Something to note on this topic: if GFP is expressed from a plasmid in the lactic acid bacteria, then antibiotic will be required in the yoghurt for the strain to maintain the plasmid and GFP expression to be efficient. In the absence of an antibiotic selection pressure, bacteria usually loose the added plasmid rapidly. I personally would not like to like to ingest antibiotics just for the fun of eating a glow in the dark yoghurt!
A solution is to integrate the GFP gene within the bacteria genome. Chromosomal edits are much more stable over generations. They are inserted along with an antibiotic resistance gene to select for the bacterial transformant, however they don't require continuous antibiotic selection to be maintained.
Another problem though: even if antibiotic are not added in the yoghurt, the antibiotic resistance gene will be present in the bacterial strain. Lactic acid bacteria are known to persist in the gut, and horizontal gene transfer is known to occur significantly within the gut microbiome. Since antibiotics used in molecular biology are the same as antibiotics used for treating bacterial infections, it's unreasonable to voluntarily eat bacteria containing the resistance genes and taking the risk to spread them.
The solution in that case is to perform 'scarless' genome editing, by removing the antibiotic resistance gene after selection. It is extra work but it is definitely feasible.
Concerning Streptococcus thermophilus: an even bigger advantage than the fact it naturally has a crispr-cas system, in my opinion, is the fact that it is a naturally transformable bacteria. Natural transformation can be harnessed to make genetic engineering extremely easy. A Streptococcus thermophilus strain with an easy way to trigger natural transformation could make a really nice strain to play with for the DIYbio community.
Has anyone ever tried anything in that direction?
2 papers showing the feasibility:
Fontaine et al. (2010). Development of a Versatile Procedure Based on Natural Transformation for Marker-Free Targeted Genetic Modification in Streptococcus thermophilus. Applied and Environmental Microbiology.
Haustenne et al. (2015). Modeling of the ComRS Signaling Pathway Reveals the Limiting Factors Controlling Competence in Streptococcus thermophilus. Frontiers in Microbiology.
Cheers,
Raphael
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Raphaël Laurenceau
Postdoc researcher at MIT
Microbiology / Horizontal Gene Transfer / Cyanobacteria
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BOSLAB
Boston Open Science Laboratory
twitter @BosOpenSci_Lab
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