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1.
Heike Schmidt Rüdiger Bode Ida A. Samsonova Dieter Birnbaum 《Applied microbiology and biotechnology》1989,31(5-6):463-466
Summary Mutants of Candida maltosa were isolated that lacked saccharopine reductase (lys9) and saccharopine dehydrogenase (lys1) and were able to accumulate -aminoadipate--semialdehyde (AASA) in the cell and excrete it into the culture medium. The effects of incubation time, lysine concentration, and carbon and nitrogen sources on AASA production were examined. In the presence of 15 g glucose/1, 1.25 g NH4H2PO4/l and 50 mg l-lysine/l in a minimal salt medium C. maltosa G285 (lys1) produced about 80–90 mg AASA/l during 48 h of growth. A simple and rapid procedure to isolate AASA from the medium using Dowex 50X4 is described. 相似文献
2.
Abstract We isolated from Candida maltosa mutants lacking saccharopine reductase ( lys9 ) and saccharopine dehydrogenase ( lys1 ). They accumulated α-aminoadipate-δ-semialdehyde (AASA) in the cell and excreted it into the culture medium. In the presence of 15 g glucose/l, 1.25 g NH4 H2 PO4 /l and 50 mg l -lysine/l in a minimal salt medium C. maltosa G285 ( lys1 ) produced about 80–90 mg AASA/l within 48 h. It is the first report of lysine-requiring yeast mutants that accumulate and excrete AASA. In contrast, Pichia guilliermondii lys9 mutants lacked this AASA overproduction. The AASA accumulation by C. maltosa mutants may be explained by the low feedback regulation of their homocitrate synthase and the equilibrium of the enzyme reactions involved in the lysine biosynthesis. 相似文献
3.
Krzysztof Kur Iwona Gabriel Joachim Morschhäuser Francesco Barchiesi Elisabetta Spreghini Sławomir Milewski 《Mycopathologia》2010,170(6):397-402
Two genes, LYS21 and LYS22, encoding isoforms of homocitrate synthase, an enzyme catalysing the first committed step in the lysine biosynthetic pathway,
were disrupted in Candida albicans using the SAT1 flipper strategy. The double null lys21Δ/lys22Δ mutant lacked homocitrate synthase activity and exhibited lysine auxotrophy in minimal media that could be fully rescued
by the addition of 0.5–0.6 mM l-lysine. On the other hand, its virulence in vivo in the model of disseminated murine candidiasis appeared identical to that
of the mother, wild-type strain. These findings strongly question a possibility of exploitation of homocitrate synthase and
possibly also other enzymes of the lysine biosynthetic pathway as targets in chemotherapy of disseminated fungal infections. 相似文献
4.
The regulatory properties of four enzymes (homocitrate synthase, -aminoadipate reductase, saccharopine reductase, saccharopine dehydrogenase) involved in the lysine biosynthesis of Pichia guilliermondii were investigated and compared with the regulatory patterns found in other yeast species. The first enzyme of the pathway, homocitrate synthase, is feedback-inhibited by L-lysine. Some other amino acids (-aminoadipate, glutamate, tryptophan, leucine) and lysine analogues are also inhibitors of one or more enzymes. It is shown that only the synthesis of homocitrate synthase is weakly repressed by L-lysine. 相似文献
5.
Summary Eight strains devoid of homocitrate synthase activity were found among lysine requiring mutants of the yeast Saccharomycopsis lipolytica. Genetic analysis of these strains showed that they were all affected at the same locus LYS 1. Three lines of evidence suggest that this locus defines a structural gene for homocitrate synthase. First, the mutations show various degrees of intragenic complementation; it could be shown in some cases that the hybrid enzyme formed in vivo displayed modified properties in vitro. Second, reversion of some of these mutations can result in a modified enzyme (desensitized). Third, a feedback mutant of homocitrate synthase was directly isolated from the wild type strain, and shown to carry a single mutation at or near LYS 1.We also present here the first attempts at genetic fine mapping in Saccharomycopsis lipolytica.Abbreviations used lys
lysine
- arg
arginine
- ade
adenine
- ura
uracile
- TDL
4,5-transdehydrolysine
-
Sm
Saccharomycopsis
- KR
kilorads
Part of a thesis submitted by C.G. to the Université de Paris VI, Paris, France 相似文献
6.
