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1.
Zong-wen Pang Jing-juan Liang Xiao-juan Qin Ji-rui Wang Jia-xun Feng Ri-bo Huang 《Biotechnology letters》2010,32(12):1847-1851
Kluyveromyces marxianus GX-15 was mutated multiple times by alternately treatment with UV irradiation and NTG for two cycles. Four mutant strains
with improved ethanol yield were obtained. The maximum ethanol concentration, ethanol yield coefficient and theoretical ethanol
yield of the best mutant strain, GX-UN120, was 69 g/l, 0.46 g/g and 91%, respectively, when fermenting 150 g glucose/l at
40°C. The corresponding values for GX-15 were 58 g/l, 0.39 g/g and 76%, respectively. GX-UN120 grew well in 11% (v/v) of ethanol,
while GX-15 could not grow when ethanol was greater than 8% (v/v). 相似文献
2.
Gutiérrez-Lomelí M Torres-Guzmán JC González-Hernández GA Cira-Chávez LA Pelayo-Ortiz C Ramírez-Córdova Jde J 《Antonie van Leeuwenhoek》2008,93(4):363-371
This work assessed the effect of the overexpression of ADH1 and HXT1 genes in the Saccharomyces cerevisiae AR5 strain during fermentation of Agave tequilana Weber blue variety must. Both genes were cloned individually and simultaneously into a yeast centromere plasmid. Two transformant
strains overexpressing ADH1 and HXT1 individually and one strain overexpressing both genes were randomly selected and named A1, A3 and A5 respectively. Overexpression
effect on growth and ethanol production of the A1, A3 and A5 strains was evaluated in fermentative conditions in A. tequilana Weber blue variety must and YPD medium. During growth in YPD and Agave media, all the recombinant strains showed lower cell
mass formation than the wild type AR5 strain. Adh enzymatic activity in the recombinant strains A1 and A5 cultivated in A. tequilana and YPD medium was higher than in the wild type. The overexpression of both genes individually and simultaneously had no
significant effect on ethanol formation; however, the fermentative efficiency of the A5 strain increased from 80.33% to 84.57%
and 89.40% to 94.29% in YPD and Agave medium respectively. 相似文献
3.
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
4.
Kenro Tokuhiro Nobuhiro Ishida Eiji Nagamori Satoshi Saitoh Toru Onishi Akihiko Kondo Haruo Takahashi 《Applied microbiology and biotechnology》2009,82(5):883-890
Expression of a heterologous l-lactate dehydrogenase (l-ldh) gene enables production of optically pure l-lactate by yeast Saccharomyces cerevisiae. However, the lactate yields with engineered yeasts are lower than those in the case of lactic acid bacteria because there
is a strong tendency for ethanol to be competitively produced from pyruvate. To decrease the ethanol production and increase
the lactate yield, inactivation of the genes that are involved in ethanol production from pyruvate is necessary. We conducted
double disruption of the pyruvate decarboxylase 1 (PDC1) and alcohol dehydrogenase 1 (ADH1) genes in a S. cerevisiae strain by replacing them with the bovine l-ldh gene. The lactate yield was increased in the pdc1/adh1 double mutant compared with that in the single pdc1 mutant. The specific growth rate of the double mutant was decreased on glucose but not affected on ethanol or acetate compared
with in the control strain. The aeration rate had a strong influence on the production rate and yield of lactate in this strain.
The highest lactate yield of 0.75 g lactate produced per gram of glucose consumed was achieved at a lower aeration rate. 相似文献
5.
