Limits...
Magnetotactic bacteria as potential sources of bioproducts.

Araujo AC, Abreu F, Silva KT, Bazylinski DA, Lins U - Mar Drugs (2015)

Bottom Line: As a result of this control, magnetosomes have narrow and uniform size ranges, relatively specific magnetic and crystalline properties, and an enveloping biological membrane.Most currently described MTB have been isolated from saline or brackish environments and the availability of their genomes has contributed to a better understanding and culturing of these fastidious microorganisms.More specifically, we discovered that the genome of the cultured MTB Magnetovibrio blakemorei, among other MTB, contains several metabolic pathways for the synthesis of secondary metabolites and other compounds, thereby raising the possibility of the co-production of new bioactive molecules along with magnetosomes by this species.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho, 373, CCS, UFRJ, Rio de Janeiro, RJ 21941-902, Brazil. acvaraujo@gmail.com.

ABSTRACT
Magnetotactic bacteria (MTB) produce intracellular organelles called magnetosomes which are magnetic nanoparticles composed of magnetite (Fe3O4) or greigite (Fe3S4) enveloped by a lipid bilayer. The synthesis of a magnetosome is through a genetically controlled process in which the bacterium has control over the composition, direction of crystal growth, and the size and shape of the mineral crystal. As a result of this control, magnetosomes have narrow and uniform size ranges, relatively specific magnetic and crystalline properties, and an enveloping biological membrane. These features are not observed in magnetic particles produced abiotically and thus magnetosomes are of great interest in biotechnology. Most currently described MTB have been isolated from saline or brackish environments and the availability of their genomes has contributed to a better understanding and culturing of these fastidious microorganisms. Moreover, genome sequences have allowed researchers to study genes related to magnetosome production for the synthesis of magnetic particles for use in future commercial and medical applications. Here, we review the current information on the biology of MTB and apply, for the first time, a genome mining strategy on these microorganisms to search for secondary metabolite synthesis genes. More specifically, we discovered that the genome of the cultured MTB Magnetovibrio blakemorei, among other MTB, contains several metabolic pathways for the synthesis of secondary metabolites and other compounds, thereby raising the possibility of the co-production of new bioactive molecules along with magnetosomes by this species.

Show MeSH

Related in: MedlinePlus

Magnetosomes purified from cells of Magnetovibrio blakemorei strain MV-1. Magnetosomes purified from cells lysed using physical methods or alkaline lysis (A) with the magnetosome membrane (MM) shown in the inset (at arrows). Note that after this treatment most magnetosomes remain in chains (at arrowhead in A); Some physical-chemical methods lead to magnetosomes losing their membranes and arrangement, forming clumps due to magnetic interactions between magnetosome crystals (B). Cell debris (arrowheads in B) is generally always present in poorly washed suspensions of magnetosomes reducing purity of the preparation and potentially interfering with specific applications of the isolated magnetosomes. Scale bars = 1 μm in A (100 nm in inset), 150 nm in B.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4306944&req=5

marinedrugs-13-00389-f006: Magnetosomes purified from cells of Magnetovibrio blakemorei strain MV-1. Magnetosomes purified from cells lysed using physical methods or alkaline lysis (A) with the magnetosome membrane (MM) shown in the inset (at arrows). Note that after this treatment most magnetosomes remain in chains (at arrowhead in A); Some physical-chemical methods lead to magnetosomes losing their membranes and arrangement, forming clumps due to magnetic interactions between magnetosome crystals (B). Cell debris (arrowheads in B) is generally always present in poorly washed suspensions of magnetosomes reducing purity of the preparation and potentially interfering with specific applications of the isolated magnetosomes. Scale bars = 1 μm in A (100 nm in inset), 150 nm in B.

Mentions: After magnetosome production, it is necessary to separate and purify magnetosomes or magnetosome crystals for use in the majority of biotechnological applications. Magnetosomes have been successfully purified from cells of MTB using a number of different procedures. Harvested cells of MTB must be first lysed prior to magnetosome purification. After cell lysis, magnetosomes can be separated from cell debris and non-lysed cells by exploiting their magnetic properties using relatively strong magnets. Cell disruption can be achieved by ultrasonication, alkaline lysis, and by use of a French press or a high-pressure homogenizer [107,108,109]. Importantly, the MM lipid bilayer is maintained as a coherent structure around the magnetite crystals with all these techniques [107,108,109]. Removal of the lipid membrane is possible with the use of detergents such as sodium dodecyl sulfate (SDS), allowing for the purification of the magnetosome magnetite crystals which tend to agglomerate due to the magnetotactic interactions between particles after detergent treatment [110]. Extensive washing of magnetosome or magnetosome crystals after separation is crucial to obtain clean material suitable for further use since cell debris (e.g., membranes) including electrostatically-charged cell proteins that might associate with the MM but are not part of it, are difficult to remove and could interfere with the performance of magnetosomes in specific applications (Figure 6).


