The study of the title indicated that both Caulobacter polymorphus 1017-41 and Caulobactsr cresczntus CB2 strains stimulated the growth and pigmentation of algae and do not belong to algal pathogens. When cultures of blue-green algae, such as Anabaena azotica 686, Anabaena variabilis 1058, Nostoc muscorum 1037 etc., were mixed with Caulobacter polymorphus 1017-41 and C.crescentus CB2, respectively, on solid or in liquid medium, the algal filaments grew much better than the control groups without Caulobacter...