Cultivable endophytic bacteria from leaf bases of Agave tequilana and their role as plant growth promoters

Agave tequilana Weber var. 'Azul' is grown for the production of tequila, inulin and syrup. Diverse bacteria inhabit plant tissues and play a crucial role for plant health and growth. In this study culturable endophytic bacteria were extracted from leaf bases of 100 healthy Agave tequilana plants. In plant tissue bacteria occurred at mean population densities of 3 million CFU/g of fresh plant tissue. Three hundred endophytic strains were isolated and 16s rDNA sequences grouped the bacteria into eight different taxa that shared high homology with other known sequences. Bacterial endophytes were identified as Acinectobacter sp., A. baumanii, A. bereziniae, Cronobacter sakazakii, Enterobacter hormaechei, Bacillus sp. Klebsiella oxytoca, Pseudomonas sp., Enterococcus casseliflavus, Leuconostoc mesenteroides subsp. mesenteroides and Gluconobacter oxydans. Isolates were confirmed to be plant growth promoting bacteria (PGPB) by their capacities for nitrogen fixation, auxin production, phosphate solubilization, or antagonism against Fusarium oxysporum AC132. E. casseliflavus JM47 and K. oxytoca JM26 secreted the highest concentrations of IAA. The endophyte Acinectobacter sp. JM58 exhibited the maximum values for nitrogen fixation and phosphate solubilization index (PSI). Inhibition of fungi was found in Pseudomonas sp. JM9p and K. oxytoca JM26. Bacterial endophytes show promise for use as bio-inoculants for agave cultivation. Use of endophytes to enhance cultivation of agave may be particularly important for plants produced by micropropagation techniques, where native endophytes may have been lost.

Acidobacteria appear to dominate the microbiome of two sympatric Caribbean Sponges and one Zoanthid

BACKGROUND: Marine invertebrate-associated microbial communities are interesting examples of complex symbiotic systems and are a potential source of biotechnological products. RESULTS: In this work, pyrosequencing-based assessment from bacterial community structures of sediments, two sponges, and one zoanthid collected in the Mexican Caribbean was performed. The results suggest that the bacterial diversity at the species level is higher in the sediments than in the animal samples. Analysis of bacterial communities' structure showed that about two thirds of the bacterial diversity in all the samples belongs to the phyla Acidobacteria and Proteobacteria. The genus Acidobacteriumappears to dominate the bacterial community in all the samples, reaching almost 80% in the sponge Hyrtios. CONCLUSIONS: Our evidence suggests that the sympatric location of these benthonic species may lead to common bacterial structure features among their bacterial communities. The results may serve as a first insight to formulate hypotheses that lead to more extensive studies of sessile marine organisms' microbiomes from the Mexican Caribbean.