In order to select halophilic microorganisms as a source of compounds with cytotoxic activities, a total of 135 bacterial strains were isolated from water and sediment samples collected from the Zipaquirá salt mine in the Colombian Andes. We determined the cytotoxic effects of 100 crude extracts from 54 selected organisms on the adherent murine mammary cell carcinoma 4T1 and human mammary adenocarcinoma MCF-7 cell lines. These extracts were obtained from strains of Isoptericola, Ornithinimicrobium, Janibacter, Nesterenkonia, Alkalibacterium, Bacillus, Halomonas, Chromohalobacter, Shewanella, Salipiger, Martellela, Oceanibaculum, Caenispirillum and Labrenzia. The extracts of 23 strains showed an IC50 of less than 100 μg mL−1. They were subsequently analyzed by LC/MS allowing dereplication of 20 compounds. The cytotoxic effect was related to a complex mixture of diketopiperazines present in many of the extracts analyzed. The greatest cytotoxic activity against both of the evaluated cell lines was obtained from the chloroform extract of Labrenzia aggregata USBA 371 which had an IC50 < 6 μg mL−1. Other extracts with high levels of cytotoxic activity were obtained from Bacillus sp. (IC50 < 50 μg mL−1) which contained several compounds such as macrolactin L and A, 7-O-succinoylmacrolactin F and iturin. Shewanella chilikensis USBA 344 also showed high levels of cytotoxic activity against both cell lines in the crude extract: an IC50 < 15 μg mL−1 against the 4T1 cell line and an IC50 < 68 μg mL−1 against the MCF-7 cell line. Nesterenkonia sandarakina CG 35, which has an IC50 of 118 µg mL−1 against 4T1, is a producer of diketopiperazines and 1-acetyl-β-carboline. Also, Ornithinimicrobium kibberense CG 24, which has IC50 < 50 μg mL−1, was a producer of diketopiperazines and lagunamycin. Our study demonstrates that these saline environments are habitats of halophilic and halotolerant bacteria that have previously unreported cytotoxic activity.Electronic supplementary materialThe online version of this article (10.1186/s13568-017-0527-6) contains supplementary material, which is available to authorized users.

Dethiosulfovibrio salsuginis sp. nov., an anaerobic, slightly halophilic bacterium isolated from a saline spring A mesophilic, strictly anaerobic, slightly halophilic bacterium, designated strain USBA 82 T , was isolated from a terrestrial saline spring in the Colombian Andes. The non-spore-forming curved rods (5-7¾1.3 mm) with pointed or rounded ends, stained Gram-negative and were motile by means of laterally inserted flagella. The strain grew optimally at 30 6C (growth range 20-40 6C), pH 7.3 (growth range pH 5.5-8.5) and 2 % (w/v) NaCl (growth range 0.1-7 % NaCl). The strain fermented peptides, amino acids and a few organic acids, but growth was not observed on carbohydrates, alcohols or fatty acids. The strain reduced thiosulfate and sulfur to sulfide. Sulfate, sulfite, nitrate and nitrite were not used as electron acceptors. On peptone alone, acetate, succinate, propionate and traces of ethanol were formed, but in the presence of thiosulfate, acetate and succinate were formed. The G+C content of the chromosomal DNA was 52 mol% (T m ). 16S rRNA gene sequence analysis indicated that strain USBA 82 T was affiliated to Dethiosulfovibrio peptidovorans within the phylum Synergistetes with a similarity value of approximately 93 %. Based on the differences between the new strain and the type species of the genus Dethiosulfovibrio, we suggest that strain USBA 82 T represents a novel species of the genus for which the name Dethiosulfovibrio salsuginis sp. nov. is proposed. The type strain is USBA 82 T (5DSM 21565 T 5KCTC 5659 T ).

A Gram-negative, aerobic, mesophilic, non-spore-forming, chemotrophic, chlorophyll-lacking, nitrogen-fixing bacterium, designated strain USBA 355 T , was isolated from the saline spring 'Salado de Consotá ' situated in the Colombian Andes. The non-flagellated cells of strain USBA 355 T were straight to slightly curved rods (0.6-0.7 ¾ 3.0-3.5 mm). Growth occurred optimally at 30 6C (growth temperature range between 20 and 40 6C), at pH 6.5-6.7 (pH growth range between 5.0 and 8.0) and at 0.5 % NaCl (w/v) (range between 0 and 4 %). The major quinone present was Q-10 and the predominant fatty acids identified were C 19 : 0 cyclo v8c, C 18 : 1 v7c and C 18 : 0 . The G+C content of the chromosomal DNA was 71±1 mol%. 16S rRNA gene sequence analysis indicated that strain USBA 355 T formed a distant phylogenetic line of descent with members of the genus Thalassobaculum, family Rhodospirillaceae, class Alphaproteobacteria (90 % gene sequence similarity). Comparison of the phylogenetic, chemotaxonomic and physiological features of strain USBA 355 T with all other members of the family Rhodospirillaceae suggested that it represents a novel genus and species for which the name Tistlia consotensis gen. nov., sp. nov. is proposed. The type strain of the type species is USBA 355 T (5JCM 15529 T 5KCTC 22406 T ).

Here we present the physiological features of Pseudomonas extremaustralis strain USBA-GBX-515 (CMPUJU 515), isolated from soils in Superparamo ecosystems, > 4000 m.a.s.l, in the northern Andes of South America, as well as the thorough analysis of the draft genome. Strain USBA-GBX-515 is a Gram-negative rod shaped bacterium of 1.0-3. 0 μm × 0.5-1 μm, motile and unable to form spores, it grows aerobically and cells show one single flagellum. Several genetic indices, the phylogenetic analysis of the 16S rRNA gene sequence and the phenotypic characterization confirmed that USBA-GBX-515 is a member of Pseudomonas genus and, the similarity of the 16S rDNA sequence was 100% with P. extremaustralis strain CT14-3 T . The draft genome of P. extremaustralis strain USBA-GBX-515 consisted of 6,143,638 Mb with a G + C content of 60.9 mol%. A total of 5665 genes were predicted and of those, 5544 were protein coding genes and 121 were RNA genes. The distribution of genes into COG functional categories showed that most genes were classified in the category of amino acid transport and metabolism (10.5%) followed by transcription (8.4%) and signal transduction mechanisms (7.3%). We performed experimental analyses of the lipolytic activity and results showed activity mainly on short chain fatty acids. The genome analysis demonstrated the existence of two genes, lip515A and est515A, related to a triacylglycerol lipase and carboxylesterase, respectively. Ammonification genes were also observed, mainly nitrate reductase genes. Genes related with synthesis of poly-hydroxyalkanoates (PHAs), especially poly-hydroxybutyrates (PHBs), were detected. The phaABC and phbABC operons also appeared complete in the genome. P. extremaustralis strain USBA-GBX-515 conserves the same gene organization of the type strain CT14-3 T . We also thoroughly analyzed the potential for production of secondary metabolites finding close to 400 genes in 32 biosynthetic gene clusters involved in their production.

An anaerobic, moderately thermophilic, terminal-spore-forming bacterium, designated strain USBA A T , was isolated from a terrestrial hot spring located at an altitude of 2683 m in the Andean region of Colombia (046 509