Cristina Selma-Lázaro

Bio: Cristina Selma-Lázaro is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Superoxide dismutase & Ochratoxin A. The author has an hindex of 3, co-authored 3 publications receiving 176 citations. Previous affiliations of Cristina Selma-Lázaro include University of Valencia.

Genome, Transcriptome, and Functional Analyses of Penicillium expansum Provide New Insights Into Secondary Metabolism and Pathogenicity

Abstract: The relationship between secondary metabolism and infection in pathogenic fungi has remained largely elusive. The genus Penicillium comprises a group of plant pathogens with varying host specificities and with the ability to produce a wide array of secondary metabolites. The genomes of three Penicillium expansum strains, the main postharvest pathogen of pome fruit, and one Pencillium italicum strain, a postharvest pathogen of citrus fruit, were sequenced and compared with 24 other fungal species. A genomic analysis of gene clusters responsible for the production of secondary metabolites was performed. Putative virulence factors in P. expansum were identified by means of a transcriptomic analysis of apple fruits during the course of infection. Despite a major genome contraction, P. expansum is the Penicillium species with the largest potential for the production of secondary metabolites. Results using knockout mutants clearly demonstrated that neither patulin nor citrinin are required by P. expansum to successfully infect apples. Li et al. ( MPMI-12-14-0398-FI ) reported similar results and conclusions in their recently accepted paper.

Effect of oxidant stressors and phenolic antioxidants on the ochratoxigenic fungus Aspergillus carbonarius.

Abstract: BACKGROUND There are few studies dealing with the relationship between oxidative stress and ochratoxin A (OTA) biosynthesis. In this work, we analyzed the effect of the oxidant stressor menadione and the antioxidants 3,5-di-tert-butyl-4-hydroxytoluene (BHT), catechin, resveratrol and a polyphenolic extract on growth, generation of reactive oxygen species (ROS), OTA production and gene expression of antioxidant enzymes of Aspergillus carbonarius. RESULTS Exposure to menadione concentrations higher than 20 µmol L−1 led to increases in ROS and OTA levels and a decrease in growth rate. Exposure to 2.5–10 mmol L−1 BHT also led to higher ROS and OTA levels, although growth rate was only affected above 5 mmol L−1. Naturally occurring concentrations of catechin, resveratrol and polyphenolic extract barely affected growth rate, but they produced widely different effects on OTA production level depending on the antioxidant concentration used. In general, gene expression of antioxidant enzymes superoxide dismutase (SOD) and peroxiredoxin (PRX) was downregulated after exposure to oxidant and antioxidant concentrations that enhanced OTA production level. CONCLUSION Aspergillus carbonarius responds to oxidative stress, increasing OTA production. Nevertheless, the use of naturally occurring concentrations of antioxidant phenolic compounds to reduce oxidative stress is not a valid approach by itself for OTA contamination control in grapes. © 2015 Society of Chemical Industry

Global analysis of biosynthetic gene clusters reveals vast potential of secondary metabolite production in Penicillium species.

Abstract: Filamentous fungi produce a wide range of bioactive compounds with important pharmaceutical applications, such as antibiotic penicillins and cholesterol-lowering statins. However, less attention has been paid to fungal secondary metabolites compared to those from bacteria. In this study, we sequenced the genomes of 9 Penicillium species and, together with 15 published genomes, we investigated the secondary metabolism of Penicillium and identified an immense, unexploited potential for producing secondary metabolites by this genus. A total of 1,317 putative biosynthetic gene clusters (BGCs) were identified, and polyketide synthase and non-ribosomal peptide synthetase based BGCs were grouped into gene cluster families and mapped to known pathways. The grouping of BGCs allowed us to study the evolutionary trajectory of pathways based on 6-methylsalicylic acid (6-MSA) synthases. Finally, we cross-referenced the predicted pathways with published data on the production of secondary metabolites and experimentally validated the production of antibiotic yanuthones in Penicillia and identified a previously undescribed compound from the yanuthone pathway. This study is the first genus-wide analysis of the genomic diversity of Penicillia and highlights the potential of these species as a source of new antibiotics and other pharmaceuticals.

