Showing papers by "Ulf Thrane published in 2008"

Preserving accuracy in GenBank

Abstract: GenBank, the public repository for nucleotide and protein sequences, is a critical resource for molecular biology, evolutionary biology, and ecology. While some attention has been drawn to sequence errors ([1][1]), common annotation errors also reduce the value of this database. In fact, for

Preserving accuracy in GenBank

Abstract: GenBank, the public repository for nucleotide and protein sequences, is a critical resource for molecular biology, evolutionary biology, and ecology. While some attention has been drawn to sequence errors ([1][1]), common annotation errors also reduce the value of this database. In fact, for

The Trichoderma brevicompactum clade: a separate lineage with new species, new peptaibiotics, and mycotoxins.

Abstract: The Brevicompactum clade is recognized as a separate lineage in Trichoderma/Hypocrea. This includes T. brevicompactum and the new species T. arundinaceum, T. turrialbense, T. protrudens and Hypocrea rodmanii. The closest relative of the Brevicompactum clade is the Lutea clade. With the exception of H. rodmanii, all members of this clade produce the simple trichothecene-type toxins harzianum A or trichodermin. All members of the clade produce peptaibiotics, including alamethicins. Strains previously reported as T. harzianum (ATCC 90237), T. viride (NRRL 3199) or Hypocrea sp. (F000527, CBS 113214) to produce trichothecenes are reidentified as T. arundinaceum. The Brevicompactum clade is not closely related to species that have biological application.

Development of a LC-MS/MS method for the analysis of enniatins and beauvericin in whole fresh and ensiled maize.

Abstract: A LC-MS/MS method for the detection of beauvericin and the four enniatins A, A1, B, and B1 in maize and maize silage was developed. The method uses direct injection of maize extracts without any tedious and laborious cleanup procedures. The limit of quantification was determined at 13 ng g(-1) for beauvericin and at 17, 34, 24, and 26 ng g(-1) for enniatins A, A1, B, and B1, respectively. The method was used in surveys of the compounds in fresh maize samples collected at harvest in 2005 and 2006. All samples had the same distribution of the enniatins: B > B1 > A1 > A. Enniatin B was present in 90% of the samples in 2005 and in 100% in 2006 at levels up to 489 and 2598 ng g(-1), respectively. Beauvericin contamination was more frequently detected in 2006 than in 2005 (89 and 10%, respectively) and in higher amounts (988 and 71 ng g(-1), respectively). The occurrence of beauvericin and the four enniatins was examined in 3-month-old maize silage stacks from 20 different farms. As observed in fresh maize, enniatin B was the most abundant compound in ensiled maize and was found from 19 stacks at levels up to 218 ng g(-1). The stability of enniatin B in maize silage was assessed by analyzing samples from 10 of the silage stacks taken after 3, 7, and 11 months of ensiling. Enniatin B could be detected at all locations after 11 months and appeared to be stable during ensiling.

Computerized screening for novel producers of Monascus-like food pigments in Penicillium species.

Abstract: Monascus pigments have been used as natural food colorants in Asia for centuries. They are not authorized for use in the European Union and the United States mainly due to the risk of coproduction of the mycotoxin citrinin by Monascus spp. In the present study, we screened for novel producers of Monascus-like pigments from ascomycetous filamentous fungi belonging to Penicillium subgenus Biverticillium that are not reported to produce citrinin or any other known mycotoxins. The screening was carried out using the X-hitting algorithm as a tool to quickly screen through chromatographic sample data files of 22 different Penicillium extracts with 12 Monascus pigment extracts as controls. The algorithm searched for the most similar UV-vis spectra of the metabolites (cross hits) present in the pigment extracts to those of the selected reference metabolites viz. monascin, rubropunctatin, rubropunctamine, and citrinin. The cross hits were then manually identified on the basis of their UV-vis and mass spectra. X-hitting was found to be a good tool in the rapid screening of crude pigment extracts. Monascus pigments were discovered in the extracts of two closely related species of Penicillium that were only distantly related to the genus Monascus. Monascorubrin, xanthomonasin A, and threonine derivatives of rubropunctatin were identified in the extract of Penicillium aculeatum IBT 14263, and monascorubrin was identified in the extract of Penicillium pinophilum IBT 13104. None of the tested Penicillium extracts showed the presence of citrinin. Thus, the present study brought out two novel promising sources of yellow, orange, and purple-red Monascus-like food pigments in the species of Penicillia that do not produce citrinin and opened the door to look for several more new promising sources of natural food colorants in the species of Penicillia.