Magnetotactic bacteria as potential sources of bioproducts.

Araujo AC, Abreu F, Silva KT, Bazylinski DA, Lins U - Mar Drugs (2015)

Magnetosomes purified from cells of Magnetovibrio blakemorei strain MV-1. Magnetosomes purified from cells lysed using physical methods or alkaline lysis (A) with the magnetosome membrane (MM) shown in the inset (at arrows). Note that after this treatment most magnetosomes remain in chains (at arrowhead in A); Some physical-chemical methods lead to magnetosomes losing their membranes and arrangement, forming clumps due to magnetic interactions between magnetosome crystals (B). Cell debris (arrowheads in B) is generally always present in poorly washed suspensions of magnetosomes reducing purity of the preparation and potentially interfering with specific applications of the isolated magnetosomes. Scale bars = 1 μm in A (100 nm in inset), 150 nm in B.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306944&req=5

marinedrugs-13-00389-f006: Magnetosomes purified from cells of Magnetovibrio blakemorei strain MV-1. Magnetosomes purified from cells lysed using physical methods or alkaline lysis (A) with the magnetosome membrane (MM) shown in the inset (at arrows). Note that after this treatment most magnetosomes remain in chains (at arrowhead in A); Some physical-chemical methods lead to magnetosomes losing their membranes and arrangement, forming clumps due to magnetic interactions between magnetosome crystals (B). Cell debris (arrowheads in B) is generally always present in poorly washed suspensions of magnetosomes reducing purity of the preparation and potentially interfering with specific applications of the isolated magnetosomes. Scale bars = 1 μm in A (100 nm in inset), 150 nm in B.
Mentions: After magnetosome production, it is necessary to separate and purify magnetosomes or magnetosome crystals for use in the majority of biotechnological applications. Magnetosomes have been successfully purified from cells of MTB using a number of different procedures. Harvested cells of MTB must be first lysed prior to magnetosome purification. After cell lysis, magnetosomes can be separated from cell debris and non-lysed cells by exploiting their magnetic properties using relatively strong magnets. Cell disruption can be achieved by ultrasonication, alkaline lysis, and by use of a French press or a high-pressure homogenizer [107,108,109]. Importantly, the MM lipid bilayer is maintained as a coherent structure around the magnetite crystals with all these techniques [107,108,109]. Removal of the lipid membrane is possible with the use of detergents such as sodium dodecyl sulfate (SDS), allowing for the purification of the magnetosome magnetite crystals which tend to agglomerate due to the magnetotactic interactions between particles after detergent treatment [110]. Extensive washing of magnetosome or magnetosome crystals after separation is crucial to obtain clean material suitable for further use since cell debris (e.g., membranes) including electrostatically-charged cell proteins that might associate with the MM but are not part of it, are difficult to remove and could interfere with the performance of magnetosomes in specific applications (Figure 6).

Bottom Line: As a result of this control, magnetosomes have narrow and uniform size ranges, relatively specific magnetic and crystalline properties, and an enveloping biological membrane.Most currently described MTB have been isolated from saline or brackish environments and the availability of their genomes has contributed to a better understanding and culturing of these fastidious microorganisms.More specifically, we discovered that the genome of the cultured MTB Magnetovibrio blakemorei, among other MTB, contains several metabolic pathways for the synthesis of secondary metabolites and other compounds, thereby raising the possibility of the co-production of new bioactive molecules along with magnetosomes by this species.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho, 373, CCS, UFRJ, Rio de Janeiro, RJ 21941-902, Brazil. acvaraujo@gmail.com.

ABSTRACT
Magnetotactic bacteria (MTB) produce intracellular organelles called magnetosomes which are magnetic nanoparticles composed of magnetite (Fe3O4) or greigite (Fe3S4) enveloped by a lipid bilayer. The synthesis of a magnetosome is through a genetically controlled process in which the bacterium has control over the composition, direction of crystal growth, and the size and shape of the mineral crystal. As a result of this control, magnetosomes have narrow and uniform size ranges, relatively specific magnetic and crystalline properties, and an enveloping biological membrane. These features are not observed in magnetic particles produced abiotically and thus magnetosomes are of great interest in biotechnology. Most currently described MTB have been isolated from saline or brackish environments and the availability of their genomes has contributed to a better understanding and culturing of these fastidious microorganisms. Moreover, genome sequences have allowed researchers to study genes related to magnetosome production for the synthesis of magnetic particles for use in future commercial and medical applications. Here, we review the current information on the biology of MTB and apply, for the first time, a genome mining strategy on these microorganisms to search for secondary metabolite synthesis genes. More specifically, we discovered that the genome of the cultured MTB Magnetovibrio blakemorei, among other MTB, contains several metabolic pathways for the synthesis of secondary metabolites and other compounds, thereby raising the possibility of the co-production of new bioactive molecules along with magnetosomes by this species.

Show MeSH
Related in: MedlinePlus