Infections with Avian Pathogenic and Fecal Escherichia coli Strains Display Similar Lung Histopathology and Macrophage Apoptosis

The purpose of this study was to compare histopathological changes in the lungs of chickens infected with avian pathogenic (APEC) and avian fecal (A(fecal)) Escherichia coli strains, and to analyze how the interaction of the bacteria with avian macrophages relates to the outcome of the infection. Chickens were infected intratracheally with three APEC strains, MT78, IMT5155, and UEL17, and one non-pathogenic A(fecal) strain, IMT5104. The pathogenicity of the strains was assessed by isolating bacteria from lungs, kidneys, and spleens at 24 h post-infection (p.i.). Lungs were examined for histopathological changes at 12, 18, and 24 h p.i. Serial lung sections were stained with hematoxylin and eosin (HE), terminal deoxynucleotidyl dUTP nick end labeling (TUNEL) for detection of apoptotic cells, and an anti-O2 antibody for detection of MT78 and IMT5155. UEL17 and IMT5104 did not cause systemic infections and the extents of lung colonization were two orders of magnitude lower than for the septicemic strains MT78 and IMT5155, yet all four strains caused the same extent of inflammation in the lungs. The inflammation was localized; there were some congested areas next to unaffected areas. Only the inflamed regions became labeled with anti-O2 antibody. TUNEL labeling revealed the presence of apoptotic cells at 12 h p.i in the inflamed regions only, and before any necrotic foci could be seen. The TUNEL-positive cells were very likely dying heterophils, as evidenced by the purulent inflammation. Some of the dying cells observed in avian lungs in situ may also be macrophages, since all four avian E. coli induced caspase 3/7 activation in monolayers of HD11 avian macrophages. In summary, both pathogenic and non-pathogenic fecal strains of avian E. coli produce focal infections in the avian lung, and these are accompanied by inflammation and cell death in the infected areas.     

Probiotic Potential of Autochthonous Bacteria Isolated from the Gastrointestinal Tract of Four Freshwater Teleosts

In this study, a total of 121 bacterial strains were isolated from the gastrointestinal tract of four teleostean species, namely striped snakehead (Channa striatus), striped dwarf catfish (Mystus vittatus), orangefin labeo (Labeo calbasu) and mrigal carp (Cirrhinus mrigala), among which 8 isolates showed promising antibacterial activity against four potential fish pathogens, Aeromonas hydrophila, Aeromonas salmonicida, Aeromonas sobria and Pseudomonas fluorescens and were non-hemolytic. The isolates were further screened in response to fish bile tolerance and extracellular digestive enzyme activity. Two bacterial strains MVF1 and MVH7 showed highest tolerance and extracellular enzymes activities, and selected for further studies. Antagonistic activity of these two isolates was further confirmed by in vitro growth inhibition assay against four selected fish pathogens in liquid medium. Finally, these two bacterial strains MVF1 and MVH7 were selected as potential probiotic candidates and thus identification by partial 16S rRNA gene sequence analysis. The bacterial isolates MVF1 and MVH7 were identified as two strains of Bacillus sp.     

Effects of oral glucosamine and chondroitin sulfate alone and in combination on the metabolism of SHR and SD rats

Glucosamine (G), often combined with chondroitin sulfate (CS), is a popular natural supplement used widely to treat osteoarthritis. However, use of glucosamine has been linked to development of insulin resistance. To assess the association between glucosamine and insulin resistance more closely, we challenged two rat strains highly sensitive to sugarinduced insulin resistance – SpragueDawley (SD) and Spontaneously Hypertensive (SHR) rats. Since elevations of systolic blood pressure (SBP) have been found to be an early and highly sensitive sign of insulin resistance in these two rat strains, we used this parameter as our primary endpoint. Four groups of both rat strains received either no agent (control), G, CS, or a combination of both for 9 weeks. The intake of each agent was calculated to be approximately 3–7 times comparable to human dose. Throughout the study, SBP of both strains consuming the two ingredients alone and in combination were not elevated. Rather, they were significantly lower than control, contrary to what is found in glucoseinduced insulin resistance in rats. Over the study period, body weights of the four groups of SD and SHR did not vary significantly. Furthermore, no consistent trends in circulating glucose concentrations were found among the four different groups in the two strains after oral challenge with glucose. Finally, no significant histological differences were found in hearts, kidneys, and livers among the various groups of SHR and SD. From the above result, we conclude that glucosamine and chondroitin sulfate given alone or together do not produce insulin resistance or other related perturbations in two rat strains highly sensitive to sugarinduced insulin resistance.     

