Ambuic acid (AA) is a highly-modified cyclohexenone and known as a promising inhibitor of quorum sensing in methicillin-resistant Staphylococcus aureus, and is thus a candidate as an antivirulence drug. This molecule is mainly produced by the species of Pestalotiopsis and, since its discovery twenty years ago, only a restricted amount of AA-derivatives have been described. Despite being a promising subject, methods for the analysis of modified AA-analogues via mass spectrometry remain unexplored. In order to adress this question, the marine fungus Pestalotiopsis sp. 4A11 associated with the ascidian Didemnum perlucidum was grown in a solid rice medium and its crude extract was chemically studied. From this extract, AA and 10-hydroxy ambuic acid (10-HAA) were isolated and identified using NMR spectroscopy with the aim of obtaining model compounds for the MS analysis. These served as reference compounds (seeds) to guide the dereplication of other AA-analogues via LC-MS/MS-based molecular networking. Based on the manual interpretation of the fragmentation pathways of the seeds and related compounds observed in the networks, six AA-derivatives were dereplicated in the extract. Furthermore, three analogues with unprecedented chemical formulas were proposed as putative unprecedented AA-derivatives. The fragmentation annotation proposed represents a fast and feasible method for characterizing AA-derivatives.

The genus Streptomyces represents one of the largest producers of molecules with antibiotic activity. The whole genome sequencing of the endophytic microorganism Streptomyces sp. CBMAI 2042 revealed 35 gene clusters encoding for secondary metabolism including 3 non-ribosomal peptide synthetases (NRPS) and 7 NRPS-hybrids. Combining genome mining and cultivation profile analysis, the depsipeptide ionophore valinomycin was identified as one of the main metabolites produced by this strain. To better understand the metabolic machinery codified in CBMAI 2042 genome an adenylation domain from a hybrid NRPS cluster was deleted through a double crossing knockout experiment. Though the deletion was not plentiful to elucidate the encoded NRP metabolite related to the adenilation domain, an astounding increase of 10.5-fold in valinomycin production was observed in the mutant. These results suggest a metabolic flux redistribution of common substrates as an outcome of a gene target deletion.

The actinobacteria Streptomyces wadayamensis A23, an endophitic strain, was recently sequenced and previous work showed qualitatively that the strain inhibits the growth of some pathogens. Herein we report the genome analysis of S. wadayamensis which reveals several antibiotic biosynthetic pathways. Using mass spectrometry, we were able to identify desferoxamines, several antimycins and candicidin, as predicted. Additionally, it was possible to confirm that the biosynthetic machinery of the strain when compared to identified known metabolites is far underestimated. As suggested by biochemical qualitative tests, genome encoded information reveals that the strain A23 has high capability to produce antibiotics.

Indigenous bacteria isolated from a crude oil sample from a deep water reservoir in the Pampo Sul Oilfield (Campos Basin-RJ, Brazil) were previously classified as strains of B. pumilus. However, their enzymatic activities with fluorogenic probes and rates of petroleum biodegradation were completely different. Some of the bacteria depleted n-alkanes, whereas others did not. Aromatic compounds reported to be recalcitrant were also biodegraded by some of these Bacillus strains, revealing their outstanding ability to deplete petroleum. Further classification using matrixassisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) followed by statistical analysis revealed that these strains could be clustered into three different groups, consistent with their enzymatic activity evaluation. A more accurate phylogenetic analysis using gyrB gene sequences confirmed the MALDI-TOF MS classification of three groups of strains and identified them as Bacillus safensis, B. cereus and B. thuringiensis.

Durante o monitoramento de ensaios de biodegradação com consórcios microbianos recuperados de amostras de petróleo do campo Pampo Sul, Bacia de Campos, RJ, observou-se a produção de substâncias exopoliméricas (EPS) a qual ocorria independentemente do processo de biodegradação. Para potencializar essa produção utilizou-se um meio mineral enriquecido com glicose e 9,10-di-hidrofenantreno, n-nonadecano, ácido nonadecanóico, petróleo levemente biodegradado (P1) e petróleo severamente biodegradado (P2) como fontes de carbono. A análise dos EPS por infravermelho e espectrometria de massas com ionização por electrospray (MS-ESI) revelou uma mistura de isoformas de surfactina, que reduziu a tensão superficial da água e do meio Zinder de 72,4 e 55,7 para 28,6 mN m"1. Além disso, demonstraram capacidade de formar emulsões de diferentes óleos em água, com resultados até melhores que de surfactantes comerciais, como Tween 80. A produção dos EPS não foi inibida por nenhum dos substratos testados.

Microbial consortia recuperated of crude oil samples from the Pampo Sul field, Campos Basin, RJ, produced biosurfactants in mineral media containing glucose and 9,10-dihydrophenantrene, n-nonadecane, nonadecanoic acid, slightly biodegraded crude oil (P1) or heavily biodegraded crude oil (P2) as carbon sources. The production of exopolimeric substances (EPS) and petroleum biodegradation do not necessarily occur simultaneously. The EPS analyses by infrared and eletronspray ionization mass spectrometry (ESI-MS) revealed a mixture of surfactine isoforms. The biosurfactants reduced the surface tension of water and Zinder medium from 72.4 and 55.7 to 28.6 mN m"1. Additionally, this surfactant emulsified different oils in water with performances similar to or better than of a conventional surfactant, Tween 80.