Four group I introns were found in the nuclear small subunit ribosomal RNA genes (SSU rDNA) of the ballistoconidiogenous anamorphic yeast genus Bensingtonia. Two of them were found in B. ciliata, type species of the genus, with the length of 335nt and 341nt. The remaining two were found in B. yamatoana with lengths of 454nt and 457nt, respectively. The four introns were located at two different sites within the SSU rDNA. The first insertion site was the same position as group I introns found in the SSU rDNA of Dunaliella parva-5′, Dunaliella sauna, Protomycesinouyei-5′ and Ustilago maydis. The second insertion site was shared among group I introns found in the SSU rDNA of Chlorella ellipsoidea, Hildenbrandia rubra, Pneumocystis carinii and Protomyces inouyei-3′. The putative secondary structures of the introns resembled those of subgroup IC1. Principal coordinate analysis of core regions of 15 group I introns found in SSU rDNA of eukaryotes showed that the sequence of B. ciliata- 5′ intron resembled that of the B. yamatoana-5′ intron, and the sequence of the B. yamatoana-3′ intron resembled that of the Protomyces inouyei-5′ intron. Bensingtonia ciliata-3′ intron had relatively different sequences compared to other group I introns examined. Group I introns in the nuclear SSU rDNA of red and green algae, ascomycetes and basidiomycetes, examined in this study, were scattered on the principal coordinate analysis.
TThe accumulation of glycerol and inorganic ions were examined in a respiration-deficient (RD) mutant isolated from the salt-tolerant yeast Zygosaccharomyces rouxii for 3h after salt stress due to 1M NaCl. After the start of salt stress, intracellular levels of glycerol continued to increase for up to 3h, while the levels of Na+ and Cl- ions in cells reached maximum values within 1h and then decreased gradually. Increases in intracellular concentrations of solutes resulted in an osmotic pressure that was almost equivalent to the external osmotic pressure within 2h after salt stress. The RD strain had the same ability to tolerate salt as the wild-type strain. Therefore, we used the RD strain to examine the mechanism in the glycolytic pathway that is responsible for the promotion of glycerol synthesis that is induced by NaCl. When exposed to medium with 1M NaCl, RD cells diverted about one-sixteenth of the amount of ethanol that was produced in the medium without NaCl to the production of glycerol. This result suggests the presence of factors that mediate a change from the normal metabolism of glucose to the promotion of glycerol synthesis in response to external NaCl. The specific activities of glycerol-3-phosphate dehydrogenase (GPDH) in extracts of cells grown with and without 1M NaCl were very low in reaction mixtures with NADH or NADPH, although the cellular activity of alcohol dehydrogenase (ADH) was high and was repressed by external NaCl. This result indicates that the pathway involving GPDH makes only a small contribution to the synthesis of glycerol and that an alternative pathway functions for the synthesis in Z. rouxii. The addition of sodium sulfite, which binds to acetaldehyde, and of glycidol, an inhibitor of triosephosphate isomerase (TPI), to the medium promoted the synthesis of glycerol in RD strain. These results suggest the possibility that the extra NADH resulted from the binding of sulfite to acetaldehyde, or the inhibition of ADH and/or TPI under the NaCl-stressed condition lead to the promotion of glycerol synthesis by Z. rouxii.
Currently, there is no suitable method for screening thermophilic bacteria for dextranases (E.C. 188.8.131.52). Here we report a procedure suitable for the identification of anaerobes grown at high temperatures (55-68°C). Water samples to be screened are inoculated into liquid medium containing Blue Dextran. Anaerobic thermophiles containing an active dextranase can be identified visually by a change in color of the medium from blue to yellow. The method may be quantified by extracting the cell-free supernatant into 70% ethanol and measuring absorbance at 420nm. Production of the yellow chromophore requires actively growing cells producing an endodextranase. Some 150 thermophiles were screened. A selection of 30 anaerobic thermophiles were ranked with respect to their dextranase activity. This method allowed the identification of organisms producing a new class of enzyme, amylodextranase, which hydrolyses both starch and dextran.
Diacetoxyscirpenol (DAS)-deacetylating bacteria were isolated from ovine rumen fluid by the ordinary anaerobic roll-tube method in which the energy source substituted glucose, cellobiose and soluble starch for DAS (10ppm) in Medium-10. The isolates were Butyrivibrio fibrisolvens, Lactobacillus sp. and an unidentified bacterium. Among these bacteria, B. fibrisolvens M-14a, which had the highest capability of DAS metabolism, was incubated in a medium containing DAS. The bacteria grew well in the 10 and 50ppm concentrations. At these concentrations of DAS recovery ratios were 7.0 and 20.1%, and 15-acetoxyscirpenol (15-ASP) recovery ratios were 52.8 and 51.2% after 120h of incubation, respectively. In the 100ppm concentration, the bacterial growth was inhibited and the recovery ratio of DAS was 36.1%, and the ratio of 15-ASP was 16.7%.
The identity of the xerophilic species Aspergillus penicillioides and related taxa has been studied chemotaxonomically using polyacrylamide slab gel electrophoresis. In a dendrogram based on the calculated similarity values of five enzymes, 14 isolates of A. penicillioides in subgenus Aspergillus section Restricti and 28 isolates of related taxa in subgenus Aspergillus formed 22 clusters at a 60% similarity level. A. penicillioides isolates were scattered over the 11 clusters. In the ubiquinone systems, all isolates of A. penicillioides, including IFO 8155 (originally described as A. vitricolae [sic]), had the Q-9 system, which was the same ubiquinone system as Eurotium spp. A case study based on comparisons between the similarity values in enzyme patterns and the homology values in DNA relatedness in subgenus Circumdati section Flavi clearly indicates that Aspergillus isolates at a 60% or greater similarity level in enzyme patterns are considered to be conspecific. According to this guideline, A. penicillioides isolates are extremely diverse and presumably assigned to several species and we revive the name A. vitricola for IFO 8155 (ex holotype). Further molecular systematic studies are needed to clarify the identity and speciation of A. penicillioides.
Six indigenous and six non-indigenous bacteria capable of degrading phenolic compounds in pure cultures were inoculated into industrial wastewater samples of Puerto Rico containing high and low concentrations of p-nitrophenol (PNP). While only one non-indigenous bacteria enhanced PNP degradation, all of the indigenous bacteria enhanced degradation of both high (20μg/ml) and low (26ng/ml) concentrations of PNP, suggesting that indigenous bacteria are more suitable for inoculation in the tropical environment of Puerto Rico. In this report we characterized three indigenous strains (Corynebacterium sp. strain Z-2, Pseudomonas putida strain GS, Acinetobacter sp. strain BR-1) capable of enhancing degradation of PNP in industrial wastewater. The three indigenous bacteria, however, were different from each other in their response to substrate concentration as well as in their rate and extent of PNP degradation.