共查询到20条相似文献,搜索用时 31 毫秒
1.
Khaliq S Akhtar K Afzal Ghauri M Iqbal R Mukhtar Khalid A Muddassar M 《Microbiological research》2009,164(4):469-477
Tylosin is a macrolide antibiotic used as veterinary drug and growth promoter. Attempts were made for hyper production of tylosin by a strain of Streptomyces fradiae NRRL-2702 through irradiation mutagenesis. Ultraviolet (UV) irradiation of wild-type strain caused development of six morphologically altered colony types on agar plates. After screening using Bacillus subtilis bioassay only morphological mutants indicated the production of tylosin. An increase of 2.7±0.22-fold in tylosin production (1500 mg/l) in case of mutant UV-2 in complex medium was achieved as compared to wild-type strain (550 mg/l). Gamma irradiation of mutant UV-2 using 60Co gave one morphologically altered colony type γ-1, which gave 2500 mg/l tylosin yield in complex medium. Chemically defined media promoted tylosin production upto 3800 mg/l. Maximum value of qp (3.34 mg/gh) was observed by mutant γ-1 as compared to wild strain (0.81 mg/gh). Moreover, UV irradiation associated changes were unstable with loss of tylosin activity whereas mutant γ-1 displayed high stability on subsequent culturing. 相似文献
2.
Rojas-Rejn Oscar A. Poggi-Varaldo Hctor M. Ramos-Valdivia Ana C. Martnez-Jimnez Alfredo Cristiani-Urbina Eliseo de la Torre Martnez Mayra Ponce-Noyola Teresa 《Journal of industrial microbiology & biotechnology》2011,38(1):257-264
Derepressed mutant PR-22 was obtained by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) mutagenic treatment of Cellulomonas flavigena PN-120. This mutant improved its xylanolytic activity from 26.9 to 40 U mg−1 and cellulolytic activity from 1.9 to 4 U mg−1; this represented rates almost 2 and 1.5 times higher, respectively, compared to its parent strain growing in sugarcane bagasse.
Either glucose or cellobiose was added to cultures of C. flavigena PN-120 and mutant PR-22 induced with sugarcane bagasse in batch culture. The inhibitory effect of glucose on xylanase activity
was more noticeable for parent strain PN-120 than for mutant PR-22. When 20 mM glucose was added, the xylanolytic activity
decreased 41% compared to the culture grown without glucose in mutant PR-22, whereas in the PN-120 strain the xylanolytic
activity decreased by 49% at the same conditions compared to its own control. Addition of 10 and 15 mM of glucose did not
adversely affect CMCase activity in PR-22, but glucose at 20 mM inhibited the enzymatic activity by 28%. The CMCase activity
of the PN-120 strain was more sensitive to glucose than PR-22, with a reduction of CMCase activity in the range of 20–32%.
Cellobiose had a more significant effect on xylanase and CMCase activities than glucose did in the mutant PR-22 and parent
strain. Nevertheless, the activities under both conditions were always higher in the mutant PR-22 than in the PN-120 strain.
Enzymatic saccharification experiments showed that it is possible to accumulate up to 10 g l−1 of total soluble sugars from pretreated sugarcane bagasse with the concentrated enzymatic crude extract from mutant PR-22. 相似文献
3.
Kathawut Sopalun Kanchit Thammasiri Keiko Ishikawa 《Plant Cell, Tissue and Organ Culture》2010,101(2):143-150
Protocorm-like bodies (PLBs) were induced from shoot tips of Grammatophyllum speciosum, a Thai orchid. The highest frequency of PLBs (93%) were observed on explants incubated on 1/2-Murashige and Skoog (MS) liquid
medium containing 2% (w/v) sucrose without any plant growth regulators (PGRs). Tests with different carbon sources compared
to sucrose revealed that maltose promoted the highest relative growth of G. speciosum PLBs (7-fold increase), while trehalose and sucrose yielded 5-fold and 4-fold increases, respectively. In 1/2 MS liquid medium,
addition of 15 mg/l of chitosan promoted a 7-fold increase in PLB growth while 25 mg/l promoted a 4-fold increase. However,
the relative growth rate in solid culture was significantly lower than that in liquid culture. In addition, chitosan supplementation
in solid medium promoted shoot formation but not rooting. Plantlet regeneration was induced using a combination of NAA and
BA supplementation in 1/2 MS solid medium with optimum induction shoot and root formation at 2.0 mg/l NAA and 1.0 mg/l BA.
