Wallace Rafael de Souza

Streptomyces araujoniae Produces a Multiantibiotic Complex with Ionophoric Properties to Control Botrytis cinerea

A recently described actinomycete species (Streptomyces araujoniae ASBV-1(T)) is effective against many phytopathogenic fungi. In this study, we evaluated the capacity of this species to inhibit Botrytis cinerea development in strawberry pseudofruit, and we identified the chemical structures of its bioactive compounds. An ethyl acetate crude extract (0.1 mg ml(-1)) of ASBV-1(T) fermentation broth completely inhibited fungus growth in strawberry pseudofruit under storage conditions. The crude extract was fractionated by preparative high-performance liquid chromatography; the active fraction was further evaluated by tandem mass spectrometry. ASBV-1(T) produced a multiantibiotic complex with ionophoric properties. This complex contained members of the macrotetralides class (including monactin, dinactin, trinactin, and tetranactin) and the cyclodepsipeptide valinomycin, all of which were active against B. cinerea. Furthermore, the addition of 2 mM MgSO4 and 1 mM ZnSO4 enhanced macrotetralide and valinomycin production, respectively, in the culture broth. These compounds are considered to be the main active molecules that S. araujoniae produces to control B. cinerea. Their low to moderate toxicity to humans and the environment justifies the application of ASBV-1(T) in biological control programs that aim to mitigate the damage caused by this phytopathogen.

Marmoricola aquaticus sp. nov., an actinomycete isolated from a marine sponge

A novel marine actinomycete, designated B374(T), was isolated from a marine sponge, Glodia corticostylifera, which was collected from São Paulo, Brasil. The taxonomic position of B374(T) was established by using data derived from a polyphasic approach. The organism showed a combination of chemotaxonomic and morphological characteristics consistent with its classification in the genus Marmoricola and it formed a distinct phyletic line in the clade of the genus Marmoricola, based on 16S rRNA gene sequences. Strain B374(T) was most closely related to Marmoricola aequoreus SST-45(T) (98.5% 16S rRNA gene sequence similarity), but was distinguished from this strain and from the other type strains of species of the genus Marmoricola on the basis of a combination of phenotypic properties. The data obtained, therefore, indicates that isolate B374(T) ( = CBMAI 1089(T) = DSM 28169(T)) should be classified as a novel species of the genus Marmoricola, for which the name Marmoricola aquaticus sp. nov. is proposed.

Amycolatopsis rhabdoformis sp. nov., an actinomycete isolated from a tropical forest soil

Strain SB026T was isolated from Brazilian rainforest soil and its taxonomic position established using data from a polyphasic study. The organism showed a combination of chemotaxonomic and morphological features consistent with its classification in the genus Amycolatopsis and formed a branch in the Amycolatopsis 16S rRNA gene tree together with Amycolatopsis bullii NRRL B-24847T, Amycolatopsis plumensis NRRL B-24324T, Amycolatopsis tolypomycina DSM 44544T and Amycolatopsis vancoresmycina NRRL B-24208T. It was related most closely to A. bullii NRRL B-24847T (99.0 % 16S rRNA gene sequence similarity), but was distinguished from this strain by a low level of DNA-DNA relatedness (~46 %) and discriminatory phenotypic properties. Based on the combined genotypic and phenotypic data, it is proposed that the isolate should be classified in the genus Amycolatopsis as representing a novel species, Amycolatopsis rhabdoformis sp. nov. The type strain is SB026T ( = CBMAI 1694T = CMAA 1285T = NCIMB 14900T).

Williamsia spongiae sp nov., an actinomycete isolated from the marine sponge Amphimedon viridis

A novel actinobacterium, designated isolate B138T, was isolated from the marine sponge, Amphimedon viridis, which was collected from Praia Guaecá (São Paulo, Brazil), and its taxonomic position was established using data from a polyphasic study. The organism showed a combination of chemotaxonomic and morphological characteristics consistent with its classification in the genus Williamsia and it formed a distinct phyletic line in the Williamsia 16S rRNA gene tree. It was most closely related to Williamsia serinedens DSM 45037T and Williamsia deligens DSM 44902T (99.0 % 16S rRNA gene sequence similarity) and Williamsia maris DSM 44693T (97.5 % 16S rRNA gene sequence similarity), but was distinguished readily from these strains by the low DNA-DNA relatedness values (62.3-64.4 %) and by the discriminatory phenotypic properties. Based on the data obtained, the isolate B138T (=CBMAI 1094T=DSM 46676T) should be classified as the type strain of a novel species of the genus Williamsia, for which the name Williamsia spongiae sp. nov. is proposed.

Antifungal Activity of Pseudomonas frederiksbergensis CMAA 1323 Isolated from the Antarctic Hair Grass Deschampsia antarctica

Aims: Epiphytic bacteria, isolated from Deschampsia antarctica, were screened for their potential to inhibit the plant pathogen Botrytis cinerea, the causal agent of gray mold disease of strawberry pseudofruits. This phytopathogenic fungus is more active and the disease is more serious in temperate climate where the temperatures are lower. Methodology: The approach involved the isolation and characterization of bacteria from the phyllosphere of D. antarctica and the evaluation of their antifungal activity. Results: A total of 56 bacterial strains were isolated and only one of them, identified by the sequencing of 16S rDNA gene, as Pseudomonas frederiksbergensis CMAA 1323, inhibited the mycelial growth and the conidial germination of the fungus. Its ethyl acetate extract also inhibited Original Research Article Melo et al.; BMRJ, 14(3): 1-11, 2016; Article no.BMRJ.25314 2 the mycelial growth. Analysis of the bioactive fraction by using liquid chromatography coupled to a mass spectrometry (LC-MS) revealed the presence of cyclo(Pro-Val), a compound belonging to the class of diketopiperazines (DKPs). Conclusion: These findings support the potential use of the psychrophilic bacterium P. frederiksbergensis as promising antifungal agent, and highlight the need for more studies with this bacterium in the biological control of plant pathogenic fungi.