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                               ...with those COOLEST guys around the world

Q1: What are magnetotactic bacteria?

One Sentence In Brief:

Magnetospirillum magneticum AMB-1 under cryotomography and 3-D reconstruction

Magnetotactic bacteria, also known as magnetic bacteria, are an evolutionarily diverse group [1] of motile, Gram-negative eubacteria expressing magnetotaxis.

Q2: Community Yearning for The Strain?
We weren't wrong, were we?: )

During our review on past iGem projects, we concluded, to more or less an extend, teams dreaming for magnetotaxis have concluded in using this strain......yet only two team ever actually tried. One of them was Duke University 2006, the other being us.

Below are several arguments about the choice of this strain and reasons stopping previous iGem teams / supporting us in standing soundly on this step.

(1) So Let's Talk About The iGem History

Throughout the history of iGem, we have gained notice from exhaustive online searching that a remarkable number of previous iGem teams have continually proposed projects related to magnetosome, magnetospirillum, and magnetotaxis every year around the world.

Among these respectful pioneers, Duke University had made their magnetotactic bacteria-based project to the official jamboree titled “Bacterial Dynamo”, focusing on the use of AMB-1 as AC voltage generator [2], but somehow limited by the lack of genetic manipulation toolkits for Magentospirillum magneticum AMB-1.

What’s worth mentioning was the diversity of ideas regarding the application of magnetotactic bacteria proposed by a great variety of iGem teams (See Table 1). This even led to one mentioning on 2009 iGem official website about “magnetic bacteria” as one of the Ideas for Bacteria.

Table 1: Magneto-related iGem teams in the history.

(2) Obstacle 1: Hard to Cultivate Yes, we have heard your voice fellow iGemers. We knew from your previous/current brainstorming pages that the main reason for your giving in lies mostly in the STRINGENT growth conditions required to successfully cultivating these bacteria. It is a good reason, indeed.

There are only a few magnetotactic strains capable of pure culture. Among them, Magnetospirillum magnetotacticum MS-1 [2], Magnetospirillum gryphiswalden MSR-1 [3], and Magnetospirillum magneticum AMB-1 [4] are used most frequently in research on magnetotactic bacteria. In recent years, significantly improved cultivating methods for MS-1 [5], MSR-1 [6], and AMB-1 [7] have also been achieved. These have lead to the field buzzing about the realization of applications spanning fMRI reporting, tumor targeting, etc., using magnetites produced by these cells [8, 9, 10, 11].

To be honest, we also encountered some problems in cultivating strain AMB-1, but finally a complete cultivating method has been established here. See Chassis for more details.

(3) Obstacle 2: Lack of Genetic Toolbox Sadly, for previous iGemers, there were way too many obstacles in front of their magnetic fantasies. This has lead to the fact that few precedents ever proceeded into thinking and encountering the BIG questions, that is, the lack of ANY available genetic tools in Parts Registry!

Fig.1 Transformation of MSR-1, AMB-1 and MS-1, plated on ACA medium [12]

To this date, provided with our utmost efforts in literature study, we've found, from previous research on magnetotactic bacteria, two strains are capable of undergoing transformation--MSR-1 [12], and AMB-1 [13].

For the genetic manipulating system on MSR-1, Dr. Dirk Schüler, et al. has developed a stable and efficient method by conjugation with Escherichia coli S17-1. Plasmids used in the system are derivatives of pBBR1MCS (broad-host-range vector[14])

In AMB-1, Dr. Long-Fei Wu used pBBR111, a pBBR1MCS derivative harboring strong, inducible promoter Ptac, to construct an expression vector [15], achieving transformation by conjugation between Escherchia coli WM3064 and AMB-1 (a method developed by Arash Komeili, et al.)[16].

Those great examples truly set lights on successfully establishing a new chassis for magnetism in Parts Registry.

                                          BUT WE AIM EVEN HIGHER!

Works from Matsunaga's lab revealed that transformation of AMB-1 by electroporation is feasible [17]. They enable a door to faster expression platform, avoiding drawbacks with conjugation, such as but not limited to: time consumption, mob gene and oriT restriction, requirement of specific E. coli strain, etc...

Furthermore, compared with the relatively adventurous adaptation of Ptac as promoter for exogenous gene expression, endogenous promoters identified from genomic DNA of magnetotactic strains provide more reliable and efficient ways. Recently identified endogenous promoters from MSR-1 [18] still lack thorough verification. Yet another endogeneous promoters system in AMB-1 [19] has been well characterized [20, 21, 22, 23, 24]. See Chassis for elaborations.

Equipped with these knowledge bases, we are now confident in saying that "the world is ready for a new chassis"!

Q3: What's The Scientific Niche For Our Project? We ARE serious about that...

(1) People Are Whispering About Opto, Bac, and Remote!

Okay, let's proceed to the core part of this page. Now, let us show you the scientific context of our project and related or competitive neuroscientific achievements we indispensably need to compare ours with.

(2) The Whole Field Is Buzzing

Let us show you these four references published very recently.

  1. A wireless multi-channel neural amplifier for freely moving animals
  2. Inducing Sleep by Remote Control Facilitates Memory Consolidation in Drosophila
  3. Mind-Altering Bugs
  4. Optical Switches for Remote and Noninvasive Control of Cell Signaling

Stop now. Please go back and click on those links. Three of them are from Science, the other one, Nature Neuroscience.

Take a deep consideration. What CORRELATIONS do you see from them?

Fig.2 Fantastic quratet, four researches showing interconnected scientific fantasies that contextualizes our project.

To us, they collectively mean that a whole story is currently divided into four parts, with different experts focusing on diverse issues, however laterally interconnected, or to say, interfaced, to weave a complete scientific fantasy.

Systems neuroscientists tried to develop a wireless recording module which also equips itself with multi-channel characteristics.

Neurophysiologists had the same dream on being wireless, but shifting from "recording" to "inducing (stimulating)".

Microbiologists ran into discovering "gut feelings" with mind-altering bacteria living on mammalian intestinal lumen.

Finally, Cell Biologists linked the whole story in a subtle manner, providing optogenetic systems on manipulating cell signalling.

They interface with each other on concepts of being wireless, stimulative, bacterial, and light-associated. However, they provided no direct link between bacteria and optogenetics. This leaves space for us to fit in the last of the five missing puzzles.

From this point on, an "optogenetics-facilitated neurostimulting system using wireless-controlled bacterial species as light source" will make the whole story complete.

(3) Among The Field Of Optogenetics: From 2-D to genuine 3-D matrices

2D matrix stimulators.gif

In the graph shown above, neuroscientists along with electronic engineers have developed an 2-dimensional optogenetic stimulation matrix using aligned LED arrays. This has been one of the greatest frontiers in neuroscientific methodologies.

However, The completion of project "Tailoring Your Avatar" (i. e., optomagnetic bacteria) will enable 3-dimensional presentation of stimulation-enabling optomagnetic bacteria by use of 2-D injection matrices with deep penetration following inject-and-withdraw cycles.