Improvement of cowpea productivity by rhizobial and mycorrhizal inoculation in Burkina Faso

Cowpea is one of the most important food legume crops in Burkina Faso. It is able to associate with arbuscular mycorrhizal fungi (AMF) and rhizobia. This dual symbiosis improves nitrogen and phosphorus nutrient uptake in cowpea. As the application of exotic inoculants frequently lacks positive responses in field experiments, this study set out to select well-adapted native symbiotic rhizobial and AMF strains. Soil samples were collected from six study sites in three different climatic zones of Burkina Faso to investigate their native symbiotic strains. Soil-extraction of native spores led to the identification of four AMF genera (Scutellospora, Gigaspora, Glomus and Entrophospora) by morpho-anatomical characterization. The two most effective cowpea fungal strains were selected after spore isolation from field-collected soils, multiplication on maize roots and inoculation on cowpea seedlings in a greenhouse experiment. Cowpea-nodulating rhizobial strains were trapped in the greenhouse by planting cowpea seeds in collected soil samples and the strains were characterized using molecular methods. This characterization led to the rhizobial isolates being classified in four clusters on the phylogenetic tree (using the Maximum-Likelihood Phylogenies method). All strains belonged to the Bradyrhizobium genus and most of them were included in the B. japonicum branch. Some groups were clearly distinct species already identified and may be new species. The two most effective strains for cowpea yield improvement in the field were selected after cowpea inoculation in a greenhouse experiment. The inoculation design in the field experiment consisted of four single inoculation treatments, either rhizobial or mycorrhizal, along with four dual inoculations, one treatment with chemical fertilizers, and one uninoculated control. The results showed that cowpea productivity was significatively improved by dual inoculation with native rhizobial and mycorrhizal strains, reaching the same level as the application of commonly used chemical fertilizers [Nitrogen, Phosphorus and Potassium fertilizers (NPK)]. In addition, dual inoculation resulted in the highest iron content in cowpea leaves.     

A Morphometric Study of Euryhalinity in Marine Populations of the Ciliate Genus Euplotes

ABSTRACT. Twenty different clonal strains of marine and brackish Euplotes , representing four morphotypes, were tested for hyposalinity tolerance by a method which gradually acclimated the cells to lower salinity medium. The lowest salinities in which the strains could thrive ranged from 60% of normal seawater to complete freshwater. The morphological effects of culture medium salinity were also examined for two strains of a small "Euplotes charon" morphotype, as well as for two mating compatible "Euplotes vannus" strains and several of their exconjugates. There were no differences between the euryhaline strains grown in fresh or saltwater, except for a slight increase in overall cell size in one strain when cultured in freshwater medium. E. vannus strains increased in overall cell size with decreased salinity; also, the dorsal surface of the cells can become disorganized when the cells are cultured in 30% normal seawater.     

Formation of thionates by freshwater and marine strains of sulfate-reducing bacteria

The formation of thionates (thiosulfate, trithionate and tetrahionate) during the reduction of sulfate or sulfite was studied with four marine and four freshwater strains of sulfate-reducing bacteria. Growing cultures of two strains of the freshwater species Desulfovibrio desulfuricans formed up to 400 M thiosulfate and 100 M trithionate under conditions of electron donor limitation. Tetrathionate was observed in lower concentrations of up to 30 M. Uncoupler-treated washed cells of the four freshwater strains formed thiosulfate and trithionate at low electron donor concentrations with sulfite in excess. In contrast, only one of four marine strains formed thionates. The freshwater strain Desulfobulbus propionicus transformed sulfite almost completely to thiosulfate and trithionate. The amounts produced increased with time, concentration of added sulfite and cell density. Tetrathionate was detected only occasionally and in low concentrations, and was probably formed by chemical oxidation of thiosulfate. The results confirm the diversity of the sulfite reduction pathways in sulfate-reducing bacteria, and suggest that thiosulfate and trithionate are normal by-products of sulfate reduction.Abbreviations CCCP carbonyl cyanide m-chlorophenylhydrazone     

Variations in genetic control of susceptibility to Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. I. Differences between susceptible SJL/J and resistant BALB/c strains map near the T cell beta-chain constant gene on chromosome 6

In some susceptible mouse strains, intracerebral (IC) inoculation of Theiler's murine encephalomyelitis virus (TMEV) results in a persistent infection leading to chronic demyelinating disease. Previous genetic analyses between susceptible SJL/J and resistant C57BL/6 mice indicated a role for multiple unlinked genes in the development of clinical and histopathological disease, including a major influence of the D region of the H-2 complex. In this study, genetic analysis of a different strain combination (susceptible SJL/J and resistant BALB/c) also demonstrates the involvement of multiple genes, but the H-2 genotype (H-2s and H-2d, respectively) does not appear to contribute significantly to susceptibility differences. In both segregation studies and recombinant-inbred (R-I) analysis, clinical and histopathological disease occurs in both H-2s homozygotes and H-2d homozygotes (as well as H-2s/H-2d heterozygotes), with the actual frequency related to the proportion of non-H-2 genome from the susceptible strain. There appear to be at least two non-H-2 genes involved in differential susceptibility of SJL/J and BALB/c to TMEV-induced disease. Analysis of R-I strains generated from BALB/c and SJL/J progenitors indicates linkage of at least one of these non-H-2 genes to those encoding the constant portion of the beta-chain of the T cell receptor on chromosome 6. Many genes may actually be involved, but each strain comparison defines a different subset of these loci--only those at which the two strains in question carry "functionally" different alleles. Thus, different strain comparisons may accent the roles of different genes in resistance to the same infectious organism or disease process. In addition to the genes identified thus far, there may be yet other genes contributing to development of TMEV-induced disease, but their recognition may require analysis of still other strain combinations.     

