lead to more controlled and optimized industrial processes. For instance, a large proportion of functional genes were remarkably altered and the efficiency of diesel biodegradation was increased by reducing the biodiversity of a microbial community from diesel-contaminated soils. Therefore, it is crucial to find reliable strategies to narrow down the diversity toward optimized microbial consortia gained from environmental samples. A reductive-screening approach was applied to construct effective minimal microbial consortia for lignocellulose degradation based on different metabolic functional groups. Additionally, artificial selection approaches (dilution, toxicity, and heat) have been also employed to obtain bacterial consortia. Among them, dilution-to-extinction has already proven its efficiency for obtaining functional microbial consortia from seawater and rumen liquor . Dilution-to-extinction is expected to provide more advantages compared to conventional isolation and assembly as it (i) generates many microbial combinations ready to be screened, (ii) includes strains from the initial microbial pool that might be lost due to cultivation/isolation biases, and (iii) ensures that all microbes are physically present and interacting spontaneously. Examples Microbialites Microbialites are lithified microbial mats that grow in benthic freshwater and marine environments. Microbialites are the earliest known fossilised evidence of life, dating back 3.7 billion years. Today modern microbialites are scarce, and are formed mainly by Pseudomonadota (formerly Proteobacteria), cyanobacteria, sulphate-reducing bacteria, diatoms, and microalgae. These microorganisms produce adhesive compounds that cement sand and join other rocky materials to form mineral "microbial mats". The mats build layer by layer, growing gradually over time. Rhizosphere Although various studies have shown that single microorganisms can exert beneficial effects on plants, it is increasingly evident that when a microbial consortium — two or more interacting microorganisms — is involved, additive or synergistic results can be expected. This occurs, in part, due to the fact that multiple species can perform a variety of tasks in an ecosystem like the plant root rhizosphere. Beneficial mechanisms of plant growth stimulation include enhanced nutrient availability, phytohormone modulation, biocontrol, biotic and abiotic stress tolerance) exerted by different microbial players within the rhizosphere, such as plant-growth-promoting bacteria (PGPB) and fungi such as Trichoderma and Mycorrhizae. The diagram on the right illustrates that rhizosphere microorganisms like plant-growth-promoting bacteria (PGPB), arbuscular mycorrhizal fungi (AMF), and fungi from the genus Trichoderma spp. can establish beneficial interactions with plants, promoting plant growth and development, increasing the plant defense system against pathogens, promoting nutrient uptake, and enhancing tolerance to different environmental stresses. Rhizosphere microorganisms can