Stoutenburg RM Perrotta JA Nakas JP 《Journal of industrial microbiology & biotechnology》2011,38(12):1939-1945
In order to improve the fermentative efficiency of sugar maple hemicellulosic hydrolysates for fuel ethanol production, various
methods to mitigate the effects of inhibitory compounds were employed. These methods included detoxification treatments utilizing
activated charcoal, anion exchange resin, overliming, and ethyl acetate extraction. Results demonstrated the greatest fermentative
improvement of 50% wood hydrolysate (v/v) by Pichia stipitis with activated charcoal treatment. Another method employed to reduce inhibition was an adaptation procedure to produce P. stipitis stains more tolerant of inhibitory compounds. This adaptation resulted in yeast variants capable of improved fermentation
of 75% untreated wood hydrolysate (v/v), one of which produced 9.8 g/l ± 0.6 ethanol, whereas the parent strain produced 0.0 g/l ± 0.0
within the first 24 h. Adapted strains RS01, RS02, and RS03 were analyzed for glucose and xylose utilization and results demonstrated
increased glucose and decreased xylose utilization rates in comparison to the wild type. These changes in carbohydrate utilization
may be indicative of detoxification or tolerance activities related to proteins involved in glucose and xylose metabolism. 相似文献
6.
Syed G. Dastager C. K. Deepa Ashok Pandey 《World journal of microbiology & biotechnology》2011,27(2):259-265
A potential bacterial strain designated as NII-0928 isolated from Western ghat forest soil with multiple plant growth promoting attributes, and it has been identified and characterized. Plant growth promoting
traits were analyzed by determining the P-solubilization efficiency, Indole acetic acid production, HCN, siderophore production
and growth in nitrogen free medium. It was able to solubilize phosphate (76.6 μg ml−1), and produce indole acetic acid (58.9 μg ml−1) at 28 ± 2°C. Qualitative detection of siderophore production and HCN were also observed. At 5°C it was found to express
all the plant growth promotion attributes except HCN production. The ability to colonize roots is a sine qua non condition
for a rhizobacteria to be considered a true plant growth-promoting rhizobacteria (PGPR). 16S rRNA gene sequencing reveals
the identity of the isolate as Serratia nematodiphila with which it shares highest sequence similarity (99.4%). Seed bacterization with black pepper cuttings in greenhouse trials
using Sand: Soil: FYM with three individual experimental sets with their respective control showed clearly the growth promoting
activity. Hence, Serratia nematodiphila NII-0928 is a promising plant growth promoting isolate showing multiple PGPR attributes that can significantly influence
black pepper cuttings. The result of this study provides a strong basis for further development of this strain as a bioinoculants
to attain the desired plant growth promoting activity in black pepper growing fields. 相似文献
7.
Jin-Ha Jeong Young-Dong Jeon O-Mi Lee Jeong-Do Kim Na-Ri Lee Geun-Tae Park Hong-Joo Son 《Biodegradation》2010,21(6):1029-1040
In this study, we isolated and characterized a novel feather-degrading bacterium that shows keratinolytic, antifungal and
plant growth-promoting activities. A bacterium S8 was isolated from forest soil and confirmed to belong to Bacillus subtilis by BIOLOG system and 16S rRNA gene analysis. The improved culture conditions for the production of keratinolytic protease
were 0.1% (w/v) sorbitol, 0.3% (w/v) KNO3, 0.1% (w/v) K2HPO4, 0.06% (w/v) KH2PO4 and 0.04% (w/v) MgCl2·6H2O (pH 8.0 and 30°C), respectively. In the improved medium containing 0.1% (w/v) feather, keratinolytic protease production
was around 53.3 ± 0.3 U/ml at 4 day; this value was 10-fold higher than the yield in the basal feather medium (5.3 ± 0.1 U/ml).
After cultivation for 5 days in the improved medium, intact feather was completely degraded. Feather degradation resulted
in free –SH group, soluble protein and amino acids production. The concentration of free –SH group in the culture medium was
15.5 ± 0.2 μM at 4 days. Nineteen amino acids including all essential amino acids were produced in the culture medium; the
concentration of total amino acid produced was 3360.4 μM. Proline (2809.9 μM), histidine (371.3 μM) and phenylalanine (172.0 μM)
were the major amino acids released in the culture medium. B. subtilis S8 showed the properties related to plant growth promotion: hydrolytic enzymes, ammonification, indoleacetic acid (IAA),
phosphate solubilization, and broad-spectrum antimicrobial activity. Interestingly, the strain S8 grown in the improved medium
produced IAA and antifungal activity, indicating simultaneous production of keratinolytic and antifungal activities and IAA
by B. subtilis S8. These results suggest that B. subtilis S8 could be not only used to improve the nutritional value of feather wastes but also is useful in situ biodegradation of
feather wastes. Furthermore, it could also be a potential biofertilizer or biocontrol agent applicable to crop plant soil. 相似文献
8.