Comparison of tolerance of four bacterial nanocellulose-producing strains to lignocellulose-derived inhibitors

Background

Through pretreatment and enzymatic saccharification lignocellulosic biomass has great potential as a low-cost feedstock for production of bacterial nanocellulose (BNC), a high value-added microbial product, but inhibitors formed during pretreatment remain challenging. In this study, the tolerance to lignocellulose-derived inhibitors of three new BNC-producing strains were compared to that of Komagataeibacter xylinus ATCC 23770. Inhibitors studied included furan aldehydes (furfural and 5-hydroxymethylfurfural) and phenolic compounds (coniferyl aldehyde and vanillin). The performance of the four strains in the presence and absence of the inhibitors was assessed using static cultures, and their capability to convert inhibitors by oxidation and reduction was analyzed.

Results

Although two of the new strains were more sensitive than ATCC 23770 to furan aldehydes, one of the new strains showed superior resistance to both furan aldehydes and phenols, and also displayed high volumetric BNC yield (up to 14.78 ± 0.43 g/L) and high BNC yield on consumed sugar (0.59 ± 0.02 g/g). The inhibitors were oxidized and/or reduced by the strains to be less toxic. The four strains exhibited strong similarities with regard to predominant bioconversion products from the inhibitors, but displayed different capacity to convert the inhibitors, which may be related to the differences in inhibitor tolerance.

Conclusions

This investigation provides information on different performance of four BNC-producing strains in the presence of lignocellulose-derived inhibitors. The results will be of benefit to the selection of more suitable strains for utilization of lignocellulosics in the process of BNC-production.

     

Strain differences in aryl hydrocarbon hydroxylase induction by 3-methylcholanthrene in rabbits.

We determined both basal and induced AHH activity in livers of six partially inbred strains of rabbits. Strain III rabbits had the highest enzyme activity upon induction by 3-MCA, i.e., four to five times that in strain WH (noninducible), which has the lowest enzyme activity. AHH induction was also "low" in strains X, OS, ACEP, and AC. F1 hybrids between strains III and WH revealed a differential response to the induction of liver AHH activity by MCA: the levels of induced hydroxylase activity were consistently higher in (III X WH)F1 rabbits than in the reciprocal (WH X III)F1 hybrids. All possible crosses between these two "extreme" strains are now being analyzed to estimate the number of genes involved in their response difference to MCA.     

On the origin and function of an insertion element VPaI-1 specific to post-1995 pandemic Vibrio parahaemolyticus strains

Since 1995, new virulent strains of Vibrio parahaemolyticus have emerged and spread throughout the world. These "pandemic" strains have four strain specific genomic islands (GIs), which are considered to be potential factors of the pandemicity. We investigated the origin and function of 24 genes in the so-called VPaI-1, one of the four GIs, by searching homologs in various species in Bacteria and Archaea. Of these 24 genes, two are found only in Vibrio vulnificus CMCP6 and Shewanella sp. MR-7. The genomic segment (- 8 kb) encompassing the two genes shows the synteny among the three species. Since many of the Shewanella species can grow at 4 degrees C, these two genes may be candidates of adaptation to temperature stress. Further, we found a candidate for a swarming gene, which is reported as the V. cholerae virulence gene. Based on these findings, we hypothesized the emergence of pandemicity and discuss the mechanism for how these strains spread throughout the world.     

Two approaches to obtaining low,extracellular deoxyribonuclease activity in cultures of heterocyst-forming cyanobacteria

Six out of 158 axenic strains of heterocyst-forming cyanobacteria consistently failed to produce circles of clearing in agar medium containing DNA-methyl green. When tested with [³H]DNA and coliphage DNA, supernatant fluids from cultures of two of these strains [University of Texas Culture Collection (UTEX) strain 2014 and 19-6C-C] showed no detectable deoxyribonuclease activity, and such fluids from another two of the six, and four others, showed low but detectable deoxyribonuclease activity. Covalently closed circular (plasmid) DNA was not detectably degraded by supernatant fluids from UTEX 2014 and 19-6C-C and from four of the other strains. When DNA was incubated with whole cells of certain strains, a sereis of fragments of discrete size was produced, perhaps by cell-bound, periplasmic, restriction endonucleases. Inclusion of one-tenth strength saline sodium citrate (SSC) in an eight-fold dilution of the medium of Allen and Arnon had little effect on growth of Anabaena variabilis American Type Culture Collection (ATCC) strain 29413 yet prevented all but slight degradation of plasmid pBR322 or of DNA.     

