= Methylorubrum extorquens AM1
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<Methylorubrum extorquens AM1> is a laboratory <bacterial strain> used to investigate <methylotrophy>, the use of reduced one-carbon compounds such as <methanol>. The ATCC collection identifies AM1 with deposit ATCC 14718 and designation NCIB 9133. It explicitly marks this as not the <type strain>. A widely used experimental strain and the reference that anchors a species name need not be the same culture.<Methylorubrum extorquens AM1 in the ATCC collection>[Strain designation, former name and type-strain fields]{ref}
AM1 makes a metabolic hypothesis testable. In a 2005 study, an AM1-derived <mutant> lacking functional <methanol dehydrogenase> could not perform the usual first oxidation from <methanol> to <formaldehyde>. Researchers compared its colonization of <Medicago truncatula> with that of a fluorescently marked reference derivative. The mutant was disadvantaged in competition, yet separately inoculated mutants could reach populations comparable to the wild type. <Methanol> utilization therefore contributed to competitive success without being indispensable for colonization in that experiment.<Methylotrophic metabolism is advantageous for Methylobacterium extorquens during colonization of Medicago truncatula under competitive conditions by Abdoulaye Sy and others>[Abstract and Figures 1–3, pathway and competitive versus separate comparisons]{ref}
For a distinct illustrative calculation, suppose both populations start at $10^4$ <cells>, but finish at $4\times10^4$ and $1.6\times10^5$. Both grew, yet the first population's fraction fell from $1/2$ to $1/5$. A declining competitive fraction is thus compatible with an increasing absolute population. The reference, <mutant>, host and measured quantity all belong to the meaning of an AM1 experimental result.
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