On the biogenesis of cytokinins in Lactobacillus acidophilus ATCC 4963

The biosynthesis of free cytokinins in the mevalonic acid auxotrophic Lactobacillus acidophilus , ATCC 4963 has been investigated. After a short pulse labelling with [¹⁴C]-mevalonic acid the labelled free cytokinins of bacteria and media and the labelled cytokinin-nucleotide moiety of tRNA and oligonucleotides were determined and compared. tRNA is the main precursor for cytokinin production. Bacteria previously starved for mevalonic acid showed the presence of at least one additional cytokinin precursor. A fraction of oligonudeotides shows rapid incorporation of ¹⁴C and contains labelled cytokinin nucleotides. There are no indications for a direct isopentenylation of adenine, adenosine or its phosphate derivatives.