Using this protocol, approximately 8 months was required to obtain a hundred plantlets from one shoot tip. The plantlets showed
no changes in ploidy when tested by flow cytometry. 相似文献
4.
Phisit Seesuriyachan Ampin Kuntiya Ken Sasaki Charin Techapun 《World journal of microbiology & biotechnology》2009,25(6):973-979
Lactobacillus casei TISTR 1500 possesses cytoplasmic azoreductase, and converts methyl orange to N,N-dimethyl-p-phenylenediamine and 4-aminobenzenesulfonic acid. In culture growth, the strain completely degraded methyl orange at 200 mg/l,
even though the pH value was lower than 4. The decolorization was inhibited in the growing culture with 800 mg of the dye/l
after incubation for 12 h. The percentage of decolorization and specific decolorization rate with 400 and 800 mg/l were 66
and 15%, and 14.2, and 8.7 mg/gCell/h, respectively. Additionally, a growing culture is more tolerant to a high initial dye
concentration than when using washed cell suspensions supplied with only sucrose. Moreover, incubation of a low cell density
in 600 μM of Na+ and 20 mM of sucrose increased the specific decolorization rate from 2.34 mg/gCell/h (without Na+) to 4.32 mg/gCell/h. However, Na+ had no effect on the enhancement of azoreductase activity in the reaction mixture. 相似文献
5.
Trichoderma reesei endoglucanase I (EGI) was used as a reporter enzyme for screening mutagenized yeast strains for increased ability to produce
protein. Sixteen haploid Saccharomyces cerevisiae strains, transformed with a yeast multicopy vector pALK222, containing the EGI cDNA under the ADH1 promoter, produced EGI activity of 10-5–10-4 g/l. On the average 93% of the total activity was secreted into the culture medium. Two strains with opposite mating types
were mutagenized, and several mutants were isolated possessing up to 45-fold higher EGI activity. The best mutants were remutagenized
and a second-generation mutant, strain 2804, with an additional twofold increase in EGI activity was selected. The mutant
strain 2804 grew more slowly and reached a lower final cell density than the parental strain. In the selective minimal medium,
the 2804 strain produced 40 mg/l immunoreactive EGI protein, but only 2% was active enzyme. In the rich medium the secreted
EGI enzyme stayed active, but without selection pressure the EGI production ceased after 2 days of cultivation, when the strain
2804 had produced 10 mg/l of EGI. A sevenfold difference was found between the parental and the 2804 strain in their total
EGI production relative to cell density. The difference in favour of the mutant strain was also detected on the mRNA level.
The 2804 mutant was found to be more active than the parental strain also in the production of T. reesei cellulases, cellobiohydrolase I, and cellobiohydrolase II.
Received: 22 December 1995/Received revision: 26 February 1996/Accepted: 17 March 1996 相似文献
6.
Kenneth M. Bischoff Siqing Liu Stephen R. Hughes Joseph O. Rich 《Biotechnology letters》2010,32(6):823-828
A strain of Bacillus coagulans that converted mixed sugars of glucose, xylose, and arabinose to l-lactic acid with 85% yield at 50°C was isolated from composted dairy manure. The strain was tolerant to aldehyde growth inhibitors
at 2.5 g furfural/l, 2.5 g 5-hydroxymethylfurfural/l, 2.5 g vanillin/l, and 1.2 g p-hydroxybenzaldehyde/l. In a simultaneous saccharification and fermentation process, the strain converted a dilute-acid hydrolysate
of 100 g corn fiber/l to 39 g lactic acid/l in 72 h at 50°C. Because of its inhibitor tolerance and ability to fully utilize
pentose sugars, this strain has potential to be developed as a biocatalyst for the conversion of agricultural residues into
valuable chemicals. 相似文献
7.
