Genome Mining, Microbial Interactions, and Molecular Networking Reveals New Dibromoalterochromides from Strains of Pseudoalteromonas of Coiba National Park-Panama.

The marine bacterial genus Pseudoalteromonas is known for their ability to produce antimicrobial compounds. The metabolite-producing capacity of Pseudoalteromonas has been associated with strain pigmentation; however, the genomic basis of their antimicrobial capacity remains to be explained. In this study, we sequenced the whole genome of six Pseudoalteromonas strains (three pigmented and three non-pigmented), with the purpose of identifying biosynthetic gene clusters (BGCs) associated to compounds we detected via microbial interactions along through MS-based molecular networking. The genomes were assembled and annotated using the SPAdes and RAST pipelines and mined for the identification of gene clusters involved in secondary metabolism using the antiSMASH database. Nineteen BGCs were detected for each non-pigmented strain, while more than thirty BGCs were found for two of the pigmented strains. Among these, the groups of genes of nonribosomal peptide synthetases (NRPS) that code for bromoalterochromides stand out the most. Our results show that all strains possess BGCs for the production of secondary metabolites, and a considerable number of distinct polyketide synthases (PKS) and NRPS clusters are present in pigmented strains. Furthermore, the molecular networking analyses revealed two new molecules produced during microbial interactions: the dibromoalterochromides D/D' (11-12).

Paenibacillus polymyxa Associated with the Stingless Bee Melipona scutellaris Produces Antimicrobial Compounds against Entomopathogens.

Social insects are frequently observed in symbiotic association with bacteria that produce antimicrobial natural products as a defense mechanism. There is a lack of studies on the microbiota associated with stingless bees and their antimicrobial compounds. To the best of our knowledge, this study is the first to report the isolation of Paenibacillus polymyxa ALLI-03-01 from the larval food of the stingless bee Melipona scutellaris. The bacterial strain was cultured under different conditions and produced (L)-(-)-3-phenyllactic acid and fusaricidins, which were active against entomopathogenic fungi and Paenibacillus larvae. Our results indicate that such natural products could be related to colony protection, suggesting a defense symbiosis between P. polymyxa ALLI-03-01 and Melipona scutellaris.

Insights into Penicillium brasilianum Secondary Metabolism and Its Biotechnological Potential.

Over the past few years Penicillium brasilianum has been isolated from many different environmental sources as soil isolates, plant endophytes and onion pathogen. All investigated strains share a great ability to produce bioactive secondary metabolites. Different authors have investigated this great capability and here we summarize the metabolic potential and the biological activities related to P. brasilianum's metabolites with diverse structures. They include secondary metabolites of an alkaloid nature, i.e., 2,5-diketopiperazines, cyclodepsipeptides, meroterpenoids and polyketides. Penicillium brasilianum is also described as a great source of enzymes with biotechnological application potential, which is also highlighted in this review. Additionally, this review will focus on several aspects of Penicillium brasilianum and interesting genomic insights.

Calcification and Oxidative Modifications Are Associated With Progressive Bioprosthetic Heart Valve Dysfunction.

BACKGROUND: Bioprosthetic heart valves (BHVs), fabricated from glutaraldehyde-pretreated bovine pericardium or porcine aortic valves, are widely used for the surgical or interventional treatment of heart valve disease. Reoperation becomes increasingly necessary over time because of BHV dysfunction. METHODS AND RESULTS: Forty-seven explanted BHV aortic valve replacements were retrieved at reoperation for clinically severe BHV dysfunction over the period 2010-2016. Clinical explant analyses of BHV leaflets for calcium (atomic absorption spectroscopy) and oxidized amino acids, per mass spectroscopy, were primary end points. Comorbidities for earlier BHV explant included diabetes mellitus and coronary artery bypass grafting. Mean calcium levels in BHV leaflets were significantly increased compared with unimplanted BHV (P<0.001); however, time to reoperation did not differ comparing calcified and noncalcified BHV. BHV dityrosine, an oxidized amino acid cross-link, was significantly increased in the explants (227.55±33.27 µmol/mol [dityrosine/tyrosine]) but was undetectable in unimplanted leaflets (P<0.001). BHV regional analyses revealed that dityrosine, ranging from 57.5 to 227.8 µmol/mol (dityrosine/tyrosine), was detectable only in the midleaflet samples, indicating the site-specific nature of dityrosine formation. 3-Chlorotyrosine, an oxidized amino acid formed by myeloperoxidase-catalyzed chlorinating oxidants, correlated with BHV calcium content in leaflet explant analyses from coronary artery bypass graft patients (r=0.62, P=0.01) but was not significantly correlated with calcification in non-coronary artery bypass graft explanted BHV. CONCLUSIONS: Both increased BHV leaflet calcium levels and elevated oxidized amino acids were associated with bioprosthesis dysfunction necessitating reoperation; however, BHV calcium levels were not a determinant of implant duration, indicating a potentially important role for oxidized amino acid formation in BHV dysfunction.

