共查询到20条相似文献,搜索用时 31 毫秒
1.
We studied the growth characteristics and oxidative capacities of Acetobacter aceti IFO 3281 in batch and chemostat cultures. In batch culture, glycerol was the best growth substrate and growth on ethanol occurred only after 6 days delay, although ethanol was rapidly oxidized to acetic acid. In continuous culture, both glycerol and ethanol were good growth substrates with similar characteristics. Resting cells in a bioreactor oxidized ribitol to l-ribulose with a maximal specific rate of 1.2 g g–1 h–1). The oxidation of ribitol was inhibited by ethanol but not by glycerol. Biomass yield (YSX; C-mmol/C-mmol) on ethanol and glycerol was low (0.21 and 0.17, respectively). In the presence of ribitol the yield was somewhat higher (0.25) with ethanol but lower (0.13) with glycerol, with respectively lower and higher CO2 production. In chemostat cultures the oxidation rate of ribitol was unaffected by ethanol or glycerol. Cell-free extract oxidized ethanol very slowly but not ribitol; the oxidative activity was located in the cell membrane fraction. Enzymatic activities of some key metabolic enzymes were determined from steady-state chemostat with ethanol, glycerol, or ethanol/glycerol mixture as a growth limiting substrate. Based on the measured enzyme activities, metabolic pathways are proposed for ethanol and glycerol metabolism. 相似文献
2.
3.
Skory CD 《Journal of industrial microbiology & biotechnology》2003,30(1):22-27
This work demonstrates the first example of a fungal lactate dehydrogenase (LDH) expressed in yeast. A L(+)-LDH gene, ldhA, from the filamentous fungus Rhizopus oryzae was modified to be expressed under control of the Saccharomyces cerevisiae adh1 promoter and terminator and then placed in a 2μ-containing yeast-replicating plasmid. The resulting construct, pLdhA68X,
was transformed and tested by fermentation analyses in haploid and diploid yeast containing similar genetic backgrounds. Both
recombinant strains utilized 92 g glucose/l in approximately 30 h. The diploid isolate accumulated approximately 40% more
lactic acid with a final concentration of 38 g lactic acid/l and a yield of 0.44 g lactic acid/g glucose. The optimal pH for
lactic acid production by the diploid strain was pH 5. LDH activity in this strain remained relatively constant at 1.5 units/mg
protein throughout the fermentation. The majority of carbon was still diverted to the ethanol fermentation pathway, as indicated
by ethanol yields between 0.25–0.33 g/g glucose. S. cerevisiae mutants impaired in ethanol production were transformed with pLdhA68X in an attempt to increase the lactic acid yield by
minimizing the conversion of pyruvate to ethanol. Mutants with diminished pyruvate decarboxylase activity and mutants with
disrupted alcohol dehydrogenase activity did result in transformants with diminished ethanol production. However, the efficiency
of lactic acid production also decreased.
Electronic Publication 相似文献
4.
D'Alva T Lara C Estrada-Torres A Castillo-Guevara C 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(7):707-712
The sporocarps of hypogeous and epigeous fungi are important dietary items for forest dwelling rodents in temperate and tropical
forests throughout the world. However, results of some pioneering works have demonstrated that fungi cannot be considered
as nutritionally high-quality food items for some mycophagous small rodents. According to these studies, when mycophagous
rodents feed on fungus, they showed a minimal digestibility, but whether this applies to most rodent species that include
fungi in their diets is unknown. In this study, we experimentally evaluated body mass changes and feed preferences in captive
deer (Peromyscus maniculatus) and volcano (P. alstoni) mice when fed on epigeous fungus (Russula occidentalis). In experiment 1, the animals were fed with fungus as the only feedstuff in comparison to regular rodent chow and oat. In
experiment 2, the animals were fed with fungus in a free-choice arrangement together with equal amounts of rodent chow and
oat. Both species lost ∼15% of their body mass within 4 days when fed on fungus alone, but gained 5–10% body mass during the
same time period when ingesting oat and rodent chow, respectively, as the only feedstuff. However, in contrast, in the free-choice
arrangement with all three feedstuffs, both species gained 20–30% body mass, and showed the highest feed preference for fungus
followed by oat and rodent chow. In addition, apparent digestibility of energy and nitrogen were analyzed in both rodent species,
which were 50–60% for fungus, whereas approximately 90–94% for rodent chow and oat. According to our results, animals need
to supplement their diets with alternative high-quality food items in order to maintain and increase their body mass, suggesting
that epigeous fungi are only of moderate nutritional value for small rodents. Futures studies should focus on exploring the
importance of a mixture of fungal species in the diet of small mycophagous rodents. 相似文献
5.