Biswas R Yamaoka M Nakayama H Kondo T Yoshida K Bisaria VS Kondo A 《Applied microbiology and biotechnology》2012,94(3):651-658
Production of 2,3-butanediol by Bacillus subtilis takes place in late-log or stationary phase, depending on the expression of bdhA gene encoding acetoin reductase, which converts acetoin to 2,3-butanediol. The present work focuses on the development of
a strain of B. subtilis for enhanced production of 2,3-butanediol in early log phase of growth cycle. For this, the bdhA gene was expressed under the control of P
alsSD
promoter of AlsSD operon for acetoin fermentation which served the substrate for 2,3-butanediol production. Addition of acetic acid in the
medium induced the production of 2,3-butanediol by 2-fold. Two-step aerobic–anaerobic fermentation further enhanced 2,3-butanediol
production by 4-fold in comparison to the control parental strain. Thus, addition of acetic acid and low dissolved oxygen
in the medium are involved in activation of bdhA gene expression from P
alsSD
promoter in early log phase. Under the conditions tested in this work, the maximum production of 2,3-butanediol, 2.1 g/l
from 10 g/l glucose, was obtained at 24 h. Furthermore, under the optimized microaerophilic condition, the production of 2,3-butanediol
improved up to 6.1 g/l and overall productivity increased by 6.7-fold to 0.4 g/l h in the engineered strain compared to that
in the parental control. 相似文献
9.
Dao-Qiong Zheng Xue-Chang Wu Pin-Mei Wang Xiao-Qin Chi Xiang-Lin Tao Ping Li Xin-Hang Jiang Yu-Hua Zhao 《Journal of industrial microbiology & biotechnology》2011,38(3):415-422
Acetic acid existing in a culture medium is one of the most limiting constraints in yeast growth and viability during ethanol
fermentation. To improve acetic acid tolerance in Saccharomyces cerevisiae strains, a drug resistance marker-aided genome shuffling approach with higher screen efficiency of shuffled mutants was developed
in this work. Through two rounds of genome shuffling of ultraviolet mutants derived from the original strain 308, we obtained
a shuffled strain YZ2, which shows significantly faster growth and higher cell viability under acetic acid stress. Ethanol
production of YZ2 (within 60 h) was 21.6% higher than that of 308 when 0.5% (v/v) acetic acid was added to fermentation medium.
Membrane integrity, higher in vivo activity of the H+-ATPase, and lower oxidative damage after acetic acid treatment are the possible reasons for the acetic acid-tolerance phenotype
of YZ2. These results indicated that this novel genome shuffling approach is powerful to rapidly improve the complex traits
of industrial yeast strains. 相似文献
10.
Ling Zhao Yongming Bao Jingyun Wang Boshi Liu Lijia An 《World journal of microbiology & biotechnology》2009,25(1):57-64
A mutant designated as UV-3 was obtained from wild-type Enterobacter aerogenes 10293 through u.v. radiation. The activities of α-acetolactate decarboxylase (Ald), lactate dehydrogenase (Ldh) and diacetyl
reductase (Dr) in UV-3 were strongly attenuated, with the lowest activities at pH 7.0–7.5, and temperature between 36 and
39°C. Compared to the wild-type, the yield of diacetyl by UV-3 was increased 18.7-fold, up to 1.05 ± 0.01 g l−1. Acetoin and ethanol productions were decreased by 48.4 and 71.4%, respectively, but acetate yield was increased by 34.6%.