7.
Haifeng Zhang Hongyu Ma Xin Xie Jun Ji Yanhan Dong Yan Du Wei Tang Xiaobo Zheng Ping Wang Zhengguang Zhang 《Proteomics》2014,14(21-22):2508-2522
The rice blast fungus Magnaporthe oryzae encodes eight regulators of G‐protein (GTP‐binding protein) signaling (RGS) proteins MoRgs1–MoRgs8 that orchestrate the growth, asexual/sexual production, appressorium differentiation, and pathogenicity. To address the mechanisms by which MoRgs proteins function, we conducted a 2DE proteome study and identified 82 differentially expressed proteins by comparing five ?Morgs mutants with wild‐type Guy11 strain. We found that the abundances of eight amino acid (AA) biosynthesis or degradation associated proteins were markedly altered in five ?Morgs mutants, indicating one of the main collective roles for the MoRgs proteins is to influence AA metabolism. We showed that MoRgs proteins have distinct roles in AA metabolism and nutrient responses from growth assays. In addition, we characterized MoLys20 (Lys is lysine), a homocitrate synthase, whose abundance was significantly decreased in the ?Morgs mutants. The ?Molys20 mutant is auxotrophic for lys and exogenous lys could partially rescue its auxotrophic defects. Deletion of MoLYS20 resulted in defects in conidiation and infection, as well as pathogenicity on rice. Overall, our results indicate that one of the critical roles for MoRgs proteins is to regulate AA metabolism, and that MoLys20 may be directly or indirectly regulated by MoRgs and participated in lys biosynthesis, thereby affecting fungal development and pathogenicity. 相似文献
8.
O. Bañuelos J. Casqueiro S. Steidl S. Gutiérrez A. Brakhage J. Martín 《Molecular genetics and genomics : MGG》2002,266(5):711-719
There are conflicting reports regarding the cellular localization in Saccharomyces cerevisiae and filamentous fungi of homocitrate synthase, the first enzyme in the lysine biosynthetic pathway. The homocitrate synthase (HS) gene (lys1) of Penicillium chrysogenum was disrupted in three transformants (HS(-)) of the Wis 54-1255 pyrG strain. The three mutants named HS1(-), HS2(-) and HS3(-) all lacked homocitrate synthase activity and showed lysine auxotrophy, indicating that there is a single gene for homocitrate synthase in P. chrysogenum. The lys1 ORF was fused in frame to the gene for the green fluorescent protein (GFP) gene of the jellyfish Aequorea victoria. Homocitrate synthase-deficient mutants transformed with a plasmid containing the lys1-GFP fusion recovered prototrophy and showed similar levels of homocitrate synthase activity to the parental strain Wis 54-1255, indicating that the hybrid protein retains the biological function of wild-type homocitrate synthase. Immunoblotting analysis revealed that the HS-GFP fusion protein is maintained intact and does not release the GFP moiety. Fluorescence microscopy analysis of the transformants showed that homocitrate synthase was mainly located in the cytoplasm in P. chrysogenum; in S. cerevisiae the enzyme is targeted to the nucleus. The control nuclear protein StuA was properly targeted to the nucleus when the StuA (targeting domain)-GFP hybrid protein was expressed in P. chrysogenum. The difference in localization of homocitrate synthase between P. chrysogenum and S. cerevisiae suggests that this protein may play a regulatory function, in addition to its catalytic function, in S. cerevisiae but not in P. chrysogenum. 相似文献
9.
