Opsin three domains of life: Archaea, Bacteria, and Eukaryota. In Eukaryota, type I opsins are found mainly in unicellular organisms such as green algae, and in fungi. In most complex multicellular eukaryotes, type I opsins have been replaced with other light-sensitive molecules such as cryptochrome and phytochrome in plants, and type II opsins in Metazoa (animals). Microbial opsins are often known by the rhodopsin form of the molecule, i.e., rhodopsin (in the broad sense) = opsin + chromophore. Among the many kinds of microbial opsins are the proton pumps bacteriorhodopsin (BR) and xanthorhodopsin (xR), the chloride pump halorhodopsin (HR) the photosensors
Mycorrhiza helper bacteria Another study found that MHB release antifungal metabolites into the soil. The anti-fungal metabolites produce antagonistic effects towards the pathogenic fungi. However, MHB can choose whether to help defend a pathogen depending on the nutrient availability and space in the rhizosphere. Further research is still necessary to understand the mechanism of how MHBs aid mycorrhiza defeat pathogens. Mycorrhiza helper bacteria Mycorrhiza helper bacteria (MHB) are a group of organisms that form symbiotic associations with both ectomycorrhiza and arbuscular mycorrhiza. MHBs are diverse and belong to different bacterial phyla including both gram-negative and gram-positive bacteria. Some of the most common types