Mycotoxins in silage

Abstract: Purpose of review: This paper reviews the present knowledge on mycotoxins in silage, focusing on grass and maize silage. This includes the occurrence of filamentous fungi preand postharvest, possible and confirmed mycotoxins in silage, toxicological concerns and means to prevent the problem. Findings: Preharvest contamination of grass and maize by Fusarium, Aspergillus and Alternaria can lead to contamination of silage. Well known mycotoxins deoxynivalenol (DON), zearalenone (ZEA), fumonisins and aflatoxins have been detected in silages but concentrations seldom exceed regulatory limits. It also appears that DON, ZEA and fumonisins are degraded in silage, but exact mechanisms are unknown. Postharvest spoilage is dominated by Penicillium roqueforti, Aspergillus fumigatus and Zygomycetes. Both P. roqueforti and Asp. fumigatus produce a wide range of secondary metabolites, some of them confirmed mycotoxins, others with antimicrobial or immunosuppressive effects. Some fungal metabolites have been detected in silage but many have not been looked for. Evidence for acute toxicosis caused by contaminated silage is rare. Mycotoxins in silage are more often associated with less specific symptoms like ill-thrift or decreasing yield. This may be caused by long-term exposure to the complex mixture of secondary metabolites that silage can contain. Mycotoxins with antimicrobial effects may also affect ruminant digestion. To prevent postharvest spoilage of silage the most important factor is omission of oxygen. Additives can improve certain silage properties but they are not conclusively an advantage and cannot replace good silage management. Directions for future research: The effects of long-term exposure and of complex mixtures of bioactive fungal compounds are subjects of interest. Especially high-yielding livestock may be subject to sub-acute symptoms under these conditions. There is also a need for analytical methods with specificity and accuracy to determine many of the less known mycotoxins and secondary metabolites in silage as well as possible unknown compounds.

Evaluation of Epicoccum nigrum for growth, morphology and production of natural colorants in liquid media and on a solid rice medium

Abstract: Four nonpathogenic and nontoxigenic Epicoccum nigrum strains were evaluated for their growth, morphology and pigment producing ability in three complex and one defined liquid media. Epicoccum nigrum IBT 41028 produced pigments in all the four media tested with a maximum pigment of 3.68 AU at 410 nm in M1 medium (unoptimized) containing 5 g/l yeast autolysate. The color hue of the crude pigment extracts ranged from 74 to 102 exhibiting dark orange to green-yellow color. Pelleted morphology was shown to have a positive influence on the pigment production by E. nigrum strain IBT 41028 in the liquid media, and the use of Bis-tris buffer was found to diminish or reduce the pellet formation. Since Monascus is a well known pigment producer on rice. Pigment producing ability of E. nigrum IBT 41028 was tested on rice and compared to liquid media with Monascus ruber IBT 7904 as control. Though, both genera preferred rice but E. nigrum produced 4.6 folds higher pigment in the liquid unoptimized fermentation medium compared to M. ruber. Solid phase extraction and subsequently HPLC-DAD analysis of the crude pigment extracts showed qualitative as well as quantitative variation in the pigment composition under solid and liquid cultivations.

Production of monascus-like azaphilone pigment

Abstract: The present invention relates to the field of biotechnological production of polyketide based colorants from filamentous fungi, in particular a method for preparing a biomass comprising a Monascus -like pigment composition from a nontoxigenic and non-pathogenic fungal source. The present invention further relates to use of the Monascus -like pigment composition as a colouring agent for food items and/or non-food items, and a cosmetic composition comprising the Monascus -like pigment composition.