Mucor circinelloides is being investigated as a possible host for the production of heterologous proteins. Thus, the environmental conditions defining the physiology and morphology of this dimorphic fungus have been investigated in submerged batch cultivation. The optimal conditions for growth of each form have been defined. Pure cultures of the multi-polar budding yeast form could be obtained under anaerobic conditions (with 70% N2/30% CO2 or 100% N2 as the sparge gas and without aeration). The highest maximum specific growth rate (0.30 h(-1)) was obtained in anaerobic cultivation, the yield of biomass on glucose (Y(SX)) was 0.12 (c-mole basis). A high maximum specific growth rate was obtained when the organism grew as the filamentous form under aerobic conditions (0.25 h(-1)), with a Y(SX) of 0.24 (c-mole basis). The maximum specific growth rates achieved are comparable to most industrial filamentous fungi under similar growth conditions. High levels of ethanol were observed with all growth conditions. The overriding effector of morphological development was found to be oxygen. In batch cultures it was therefore possible to induce the dimorphic shift by controlling the influent gas atmosphere. A specific growth rate of 0.19 h(-1) was maintained during the shift from the yeast to the filamentous form. 相似文献
6.
1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) was used as the substrate for a degradation experiment with the white
rot fungi Phlebia lindtneri GB-1027 and Phlebia brevispora TMIC34596, which are capable of degrading polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated biphenyls (PCBs). Pure culture of P. lindtneri and P. brevispora with DDT (25 μmol l−1) showed that 70 and 30% of DDT, respectively, disappeared in a low-nitrogen medium after a 21-day incubation period. The
metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS). Both fungi metabolized DDT to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane
(DDD), 2,2-bis(4-chlorophenyl)acetic acid (DDA) and 4,4-dichlorobenzophenone (DBP). Additionally, DDD was converted to DDA
and DBP. DDA was converted to DBP and 4,4-dichlorobenzhydrol (DBH). While DBP was treated as substrate, DBH and three hydroxylated
metabolites, including one dihydroxylated DBP and two different isomers of monohydroxylated DBH, were produced from fungal
cultures, and these hydroxylated metabolites were efficiently inhibited by the addition of a cytochrome P-450 inhibitor, piperonyl
butoxide. These results indicate that the white rot fungi P. lindtneri and P. brevispora can degrade DBP/DBH through hydroxylation of the aromatic ring. Moreover, the single-ring aromatic metabolites, such as 4-chlorobenzaldehyde, 4-chlorobenzyl alcohol and 4-chlorobenzoic acid, were found as metabolic
products of all substrate, demonstrating that the cleavage reaction of the aliphatic-aryl carbon bond occurs in the biodegradation
process of DDT by white rot fungi. 相似文献
7.
Pakala SB Gorla P Pinjari AB Krovidi RK Baru R Yanamandra M Merrick M Siddavattam D 《Applied microbiology and biotechnology》2007,73(6):1452-1462
A soil bacterium capable of utilizing methyl parathion as sole carbon and energy source was isolated by selective enrichment
on minimal medium containing methyl parathion. The strain was identified as belonging to the genus Serratia based on a phylogram constructed using the complete sequence of the 16S rRNA. Serratia sp. strain DS001 utilized methyl parathion, p-nitrophenol, 4-nitrocatechol, and 1,2,4-benzenetriol as sole carbon and energy sources but could not grow using hydroquinone
as a source of carbon. p-Nitrophenol and dimethylthiophosphoric acid were found to be the major degradation products of methyl parathion. Growth on
p-nitrophenol led to release of stoichiometric amounts of nitrite and to the formation of 4-nitrocatechol and benzenetriol.
When these catabolic intermediates of p-nitrophenol were added to resting cells of Serratia sp. strain DS001 oxygen consumption was detected whereas no oxygen consumption was apparent when hydroquinone was added to
the resting cells suggesting that it is not part of the p-nitrophenol degradation pathway. Key enzymes involved in degradation of methyl parathion and in conversion of p-nitrophenol to 4-nitrocatechol, namely parathion hydrolase and p-nitrophenol hydroxylase component “A” were detected in the proteomes of the methyl parathion and p-nitrophenol grown cultures, respectively. These studies report for the first time the existence of a p-nitrophenol hydroxylase component “A”, typically found in Gram-positive bacteria, in a Gram-negative strain of the genus
Serratia.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
8.
