scholarly journals Statistical optimisation of polyhydroxyalkanoate production in Bacillus endophyticus using sucrose as sole source of carbon

2021 ◽  
Author(s):  
M. Geethu ◽  
H. Raghu Chandrashekar ◽  
M. S. Divyashree
Keyword(s):  
Carbon Source ◽  
Large Scale ◽  
Wild Type Strain ◽  
Maximum Yield ◽  
Sole Source ◽  
Wild Type ◽  
Bacillus Endophyticus ◽  
Pha Production ◽  
Promising Source ◽  
The Given

AbstractMicroorganisms have been contemplated as a promising source for the inexhaustible synthesis of many novel materials utilizing renewable sources. Among many of such products, polyhydroxyalkanoate (PHA) remains as an essential biodegradable polymer with functions similar to conventional plastics. Bacillus endophyticus is capable of accumulating biopolymer PHA in nutrient limiting conditions with excess of carbon source. Screening and optimizing the parameters for increased PHA production was done statistically. The optimized medium gave a maximum yield of 46.57% which was in well agreement with the given predicted value provided by response surface methodology model yield of 47.02%. Optimal media conditions when extrapolated in bioreactor gave an even higher production percentage of 49.9. This is the first report highlighting 49% of polyhydroxybutyrate statistically using sucrose as a source. The main highlight of the study was the use of wild type strain for producing high quality PHA using simple carbon source which can be a starting platform for using this strain for large scale PHA production industrially. FTIR and 1HNMR analysis confirmed the polymer produced.

Development of mutants of Gliocladium virens tolerant to benomyl

1990 ◽  
Vol 36 (7) ◽  
pp. 484-489 ◽  
Author(s):  
G. C. Papavizas ◽  
D. P. Roberts ◽  
K. K. Kim
Keyword(s):  
Carbon Source ◽  
Type Strain ◽  
Wild Type Strain ◽  
Carbon Sources ◽  
Sclerotium Rolfsii ◽  
Wild Type ◽  
Gliocladium Virens ◽  
Rhizosphere Competence ◽  
Filter Paper Cellulase ◽  
Type Strains

Aqueous suspensions of conidia of Gliocladium virens strains Gl-3 and Gl-21 were exposed to both ultraviolet radiation and ethyl methanesulfonate. Two mutants of Gl-3 and three of Gl-21 were selected for tolerance to benomyl at 10 μg∙mL−1, as indicated by growth and conidial germination on benomyl-amended potato dextrose agar. The mutants differed considerably from their respective wild-type strains in appearance, growth habit, sporulation, carbon-source utilization, and enzyme activity profiles. Of 10 carbon sources tested, cellobiose, xylose, and xylan were the best for growth, galactose and glucose were intermediate, and arabinose, ribose, and rhamnose were poor sources of carbon. The wild-type strains and the mutants did not utilize cellulose as the sole carbon source for growth. Two benomyl-tolerant mutants of Gl-3 produced less cellulase (β-1,4-glucosidase, carboxymethylcellulase, filter-paper cellulase) than Gl-3. In contrast, mutants of Gl-21 produced more cellulase than the wild-type strain. Only Gl-3 provided control of blight on snapbean caused by Sclerotium rolfsii. Wild-type strain Gl-21 and all mutants from both strains were ineffective biocontrol agents. Key words: Gliocladium, benomyl tolerance, Sclerotium, rhizosphere competence.

scholarly journals Engineering of Bacillus megaterium for improving PHA production from glycerol

2019 ◽  
pp. 64-72
Author(s):  
Javier Ricardo Gómez Cardozo ◽  
Rodrigo Velasco Buscheli ◽  
Carlos del Cerro Sánchez ◽  
Isabel de la Mata Riesco ◽  
Amanda Lucía Mora Martínez
Keyword(s):  
Carbon Source ◽  
Bacillus Megaterium ◽  
Recombinant Strain ◽  
Glycerol Dehydrogenase ◽  
Wild Type ◽  
Pha Production ◽  
Glycerol Uptake