Optimum medium for diacetyl production by UV-3 contained 10% glucose, 0.5% peptone, 0.5% yeast extract powder, 0.01% (NH4)2SO4, 0.1% citric acid, 0.2% MnSO4 and 0.2% MgSO4, and this was determined by one-factor-at-a-time approach. Data from the five level central composite designs demonstrated
that initial pH of 7.0, temperature of 37°C and rotational speed of 180 rev/min were optimum processing parameters for diacetyl
production. The maximum yield of diacetyl could reach 1.35 g l−1 in a 5-l bioreactor. These results showed an enhancement of the non-enzymatic oxidative decarboxylation of α-acetolactate
and a decrease in the activities of Ald, Ldh and Dr as a consequence of diacetyl accumulation in UV-3. 相似文献
11.
We report here the degradation of a pesticide, malathion, by Brevibacillus sp. strain KB2 and Bacillus cereus strain PU, isolated from soil samples collected from malathion contaminated field and an army firing range respectively.
Both the strains were cultured in the presence of malathion under aerobic and energy-limiting conditions. Both strains grew
well in the medium having malathion concentration up to 0.15%. Reverse phase HPLC–UV analysis indicated that Strain KB2 was
able to degrade 72.20% of malaoxon (an analogue of malathion) and 36.22% of malathion, while strain PU degraded 87.40% of
malaoxon and 49.31% of malathion, after 7 days of incubation. The metabolites mal-monocarboxylic acid and mal-dicarboxylic
acid were identified by Gas chromatography/mass spectrometry. The factors affecting biodegradation efficiency were investigated
and effect of malathion concentration on degradation rate was also determined. The strain was analyzed for carboxylesterase
activity and maximum activity 210 ± 2.5 U ml−1 and 270 U ± 2.7 ml−1 was observed for strains KB2 and PU, respectively. Cloning and sequencing of putative malathion degrading carboxylesterase
gene was done using primers based PCR approach. 相似文献
12.
Hyun-Soo Kim 《Biotechnology letters》2016,38(11):1955-1960
Objective
To identify a novel gene responsible for organic solvent-tolerance by screening a transposon-mediated deletion mutant library based on Saccharomyces cerevisiae L3262.Results
One strain tolerant of up to 0.5 % (v/v) n-hexane and cyclohexane was isolated. The determination of transposon insertion site identified one gene, YLR162W, and revealed disruption of the ORF of this gene, indicating that organic solvent tolerance can be conferred. Such a tolerant phenotype reverted to the sensitive phenotype on the autologous or overexpression of this gene. This transposon mutant grew faster than the control strain when cultured at 30 °C in YPD medium containing 0.5 % (v/v) n-hexane and cyclohexane respectively.Conclusion
Disruption of YLR162W in S. cerevisiae results in increased tolerance to organic solvents.13.
Tashiro Y Kaneko W Sun Y Shibata K Inokuma K Zendo T Sonomoto K 《Applied microbiology and biotechnology》2011,89(6):1741-1750
We isolated and characterized a d-lactic acid-producing lactic acid bacterium (d-LAB), identified as Lactobacillus delbrueckii subsp. lactis QU 41. When compared to Lactobacillus coryniformis subsp. torquens JCM 1166 T and L. delbrueckii subsp. lactis JCM 1248 T, which are also known as d-LAB, the QU 41 strain exhibited a high thermotolerance and produced d-lactic acid at temperatures of 50 °C and higher. In order to optimize the culture conditions of the QU 41 strain, we examined
the effects of pH control, temperature, neutralizing reagent, and initial glucose concentration on d-lactic acid production in batch cultures. It was found that the optimal production of 20.1 g/l d-lactic acid was acquired with high optical purity (>99.9% of d-lactic acid) in a pH 6.0-controlled batch culture, by adding ammonium hydroxide as a neutralizing reagent, at 43 °C in MRS
medium containing 20 g/l glucose. As a result of product inhibition and low cell density, continuous cultures were investigated
using a microfiltration membrane module to recycle flow-through cells in order to improve d-lactic acid productivity. At a dilution rate of 0.87 h−1, the high cell density continuous culture exhibited the highest d-lactic acid productivity of 18.0 g/l/h with a high yield (ca. 1.0 g/g consumed glucose) and a low residual glucose (<0.1 g/l)
in comparison with systems published to date. 相似文献
14.
