| 1. |
- Ahmed, Engy, et al.
(författare)
-
Siderophores in environmental research : roles and applications
- 2014
-
Ingår i: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 7:3, s. 196-208
-
Forskningsöversikt (refereegranskat)abstract
- Siderophores are organic compounds with low molecular masses that are produced by microorganisms and plants growing under low iron conditions. The primary function of these compounds is to chelate the ferric iron [Fe(III)] from different terrestrial and aquatic habitats and thereby make it available for microbial and plant cells. Siderophores have received much attention in recent years because of their potential roles and applications in various areas of environmental research. Their significance in these applications is because siderophores have the ability to bind a variety of metals in addition to iron, and they have a wide range of chemical structures and specific properties. For instance, siderophores function as biocontrols, biosensors, and bioremediation and chelation agents, in addition to their important role in weathering soil minerals and enhancing plant growth. The aim of this literature review is to outline and discuss the important roles and functions of siderophores in different environmental habitats and emphasize the significant roles that these small organic molecules could play in applied environmental processes.
|
|
| 2. |
- Chen, Genqiang, et al.
(författare)
-
Comparison of productivity and quality of bacterial nanocellulose synthesized using culture media based on seven sugars from biomass
- 2019
-
Ingår i: Microbial Biotechnology. - : John Wiley & Sons. - 1751-7907 .- 1751-7915. ; 12:4, s. 677-687
-
Tidskriftsartikel (refereegranskat)abstract
- Komagataeibacter xylinus ATCC 23770 was statically cultivated in eight culture media based on different carbon sources, viz. seven biomass‐derived sugars and one sugar mixture. The productivity and quality of the bacterial nanocellulose (BNC) produced in the different media were compared. Highest volumetric productivity, yield on consumed sugar, viscometric degree of polymerization (DPv, 4350–4400) and thermal stability were achieved using media based on glucose or maltose. Growth in media based on xylose, mannose or galactose resulted in lower volumetric productivity and DPv, but in larger fibril diameter and higher crystallinity (76–78%). Growth in medium based on a synthetic sugar mixture resembling the composition of a lignocellulosic hydrolysate promoted BNC productivity and yield, but decreased fibril diameter, DPv, crystallinity and thermal stability. This work shows that volumetric productivity, yield and properties of BNC are highly affected by the carbon source, and indicates how industrially relevant sugar mixtures would affect these characteristics.
|
|
| 3. |
- Cvijovic, Marija, 1977, et al.
(författare)
-
Mathematical models of cell factories: moving towards the core of industrial biotechnology
- 2011
-
Ingår i: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 4:5, s. 572-584
-
Tidskriftsartikel (refereegranskat)abstract
- Industrial biotechnology involves the utilization of cell factories for the production of fuels and chemicals. Traditionally, the development of highly productive microbial strains has relied on random mutagenesis and screening. The development of predictive mathematical models provides a new paradigm for the rational design of cell factories. Instead of selecting among a set of strains resulting from random mutagenesis, mathematical models allow the researchers to predict in silico the outcomes of different genetic manipulations and engineer new strains by performing gene deletions or additions leading to a higher productivity of the desired chemicals. In this review we aim to summarize the main modelling approaches of biological processes and illustrate the particular applications that they have found in the field of industrial microbiology.
|
|
| 4. |
- Gustavsson, Martin, 1984-, et al.
(författare)
-
Prospects of microbial cell factories developed through systems metabolic engineering
- 2016
-
Ingår i: Microbial Biotechnology. - : John Wiley & Sons. - 1751-7907 .- 1751-7915. ; 9:5, s. 610-617
-
Tidskriftsartikel (refereegranskat)abstract
- While academic-level studies on metabolic engineering of microorganisms for production of chemicals and fuels are ever growing, a significantly lower number of such production processes have reached commercial-scale. In this work, we review the challenges associated with moving from laboratory-scale demonstration of microbial chemical or fuel production to actual commercialization, focusing on key requirements on the production organism that need to be considered during the metabolic engineering process. Metabolic engineering strategies should take into account techno-economic factors such as the choice of feedstock, the product yield, productivity and titre, and the cost effectiveness of midstream and downstream processes. Also, it is important to develop an industrial strain through metabolic engineering for pathway construction and flux optimization together with increasing tolerance to products and inhibitors present in the feedstock, and ensuring genetic stability and strain robustness under actual fermentation conditions.
|
|
| 5. |
- Guzman-Chavez, F., et al.