A highly efficient tissue culture system and Agrobacterium-mediated transformation protocol for Chinese upland rice cultivar Handao297 has been established with mature embryos as explants.
Up to 81.2% of mature embryos were induced to regenerate good-quality calli on NB medium (a medium combining N6 macronutrient
components and B5 micronutrient and organic components) containing 3 mg/l 2,4-dichlorophenoxyacetic acid in 10 days. More
than 80% of the calli were morphogenic within 1 week and regenerated green plantlets within 1 month on Murashige and Skoog
medium supplemented with 0.5 mg/l 6-benzyladenine, 0.5 mg/l kinetin, 1 mg/l zeatin, 0.5 mg/l thidizazuron (TDZ), 0.5 mg/l
naphthaleneacetic acid, 0.15 mg/l indoleacetic acid, and 0.15 mg/l indolebutyric acid. This tissue culture system was suitable
for Agrobacterium-mediated transformation of upland rice Handao297. Furthermore, some important factors affecting transformation frequency
were investigated with Agrobacterium strain AGL1 containing the plasmid pCAMBIA1381. The addition of 30 mg/l hygromycin B followed by 60 mg/l hygromycin B to
the selection induction medium facilitated the revival of calli from selection and reduced false positive calli. Hygromycin
B at 10 mg/l was most effective in suppressing non-transgenic callus growth in the differentiation medium. The addition of
TDZ to the differentiation medium promoted the morphogenesis of calli and facilitated the generation of adventitious shoots
by five to tenfold in comparison to medium without TDZ. 相似文献
8.
Maricela Martínez Jiménez Selenia Miranda Bahena César Espinoza Ángel Trigos 《Mycopathologia》2010,169(4):309-314
A red pigment produced by a Mexican isolate of Cercospora piaropi (waterhyacinth pathogen) has been isolated and identified as cercosporin. The kinetic of cercosporin production in culture
media during dark/light regimes was evaluated. When C. piaropi was cultivated in continuous light and potato dextrose broth culture, a maximum of cercosporin production was observed (72.59 mg/l).
Despite other reports, C piaropi Mexican isolate produce cercosporin in dark conditions (25.70 mg/l). The results suggest that production of cercosporin in
C. piaropi-waterhyacinth pathogenesis is an important factor to take into account in biocontrol strategies. 相似文献
9.
10.
Hexavalent chromium reduction and accumulation by Acinetobacter AB1 isolated from Fez tanneries effluents were tested. The effects of some environmental factors such as pH, temperature,
and exposure time on Cr(VI) reduction and resistance were investigated. We found that this strain was able to resist to concentrations
as high as 400 mg/l of Cr(VI). Moreover, pH 10 and the temperature 30°C constitute favourable conditions to the growth and
reduction of Acinetobacter AB1. Complete reduction of Cr(VI) was observed at low initial Cr(VI) concentrations of 50 mg/l after 72 h of incubation.
Furthermore, Transmission electron microscope (TEM) analysis showed morphological changes in AB1 strain due 48H exposure to
100 mg/l chromate concentration and revealed circular electron dense (dark black point) inclusion within the cell cytoplasm
suggesting chromium deposition within the cells. 相似文献
11.
A new 10-hydroxycamptothecin (HCPT)-producing fungus was isolated from Camptotheca
acuminata. The strain was classified as a Xylaria sp. based on the internal transcribed spacer and 18S rDNA gene analysis. All elicitors tested, except methyl jasmonate, increased
HCPT production in submerged culture. The maximum yield was 5.4 mg HCPT/l−1, when salicylic acid was added at 0.1 mM to the culture medium 相似文献
12.
