RESUMO
During durst storms, also biological material is transported from arid areas such as the Sahara Desert. In the present work, rain samples containing significant amounts of mineral dust have been collected in Granada during different red rain episodes. Biological features (bacteria, biofilm, pollen grain and fungal spore) as well as size-particle distribution and mineralogical composition were studied by SEM. Nanobacteria were observed for the first time in red rain samples. A preliminary metabarcoding analysis was performed on three red rain samples. Here, Bacillota made up 18 % and Pseudomonadota 23 % of the whole prokaryotic community. The fungal community was characterized by a high abundance of Ascomycota and, dependent on the origin, the presence of Chytridiomycota. By means of 16S rRNA sequencing, 18 cultivable microorganisms were identified. In general, members of the phyla Pseudomonadota and Bacillota made up the majority of taxa. Some species, such as Peribacillus frigoritolerans and Bacillus halotolerans were isolated during three different red rain episodes. Generally, red rain carries a wide variety of microorganisms, being their ecosystem and health effects largely unknown.
Assuntos
Poeira , Ecossistema , Poeira/análise , Espanha , RNA Ribossômico 16S/genética , Chuva , África do NorteRESUMO
A strictly aerobic, chemoheterotrophic, endospore-forming, Gram-positive, rod-shaped bacterial strain N3T was isolated from the feces of a river otter in Castril (Granada, southern Spain). It is halotolerant, motile, and catalase-, oxidase-, ACC deaminase-, and C4- and C8-lipase-positive. It promotes tomato plant growth and can reduce virulence in Erwinia amylovora CECT 222T and Dickeya solani LMG 25993T through interference in their quorum-sensing systems, although other antagonistic mechanisms could also occur. A phylogenetic analysis of the 16S rRNA gene sequence as well as the phenotypic and phylogenomic analyses indicated that the strain N3T is a novel species of the genus Peribacillus, with the highest 16S rRNA sequence similar to that of Bacillus frigoritolerans DSM 8801T (99.93%) and Peribacillus simplex DSM 1321T (99.80%). Genomic digital DNA-DNA hybridization (dDDH) between the strain N3T and Bacillus frigoritolerans DSM 8801T and Peribacillus simplex was 12.8 and 69.1%, respectively, and the average nucleotide identity (ANIb) of strain N3T and Bacillus frigoritolerans DSM 8801T and Peribacillus simplex was 67.84 and 93.21%, respectively. The genomic G + C content was 40.3 mol%. Its main cellular fatty acids were anteiso-C15:0 and iso-C15:0. Using 16S rRNA phylogenetic and in silico phylogenomic analyses, together with the chemotaxonomic and phenotypic data, we demonstrated that the type strain N3T (=CECT 30509T = LMG 32505T) is a novel species of the genus Peribacillus and the name Peribacillus castrilensis sp. nov. is proposed.
RESUMO
We have carried out a polyphasic taxonomic study of strain 11ST, a halophilic, Gram-negative bacterium that is able to respire on nitrate and nitrite in anaerobiosis. Strain 11ST was isolated from a solar saltern in Cahuil, a region next to Pichilemu (Chile). It grows at NaCl concentrations within the range of 3-20 % w/v (optimum 5-7.5 %), temperatures from 4 to 45 degrees C (optimum 20-32 degrees C) and within a pH range of 5-10 (optimum pH 7-9). Its 16S rRNA gene sequence indicates that it belongs to the genus Halomonas in the class Gammaproteobacteria. Its closest relatives are Halomonas alimentaria, H. denitrificans, H. organivorans and H. ventosae, with the type strains of which our strain showed maximum 16S rRNA gene sequence similarity values of 97.1-98.1 %. Its G+C content is 65.3 mol%. DNA-DNA hybridization studies showed 54.2 % relatedness between strain 11ST and H. alimentaria DSM 15356T and 47.2 % relatedness between strain 11ST and H. organivorans CECT 5995T. Lower DNA-DNA hybridization percentages were obtained against the type strains of other related Halomonas species. Its major fatty acids are C12 : 0 3-OH (5.56 %), iso-C15 : 0 2-OH/C16 : 1 omega 7c (22.30 %), C16 : 0 (27.80 %) and C18 : 1 omega 7c (29.92 %). The proposed name for the novel species is Halomonas nitroreducens sp. nov., with strain 11ST (=CECT 7281T =LMG 24185T) being the type strain.