9.
Some strains of white rot fungi, non-lignolytic fungi and litter-decomposing basidiomycetes have been recognized as PAH degraders.
The purpose of our research was to enlarge the scope of PAH-degrading fungi and explore the huge endophytic microorganism
resource for bioremediation of PAHs. In this study, phenanthrene was used as a model PAHs compound. Nine strains of endophytic
fungi isolated from four kinds of plant from Eupharbiaceae were screened for degradation of phenanthrene. The endophytic fungus Ceratobasidum stevensii (strain B6) isolated from Bischofia polycarpam showed high degradation efficiency and was selected for further studies. Into the fungal culture, 100 mg l−1 phenanthrene was added, and after 10 days of incubation, about 89.51% of the phenanthrene was removed by strain B6. Extracellular
ligninolytic enzyme activities of strain B6 were tested. The results showed that manganese peroxidase [MnP] was the predominant
ligninolytic enzyme and that its production was greatly induced by the presence of phenanthrene. To confirm the involvement
of MnP in phenanthrene degradation, promotion and inhibition studies on MnP in different concentration level of Mn2+ and NaN3 were performed. Additionally, fungal mycelium-free and resuspended experiments were carried out. The results showed no apparent
correlation between MnP activity and phenanthrene degradation. The mycelium and fresh medium were the crucial factors affecting
the degradation of phenanthrene. To date, this is the first report on PAH degradation by Ceratobasidum stevensii. This study suggests that endophytic fungi might be a novel and important resource for microorganisms that have PAH-degrading
capabilities. 相似文献
10.
Xuechang Wu Lijie Zhang Xinna Jin Yahong Fang Ke Zhang Lei Qi Daoqiong Zheng 《Biotechnology letters》2016,38(7):1097-1106
11.
Nitrosomonas europaea is a chemolithoautotrophic nitrifier, a gram-negative bacterium that can obtain all energy required for growth from the oxidation of ammonia to nitrite, and this may be beneficial for various biotechnological and environmental applications. However, compared to other bacteria, growth of ammonia oxidizing bacteria is very slow. A prerequisite to produce high cell density N. europaea cultures is to minimize the concentrations of inhibitory metabolic by-products. During growth on ammonia nitrite accumulates, as a consequence, N. europaea cannot grow to high cell concentrations under conventional batch conditions. Here, we show that single-vessel dialysis membrane bioreactors can be used to obtain substantially increased N. europaea biomasses and substantially reduced nitrite levels in media initially containing high amounts of the substrate. Dialysis membrane bioreactor fermentations were run in batch as well as in continuous mode. Growth was monitored with cell concentration determinations, by assessing dry cell mass and by monitoring ammonium consumption as well as nitrite formation. In addition, metabolic activity was probed with in vivo acridine orange staining. Under continuous substrate feed, the maximal cell concentration (2.79?×?1012/L) and maximal dry cell mass (0.895 g/L) achieved more than doubled the highest values reported for N. europaea cultivations to date. 相似文献
12.
Lomascolo A Uzan-Boukhris E Herpoël-Gimbert I Sigoillot JC Lesage-Meessen L 《Applied microbiology and biotechnology》2011,92(6):1129-1149
The genus Pycnoporus forms a cosmopolitan group of four species belonging to the polyporoid white-rot fungi, the most representative group of
homobasidiomycetes causing wood decay. Pycnoporus fungi are listed as food- and cosmetic-grade microorganisms and emerged in the early 1990s as a genus whose biochemistry,
biodegradation and biotechnological properties have since been progressively detailed. First highlighted for their original
metabolic pathways involved in the functionalization of plant cell wall aromatic compounds to yield high-value molecules,
e.g. aromas and antioxidants, the Pycnoporus species were later explored for their potential to produce various enzymes of industrial interest, such as hydrolases and
oxidases. However, the most noteworthy feature of the genus Pycnoporus is its ability to overproduce high redox potential laccase—a multi-copper extracellular phenoloxidase—as the predominant
ligninolytic enzyme. A major potential use of the Pycnoporus fungi is thus to harness their laccases for various applications such as the bioconversion of agricultural by-products and
raw plant materials into valuable products, the biopulping and biobleaching of paper pulp and the biodegradation of organopollutants,
xenobiotics and industrial contaminants. All the studies performed in the last decade show the genus Pycnoporus to be a strong contender for white biotechnology. In this review, we describe the properties of Pycnoporus fungi in relation to their biotechnological applications and potential. 相似文献
13.
