A microbial consortium or microbial community, is two or more bacterial or microbial groups living symbiotically. Consortiums can be endosymbiotic or ectosymbiotic, or occasionally may be both. The protist Mixotricha paradoxa, itself an endosymbiont of the Mastotermes darwiniensis termite, is always found as a consortium of at least one endosymbiotic coccus, multiple ectosymbiotic species of flagellate or ciliate bacteria, and at least one species of helical Treponema bacteria that forms the basis of Mixotricha protists' locomotion. The concept of a consortium was first introduced by Johannes Reinke in 1872, and in 1877 the term symbiosis was introduced and later expanded on. Evidence for symbiosis between microbes strongly suggests it to have been a necessary precursor of the evolution of land plants and for their transition from algal communities in the sea to land. Overview Microbes hold promising application potential to raise the efficiency of bioprocesses when dealing with substances that are resistant to decomposition. A large number of microorganisms have been isolated based on their ability to degrade recalcitrant materials such as lignocellulose and polyurethanes. In many cases of degradation efficiency, microbial consortia have been found superior when compared to single strains. For example, novel thermophilic consortia of Brevibacillus spp. and Aneurinibacillus sp. have been isolated from the environment to enhance polymer degradation. Two approaches exist to obtain microbial consortia involving either (i) a synthetic assembly from scratch by combining several isolated strains, or (ii) obtainment of complex microbial communities from environmental samples. For the later, enrichment process is often used to get the desired microbial consortia. For instance, a termite gut-derived consortium showing a high xylanase activity was enriched on raw wheat straw as the sole carbon source, which was able to transform lignocellulose into carboxylates under anaerobic conditions. Relatively high diversity levels are still observed despite the use of enrichment steps when working from environmental samples, likely due to the high functional redundancy observed in environmental microbial communities, being a key asset of their functional stability. This intrinsic diversity may stand as a bottleneck in attempts to move forward to practical application due to (i) potential negative correlation with efficiency, (ii) real microbial cheaters whose presence has no impacts on degradation, (iii) security threats posed by the presence of known or unknown pathogens, and (iv) risks of losing the properties of interest if supported by rare taxa. Utilization of microbial consortia with less complexity, but equal efficiency, can