Aspergillus waksmanii sp. nov. and Aspergillus marvanovae sp. nov., two closely related species in section Fumigati

Two new and phylogenetically closely related species in Aspergillus section Fumigati are described and illustrated. Homothallic Aspergillus waksmanii sp. nov. was isolated from New Jersey soil (USA) and is represented by the ex-type isolate NRRL 179T ( = CCF 4266T = Thom 4138.HS2T = IBT 31900T). Aspergillus marvanovae sp. nov. was isolated from water with high boracic acid anions content in Dukovany nuclear power station (Czech Republic). The sexual stage of this species is unknown, but the MAT1-1 locus was successfully amplified suggesting that the species is probably heterothallic and teleomorphic but is represented by only the ex-type isolate CCM 8003T ( = CCF 4037T = NRRL 62486T = IBT 31279T = IFM 60873T). Both species can be distinguished from all previously described species in section Fumigati based on morphology, maximum growth temperature, sequence data from five unlinked loci and unique secondary metabolites profiles.

First Report of Natural Hybrids of Phytophthora nicotianae and P. cactorum on Loquat in Taiwan

In 1995 loquat trees (Eriobotrya japonica [Thunb.] Lindl.) in several orchards in central Taiwan suffered from a severe stemrot and rootrot (2). Two populations of Phytophthora spp. isolates were recovered from diseased trees by placing pieces of plant tissue in a petri dish containing selective medium (2). One group of isolates possessed papillate sporangia, appeared to be heterothallic with amphigynous antheridia, and had a maximum growth temperature of 36°C. Upon mating, isolates of this group produced oogonia and oospores measuring 26.1 and 21.4 μm in diameter, respectively. These isolates were identified as typical strains of P. parasitica (=P. nicotianae) (2). The second group of isolates showed papillate sporangia, was homothallic with predominantly amphigynous antheridia, and had a maximum growth temperature of 34.5°C. However, the sizes of oogonia and oospores were considerably larger (average 34.7 and 30.3 μm in diameter, respectively) than those of P. nicotianae. Amplification of genomic DNA of one isolate (95023) of the second group by polymerase chain reaction (PCR) using P. nicotianae species specific primers PAR1 and PAR2, produced a special 1,000 bp sequence, indicating that the atypical isolates of second group were closely related to P. nicotianae. Isozyme analysis of two isolates (95023 and 95034, provided by L. L. Chern, Taiwan) of the second group, using the dimeric enzymes malic enzyme (MDHP; EC 1.1.1.40) and malate dehydrogenase (MDH; EC 1.1.1.37), was applied as described before (1,3). These two isolates generated the same three banded patterns using either enzyme (genotype: MDHP: 92/100; MDH-2: 93/100); the Mdhp92 allele and the Mdh-293 allele are diagnostic for P. cactorum, whereas the Mdhp100 allele and the Mdh-2100 allele are diagnostic for P. nicotianae. These well-defined heterozygous band patterns were exactly identical to those generated in atypical isolates which were identified earlier as hybrids of P. nicotianae and P. cactorum (1,3). Based on their atypical morphology and isozyme genotyping, it was concluded that these two isolates of the second group represent hybrids of P. nicotianae and P. cactorum. One of the parents, P. nicotianae, was also found closely associated with diseased loquat trees; the other parental species, P. cactorum, was not isolated from loquat in this study. It is the first time that natural hybrids of P. nicotianae and P. cactorum were found on loquat in Asia. References: (1) P. J. M. Bonants et al. Phytopathology 90:867–874, 2000. (2) L. L. Chern et al. Plant Dis. 82:651–656, 1998. (3) W. A. Man in 't Veld et al. Phytopathology 88:922–929, 1998.

Growth Temperatures of Ropy Slime-Producing Lactic Acid Bacteria

The minimum, optimum, and maximum growth temperatures of ropy slime-producing lactic acid bacteria able to spoil vacuum-packed cooked meat products were determined on MRS-agar with temperature-gradient incubator GradiplateR W10. The minimum growth temperatures of slime-producing lactobacilli and Leuconostoc mesenteroides strain D1 were below −1°C and 4°C, respectively. The low minimum growth temperature allows these bacteria to compete with other bacteria in meat processing plants and in meat products causing ropiness problems. The maximum growth temperatures varied between 36.6–39.8°C. The maximum growth temperature of lactobacilli seemed to be an unstable character. Single lactobacilli colonies were able to grow above the actual maximum growth temperature, which is determined as the edge of continuous growth of the bacteria. The significance of this phenomenon needs further study.