Peng Geng Yin Xiao Yun Hu Haiye Sun Wei Xue Liang Zhang Gui-yang Shi 《World journal of microbiology & biotechnology》2016,32(9):145
Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8–65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains. 相似文献
14.
Uricase is an important medical enzyme which can be used to determine urate in clinical analysis, to therapy gout, hyperuricemia, and tumor lysis syndrome. Uricase of Candida utilis was successfully expressed in Hansenula polymorpha under the control of methanol oxidase promoter using Saccharomyces cerevisiae alpha-factor signal peptide as the secretory sequence. Recombinant H. polymorpha MU200 with the highest extracellular uricase production was characterized with three copies of expression cassette and selected for process optimization for the production of recombinant enzyme. Among the parameters investigated in shaking flask cultures, the pH value of medium and inoculum size had great influence on the recombinant uricase production. The maximum extracellular uricase yield of 2.6 U/ml was obtained in shaking flask culture. The yield of recombinant uricase was significantly improved by the combined use of a high cell-density cultivation technique and a pH control strategy of switching culture pH from 5.5 to 6.5 in the induction phase. After induction for 58 h, the production of recombinant uricase reached 52.3 U/ml (about 2.1 g/l of protein) extracellularly and 60.3 U/ml (about 2.4 g/l) intracellularly in fed-batch fermentation, which are much higher than those expressed in other expression systems. To our knowledge, this is the first report about the heterologous expression of uricase in H. polymorpha. 相似文献
15.
Peter S. R. Metivier Edward C. Yeung Kamlesh R. Patel Trevor A. Thorpe 《In vitro cellular & developmental biology. Plant》2007,43(2):119-123
Studies on rooting of microshoots of smokebush (Cotinus coggygria Mill, var. Royal Purple), a woody ornamental, were carried out in vitro. Microshoots were rooted in a mixed-auxin regime (indole 3-acetic acid, indole butyric acid [IBA], and naphthalene acetic
acid) or singly in the above auxins and the 2,4 dichlorophenoxyacetic acid (2,4-D) over a wide concentration range. Indole
butyric acid at 10 μM proved to be the most suitable treatment, producing less basal callus, 100% rooting, and earlier root
emergence than the other treatments. No roots were formed with 2,4-D. A 6-day root induction period was obtained with 10 μM
of IBA. Histological studies revealed increased mitotic activity after 3 d in culture in the medullary ray cells, which led
to root primordium formation, several of which were formed simultaneously around the base of the explant. The vascular tissues
of these primordia connected to those of the explant, and roots began to emerge from the base by day 10. Thus, direct rhizogenesis
occurred with the IBA treatment, as opposed to the roots that were formed in the basal callus under the mixed-auxin regime. 相似文献
16.
KiBeom Lee 《World journal of microbiology & biotechnology》2007,23(9):1317-1320
Lactobacillus
delbrueckii subsp. lactis strains were developed having increased activity, by gradually acclimatizing the bacteria to acidic conditions over repeated
batch culture. Cells from one batch culture were used as the inoculum for the subsequent batch culture and thereby an adapted
strain of Lactobacillus was obtained showing improved lactic acid productivity, cell growth and total glucose utilization. Furthermore, the acclimatized
cells used significantly less nitrogen for a given level of lactic acid production, which is significant from an industrial
point of view. The developed procedure decreases fermentation time and nutrient use, leading to reduced operation costs, while
providing a lactic acid yield superior to previously reported methods. 相似文献
17.
Victor E. Balderas-Hernández Kevin Correia Radhakrishnan Mahadevan 《Journal of industrial microbiology & biotechnology》2018,45(8):735-751
Toxic concentrations of monocarboxylic weak acids present in lignocellulosic hydrolyzates affect cell integrity and fermentative performance of Saccharomyces cerevisiae. In this work, we report the deletion of the general catabolite repressor Mig1p as a strategy to improve the tolerance of S. cerevisiae towards inhibitory concentrations of acetic, formic or levulinic acid. In contrast with the wt yeast, where the growth and ethanol production were ceased in presence of acetic acid 5 g/L or formic acid 1.75 g/L (initial pH not adjusted), the m9 strain (Δmig1::kan) produced 4.06?±?0.14 and 3.87?±?0.06 g/L of ethanol, respectively. Also, m9 strain tolerated a higher concentration of 12.5 g/L acetic acid (initial pH adjusted to 4.5) without affecting its fermentative performance. Moreover, m9 strain produced 33% less acetic acid and 50–70% less glycerol in presence of weak acids, and consumed acetate and formate as carbon sources under aerobic conditions. Our results show that the deletion of Mig1p provides a single gene deletion target for improving the acid tolerance of yeast strains significantly. 相似文献
18.
