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Four Gram-positive, aerobic, catalase- and oxidase-negative, rod-shaped, motile endophytic bacterial strains, designated NM3R9T, NE1TT3, NE2TL11 and NE2HP2T, were isolated from the inner tissues (leaf and stem) of Sphaeralcea angustifolia and roots of Prosopis laevigata. They were characterized using a polyphasic approach, which revealed that they represent two novel Microbacterium species. Phylogenetic analysis based on 16S rRNA gene sequencing showed that the species closest to NE2HP2T was Microbacterium arborescens DSM 20754T (99.6 %) and that closest to NM3R9T, NE2TL11 and NE2TT3 was Microbacterium oleivorans NBRC 103075T (97.4 %). The whole-genome average nucleotide identity value between strain NM3R9T and Microbacterium imperiale DSM 20530T was 90.91 %, and that between strain NE2HP2T and M. arborecens DSM 20754T was 91.03 %. Digital DNA-DNA hybridization showed values of less than 70 % with the type strains of related species. The polar lipids present in both strains included diphosphatidylglycerol, phosphatidylglycerol, glycolipids and unidentified lipids, whereas the major fatty acids included anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and C16 : 0. Whole-cell sugars included mannose, rhamnose and galactose. Strains NM3R9T and NE2HP2T showed physiological characteristics different from those present in closely related Microbacterium species. According to the taxonomic analysis, both strains belong to two novel species. The name Microbacterium plantarum sp. nov. is proposed for strain NE2HP2T (=LMG 30875T=CCBAU 101117T) and Microbacterium thalli sp. nov. for strains NM3R9T (=LMG 30873T=CCBAU 101116T), NE1TT3 (=CCBAU 101114) and NE2TL11 (=CCBAU 101115).

Parte del éxito evolutivo y ecológico de los insectos se atribuye a las bacterias y hongos asociados a ellos que amplían sus capacidades metabólicas o les permiten resistir estrés o parasitosis. Las asociaciones posiblemente se originaron hace cientos de millones de años y el resultado es una interdependencia que, en algunos casos, insecto y bacteria no pueden existir separadamente, lo que ha llevado a una reducción significativa de los genomas de los simbiontes bacterianos y a la transferencia por vía materna de éstos a la progenie. Recientemente, el estudio de los simbiontes de insectos ha cobrado gran interés y se han identificado algunas de sus funciones biológicas dentro de los hospederos. Los insectos escama o cochinillas se alimentan de la savia de las plantas, por lo que requieren simbiontes para compensar las deficiencias de su dieta, rica en carbono pero pobre en compuestos nitrogenados. Algunas de las plagas más agresivas de los cultivos agrícolas son los insectos escama. En este artículo revisamos los simbiontes de la cochinilla del carmín y de la laca, de gran interés comercial y artesanal. En las cochinillas que se estudiaron encontramos diversas comunidades microbianas con la capacidad de sintetizar aminoácidos, vitaminas, fijar nitrógeno o reciclar los productos de desecho del metabolismo nitrogenado., The evolutionary and ecological success of insects is largely due to their associated bacteria and fungi that expand their metabolic capacities or allow them to resist stress or parasites. Some of these associations possibly originated hundreds of millions of years ago and have resulted in such interdependence that in some cases the insect and bacteria may not exist separately. This has also led to a significant reduction in the genome size of bacterial symbionts and to the maternal transfer of symbionts to progeny. The study of insect symbionts has recently gained great interest and some of the biological functions of symbionts within hosts have been identified. Scale insects or cochineals feed on the sap of plants, which is rich in carbon but poor in nitrogen and so they require symbionts to compensate for diet deficiencies. Some scale insects are devastating crop pests. In this article, we review the symbionts of some scale insects focusing on carmine- and wax cochineals, which have commercial, art and craft interest. In the cochineals studied we found diverse microbial communities that can synthesize amino acids, vitamins, fix nitrogen or recycle the waste products of nitrogen metabolism.