Yuriy V. Pynyaha Yuriy R. Boretsky Daria V. Fedorovych Lubov R. Fayura Andriy I. Levkiv Vira M. Ubiyvovk Olha V. Protchenko Caroline C. Philpott Andriy A. Sibirny 《Biometals》2009,22(6):1051-1061
Pichia guilliermondii is a representative of yeast species that overproduce riboflavin (vitamin B2) in response to iron deprivation. P. guilliermondii
YFH1 gene coding for frataxin homologue, eukaryotic mitochondrial protein involved in iron trafficking and storage, was identified
and deleted. Constructed P. guilliermondii Δyfh1 mutant grew very poorly in a sucrose-containing synthetic medium supplemented with sulfate or sulfite as a sole sulfur source.
Addition of sodium sulfide, glutathione, cysteine, methionine, N-acetyl-l-cysteine partially restored growth rate of the mutant suggesting that it is impaired in sulfate assimilation. Cellular iron
content in Δyfh1 mutant was ~3–3.5 times higher as compared to the parental strain. It produced 50–70 times more riboflavin in iron sufficient
synthetic media relative to the parental wild-type strain. Biomass yield of the mutant in the synthetic glutathione containing
medium supplemented with glycerol as a sole carbon source was 1.4- and 2.6-fold increased as compared to sucrose and succinate
containing media, respectively. Oxygen uptake of the Δyfh1 mutant on sucrose, glycerol or succinate, when compared to the parental strain, was decreased 5.5-, 1.7- and 1.5-fold, respectively.
Substitution of sucrose or glycerol in the synthetic iron sufficient medium with succinate completely abolished riboflavin
overproduction by the mutants. Deletion of the YFH1 gene caused hypersensitivity to hydrogen peroxide and exogenously added riboflavin and led to alterations in superoxide dismutase
activities. Thus, deletion of the gene coding for yeast frataxin homologue has pleiotropic effect on metabolism in P. guilliermondii. 相似文献
10.
Mariana Fensterseifer Fabricio Patricia Valente Marco Antônio Záchia Ayub 《Biotechnology progress》2019,35(6):e2895
We studied the biotechnological potential of the recently isolated yeast Meyerozyma guilliermondii BI281A to produce polyunsaturated fatty acids and ethanol, comparing products yields using glucose, raw glycerol from biodiesel synthesis, or whey permeate as substrates. The yeast metabolism was evaluated for different C/N ratios (100:1 and 50:1). Results found that M. guilliermondii BI281A was able to assimilate all tested substrates, and the most efficient conversion obtained was observed using raw glycerol as carbon source (C/N ratio 50:1), concerning biomass formation (5.67 g·L−1) and lipid production (1.04 g·L−1), representing 18% of dry cell weight. Bioreactors experiments under pH and aeration-controlled conditions were conducted. Obtained fatty acids were composed of ~67% of unsaturated fatty acids, distributed as palmitoleic acid (C16:1, 9.4%), oleic acid (C18:1, 47.2%), linoleic acid (C18:2 n−6, 9.6%), and linolenic acid (C18:3 n−3, 1.3%). Showing fermentative metabolism, which is unusual for oleaginous yeasts, M. guilliermondii produced 13.7 g·L−1 of ethanol (yields of 0.27) when growing on glucose medium. These results suggest the promising use of this uncommonly studied yeast to produce unsaturated fatty acids and ethanol using cheap agro-industrial residues as substrates in bioprocess. 相似文献
11.
Rogério S. Pereira Solange I. Mussatto Inês C. Roberto 《Journal of industrial microbiology & biotechnology》2011,38(1):71-78
The inhibitory action of acetic acid, ferulic acid, and syringaldehyde on metabolism of Candida guilliermondii yeast during xylose to xylitol bioconversion was evaluated. Assays were performed in buffered and nonbuffered semidefined
medium containing xylose as main sugar (80.0 g/l), supplemented or not with acetic acid (0.8–2.6 g/l), ferulic acid (0.2–0.6 g/l),
and/or syringaldehyde (0.3–0.8 g/l), according to a 23 full factorial design. Since only individual effects of the variables were observed, assays were performed in a next step
in semidefined medium containing different concentrations of each toxic compound individually, for better understanding of
their maximum concentration that can be present in the fermentation medium without affecting yeast metabolism. It was concluded
that acetic acid, ferulic acid, and syringaldehyde are compounds that may affect Candida guilliermondii metabolism (mainly cell growth) during bioconversion of xylose to xylitol. Such results are of interest and reveal that complete
removal of toxic compounds from the fermentation medium is not necessary to obtain efficient conversion of xylose to xylitol
by Candida guilliermondii. Fermentation in buffered medium was also considered as an alternative to overcome the inhibition caused by these toxic compounds,
mainly by acetic acid. 相似文献
12.