Ecophysiology of Fusarium temperatum isolated from maize in Argentina.

The effect of water activity (aw = 0.95, 0.98 and 0.995), temperature (15, 25 and 30°C), incubation time (7, 14, 21 and 28 days), and their interactions on growth and moniliformin (MON), beauvericin (BEA), fusaproliferin (FUS) and fumonisin B1 (FB1) production by two strains of Fusarium temperatum isolated from Argentinean maize were determined in vitro on sterile layers of maize grains. The results showed that there was a wide range of conditions for growth and mycotoxins production by F. temperatum. Both strains were found to grow faster with increasing aw and at 30°C. In relation to mycotoxin production, the two strains produced more FUS than the other mycotoxins regardless of aw or temperature evaluated (maximum = 50,000 µg g(-1)). For FUS, MON and BEA, the maximum levels were observed at 0.98 aw and 30°C (50,000, 5000 and 2000 µg g(-1) respectively). The lowest levels for these three mycotoxins were detected at 15°C and 0.95 aw (1700 and 100 µg g(-1) for FUS and MON respectively), and at 0.98 aw (400 µg g(-1) for BEA). The maximum levels of FB1 were produced at 15°C and 0.98 aw (1000 µg g(-1)). At all aw and temperatures combinations evaluated there was an increase in toxin concentrations with time incubation. The maximum levels were detected at 21 days. Statistical analyses of aw, temperature, incubation time, and the two- and three-way interactions between them showed significant effects on mycotoxins production by F. temperatum. For its versatility on growth and mycotoxin production, F. temperatum represents a toxicological risk for maize in the field and also during grain storage.

Enterotoxigenic and genetic profiles of Bacillus cereus strains of food origin in Brazil.

In Brazil, the incidence of Bacillus cereus outbreaks is unknown, and there is little information about B. cereus occurrence in food. In addition, data on toxin production and genetic characterization of the B. cereus isolates cannot be found. This pathogen causes two distinct types of toxin-mediated foodborne illnesses known as diarrheal and emetic syndromes. Diarrheal syndrome has been linked to three different enterotoxins: two protein complexes, hemolysin BL (HBL) and nonhemolytic enterotoxin (NHE); and an enterotoxic protein, cytotoxin K (cytK). Emetic syndrome is related to cereulide, a toxin encoded by the ces gene. In this study, NHE and HBL production capacities of 155 strains of B. cereus isolated from Brazilian food products were evaluated with an immunoassay. Strains were also tested for the presence of the genes of the HBL and NHE complexes, cytK, cytK-1, cytK-2, and ces, using PCR. HBL was detected in 105 (67.7%) strains and NHE in 154 (99.4%) strains. All the strains harbored at least one gene of the NHE complex, while 96.1% of them were positive for at least one of those of the HBL complex. Genes cytK1 and ces were not detected. All strains showed toxigenic capacity and could represent a risk for consumers if good practices are not followed. This is the first report on toxigenic and genetic profiles of B. cereus strains isolated in Brazil.

Para-position derivatives of fungal anthelmintic cyclodepsipeptides engineered with Streptomyces venezuelae antibiotic biosynthetic genes.

PF1022A, a cyclooctadepsipeptide possessing strong anthelmintic properties and produced by the filamentous fungus Rosellinia sp. PF1022, consists of four alternating residues of N-methyl-L-leucine and four residues of D-lactate or D-phenyllactate. PF1022A derivatives obtained through modification of their benzene ring at the para-position with nitro or amino groups act as valuable starting materials for the synthesis of compounds with improved anthelmintic activities. Here we describe the production of such derivatives by fermentation through metabolic engineering of the PF1022A biosynthetic pathway in Rosellinia sp. PF1022. Three genes cloned from Streptomyces venezuelae, and required for the biosynthesis of p-aminophenylpyruvate from chorismate in the chloramphenicol biosynthetic pathway, were expressed in a chorismate mutase-deficient strain derived from Rosellinia sp. PF1022. Liquid chromatography-mass spectrometry and NMR analyses confirmed that this approach facilitated the production of PF1022A derivatives specifically modified at the para-position. This fermentation method is environmentally safe and can be used for the industrial scale production of PF1022A derivatives.