There are a few PHA-producer bacteria that can uptake glycerol to produce this biopolymer. Among them, Bacillus megaterium LVN01 has demonstrated to be able to grow up using glycerol as a carbon source. Glycerol dehydrogenase (GD) plays a key role in the synthesis of PHA from glycerol. In this study, the improvement of glycerol uptake by a recombinant strain of B. megaterium carrying pHT01-bmgd was evaluated in order to enhance PHA production. The biomass and PHA production were evaluated and compared to wild-type. It was determined that the PHA produced by both strains was PHB and the highest improvement in PHB yield was 226% at 30 h.

scholarly journals Glutathione Is Required by Rhizobium etli for Glutamine Utilization and Symbiotic Effectiveness

2012 ◽  
Vol 25 (3) ◽  
pp. 331-340 ◽  
Author(s):  
Rosarita Taté ◽  
Michele Cermola ◽  
Anna Riccio ◽  
Graciana Diez-Roux ◽  
Eduardo J. Patriarca
Keyword(s):  
Wild Type Strain ◽  
Sole Source ◽  
Symbiotic Effectiveness ◽  
Rhizobium Etli ◽  
Wild Type ◽  
Synthesis Inhibitor ◽  
Symbiotic Efficiency ◽  
In The Wild ◽  
Degradation Ability ◽  
Glutamine Uptake

Here, we provide genetic and biochemical evidence indicating that the ability of Rhizobium etli bacteria to efficiently catabolize glutamine depends on its ability to produce reduced glutathione (l-γ-glutamyl-l-cysteinylglycine [GSH]). We find that GSH-deficient strains, namely a gshB (GSH synthetase) and a gor (GSH reductase) mutant, can use different amino acids, including histidine, alanine, and asparagine but not glutamine, as sole source of carbon, energy, and nitrogen. Moreover, l-buthionine(S,R)-sulfoximine, a GSH synthesis inhibitor, or diamide that oxidizes GSH, induced the same phenotype in the wild-type strain. Among the steps required for its utilization, glutamine uptake, occurring through the two well-characterized carriers (Aap and Bra systems) but not glutamine degradation or respiration, was largely reduced in GSH-deficient strains. Furthermore, GSH-deficient mutants of R. etli showed a reduced symbiotic efficiency. Exogenous GSH was sufficient to rescue glutamine uptake or degradation ability, as well as the symbiotic effectiveness of GSH mutants. Our results suggest a previously unknown GSH–glutamine metabolic relationship in bacteria.

scholarly journals Characterization of the Second LysR-Type Regulator in the Biphenyl-Catabolic Gene Cluster of Pseudomonas pseudoalcaligenes KF707

2003 ◽  
Vol 185 (12) ◽  
pp. 3575-3582 ◽  
Author(s):  
Takahito Watanabe ◽  
Hidehiko Fujihara ◽  
Kensuke Furukawa
Keyword(s):  
Gene Cluster ◽  
Wild Type Strain ◽  
Dienoic Acid ◽  
Sole Source ◽  
Wild Type ◽  
Transcription Level ◽  
Pseudomonas Pseudoalcaligenes ◽  
High Level ◽  
Lysr Family

ABSTRACT Pseudomonas pseudoalcaligenes KF707 possesses a biphenyl-catabolic (bph) gene cluster consisting of bphR1A1A2-(orf3)-bphA3A4BCX0X1X2X3D. The bphR1 (formerly orf0) gene product, which belongs to the GntR family, is a positive regulator for itself and bphX0X1X2X3D. Further analysis in this study revealed that a second regulator belonging to the LysR family (designated bphR2) is involved in the regulation of the bph genes in KF707. The bphR2 gene was not located near the bph gene cluster, and its product (BphR2) exhibited a high level of similarity to NahR (the naphthalene- and salicylate-catabolic regulator belonging to the LysR family) in plasmid NAH7 of Pseudomonas putida. A strain containing a disrupted bphR2 gene failed to grow on biphenyl as a sole source of carbon, and the BphD (2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid hydrolase) activity was significantly reduced compared to that of wild-type strain KF707. Furthermore, the same strain exhibited extremely low transcription of bphR1, bphA1, bphC, bphX0, and bphD. However, when the bphR2 gene was provided in trans to the bphR2-disrupted strain, the transcription level of these genes was restored. These results indicate that bphR2 regulates the bph genes positively as a second regulator together with BphR1.