Camille L. Hyde Gregory C. Phillips 《In vitro cellular & developmental biology. Plant》1996,32(2):72-80
Summary Chile pepper (Capsicum annuum L.) plants were regenerated from cotyledon explantsin vitro in four major stages: bud induction, bud enlargement, shoot elongation, and root development. Bud induction medium contained
0.5 mg/L (2.9μM) indole-3-acetic acid and 2 mg/L (8.9 μM) N6-benzyladenine. Bud enlargement occurred, and an occasional shoot appeared when medium with 2 mg/L (6μM) gibberellic acid, 2 mg/L (8.9 μM) N6-benzyladenine, and 5 mg/L (29.4 μM) silver nitrate was used. Most shoots elongated after placement on a third medium without plant growth regulators or on fresh
plates of bud enlargement medium. Incubations were for 2, 2, and 4 weeks, respectively, at 28.5°C and continuous light. Treatment
with silver nitrate was necessary for multiple shoot production and elongation to occur in the third culture stage and was
most effective when present in the second-stage medium but not in the bud induction medium. Sixteen to 26% of the shoots rooted
in medium with 1 mg/L (5.4 μM) 1-naphthaleneacetic acid after 1 month. Additional shoots transferred to a second rooting medium with 0.1 or 1.0 mg/L (0.54
or 5.4 μM) 1-naphthaleneacetic acid developed roots, increasing the overall rooting efficiency to 70–72%. Most rooted shoots grew well
and produced viable seeds when grown in the greenhouse. Other cytokinins tested for plant regeneration were zeatin and thidiazuron.
Zeatin induced few shoots and fewer well-developed plants. Thidiazuron induced multiple shoots 4 months after culture began,
but many were small and did not elongate further. Phytagar tissue culture grade proved superior to other agars tested, increasing
bud induction frequency from 0-33% to 80–93% and eliminating explant hyperhydricity. 相似文献
13.
《Biocatalysis and Biotransformation》2013,31(1):34-38
AbstractThe effect of NADP+ and glucose-6-phosphate (G6P) on the biotransformation of D-xylose to xylitol by cells of Candida guilliermondii permeabilized with surfactant Triton X-100 was evaluated. The experimental runs were performed with 12 g L?1 of permeabilized cells and a reaction medium composed of Tris–HCl buffer (0.1 M pH 7), D-xylose (57 g L?1), and MgCl2.6H2O (5 mM). The levels of NADP+ (from 0.0 to 1.7 mM) and G6P (from 0.00 to 0.17 M) were varied according a 22-full factorial composed design. Under optimized conditions (NADP+ 0.5 mM and 0.05 M G6P), the xylitol volumetric productivity (QP) and yield factor (YP/S) predicted were 1.86 ± 0.03 g L?1 h? 1 and 0.64 ± 0.03 g g?1, respectively. These values were 94% and 19% higher than those obtained with unpermeabilized cells under fermentation conditions (0.97 g L?1 h?1 and 0.53 g g?1, respectively). On the basis of the results, it can be concluded that xylitol production by biotransformation with cells of C. guilliermondii permeabilized with Triton X-100 is a promising alternative to the fermentative process. 相似文献
14.
