N-acyl glutamines are key signal molecules mediating the plant-insect interaction. A protein fraction has been isolated from a bacterium, Microbacterium arborescens SE14 living commensally in herbivore insect gut. The protein belongs to the bacterial Dps protein family (DNA-binding protein from starved cell), and catalyses reversible formation of N-acyl glutamines when free fatty acids and amino acids were supplied exogenously. The protein has some novel properties adapted well to the insect gut environment. The cloned gene increased the activity of strain M. arborescens DSM20754 when transformed into it.