Anne Deen Christensen Zsófia Kádár Piotr Oleskowicz-Popiel Mette Hedegaard Thomsen 《Journal of industrial microbiology & biotechnology》2011,38(2):283-289
Ethanol production by K. marxianus in whey from organic cheese production was examined in batch and continuous mode. The results showed that no pasteurization
or freezing of the whey was necessary and that K. marxianus was able to compete with the lactic acid bacteria added during cheese production. The results also showed that, even though
some lactic acid fermentation had taken place prior to ethanol fermentation, K. marxianus was able to take over and produce ethanol from the remaining lactose, since a significant amount of lactic acid was not produced
(1–2 g/l). Batch fermentations showed high ethanol yield (~0.50 g ethanol/g lactose) at both 30°C and 40°C using low pH (4.5)
or no pH control. Continuous fermentation of nonsterilized whey was performed using Ca-alginate-immobilized K. marxianus. High ethanol productivity (2.5–4.5 g/l/h) was achieved at dilution rate of 0.2/h, and it was concluded that K. marxianus is very suitable for industrial ethanol production from whey. 相似文献
15.
16.
Jing Yu Jiaxi Jiang Zian Fang Yuyang Li Hong Lv Jianping Liu 《Biotechnology letters》2010,32(4):507-512
Inulinase gene (Kcinu) derived from Kluyveromyces cicerisporus was expressed extracellularly in Kluyveromyces lactis using an episomal vector directed by Kcinu promoter. The influence of hap1 gene disruption on the expression of inulinase was studied. Inulinase activity in the supernatant of the recombinant Klhap1Δ strain was 391 U ml−1 after cultured 120 h, which was 2.2-fold that of the wild type host. The relative inulinase mRNA level of the Klhap1Δ strain was 11.3-fold that of the wild type strain, and the expression plasmid was more stable in the mutant host. Based on
these results, the disruption of hap1 facilitated the high and stable expression of inulinase controlled by Kcinu promoter in K. lactis. 相似文献
17.
The extracellular inulinase structural gene was isolated from the genomic DNA of the marine yeast Pichia guilliermondii strain 1 by PCR. The gene had an open reading frame of 1,542 bp long encoding an inulinase. The coding region of the gene
was not interrupted by any intron. It encoded 514 amino acid residues of a protein with a putative signal peptide of 18 amino
acids and the calculated molecular mass of 58.04 kDa. The protein sequence deduced from the inulinase structural gene contained
the inulinase consensus sequences (WMNXPNGL) and (RDPKVF). It also had ten conserved putative N-glycosylation sites. The inulinase from P. guilliermondii strain 1 was found to be closely related to that from Kluyveromyces marxianus. The inulinase gene without the signal sequence was subcloned into pPICZαA expression vector and expressed in Pichia pastoris X-33. The expressed fusion protein was analyzed by SDS-PAGE and western blotting and a specific band with molecular mass
of about 60 kDa was found. Enzyme activity assay verified the recombinant protein as an inulinase. A maximum activity of 58.7 ± 0.12 U/ml
was obtained from the culture supernatant of P. pastoris X-33 harboring the inulinase gene. A large amount of monosaccharides, disaccharides and oligosaccharides were detected after
the hydrolysis of inulin with the crude recombinant inulinase. 相似文献
18.
