Peculiarities of Actinoplanes teichomyceticus NRRL-B16726 morphology and life cycle
O. Yushchuk1, L. Horbal1, Ju. Datsyuk1, E. Stegmann2, V. Fedorenko1
1 Ivan Franko National University of Lviv
4, Hrushevskyi St., Lviv 79005, Ukraine
2 Eberhard Karls University of Tübingen
28, Auf der Morgenstelle, Tübingen 72076, Germany
Actinoplanes teichomyceticus represents a group of sporangia-forming Actinobacteria from Micromonosporaceae family and is the only known natural producer of industrially important drug teicoplanin. A. teichomyceticus has unique pattern of development, likely involving regulatory mechanisms different from described in streptomycetes, which also fall into the phylum Actinobacteria. Investigation of these regulatory mechanisms will likely shed light on sporangia formation and even give the clues about increasing secondary metabolite production levels in Micromonosporaceae species. To date only limited information that describes morphology and the life cycle of A. teichomyceticus is available. In current paper we made a detailed study of certain traits of A. teichomyceticus morphology by means of scanning electron microscopy and using tools of bioinformatics and molecular genetics. We managed to observe and describe stages of the A. teichomyceticus life cycle while growing on different solid media. Development of A. teichomyceticus on the solid media starts with the germination of spores and growth of the substrate mycelium. We observed that after two days of growth on the surface of substrate mycelium aerial mycelium appears. It is known that in streptomycetes the germination of aerial hyphae is facilitated by the SapB-surfactant; A. teichomyceticus has genetic potential to synthesize the SapB-like surfactant as well. We managed to show that correspondent genes are expressed under sporulating conditions and silent under non-sporulating conditions. Further aerial hyphae grow and sporangial primordia appear on their ends. Primordia develop into mature sporangia with diameter of more than 20 Ám. Wetting of the mature sporangia results in spore release. Motility of the spores is most probably achieved with involvement of a FliC flagellin. Thus, in current paper we have been able to describe the complete lifecycle of Micromonosporaceae family representative A. teichomyceticus for the first time.
Keywords: Actinoplanes, sporangia, morphogenesis, scanning electron microscopy