Anaerobic biodegradation of phenol by <Emphasis Type="Italic">Candida albicans</Emphasis> PDY-07 in the presence of 4-chlorophenol 总被引:1,自引:0,他引:1
Guoying Wang Jianping Wen Guanghai Yu Hongmei Li 《World journal of microbiology & biotechnology》2008,24(11):2685-2691
Biodegradation of phenol and 4-chlorophenol (4-cp) using pure culture of Candida albicans PDY-07 under anaerobic condition was studied. The results showed that the strain could completely degrade up to 1,800 mg/l
phenol within 68 h. The capacity of the strain to degrade phenol was higher than that to degrade 4-cp. In the dual-substrate
system, 4-cp intensely inhibited phenol biodegradation. Comparatively, low-concentration phenol from 25 to 150 mg/l supplied
a carbon and energy source for Candida albicans PDY-07 in the early phase of biodegradation and accelerated the assimilation of 4-cp, which resulted in that 50 mg/l 4-cp
was degraded within less time than that without phenol. While the biodegradation of 50 mg/l 4-cp was inhibited in the presence
of 200 mg/l phenol. In addition, the intrinsic kinetics of cell growth and substrate degradation were investigated with phenol
and 4-cp as single and dual substrates in batch cultures. The results demonstrated that the models adequately described the
dynamic behaviors of biodegradation by Candida albicans PDY-07. 相似文献
13.
Zhen-Lin Li Yong-Hong Wang Ju Chu Ying-Ping Zhuang Si-Liang Zhang 《Bioprocess and biosystems engineering》2009,32(5):641-647
Bitespiramycin, a group of 4″-O-acylated spiramycins with 4″-O-isovalerylspiramycins as the major components, is produced by recombinant spiramycin-producing strain Streptomyces spiramyceticus harboring a 4″-O-acyltransferase gene from a carbomycin-producing strain S. mycarofaciens 1748. The effects of leucine feeding on the bitespiramycin fermentation, especially the synthesis of isovalerylspiramycin
components, were investigated. The experiment was initially performed in flask culture under the condition of feeding 15.4 mmol/l
of leucine at 72 h fermentation, and the culture without leucine feeding was used as control. When 15.4 mmol/l leucine was
fed at 72 h, 51.3 ± 0.33% total isovalerylspiramycins was recorded compared to 40.9 ± 0.26% under the control condition after
96 h of fermentation. The improvement of total isovalerylspiramycin content was further achieved in 15 l fermentation when
15.4 mmol/l of leucine was supplemented from 65 to 72 h. These results indicated that isovaleryl group derived from leucine
catabolism could act as the precursor of the 4″ side chain of bitespiramycin, which profoundly enhanced the synthesis of isovalerylspiramycins
in the bitespiramycin complex. 相似文献
14.
Three mutants, isolated by repeated UV mutagenesis of Lactobacillus lactis NCIM 2368, produced increased d-lactic acid concentrations. These mutants were compared with the wild type using 100 g hydrolyzed cane sugar/l in the fermentation
medium. One mutant, RM2-24, produced 81 g lactic acid/l which was over three times that of the wild type. The highest d-lactic acid (110 g/l) in batch fermentation was obtained with 150 g cane sugar/l with a 73% lactic acid yield. The mutant
utilizes cellobiose efficiently, converting it into d-lactic acid suggesting the presence of cellobiase. Thus, this strain could be used to obtain d-lactic acid from cellulosic materials that are pre-hydrolyzed with cellulase. 相似文献
15.
Diastereoselectivity-enhanced mutants of l-threonine aldolase (l-TA) for l-threo-3,4-dihydroxyphenylserine (l-threo-DOPS) synthesis were isolated by error-prone PCR followed by a high-throughput screening. The most improved mutant was achieved
from the mutant T3-3mm2, showing a 4-fold increase over the wild-type l-TA. When aldol condensation activity was examined using whole cells of T3-3mm2, its de was constantly maintained at 55% during
the batch reactions for 80 h, yielding 3.8 mg l-threo-DOPS/ml. 相似文献
16.
