Carbon and nitrogen source requirements ofFrankiastrains

Abstract

The isolation and in vitro cultivation of a Frankia sp. viz. Frankia CpI1, an actinomycete that gives rise to the formation of nitrogen-fixing root nodules on Comptonia peregrina was reported by Callaham et al. in 1978 [1]. Since that time a number of other Frankia strains has been isolated from root nodules of various non-leguminous plants, viz. Alnus glutinosa [2,3], Alnus rubra [4], Alnus viridis ssp. crispa [5,6], Myrica pennsylvanica [7], Elaeagnus umbellata [8,9], Casuarina equisetifolia [10], Hippopha~ sp. [11] and Shepherdia sp. [11]. Some research has been done in this laboratory on the Cand N-metabolism of Frankia AvcI 1, isolated from root nodules of Alnus viridis ssp. crispa [12-14]. It was shown that Frankia AvcI1 can utilize a number of fatty acids and the fatty acid residues of some Tweens as sole carbon source ([13], [12], respectively). No growth of Frankia AvcI 1 was observed on media containing glucose as sole carbon source, while the organism does not take up glucose from a medium containing both Tween-80 and glucose [12,14]. In the present contribution it was investigated whether other Frankia strains behave similarly to Frankia AvcI1 regarding their nutritional demands. Further investigations concerning some of the above-mentioned Frankia strains include the ability of these actinomycetes to form root nodules on A lnus glutinosa. Earlier it was shown [12] that Frankia AvcI1 cannot utilize succinate as sole carbon source. This phenomenon is due to the fact that no uptake of this compound occurs as shown in the present paper. Also some additional work has been done on the nitrogen metabolism of Frankia AvcI1. In earlier papers it was shown that free-living Frankia AvcI1 can utilize either NH~[13] or Casamino acids [12] as N-source. Glutamic acid and aspartic acid were found to be preferably taken up from a mixture of amino acids, whereas the concentrations of the other amino acids remained unchanged during the growth of the organism [12]. Some more details on the utilization of amino acids by Frankia AvcI1 are reported in the present work.