scholarly journals Megaplasmid pRme2011a of Sinorhizobium meliloti Is Not Required for Viability

2000 ◽  
Vol 182 (12) ◽  
pp. 3582-3586 ◽  
Author(s):  
Ivan J. Oresnik ◽  
Shu-Lin Liu ◽  
Christopher K. Yost ◽  
Michael F. Hynes
Keyword(s):  
Gel Electrophoresis ◽  
Type Strain ◽  
Sinorhizobium Meliloti ◽  
Wild Type Strain ◽  
Sole Source ◽  
Pulsed Field Gel Electrophoresis ◽  
Selection Strategy ◽  
Wild Type ◽  
Defined Media

ABSTRACT We report the curing of the 1,360-kb megaplasmid pRme2011a fromSinorhizobium meliloti strain Rm2011. With a positive selection strategy that utilized Tn5B12-S containing thesacB gene, we were able to cure this replicon by successive rounds of selecting for deletion formation in vivo. Subsequent Southern blot, Eckhardt gel, and pulsed-field gel electrophoresis analyses were consistent with the hypothesis that the resultant strain was indeed missing pRme2011a. The cured derivative grew as well as the wild-type strain in both complex and defined media but was unable to use a number of substrates as a sole source of carbon on defined media.

scholarly journals The BfeR Regulator Mediates Enterobactin-Inducible Expression of Bordetella Enterobactin Utilization Genes

2004 ◽  
Vol 186 (21) ◽  
pp. 7302-7311 ◽  
Author(s):  
Mark T. Anderson ◽  
Sandra K. Armstrong
Keyword(s):  
Wild Type Strain ◽  
Transcriptional Regulator ◽  
Sole Source ◽  
Bordetella Bronchiseptica ◽  
Transcriptional Analysis ◽  
Respiratory Pathogens ◽  
Wild Type ◽  
Outer Membrane Receptor ◽  
Reading Frame ◽  
Type Strains

ABSTRACT Utilization of the enterobactin siderophore by the respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica is dependent on the BfeA outer membrane receptor. This study determined that production of BfeA was increased significantly in iron-starved bacteria upon supplementation of cultures with enterobactin. A 1.01-kb open reading frame, designated bfeR, encoding a predicted positive transcriptional regulator of the AraC family was identified upstream and divergently oriented from bfeA. In iron-depleted cultures containing enterobactin, a Bordetella bfeR mutant exhibited markedly decreased BfeA receptor production compared to that of the wild-type strain. Additionally, B. pertussis and B. bronchiseptica bfeR mutants exhibited impaired growth with ferric enterobactin as the sole source of iron, demonstrating that effective enterobactin utilization is bfeR dependent. Transcriptional analysis using bfeA-lacZ reporter fusions in wild-type strains demonstrated that bfeA transcription was stimulated in iron-depleted conditions in the presence of enterobactin, compared to modest expression levels in cultures lacking enterobactin. In contrast, bfeA transcription in B. pertussis and B. bronchiseptica bfeR mutants was completely unresponsive to the enterobactin inducer. bfeA transcriptional analyses of a bfeA mutant demonstrated that induction by enterobactin did not require BfeA receptor-mediated uptake of the siderophore. These studies establish that bfeR encodes an enterobactin-dependent positive regulator of bfeA transcription in these Bordetella species.

scholarly journals Metabolic Flux Analysis of Escherichia coli creB and arcA Mutants Reveals Shared Control of Carbon Catabolism under Microaerobic Growth Conditions

2009 ◽  
Vol 191 (17) ◽  
pp. 5538-5548 ◽  
Author(s):  
Pablo I. Nikel ◽  
Jiangfeng Zhu ◽  
Ka-Yiu San ◽  
Beatriz S. Méndez ◽  
George N. Bennett
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Type Strain ◽  
Wild Type Strain ◽  
Tricarboxylic Acid Cycle ◽  
Pyruvate Dehydrogenase Complex ◽  
Building Blocks ◽  
Flux Analysis ◽  
Wild Type ◽  
Mutant Strains

