Protist both microbial eukaryotes and macroscopic organisms that do not fit into the other traditional kingdoms. In cladistic systems (classifications based on common ancestry), there are no equivalents to the taxa Protista or Protoctista, both terms referring to a paraphyletic group that spans the entire eukaryotic tree of life. In cladistic classification, the contents of Protista are distributed among various "supergroups" (SAR, such as protozoa and some algae, Archaeplastida, such as land plants and some algae, Excavata, which are a group of unicellular organisms, and Opisthokonta, such as animals and fungi, etc.). "Protista", <nowiki>"Protoctista"</nowiki> and "Protozoa" are considered obsolete. However, the
Mycorrhiza helper bacteria they found that the bacteria helped ectomycorrhizal fungi promote a symbiotic relationship with the plant by examining an increase in formation of mycorrhiza. Some bacteria improve root colonization and plant growth when associated with arbuscular mycorrhiza. The improvement of growth has been hypothesized that MHB aid the plant to defend against pathogens by improving the nutrient uptake. However, the mechanism these species use to help both of the fungi is still unknown and needs to be further investigated. Actinobacteria are gram-positive bacteria, and they are found in the soil. In this phylum, "Streptomyces" is the largest genus of bacteria, and