Sangwon Jung Sunghyun Moon Kyungsun Lee Youn-Je Park Sewang Yoon Young Je Yoo 《Journal of industrial microbiology & biotechnology》2009,36(12):1467-1471
An immunosuppressant tacrolimus-producing strain of Streptomyces sp. TST8 was isolated and developed by the TS corporation in Korea using the sequential adaptation of media containing tacrolimus
(600–1600 mg/l). The aim of the tacrolimus sequential adaptation protocol was to select those cells with tacrolimus resistance
and to reduce product inhibition of the tacrolimus-producing strain. The developed strains produced more tacrolimus than the
original strain. In particular, the TST10 strain adapted in the medium containing 900 mg/l of tacrolimus produced 972 mg/l
of tacrolimus in the final titer after 7 days of cultivation in a 5-l jar fermenter. This is the largest final titer of tacrolimus
produced by a specific strain to date. Because the sequential adaptation protocol is limited by the solubility of tacrolimus
in water, the final tacrolimus titer of TST11 adapted in the medium containing 1600 mg/l of tacrolimus was lower than that
of TST10. The developed strains and the development method using sequential adaptation can facilitate the efficient and economical
production of tacrolimus. 相似文献
17.
Archana Kumari Gaurav Sharma Sumangala Bhat Ramesh S. Bhat P. U. Krishnaraj M. S. Kuruvinashetti 《Plant Cell, Tissue and Organ Culture》2011,107(2):215-224
An α-amylase signal peptide from rice was synthesized and fused with endochitinase (ech42) gene cloned from Trichoderma virens. The chimeric gene was designated as PSPα-amyech42, and this was transferred to a plant transformation vector, referred to as pMASGK. Leaf explants of tobacco cv White Burley
were co-cultivated with Agrobacterium tumefaciens strain LBA4404 carrying ech42 with its own signal peptide(ech42SP) and PSPα-amyech42(pMASGK) separately. Putative transformants were selected on Murashige and Skoog (MS) medium, supplemented with 1 mg/l bezyladenine
(BA), 0.5 mg/l naphthalene acetic acid(NAA), and containing 200 mg/l kanamycin and 200 mg/l cefotaxime. Transformation was
further confirmed by PCR with specific primers and Southern blot hybridization. Endochitinase secretion was quantified in
1-week-old cell suspension cultures obtained from 3-week-old callus cultures of transformants carrying PSPα-amyech42, transformants with ech42 and of control (untransformed) plant. Callus cultures of PSPα-amyech42 showed higher endochitinase activity (9–12 times) than those carrying ech42SP (7–8 times) in both medium and cell extracts. Media collected (200 μg of total protein) from PSPα-amyech42 suspension cultures in Potato Dextrose Agar plates showed growth inhibition of 73 and 53% against Sclerotium rolfsii and Rhizoctonia bataticola, respectively, whereas media collected (200 μg of total protein) from ech42SP suspension culture showed inhibition of 14 and 24% against Sclerotium rolfsii and Rhizoctonia bataticola, respectively. 相似文献
18.
Kiran D. Pawar Amit V. Yadav Yogesh S. Shouche Shubhada R. Thengane 《Plant Cell, Tissue and Organ Culture》2011,106(2):345-352
The influence of dried cell powder and culture filtrates of endophytic fungi on production of inophyllum in cell suspension
cultures of leaf- and stem-derived callus of Calophyllum inophyllum was investigated. Two fungi, Nigrospora sphaerica and Phoma spp., endophytic to C. inophyllum, were isolated from leaf tissues, and were identified by both 18S rRNA gene amplification and sequencing. Elicitation of
suspension cultures of both callus types of C. inophyllum with dried cell powder and culture filtrates of both fungi consistently elicited production of inophyllum A, B, C, and P.
