MORPHOLOGY AND ULTRASTRUCTURE OF CYANOBACTERIUM SYNECHOCOCCUS-ELONGATUS GROWN IN ASSOCIATION WITH PLANT-CELLS

Microscopic methods were used to study the structural variability of t he wild strain and biotin-dependent mutant of the obligate phototrophi c cyanobacterium Synechococcus elongatus in associations with heterotr ophically grown plant cells. The wild strain of cynobacteria was found to differ from tobacco and dioscorea cells in the formation of mixed aggregates, adhesion on the plant cells, and degree of morphological c hanges. In associations with tobacco cells the cells of both cyanobact erial strains changed in size and shape. These changes were more evide nt in biotin-dependent mutans and were apparently connected with distu rbed division and reduced hardness of the cell wall peptidoglycan laye r. The ultrastructure and location of thylakoids in the cells of both cyanobacterial strains in mixed aggregates with tobacco cells were sim ilar to those in pure culture cyanobacteria This was evidence of intac tness of the photosynthetic apparatus. At the same time, the depositio n of glycogen increased essentially in associations. This pointed to t he possible utilization of exogenous carbohydrates by them. The correl ation of S. elongatus capacity for structural and metabolic modificati ons with the possibility of formation of stable associations with plan t cells of the autotroph-heterotroph type is discussed.