluent using Phanerochaete chrysosporium (white rot fungus) is investigated. This study confirmed that lignin is the major pollutant component in this effluent followed
by different carbohydrates. The treatment conditions must be very proper, especially in terms of biomass culture to achieve
a successful treatment. The best conditions of temperature, biomass concentration, pH and duration for biotreatment of this
effluent were 35°C, 552 mg l−1, 6 and 5 to 9 days, respectively. Under these conditions, a 9 days long treatment reduced by 98.7% the original biochemical
oxygen demand (of 2,780 mg l−1) and by 98.5% the dissolved chemical oxygen demand (initial 4,200 mg l−1). Moreover, fungal treatment reduced total dissolved solids from 3,950 to 575 mg l−1 and color from 560 mg l−1 PtCo to 111 mg l−1 PtCo. 相似文献
19.
A strain of Bacillus subtilis was able to grow and produce a biosurfactant on 2% sucrose at 45°C. As a result of biosurfactant synthesis the surface tension
of the medium was reduced from 68 dynes cm−1 to 28 dynes cm−1. The strain had the capacity to produce the biosurfactant at high NaCl concentrations (4%) and a wide range of pH (4.5–10.5).
The biosurfactant retained its surface-active properties after heating at 100°C for 2 h and at different pH values (4.5–10.5).
A maximum amount of biosurfactant was produced when urea or nitrate ions were supplied as nitrogen source. The use of the
biosurfactant at high temperatures, acidic, alkaline and saline environments is discussed. As a result of its action, 62%
of oil in a sand pack column could be recovered, indicating its potential application in microbiologically enhanced oil
recovery.
Received 28 March 1996/ Accepted in revised form 16 September 1996 相似文献
20.
Beshkova D.M. Simova E.D. Frengova G.I. Simov Zh.I. Spasov Z.N. 《World journal of microbiology & biotechnology》2002,18(4):365-369
A yogurt culture (Streptococcus thermophilus 15HA + Lactobacillus delbrueckii subsp. bulgaricus 2-11) was studied in conditions of aerobic batch fermentation (10–40% dissolved oxygen in milk). The growth and acidification
of S. thermophilus 15HA were stimulated at 20% oxygen concentration and the lactic acid process in a mixed culture was shortened by 1 h (2.5
h for the aerobic culture and 3.5 h for the anaerobic mixed culture). Streptococcus thermophilus 15HA oxygen tolerance was significantly impaired at oxygen concentrations in the milk above 30%. Though S. thermophilus 15HA was able to overcome to some extent the impact of high oxygen concentration (40%), the lactic acid produced was insufficient
to coagulate the milk casein (4.0 g lactic acid l−1 in the mixed culture and 3.8 g lactic acid l−1 in the pure culture). A dramatic decrease in the viable cell count of L. delbrueckii subsp. bulgaricus 2-11 in the pure and mixed cultures was recorded at 30% dissolved oxygen.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献