In comparison to stem-derived callus, suspension cultures of leaf-derived callus enhanced production of most inophyllum. Of
the four inophyllum studied, the highest production of inophyllum A, C, and P was achieved in elicited suspension cultures
of leaf-derived callus. Suspension cultures of stem-derived callus enhanced production only of inophyllum B. When suspension
cultures of leaf-derived callus were elicited with 40 mg dried cell powder of Phoma spp., a level of 751-fold (6.84 mg/100 g elicited biomass) of inophyllum A was produced, compared to control. Whereas, a
level of 414-fold (6.22 mg/100 g elicited biomass) of inophyllum B was produced when suspension cultures of stem-derived callus
were elicited with 20 mg dried cell powder of N. sphaerica. When compared to control, a 10% culture filtrate of N. sphaerica in suspension cultures of leaf-derived callus elicited inophyllum C and P production by 928-fold (7.43 mg/100 g elicited
biomass) and 750-fold (1.5 mg/100 g elicited biomass), respectively. 相似文献
19.
This study examines the effect of four herbicides, quizalafop-p-ethyl, clodinafop, metribuzin and glyphosate, on plant growth promoting activities like phosphate solubilization, siderophores,
indole acetic acid, exo-polysaccharides, hydrogen cyanide and ammonia production by herbicide tolerant Klebsiella sp. strain PS19. The strain was isolated from mustard rhizosphere. The selected herbicides were applied two to three times
at the recommended rates. Klebsiella sp. strain PS19 tolerated a concentration of 1600 μg/ml each of quizalafop-p-ethyl and clodinafop, and 3200 and 2800 μg/ml of metribuzin and glyphosate, respectively. The activities of Klebsiella sp. strain PS19 observed under in vitro environment were persistent in the presence of all herbicides at lower rates. The
plant growth promoting activities even-though decreased regularly, but was not lost completely, as the concentration of each
herbicide was increased from the recommended to three times of higher doses. Among all herbicides, quizalafop-p-ethyl, generally, showed maximum toxicity to plant growth promoting activities of Klebsiella sp. strain PS19. As an example, 40, 80 and 120 μg/l of quizalafop-p-ethyl added to liquid culture Pikovskaya medium, decreased phosphate solubilizing activity of strain PS19 by 93, 95 and 97%,
respectively over untreated control. The study revealed that the higher rates of herbicides though decreased the plant growth
promoting activity but it did not completely inhibit the metabolic activities of strain PS19. The herbicide tolerance together
with growth promoting activities observed under herbicide stress suggests that Klebsiella sp. strain PS19 could be used as bacterial preparation for facilitating the growth and yields of crops even in soils polluted
with herbicides. 相似文献
20.
Eight swainsonine (SW)-degrading bacteria were isolated from the soil where locoweed was buried for 6 months and one of the
strains (YLZZ-1) was selected for further study. Based on morphology, physiologic tests, 16S rRNA gene sequence, and phylogenetic
characteristics, the strain showed the greatest similarity to members of the order Acinetobacters and within the order to members of the Acinetobacter calcoaceticus group. The ability of the strain for degrading SW, as sole carbon source, was investigated under different culture conditions.
The preferential temperature and initial pH for the strain were 25–35°C and 6–9, respectively. The optimal temperature for
the strain was 30°C and the optimal pH was 7.0. There was a positive correlation between degradation rate and inoculation
amount. The concentration of SW affected the degradation ability. When the concentration of SW was lower than 100 mg/l, SW
decreased immediately after incubation, and when the concentration of SW was 200 mg/l, there was an inhibiting effect for
bacteria growth and SW degradation. The strain could degrade SW completely within 14 h when the concentration of SW was 50 mg/l.
These results highlight the potential of this bacterium to be used in detoxifying of SW in livestock consuming locoweed. 相似文献