Effects of yeast antagonist in combination with UV-C treatment on postharvest diseases of pear fruit 总被引:1,自引:0,他引:1
The yeast antagonist Candida guilliermondii and ultraviolet-C (UV-C) treatment were investigated for controlling infection following artificial inoculation with Penicillium expansum or Botrytis cinerea, or natural infection in pear fruit stored at 20°C. Applied separately, both C. guilliermondii and UV-C (5 kJ m−2) effectively inhibited decay caused by P. expansum or B. cinerea, and natural infection. The combination of C. guilliermondii and UV-C showed better control efficacy. Application of UV-C did not affect the growth of C. guilliermondii in pear fruit wounds, while UV-C induced a significant increase in the activities of chitinase, β-1,3-glucanase, catalase
and peroxidase in pear fruit. The mechanism by which UV-C enhanced the biocontrol efficacy of C. guilliermondii may be related to the elicitation of defense responses in pear fruit. The combination of C. guilliermondii and UV-C radiation could be a promising method for the control of P. expansum and B. cinerea in pear fruit. 相似文献
15.
Enhanced Xylitol Production by Precultivation of Candida guilliermondii Cells in Sugarcane Bagasse Hemicellulosic Hydrolysate 总被引:1,自引:0,他引:1
The present work evaluated the key enzymes involved in xylitol production (xylose reductase [XR] and xylitol dehydrogenase
[XDH]) and their correlation with xylose, arabinose, and acetic acid assimilation during cultivation of Candida guilliermondii FTI 20037 cells in sugarcane bagasse hemicellulosic hydrolysate. For this purpose, inocula previously grown either in sugarcane
bagasse hemicellulosic hydrolysate (SBHH) or in semidefined medium (xylose as a substrate) were used. The highest xylose/acetic
acid consumption ratio (1.78) and the lowest arabinose consumption (13%) were attained in the fermentation using inoculum
previously grown in semidefined medium (without acetic acid and arabinose). In this case, the highest values of XR (1.37 U
mg prot−1) and XDH (0.91 U mg prot−1) activities were observed. The highest xylitol yield (∼0.55 g g−1) and byproducts (ethanol and glycerol) formation were not influenced by inoculum procedure. However, the cell previously
grown in the hydrolysate was effective in enhancing xylitol production by keeping the XR enzyme activity at high levels (around
0.99 U·mgprot−1), reducing the XDH activity (34.0%) and increasing xylitol volumetric productivity (26.5%) with respect to the inoculum cultivated
in semidefined medium. Therefore, inoculum adaptation to SBHH was shown to be an important strategy to improve xylitol productivity. 相似文献
16.
Batch fermentations for xylitol production were conducted using Candida boidinii (BCRC 21432), C. guilliermondii (BCRC 21549), C. tropicalis (BCRC 20520), C. utilis (BCRC 20334), and P. anomala (BCRC 21359) together with a mixture of sugars simulating lignocellulosic hydrolysates as the carbon source. C. tropicalis had the highest bioconversion yield (YP/S) of 0.79 g g−1 (g xylitol·g xylose−1) over 48 h. Additional fermentations with C. tropicalis achieved YP/S values of 0.6 and 0.39 g g−1 after 96 and 72 h using urea and soybean meal as the nitrogen sources, respectively. Ethanol and arabitol were also produced
in all fermentation. Xylitol in the fermentation broth was recovered by cross-flow ultrafiltration. With prior application
of 2 mg polydiallyl dimethylammonium chloride l−1 on the membrane surface, protein in the permeate was reduced from 7.1 to 1.5 mg l−1 after 2 h. 相似文献
17.
The effect of glycerol on xylose-to-xylitol bioconversion by Candida guilliermondii was evaluated by its addition (0.7 and 6.5 g/l) to semidefined media (xylose as a substrate). The glycerol concentrations
were chosen based on the amounts produced during previous studies on xylitol production by C. guilliermondii. Medium without glycerol addition (control) and medium containing glycerol (53 g/l) in substitution to xylose were also evaluated.
According to the results, the addition of 0.7 g/l glycerol to the fermentation medium favored not only the yield (Y
P/S = 0.78 g/g) but also the xylitol productivity (Q
P = 1.13 g/l/h). During the xylose-to-xylitol bioconversion, the formation of byproducts (glycerol and ethanol) was observed
for all conditions employed. In relation to the cellular growth, glycerol as the only carbon source for C. guilliermondii was better than xylose or xylose and glycerol mixtures, resulting in a maximum cellular concentration (5.34 g/l). 相似文献
18.
