Rufibacter hautae sp. nov., a red-pigmented bacterium from freshwater lake sediment, and proposal of Rufibacter quisquiliarum as a latter heterotypic synonym of Rufibacter ruber

A taxonomic identification using a polyphasic approach was performed on strain NBS58-1^T, which was isolated from the interfacial sediment of Taihu Lake in China. Strain NBS58-1^T was Gram-stain-negative, aerobic, non-spore-forming and catalase-positive. Phylogenetic analyses based on 16S rRNA gene and three housekeeping genes (rpoB, gyrB and dnaK) sequences supported the position that strain NBS58-1^T should be classified within the genus Rufibacter. The 16S rRNA gene sequence of strain NBS58-1^T possessed the highest similarity to Rufibacter sediminis H-1^T (96.60 %), followed by Rufibacter glacialis MDT1-10-3^T (96.17 %). And the ANI value between strain NBS58-1^T and R. glacialis MDT1-10-3^T was 79.3 %. The respiratory quinone was menaquinone 7 (MK-7). The major cellular fatty acids comprised iso-C_15 : 0 and summed feature 3. Phosphatidylethanolamine, two unidentified phospholipids and four unidentified lipids were the main polar lipids. The genomic DNA G+C content was 51.3 mol%. Based on phenotypic features and phylogenetic position, a novel species with the name Rufibacter hautae sp. nov. is proposed. The type strain is NBS58-1^T=(KACC 21309^T=MCCC 1K04037^T). We also proposed Rufibacter quisquiliarum as a latter heterotypic synonym of Rufibacter ruber.

isolated from Spanish semi-hard ripened cheeses

Fifteen samples of semi-hard ripened cheeses, both spoiled (10) and unspoiled (5), and obtained from cheese factories located in Northwest of Spain, were analysed by a dilution plating technique and direct sampling. A total of 32 isolates were identified at species level by a polyphasic approach (phenotypic characterization, partial extrolite analysis and molecular identification). Most isolates (65.6%) belonged to the species P. commune; other species found were P. solitum, P. chrysogenum, P. nordicum, P. expansum and P. cvjetkovicii. All of the P. commune isolates were able to produce cyclopiazonic acid, while the P. nordicum and the P. expansum isolates were producers of ochratoxin A and patulin respectively. Despite this, the role of P. commune as beneficial fungi in cheese ripening should be investigated. Molecular identification based on BenA sequence analysis was able to identify the majority of isolates. The three mycotoxins investigated can be considered key for identification. The polyphasic approach seems to be a very valuable tool for identification of isolates of this complex genus.

Several species of Penicillium isolated from chestnut flour processing are pathogenic on fresh chestnuts and produce mycotoxins

A collection of 124 isolates of Penicillium spp. was created by monitoring fresh chestnuts, dried chestnuts, chestnut granulates, chestnut flour and indoor chestnut mills. Sequencing of the ITS region, β-tubulin and calmodulin, macro-morphology and secondary metabolite production made it possible to determine 20 species of Penicillium. P. bialowiezense was dominant in the fresh chestnuts, while P. crustosum was more frequent in the other sources. A pathogenicity test on chestnut showed that around 70% of the isolates were virulent. P. corylophilum and P. yezoense were not pathogenic, while the other 18 species had at least one virulent isolate. P. expansum and P. crustosum were the most virulent. The isolates were characterized to establish their ability to produce 14 toxic metabolites in vivo: 59% were able to produce at least one mycotoxin. P. expansum was able to produce patulin, chaetoglobosin A and roquefortine, while P. bialowiezense produced C. Mycophenolic acid. Cyclopenins and viridicatins were produced by most of the P. crustosum, P. polonicum, P. solitum and P. discolour isolates. Some of the P. crustosum isolates were also able to produce roquefortine C or penitrem A. Information about the occurrence of Penicillium spp. and their mycotoxins will help producers to set up management procedures that can help to control the fungal growth and the mycotoxin production of chestnuts.

Diversity of black Aspergilli isolated from raisins in Argentina: Polyphasic approach to species identification and development of SCAR markers for Aspergillus ibericus

Aspergillus section Nigri is a heterogeneous fungal group including some ochratoxin A producer species that usually contaminate raisins. The section contains the Series Carbonaria which includes the toxigenic species Aspergillus carbonarius and nontoxigenic Aspergillus ibericus that are phenotypically undistinguishable. The aim of this study was to examine the diversity of black aspergilli isolated from raisins and to develop a specific genetic marker to distinguish A. ibericus from A. carbonarius. The species most frequently found in raisins in this study were Aspergillus tubingensis (35.4%) and A. carbonarius (32.3%), followed by Aspergillus luchuensis (10.7%), Aspergillus japonicus (7.7%), Aspergillus niger (6.2%), Aspergillus welwitschiae (4.6%) and A. ibericus (3.1%). Based on inter-simple sequence repeat (ISSR) fingerprinting profiles of major Aspergillus section Nigri members, a sequence-characterized amplified region (SCAR) marker was identified. Primers were designed based on the conserved regions of the SCAR marker and were utilized in a PCR for simultaneous identification of A. carbonarius and A. ibericus. The detection level of the SCAR-PCR was found to be 0.01 ng of purified DNA. The present SCAR-PCR is rapid and less cumbersome than conventional identification techniques and could be a supplementary strategy and a reliable tool for high-throughput sample analysis.