ABSTRACT Escherichia coli has several elaborate sensing mechanisms for response to availability of oxygen and other electron acceptors, as well as the carbon source in the surrounding environment. Among them, the CreBC and ArcAB two-component signal transduction systems are responsible for regulation of carbon source utilization and redox control in response to oxygen availability, respectively. We assessed the role of CreBC and ArcAB in regulating the central carbon metabolism of E. coli under microaerobic conditions by means of 13C-labeling experiments in chemostat cultures of a wild-type strain, ΔcreB and ΔarcA single mutants, and a ΔcreB ΔarcA double mutant. Continuous cultures were conducted at D = 0.1 h−1 under carbon-limited conditions with restricted oxygen supply. Although all experimental strains metabolized glucose mainly through the Embden-Meyerhof-Parnas pathway, mutant strains had significantly lower fluxes in both the oxidative and the nonoxidative pentose phosphate pathways. Significant differences were also found at the pyruvate branching point. Both pyruvate-formate lyase and the pyruvate dehydrogenase complex contributed to acetyl-coenzyme A synthesis from pyruvate, and their activity seemed to be modulated by both ArcAB and CreBC. Strains carrying the creB deletion showed a higher biomass yield on glucose compared to the wild-type strain and its ΔarcA derivative, which also correlated with higher fluxes from building blocks to biomass. Glyoxylate shunt and lactate dehydrogenase were active mainly in the ΔarcA strain. Finally, it was observed that the tricarboxylic acid cycle reactions operated in a rather cyclic fashion under our experimental conditions, with reduced activity in the mutant strains.

scholarly journals Purification, Characterization, and Overexpression of Flavin Reductase Involved in Dibenzothiophene Desulfurization byRhodococcus erythropolis D-1

2001 ◽  
Vol 67 (3) ◽  
pp. 1179-1184 ◽  
Author(s):  
Toshiyuki Matsubara ◽  
Takashi Ohshiro ◽  
Yoshihiro Nishina ◽  
Yoshikazu Izumi
Keyword(s):  
Wild Type Strain ◽  
Specific Activity ◽  
Rhodococcus Erythropolis ◽  
Sole Source ◽  
Flavin Mononucleotide ◽  
Flavin Reductase ◽  
Wild Type ◽  
Reductase Gene ◽  
Terminal Amino

ABSTRACT The dibenzothiophene (DBT)-desulfurizing bacterium,Rhodococcus erythropolis D-1, removes sulfur from DBT to form 2-hydroxybiphenyl using four enzymes, DszC, DszA, DszB, and flavin reductase. In this study, we purified and characterized the flavin reductase from R. erythropolis D-1 grown in a medium containing DBT as the sole source of sulfur. It is conceivable that the enzyme is essential for two monooxygenase (DszC and DszA) reactions in vivo. The purified flavin reductase contains no chromogenic cofactors and was found to have a molecular mass of 86 kDa and four identical 22-kDa subunits. The enzyme catalyzed NADH-dependent reduction of flavin mononucleotide (FMN), and the Km values for NADH and FMN were 208 and 10.8 μM, respectively. Flavin adenine dinucleotide was a poor substrate, and NADPH was inert. The enzyme did not catalyze reduction of any nitroaromatic compound. The optimal temperature and optimal pH for enzyme activity were 35°C and 6.0, respectively, and the enzyme retained 30% of its activity after heat treatment at 80°C for 30 min. The N-terminal amino acid sequence of the purified flavin reductase was identical to that of DszD of R. erythropolis IGTS8 (K. A. Gray, O. S. Pogrebinsky, G. T. Mrachko, L. Xi, D. J. Monticello, and C. H. Squires, Nat. Biotechnol. 14:1705–1709, 1996). The flavin reductase gene was amplified with primers designed by using dszD ofR. erythropolis IGTS8, and the enzyme was overexpressed inEscherichia coli. The specific activity in crude extracts of the overexpressed strain was about 275-fold that of the wild-type strain.

scholarly journals Physiological Role of β-Phosphoglucomutase inLactococcus lactis

2001 ◽  
Vol 67 (10) ◽  
pp. 4546-4553 ◽  
Author(s):  
Fredrik Levander ◽  
Ulrika Andersson ◽  
Peter Rådström
Keyword(s):  
Growth Rate ◽  
Carbon Source ◽  
Specific Growth Rate ◽  
Type Strain ◽  
Wild Type Strain ◽  
Specific Growth ◽  
Maximum Specific Growth Rate ◽  
Wild Type ◽  
Cell Extracts