Mycobacterium
chubuense strain NBB4 can grow on both alkanes and alkenes as carbon sources, and was hypothesised to be an effective bioremediation
agent for chlorinated aliphatic pollutants. In this study, the ability of NBB4 to biodegrade vinyl chloride (VC), cis-dichloroethene
(cDCE) and 1,2-dichloroethane (DCA) was investigated under pure-culture conditions and in microcosms. Ethene-grown NBB4 cells
were capable of biodegrading VC and cDCE, while ethane-grown cells could biodegrade cDCE and DCA. The stoichiometry of inorganic
chloride release (1 mol/mol in each case) indicated that VC was completely dechlorinated, while cDCE and DCA were only partially
dechlorinated, yielding chloroacetate in the case of DCA, and unknown metabolites in the case of cDCE. The apparent maximum
specific activities (k) of whole cells against ethene, cDCE, ethane and DCA were 93 ± 4.6, 89 ± 18, 39 ± 5.5, and 4.8 ± 0.9 nmol/min/mg
protein, respectively, while the substrate affinities (KS) of whole cells with the same substrates were 2.0 ± 0.15, 46 ± 11, 11 ± 0.33 and 4.0 ± 3.2 μM, respectively. In microcosms
containing contaminated aquifer sediments and groundwater, NBB4 cells removed 85-95% of the pollutants (cDCE or DCA at 2 mM)
within 24 h, and the cells remained viable for >1 month. Due to its favourable kinetic parameters, and robust survival and
biodegradation activities, strain NBB4 is a promising candidate for bioremediation of chlorinated aliphatic pollutants. 相似文献
19.
Sachin Kumar Surendra P. Singh Indra M. Mishra Dilip K. Adhikari 《Journal of industrial microbiology & biotechnology》2009,36(12):1483-1489
A yeast strain Kluyveromyces sp. IIPE453 (MTCC 5314), isolated from soil samples collected from dumping sites of crushed sugarcane bagasse in Sugar Mill,
showed growth and fermentation efficiency at high temperatures ranging from 45°C to 50°C. The yeast strain was able to use
a wide range of substrates, such as glucose, xylose, mannose, galactose, arabinose, sucrose, and cellobiose, either for growth
or fermentation to ethanol. The strain also showed xylitol production from xylose. In batch fermentation, the strain showed
maximum ethanol concentration of 82 ± 0.5 g l−1 (10.4% v/v) on initial glucose concentration of 200 g l−1, and ethanol concentration of 1.75 ± 0.05 g l−1 as well as xylitol concentration of 11.5 ± 0.4 g l−1 on initial xylose concentration of 20 g l−1 at 50°C. The strain was capable of simultaneously using glucose and xylose in a mixture of glucose concentration of 75 g l−1 and xylose concentration of 25 g l−1, achieving maximum ethanol concentration of 38 ± 0.5 g l−1 and xylitol concentration of 14.5 ± 0.2 g l−1 in batch fermentation. High stability of the strain was observed in a continuous fermentation by feeding the mixture of glucose
concentration of 75 g l−1 and xylose concentration of 25 g l−1 by recycling the cells, achieving maximum ethanol concentration of 30.8 ± 6.2 g l−1 and xylitol concentration of 7.35 ± 3.3 g l−1 with ethanol productivity of 3.1 ± 0.6 g l−1 h−1 and xylitol productivity of 0.75 ± 0.35 g l−1 h−1, respectively. 相似文献
20.
Daisuke Sugimori 《Applied microbiology and biotechnology》2009,82(2):351-357
To develop a microbial treatment of edible oil-contaminated wastewater, microorganisms capable of rapidly degrading edible
oil were screened. The screening study yielded a yeast coculture comprising Rhodotorula pacifica strain ST3411 and Cryptococcus laurentii strain ST3412. The coculture was able to degrade efficiently even at low contents of nitrogen ([NH4–N] = 240 mg/L) and phosphorus sources ([PO4–P] = 90 mg/L). The 24-h degradation rate of 3,000 ppm mixed oils (salad oil/lard/beef tallow, 1:1 w/w) at 20°C was 39.8% ± 9.9% (means ± standard deviations of eight replicates). The highest degradation rate was observed at
20°C and pH 8. In a scaled-up experiment, the salad oil was rapidly degraded by the coculture from 671 ± 52.0 to 143 ± 96.7 ppm
in 24 h, and the degradation rate was 79.4% ± 13.8% (means ± standard deviations of three replicates). In addition, a repetitive
degradation was observed with the cell growth by only pH adjustment without addition of the cells. 相似文献