(författare)
-
Mechanism and regulation of sorbicillin biosynthesis by Penicillium chrysogenum
- 2017
-
Ingår i: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 10:4, s. 958-968
-
Tidskriftsartikel (refereegranskat)abstract
- Penicillium chrysogenum is a filamentous fungus that is used to produce -lactams at an industrial scale. At an early stage of classical strain improvement, the ability to produce the yellow-coloured sorbicillinoids was lost through mutation. Sorbicillinoids are highly bioactive of great pharmaceutical interest. By repair of a critical mutation in one of the two polyketide synthases in an industrial P.chrysogenum strain, sorbicillinoid production was restored at high levels. Using this strain, the sorbicillin biosynthesis pathway was elucidated through gene deletion, overexpression and metabolite profiling. The polyketide synthase enzymes SorA and SorB are required to generate the key intermediates sorbicillin and dihydrosorbicillin, which are subsequently converted to (dihydro)sorbillinol by the FAD-dependent monooxygenase SorC and into the final product oxosorbicillinol by the oxidoreductase SorD. Deletion of either of the two pks genes not only impacted the overall production but also strongly reduce the expression of the pathway genes. Expression is regulated through the interplay of two transcriptional regulators: SorR1 and SorR2. SorR1 acts as a transcriptional activator, while SorR2 controls the expression of sorR1. Furthermore, the sorbicillinoid pathway is regulated through a novel autoinduction mechanism where sorbicillinoids activate transcription.
|
|
| 6. |
- Heitor Colombelli Manfrão-Netto, João, et al.
(författare)
-
Metabolic engineering of Pseudomonas putida for production of vanillylamine from lignin-derived substrates
- 2021
-
Ingår i: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 14:6, s. 2448-2462
-
Tidskriftsartikel (refereegranskat)abstract
- Whole-cell bioconversion of technical lignins using Pseudomonas putida strains overexpressing amine transaminases (ATAs) has the potential to become an eco-efficient route to produce phenolic amines. Here, a novel cell growth-based screening method to evaluate the in vivo activity of recombinant ATAs towards vanillylamine in P. putida KT2440 was developed. It allowed the identification of the native enzyme Pp-SpuC-II and ATA from Chromobacterium violaceum (Cv-ATA) as highly active towards vanillylamine in vivo. Overexpression of Pp-SpuC-II and Cv-ATA in the strain GN442ΔPP_2426, previously engineered for reduced vanillin assimilation, resulted in 94- and 92-fold increased specific transaminase activity, respectively. Whole-cell bioconversion of vanillin yielded 0.70 ± 0.20 mM and 0.92 ± 0.30 mM vanillylamine, for Pp-SpuC-II and Cv-ATA, respectively. Still, amine production was limited by a substantial re-assimilation of the product and formation of the by-products vanillic acid and vanillyl alcohol. Concomitant overexpression of Cv-ATA and alanine dehydrogenase from Bacillus subtilis increased the production of vanillylamine with ammonium as the only nitrogen source and a reduction in the amount of amine product re-assimilation. Identification and deletion of additional native genes encoding oxidoreductases acting on vanillin are crucial engineering targets for further improvement.
|
|
| 7. |
- Karlsson, Christofer M. G., et al.