Guoying Wang Jianping Wen Hongmei Li Chunsheng Qiu 《Journal of industrial microbiology & biotechnology》2009,36(6):809-814
Strain Candida albicans PDY-07 was used to study the anaerobic biodegradation of phenol and m-cresol as single and dual substrates in batch cultures. The strain had a higher potential to degrade phenol than m-cresol. The cell growth kinetics of batch cultures with various initial m-cresol concentrations was investigated, and the Haldane kinetic model adequately described the dynamic behavior of cell growth
on m-cresol. When cells grew on the mixture of phenol and m-cresol, substrate interactions were observed. Phenol inhibited the utilization of m-cresol; on the other hand, m-cresol also inhibited the degradation of phenol. However, the presence of low-concentration phenol enhanced m-cresol biodegradation; 100 mg/l m-cresol could be completely degraded within a shorter period of time than m-cresol alone in the presence of 150–300 mg/l phenol. The maximum m-cresol biodegradation rate was obtained at the existence of 200 mg/l phenol. Phenol was preferably utilized by the strain
as a carbon and energy source. In addition, a sum kinetics model was used to describe the cell growth behavior in binary mixture
of phenol and m-cresol, and the interaction parameters were determined. The model adequately predicted the growth kinetics and the interaction
between the substrates. 相似文献
19.
Adam Dawidziuk Delfina Popiel Magda Luboinska Michal Grzebyk Maciej Wisniewski Grzegorz Koczyk 《Journal of applied genetics》2017,58(2):277-285
Due to its superior antioxidant capabilities and higher activity than other carotenoids, astaxanthin is used widely in the nutraceutical and medicine industries. The most prolific natural producer of astaxanthin is the unicellular green microalga Haematococcus pluvialis. The correct identification of any contaminants in H. pluvialis cultures is both essential and nontrivial for several reasons. Firstly, while it is possible to distinguish the main microalgal contaminant Coelastrella sp. (in H. pluvialis cultures), in practice, it is frequently a daunting and error-prone task for personnel without extensive experience in the microscopic identification of algal species. Secondly, the undetected contaminants may decrease or stop production of astaxanthin. Lastly, the presence of other contaminants such as fungi can eventually infect and destroy the whole algae collection. In this study, high-resolution melting (HRM) analysis was developed to detect microalgal and fungal contamination. The developed diagnostic procedure allowed to distinguish pure H. pluvialis samples from cultures contaminated with low amounts (1.25 ng/ml) of microalgal DNA and fungal DNA (2.5 ng/ml). Such discrimination is not possible with the use of microscopy observations and allows fast and efficient collection testing. 相似文献
20.
MA Nakisah MY Ida Muryany H Fatimah R Nor Fadilah MR Zalilawati S Khamsah M Habsah 《World journal of microbiology & biotechnology》2012,28(3):1237-1244
Crude methanol extracts of a marine sponge, Aaptos
aaptos, collected from three different localities namely Kapas, Perhentian and Redang Islands, Terengganu, Malaysia, were tested
in vitro on a pathogenic Acanthamoeba castellanii (IMR isolate) to examine their anti-amoebic potential. The examination of anti-Acanthamoebic activity of the extracts was
conducted in 24 well plates for 72 h at 30 °C. All extracts possessed anti-amoebic activity with their IC50 values ranging from 0.615 to 0.876 mg/mL. The effect of the methanol extracts on the surface morphology of A. castellanii was analysed under scanning electron microscopy. The ability of the extracts to disrupt the amoeba cell membrane was indicated
by extensive cell’s blebbing, changes in the surface morphology, reduced in cell size and with cystic appearance of extract-treated
Acanthamoeba. Number of acanthapodia and food cup was also reduced in this Acanthamoeba. Morphological criteria of apoptosis in Acanthamoeba following treatment with the sponge’s extracts was determined by acridine orange-propidium iodide staining and observed by
fluorescence microscopy. By this technique, apoptotic and necrotic cells can be visualized and quantified. The genotoxic potential
of the methanol extracts was performed by the alkaline comet assay. All methanol extracts used were significantly induced
DNA damage compared to untreated Acanthamoeba by having high percentage of scores 1, 2, and 3 of the DNA damage. Results from cytotoxicity and genotoxicity studies carried
out in the present study suggest that all methanol extracts of A. aaptos have anti-amoebic properties against A. castellanii. 相似文献