ABSTRACT A β-phosphoglucomutase (β-PGM) mutant of Lactococcus lactis subsp. lactis ATCC 19435 was constructed using a minimal integration vector and double-crossover recombination. The mutant and the wild-type strain were grown under controlled conditions with different sugars to elucidate the role of β-PGM in carbohydrate catabolism and anabolism. The mutation did not significantly affect growth, product formation, or cell composition when glucose or lactose was used as the carbon source. With maltose or trehalose as the carbon source the wild-type strain had a maximum specific growth rate of 0.5 h−1, while the deletion of β-PGM resulted in a maximum specific growth rate of 0.05 h−1 on maltose and no growth at all on trehalose. Growth of the mutant strain on maltose resulted in smaller amounts of lactate but more formate, acetate, and ethanol, and approximately 1/10 of the maltose was found as β-glucose 1-phosphate in the medium. Furthermore, the β-PGM mutant cells grown on maltose were considerably larger and accumulated polysaccharides which consisted of α-1,4-bound glucose units. When the cells were grown at a low dilution rate in a glucose and maltose mixture, the wild-type strain exhibited a higher carbohydrate content than when grown at higher growth rates, but still this content was lower than that in the β-PGM mutant. In addition, significant differences in the initial metabolism of maltose and trehalose were found, and cell extracts did not digest free trehalose but only trehalose 6-phosphate, which yielded β-glucose 1-phosphate and glucose 6-phosphate. This demonstrates the presence of a novel enzymatic pathway for trehalose different from that of maltose metabolism in L. lactis.

scholarly journals Comparative study on growth and morphological characteristics of a wild type strain Rhizobium spp. (RCA-220) and a genetically engineered E. coli BL21

2014 ◽  
Vol 20 ◽  
pp. 75-82
Author(s):  
MM Rahman ◽  
M Salah Uddin ◽  
S Zaman ◽  
MA Saleh ◽  
AE Ekram ◽  
...  
Keyword(s):  
Growth Rate ◽  
Carbon Source ◽  
Salt Concentration ◽  
Type Strain ◽  
Wild Type Strain ◽  
Genetically Modified ◽  
Growth Characteristics ◽  
Wild Type ◽  
E Coli ◽  
Rhizobium Spp

Context: Comparison between a wild type strain Rhizobium spp. (RCA-220) and a genetically modified strain E. coli BL21 in context of growth features. Objective: To observe the comparative growth characteristics of a genetically modified E. coli BL21 and an isolated wild type strain Rhizobium spp. (RCA-220). Materials and Methods: Different kinds of investigations were accomplished in both Luria-Bertani (LB) liquid and semi-solid media to observe the growth and maintenance of these strains. For the isolation of Rhizobium spp. selective Yeast Extract Manitol Agar (YEMA) was used. Colony morphology, pH, temperature, carbon source, salt concentration and light were taken under consideration and optimized for growth characteristics. Results: For the strain E. coli BL21, the maximum growth rate was 1.9 at incubation time 72 h, pH 7.2, temperature 37°C (optimized) while for Rhizobium spp. the growth rate was significantly higher (OD 2) at pH 6.8, temperature 28°C (optimized). Among all used carbon sources, strains grown in the medium supplemented with peptone showed rapid and good performance. So, peptone was proved as the best carbon source for both strains. The maximum growths of these strains were observed at 0g/100ml NaCl salt concentration. RCA-220 strain was comparatively more tolerable to salt than E. coli BL21 strain. In this work, E. coli BL21 showed rapid and good performance in presence of light while Rhizobium spp. showed better performance in absence of light. Statistical analysis showed that the growth rate of Rhizobium spp. was significantly higher than E. coli BL21. Conclusion: From the experimental results, it can be concluded that naturally obtained microbial strains were stable and could tolerate any stress condition where the modified strains lose their growth capability and the overall growth performances were reduced or slowed down than the wild type strain. DOI: http://dx.doi.org/10.3329/jbs.v20i0.17718 J. bio-sci.  20:  75-82, 2012

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