Optimization of Magnetosome Production and Growth by the Magnetotactic Vibrio Magnetovibrio blakemorei Strain MV-1 through a Statistics-Based Experimental Design

Abstract

The growth and magnetosome production of the marine magnetotactic vibrio Magnetovibrio blakemorei strain MV-1 were optimized through a statistics-based experimental factorial design. In the optimized growth medium, maximum magnetite yields of 64.3 mg/liter in batch cultures and 26 mg/liter in a bioreactor were obtained. Magnetotactic bacteria produce intracellular linear chains of nano-sized magnetic organelles called magnetosomes (1). Each magnetosome consists of a magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 ) crystal enveloped by a lipid bilayer membrane that contains magnetosome-specific proteins, some of which are responsible for the biomineralization process (1). The biomineralization of magnetosomes is a highly controlled process regulated at the gene level that results in high-purity, single-magnetic-domain particles with defined crystallographic properties and narrow size distributions (1). Because of their unique characteristics, magnetosomes have a great potential for biotechnological applications. In fact, magnetosomes have been used in the immobilization of biological molecules such as enzymes, antibodies, and nucleic acids (2). Moreover, the production of functionalized magnetosomes by the expression of different proteins on or in the magnetosome membrane is among the most promising immobilization approaches for biotechnological use (3) because it combines biologically active macromolecules with the relatively smooth surface of the nano-sized magnetic crystal of the magnetosome. In contrast, the use of nonbiological magnetic carriers with membranes and proteins is a challenge that remains to be met satisfactorily (4).Thus far, biotechnological studies involving magnetosomes have been focused on a very limited number of strains of the genus Magnetospirillum, mostly Magnetospirillum gryphiswaldense strain MSR-1 and Magnetospirillum magneticum strain AMB-1 (5, 6), both of which biomineralize cuboctahedral crystals of magnetite. Little information exists on other cultivated magnetotactic strains like the magnetotactic vibrio Magnetovibrio blakemorei strain MV-1, which produces chains of elongated prismatic magnetosomes (7). Size and shape are important parameters when designing nanoparticles in numerous biomedical applications like drug delivery because the dimensional properties (aspect ratio) of the nanoparticles affect fluid dynamics, retention times, and internalization by cells (8). The magnetosomes of M. blakemorei are a promising alternative in biotechnology applications such as the immobilization of macromolecules because (i) they have an aspect ratio different from that of cuboctahedral magnetosomes, (ii) they intrinsically contain more magnetite than cuboctahedral magnetosomes because of their size (length, ϳ50 nm; width, ϳ40 nm; 40 nm for Magnetospirillum magnetosomes), and (iii) they have a larger surface volume available for immobilization. Thus, M. blakemorei should be an excellent candidate for the development of high-yield cultivation strategies aimed at potential applications of elongat...

Yield cultivation of magnetotactic bacteria and magnetosomes: A review

“…Although it is still a challenging job because the main objective is to use minimal cost and energy for high yield of MS. Most often, MTB strains such as Magnetospirillum gryphiswaldense (MSR‐1), Magnetospirillum magnetotacticum (MS‐1) and Magnetospirillum magneticum (AMB‐1), Magnetovibrio blakemorei (MV‐1), and Desulfovibrio magneticus (RS‐1) are employed for a yield cultivation of MS in the laboratory scale, but unfortunately the level of production was not up to mark for its commercial applications . It was supposed that by altering the composition of culture media and environmental condition, MS yield might be improved, but very few reports are available on the optimization and improvement of culture media for elevating MS yield .…”

Nanomicrobiology

“…This study is significant for several reasons, including: (1) M. blakemorei biomineralizes elongated prismatic magnetite crystals which could be superior to the cuboctahedral produced by Magnetospirillum species in certain applications, and (2) it represents the first attempt at mass culture of a marine magnetotactic bacterium. Using the optimized growth medium in this study, maximum magnetite yields of 64.3 mg/L in batch cultures and 26 mg/L in a fermenter were obtained (Silva et al 2013).…”

“…A strategy different from those described above was used to obtain optimal growth and magnetosome yields in mass culture of the marine magnetotactic bacterium M. blakemorei (Silva et al 2013). In this case, a statistics-based experimental factorial design approach was used to determine the key components and amounts in growth medium for maximum yields.…”

“…One of the most interesting applications of magnetotactic bacteria is their use as microrobots (e.g., Martel 2008Martel , 2012. Cells of the polar magnetotactic cocci, M. marinus (Bazylinski et al 2013) and strain MO-1 (Lefèvre et al 2009), have been used to transport 2-3 mm diameter microbeads efficiently and towards a specific area through microfluidic channels (Ma et al 2012;Martel 2012;Felfoul and Martel 2013). These studies demonstrate possible uses of magnetotactic bacteria in chemical analyses and medical diagnoses using biochips, as well as in nano/microscale transport of, for example, drugs.…”

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

“…www.advancedsciencenews.com www.advhealthmat.de culture high yields of the marine MTB M. blakemorei by determining the key components and amounts in growth medium for maximum yields. [285] After cultivation of MTB, mature magnetosomes are extracted from the MTB through methods which use sodium hydroxide (NaOH), sonication, a French press, or a pressure homogenizer to lyse the bacterial cells. [279] Subsequently, magnetosomes are purified, most commonly by using a system of magnetic isolation which is followed by low power ultrasonication and a proper treatment with proteins K and electro-elution to remove adsorbed and surface proteins as nucleic acids.…”