(författare)
-
Direct effects of organic pollutants on the growth and gene expression of the Baltic Sea model bacterium Rheinheimera sp. BAL341
- 2019
-
Ingår i: Microbial Biotechnology. - : John Wiley & Sons. - 1751-7907 .- 1751-7915. ; 12:5, s. 892-906
-
Tidskriftsartikel (refereegranskat)abstract
- Organic pollutants (OPs) are critically toxic, bioaccumulative and globally widespread. Moreover, several OPs negatively influence aquatic wildlife. Although bacteria are major drivers of the ocean carbon cycle and the turnover of vital elements, there is limited knowledge of OP effects on heterotrophic bacterioplankton. We therefore investigated growth and gene expression responses of the Baltic Sea model bacterium Rheinheimera sp. BAL341 to environmentally relevant concentrations of distinct classes of OPs in 2-h incubation experiments. During exponential growth, exposure to a mix of polycyclic aromatic hydrocarbons, alkanes and organophosphate esters (denoted MIX) resulted in a significant decrease (between 9% and 18%) in bacterial abundance and production compared with controls. In contrast, combined exposure to perfluorooctanesulfonic acids and perfluorooctanoic acids (denoted PFAS) had no significant effect on growth. Nevertheless, MIX and PFAS exposures both induced significant shifts in gene expression profiles compared with controls in exponential growth. This involved several functional metabolism categories (e.g. stress response and fatty acids metabolism), some of which were pollutant-specific (e.g. phosphate acquisition and alkane-1 monooxygenase genes). In stationary phase, only two genes in the MIX treatment were significantly differentially expressed. The substantial direct influence of OPs on metabolism during bacterial growth suggests that widespread OPs could severely alter biogeochemical processes governed by bacterioplankton.
|
|
| 8. |
- Kroll, Jens, et al.
(författare)
-
Plasmid addiction systems : Perspectives and applications in biotechnology
- 2010
-
Ingår i: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 3:6, s. 634-657
-
Forskningsöversikt (refereegranskat)abstract
- Biotechnical production processes often operate with plasmid-based expression systems in well-established prokaryotic and eukaryotic hosts such as Escherichia coli or Saccharomyces cerevisiae, respectively. Genetically engineered organisms produce important chemicals, biopolymers, biofuels and high-value proteins like insulin. In those bioprocesses plasmids in recombinant hosts have an essential impact on productivity. Plasmid-free cells lead to losses in the entire product recovery and decrease the profitability of the whole process. Use of antibiotics in industrial fermentations is not an applicable option to maintain plasmid stability. Especially in pharmaceutical or GMP-based fermentation processes, deployed antibiotics must be inactivated and removed. Several plasmid addiction systems (PAS) were described in the literature. However, not every system has reached a full applicable state. This review compares most known addiction systems and is focusing on biotechnical applications.
|
|
| 9. |
- Martín-Rodríguez, A. J., et al.
(författare)
-
Regulation of colony morphology and biofilm formation in Shewanella algae
- 2021
-
Ingår i: Microbial Biotechnology. - : Wiley. - 1751-7907 .- 1751-7915. ; 14:3, s. 1183-1200
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial colony morphology can reflect different physiological stages such as virulence or biofilm formation. In this work we used transposon mutagenesis to identify genes that alter colony morphology and cause differential Congo Red (CR) and Brilliant Blue G (BBG) binding in Shewanella algae, a marine indigenous bacterium and occasional human pathogen. Microscopic analysis of colonies formed by the wild-type strain S. algae CECT 5071 and three transposon integration mutants representing the diversity of colony morphotypes showed production of biofilm extracellular polymeric substances (EPS) and distinctive morphological alterations. Electrophoretic and chemical analyses of extracted EPS showed differential patterns between strains, although the targets of CR and BBG binding remain to be identified. Galactose and galactosamine were the preponderant sugars in the colony biofilm EPS of S. algae. Surface-associated biofilm formation of transposon integration mutants was not directly correlated with a distinct colony morphotype. The hybrid sensor histidine kinase BarA abrogated surface-associated biofilm formation. Ectopic expression of the kinase and mutants in the phosphorelay cascade partially recovered biofilm formation. Altogether, this work provides the basic analysis to subsequently address the complex and intertwined networks regulating colony morphology and biofilm formation in this poorly understood species.
|
|
| 10. |
|
|