T. Chakbavarty J. G. Norcini J. H. Aldrich R. S. Kalmbacher 《In vitro cellular & developmental biology. Plant》2001,37(5):550-554
Summary Creeping bluestem (Schizachyrium scoparium (Michx.) Nash var. stoloniferum (Nash) J. Wipff) embryogenic callus growing on solid medium was used to establish a cell suspension culture in Murashige
and Skoog (MS) basal medium supplemented with 1.5 mg l−1 (6.8 μM) 2,4-dichlorophenoxyacetic acid (2,4-D), 0.2 mg l−1 (0.88 μM) 6-benzylaminopurine (BA), 0.5 mg l−1 (1.4 μM) zeatin, 0.2 mg l−1 (0.58 μM) gibberellic acid (GA3), and 10% (v/v) of coconut water (CW). Pro-embryos from suspension culture matured on semi-solid MS medium in about 18 wk,
and were then cultured on semi-solid MS medium without growth regulators for 2–3 wk. Shoots were regenerated on MS basal medium
supplemented with 3.0 mg L−1 (13.6 μM) 2,4-D, 1.0 mg l−1 (4.4 μM) BA, 1.0 mg l−1 (2.9 μM) GA3, 0.5 mg l−1 (2.7 μM) 1-naphthaleneacetic acid (NAA), 500 mg l−1 easein hydrolysate, and 10% (v/v) CW. Rooted plantlets were successfully accelimatized to greenhouse and outdoor conditions.
Using this protocol, it would be possible to produce at least 1300 fully acclimatized plantlets annually. 相似文献
19.
Archana Giri Paramvir Singh Ahuja P. V. Ajay Kumar 《Plant Cell, Tissue and Organ Culture》1993,32(2):213-218
Plants were obtained via somatic embryogenesis in callus derived from in vitro raised leaf and petiole explants of Aconitum heterophyllum Wall. Callus was induced on a Murashige-Skoog medium supplemented with either 2,4-dichlorophenoxy acetic acid (2,4-d 1 mg l-1) and kinetin (KN 0.5 mg l-1) with coconut water (CW 10% v/v) or naphthalene acetic acid (NAA 5 mg l-1) and benzylaminopurine (BAP 1 mg l-1). Somatic embryos appeared after 2–3 months or 2 subculture passages when 2,4-d or NAA induced source of the callus was transferred to a MS medium containing BAP (1 mg l-1) and NAA (0.1 mg l-1). For successful plantlet formation, the somatic embryos were transferred to a medium containing 1/4 strength MS nutrient with indole-3-butyric acid (IBA 1 mg l-1). Alternatively, the somatic embryos were dipped in a concentrated solution of IBA for 5 min and placed on a hormone free medium. Complete plantlets were formed after 4 weeks and were transferred successfully to soil.CIMAP Publication No. 1020. 相似文献
20.
Summary Callus of Phalaenopsis Nebula was induced from seed-derived protocorms on 1/2 Murashige and Skoog (MS) basal medium plus 0–1.0 mg l−1 (0–4.52 μM) N-phenyl-N′-1,2,3,-thiadiazol-5-yl urea (TDZ) and/or 0–10 mg l−1 (0–45.24 μ M) 2,4-dichlorophenoxyacetic acid (2,4-D). Protocorms 2 mo. old performed better than 1-mo.-old protocorms for callus induction.
More calluses formed on 1/2 MS basal medium supplemented with 0.1–1.0 mg l−1 (0.45–4.52 μM) TDZ. These calluses could be maintained by subculturing every month with basal medium supplemented with 0.5 mg l−1 (2.27 μM) TDZ and 0.5 mg l−1 (2.26 μM) 2,4-D. Protocorm-like bodies were formed, and plants regenerated from these calluses on 1/2 MS basal medium alone or supplemented
with 0.1–1.0 mg l−1 (0.45–4.52 μM) TDZ. Plantlets were then potted on sphagnum moss in the greenhouse and grew well. No chromosomal abnormalities were found
among the root-tip samples of 21 of the regenerated plantlets that were successfully acclimatized. 相似文献