Genome, Transcriptome, and Functional Analyses of Penicillium expansum Provide New Insights Into Secondary Metabolism and Pathogenicity

Abstract: The relationship between secondary metabolism and infection in pathogenic fungi has remained largely elusive. The genus Penicillium comprises a group of plant pathogens with varying host specificities and with the ability to produce a wide array of secondary metabolites. The genomes of three Penicillium expansum strains, the main postharvest pathogen of pome fruit, and one Pencillium italicum strain, a postharvest pathogen of citrus fruit, were sequenced and compared with 24 other fungal species. A genomic analysis of gene clusters responsible for the production of secondary metabolites was performed. Putative virulence factors in P. expansum were identified by means of a transcriptomic analysis of apple fruits during the course of infection. Despite a major genome contraction, P. expansum is the Penicillium species with the largest potential for the production of secondary metabolites. Results using knockout mutants clearly demonstrated that neither patulin nor citrinin are required by P. expansum to successfully infect apples. Li et al. ( MPMI-12-14-0398-FI ) reported similar results and conclusions in their recently accepted paper.

Co-occurrence of patulin and citrinin in Portuguese apples with rotten spots Part A Chemistry, analysis, control, exposure & risk assessment

Abstract: Patulin and citrinin are mycotoxins produced by certain fungi mainly belonging to Penicillium and Aspergillus and may be detected in mouldy fruits and fruit products. The data presented here refer to the simultaneous occurrence of patulin and citrinin in 351 samples of seven different varieties of apples with small rotten areas (Casanova, Golden Delicious, Red Delicious, Reineta, Richared, Rome Beauty, Starking). A rapid multidetection thin layer chromatography (TLC) method was used. The minimum detectable concentrations of patulin and citrinin were 120-130 and 15-20 micrograms kg-1 respectively. The percentage contamination with patulin only was higher (68.6%) than that with citrinin only (3.9%). Patulin and citrinin (19.6%) were also detected simultaneously. The highest mean patulin content was 80.50 mg kg-1 for the Richared variety, but the mean level of citrinin was lower. The lowest mean contaminations of patulin were found in Rome Beauty, Red Delicious and Reineta, ranging from 3.06 to 5.37 mg kg-1. All analysed apples varieties had low citrinin contamination, ranging from 0.32 to 0.92 mg kg-1. These findings indicate that there may be a risk of human exposure to patulin through the consumption of juices and jams manufactured with apples with small rotten areas.

The molecular steps of citrinin biosynthesis in fungi

Abstract: The individual steps of citrinin 1 biosynthesis in Monascus ruber M7 were determined by a combination of targeted gene knockout and heterologous gene expression in Aspergillus oryzae. The pathway involves the synthesis of an unreduced trimethylated pentaketide 10 by a non-reducing polyketide synthase (nrPKS) known as CitS. Reductive release yields the keto-aldehyde 2 as the first enzyme-free intermediate. The nrPKS appears to be assisted by an as-yet cryptic hydrolysis step catalysed by CitA which was previously wrongly annotated as an oxidase. CitB is a non-heme iron oxidase which oxidises the 12-methyl of 2 to an alcohol. Subsequent steps are catalysed by CitC which oxidises the 12-alcohol to an aldehyde and CitD which converts the 12-aldehyde to a carboxylic acid. Final reduction of C-3 by CitE yields citrinin. The pathway rules out alternatives involving intramolecular rearrangements, and fully defines the molecular steps for the first time and corrects previous errors in the literature. The activity of CitB links the pathway to fungal tropolone biosynthesis and the observation of aminated shunt products links the pathway to azaphilone biosynthesis. Production of citrinin by coordinated production of CitS + CitA–CitE in the heterologous host A. oryzae, in which each gene was driven by a constitutive promoter, was achieved in high yield.