Cattleya milleri is a microendemic orchid of iron-rich rupestrian grasslands in the Brazilian savanna hotspot. It is under critical threat due to illegal collections and habitat destruction. As endophytic and mycorrhizal fungi have potential application during C. milleri propagation and conservation, we investigated its root fungal community. C. milleri roots were sampled in five natural sites and at a greenhouse. Fungal root endophytes were isolated for cultural characterization and molecular ITS (Internal Transcribed Spacer) identification. Total DNA was extracted from root endorhiza and rhizosphere to ITS amplification and sequencing. Sixteen fungal isolates were clustered in 6 Operational Taxonomic Units (OTUs), while endorhizal and rhizospheric sequences were clustered in 327 OTUs. Endorhiza richness (OTUs number) ranged from 25 to 89 OTUs, and rhizosphere presented 56 OTUs. Cluster analysis showed high divergence between natural and greenhouse environments, but a small distance among natural samples. Four phyla, 48 orders, 81 families, and 94 genera were annotated. The putative role of 134 OTUs was annotated, and 24 genera were endophytes, 2 mycorrhizas, 33 pathotrophs, 40 saprotrophs and 17 symbiotrophs. Three orders containing endophytes (Capnodiales, Hypocreales, and Pleosporales) and one containing mycorrhizae (Sebacinales) occurred in all sites. The mycorrhizae Tulasnella occurred in all natural samples. The presence of only two mycorrhizal taxa suggested the mycorrhizae may limit C. milleri distribution. However, many fungi can be recruited from the environment as non-mycorrhizal endophytes. Considering their abundance and role in orchid development, Pleosporales, Tulasnella, and Sebacinalles may be considered for C. milleri propagation and conservation.

No abstract

In the oil industry, biofilms formed by Sulfate-Reducing Bacteria (SRB) cause great damage related to the corrosion of tanks and pipes, and produce toxic gases such as H2S. The application of biocides is currently the most used form of treatment to control these microorganisms. However, these biocides are often ineffective against biofilms. Thus, the use of bacteriophages (or phages) has been studied as an alternative treatment. Phages are viruses that infect bacteria and may have the ability to degrade polymeric substances in the biofilm matrix, exposing the bacteria to infection by new phage particles or physical and chemical stresses. In this context, the present work aimed to formulate phage cocktails and evaluate their potential to control the biofilm formed by an SRB mixed culture of unknown composition. For this, 10 phages were isolated from sewage samples and analyzed by transmission electron microscopy (TEM). Fast-growing bacteria were then used to screen these isolated phages for their potential to reduce biofilm formation and also to assess their host spectrum. The host spectrum was investigated by analyzing the growth curve of each bacterium in the presence and absence of the phage, while the biofilm control potential was investigated by quantifying the biofilm biomass, using the crystal violet staining method. As all phages showed promise in controlling these biofilms, all were tested separately against a mixed SRB culture. From the results obtained with the phages tested separately, 6 cocktails were formulated by combining the isolates, which were then tested in the control of biofilm formation by the SRB culture. The members of the cocktails were also analyzed for stability after incubation under different conditions of temperature and pH, as well as in seawater. Microscopy analysis revealed the presence of 4 myoviruses, 3 siphoviruses and 3 podoviruses. Three of these isolates were able to infect more than one bacterial genus, being, therefore, polyvalent phages. All phages were able to, separately, reduce the biofilm formation of at least one non-host bacterial species, and 5 were able to reduce the biofilm formation by the SRB culture. Three of the six cocktails tested, Coq3, Coq5 and Coq6, reduced biofilm formation by the SRB culture by 15%, 44% and 43%, respectively. Although Coq5 showed the highest percentage of reduction (albeit with little difference from Coq6), Coq6 was the most promising since these phages had better stability under the different conditions studied compared to Coq5 phages. All Coq6 phages remained completely stable when incubated in seawater and showed viability above 50% when incubated at pH 4, interesting characteristics for a field application in the oil industry where low pH values and high salinity can be reached. In contrast, only one Coq6 phage maintained 100% viability when tested at higher temperatures (55 °C). Future analysis of the phages' genomes and identification of the component species of the mixed SRB culture should be carried out to obtain a better under...

Na indústria petrolífera, os biofilmes formados por Bactérias Redutoras de Sulfato (BRS) causam grandes danos relacionados à corrosão de tanques e tubulações, além da produção de gases tóxicos como o H 2 S. Os biocidas químicos, atualmente mais utilizados para o controle desses microrganismos, são frequentemente ineficazes contra biofilmes. Assim, os bacteriófagos (ou fagos) tem sido estudado como agentes alternativos de tratamento. Fagos são vírus que infectam bactérias e podem degradar substâncias poliméricas na matriz do biofilme, expondo as bactérias à infecção por novas partículas virais ou à estresses físicos e químicos. Nesse contexto, o presente trabalho teve como objetivo formular coquetéis de fagos e avaliar seu potencial no controle do biofilme formado por uma cultura mista de BRS de composição desconhecida. Para isso, 10 fagos foram isolados de amostras de esgoto e analisados por microscopia eletrônica de transmissão (MET). Bactérias de crescimento rápido foram então usadas para triar os fagos isolados quanto ao potencial para reduzir a formação de biofilme e para avaliar o espectro de hospedeiro. O espectro do hospedeiro foi investigado pela análise da curva de crescimento de cada bactéria e o potencial para reduzir a formação de biofilme foi investigado pela quantificação da biomassa do biofilme. Como todos os fagos mostraram-se promissores no controle desses biofilmes, todos foram testados separadamente contra a cultura de BRS. A partir dos resultados obtidos com os fagos testados separadamente, 6 coquetéis foram formulados pela combinação dos isolados, que foram então testados para o controle da formação de biofilme pela cultura de BRS. Os fagos dos coquetéis também foram analisados quanto à estabilidade após incubação em diferentes condições de temperatura e pH, bem como em água do mar. A análise microscópica revelou a presença de 4 miovírus, 3 sifovírus e 3 podovírus. Três desses isolados foram capazes de infectar mais de um gênero bacteriano, sendo, portanto, fagos polivalentes. Todos os fagos foram capazes de, separadamente, reduzir a formação de biofilme de pelomenos uma espécie bacteriana não hospedeira, e 5 foram capazes de reduzir a formação de biofilme pela cultura de BRS. Três dos seis coquetéis testados, Coq3, Coq5 e Coq6, reduziram a formação de biofilme pela cultura de BRS em 15%, 44% e 43%, respectivamente. Embora Coq5 tenha mostrado a maior porcentagem de redução (embora com pouca diferença de Coq6), Coq6 foi o mais promissor, uma vez que esses fagos tiveram melhor estabilidade nas diferentes condições estudadas em comparação com os fagos do Coq5. Todos os fagos do Coq6 permaneceram completamente estáveis quando incubados em água do mar e apresentaram viabilidade acima de 50% quando incubados em pH 4, características interessantes para uma aplicação de campo na indústria petrolífera onde baixos valores de pH e alta salinidade podem ser alcançados. Análises futuras de sequenciamento de genoma dos fagos e a identificação das espécies que compõem a cultura de BRS, bem como análise dos componentes do biofilme, devem ser realizadas para obter uma melhor compreensão das relações fago-biofilme. Em conclusão, a abordagem para seleção de coquetéis parece ser uma estratégia promissora. Palavras-chave: Bacteriófagos. Biocontrole. Fagos polivalentes.