Strategy for identification of Bacillus cereus and Bacillus thuringiensis strains closely related to Bacillus anthracis

Bacillus cereus strains that are genetically closely related to B. anthracis can display anthrax-like virulence traits (A. R. Hoffmaster et al., Proc. Natl. Acad. Sci. USA 101:8449-8454, 2004). Hence, approaches that rapidly identify these "near neighbors" are of great interest for the study of B. anthracis virulence mechanisms, as well as to prevent the use of such strains for B. anthracis-based bioweapon development. Here, a strategy is proposed for the identification of near neighbors of B. anthracis based on single nucleotide polymorphisms (SNP) in the 16S-23S rRNA intergenic spacer (ITS) containing tRNA genes, characteristic of B. anthracis. By using restriction site insertion-PCR (RSI-PCR) the presence of two SNP typical of B. anthracis was screened in 126 B. cereus group strains of different origin. Two B. cereus strains and one B. thuringiensis strain showed RSI-PCR profiles identical to that of B. anthracis. The sequencing of the entire ITS containing tRNA genes revealed two of the strains to be identical to B. anthracis. The strict relationship with B. anthracis was confirmed by multilocus sequence typing (MLST) of four other independent loci: cerA, plcR, AC-390, and SG-749. The relationship to B. anthracis of the three strains described by MLST was comparable and even higher to that of four B. cereus strains associated with periodontitis in humans and previously reported as the closest known strains to B. anthracis. SNP in ITS containing tRNA genes combined with RSI-PCR provide a very efficient tool for the identification of strains closely related to B. anthracis.     

Phenotypic characteristics of thermotolerantCampylobacter from human and animal sources

Five reference strains and 314 field strains ofCampylobacter growing at 42°C, but not at 25°C, were characterized by tests of hippurate hydrolysis and sensitivity to nalidixic acid, to metronidazole, and to 2,3,5-triphenyltetrazolium chloride (TTC). All strains but seven were TTC-resistant by the disc test used. Of 168 human isolates, 87% hydrolyzed hippurate; three of these strains were nalidixic acid-resistant. Also hippurate-positive were all 23 strains from ovine abortion, 79% of 43 avian strains, two of six bovine isolates, and one of two strains of equine origin. Seventy-two porcine strains were all hippurate-negative. Metronidazole sensitivity was found to be a variable property in hippurate-positive strains, although present in all but four hippurate-negative strains. A group of eight nalidixic acid-resistant, hippurate-negative isolates of porcine and bovine origin probably represent a new group ofCampylobacter.     

Common Cutaneous Bacteria Isolated from Snakes Inhibit Growth of <Emphasis Type="Italic">Ophidiomyces ophiodiicola</Emphasis>

There is increasing concern regarding potential impacts of snake fungal disease (SFD), caused by Ophidiomyces ophiodiicola (Oo), on free-ranging snake populations in the eastern USA. The snake cutaneous microbiome likely serves as the first line of defense against Oo and other pathogens; however, little is known about microbial associations in snakes. The objective of this study was to better define the composition and immune function of the snake cutaneous microbiome. Eight timber rattlesnakes (Crotalus horridus) and four black racers (Coluber constrictor) were captured in Arkansas and Tennessee, with some snakes exhibiting signs of SFD. Oo was detected through real-time qPCR in five snakes. Additional histopathological techniques confirmed a diagnosis of SFD in one racer, the species’ first confirmed case of SFD in Tennessee. Fifty-eight bacterial and five fungal strains were isolated from skin swabs and identified with Sanger sequencing. Non-metric multidimensional scaling and PERMANOVA analyses indicated that the culturable microbiome does not differ between snake species. Fifteen bacterial strains isolated from rattlesnakes and a single strain isolated from a racer inhibited growth of Oo in vitro. Results shed light on the culturable cutaneous microbiome of snakes and probiotic members that may play a role in fighting an emergent disease.     

Histopathological Effects and Growth Reduction in a Susceptible and a Resistant Strain of Heliothis virescens (Lepidoptera: Noctuidae) Caused by Sublethal Doses of Pure Cry1A Crystal Proteins from Bacillus thuringiensis

Two strains of the tobacco budworm Heliothis virescens, one selected in the laboratory for resistance to Cry1Ac crystal protein from Bacillus thuringiensis (for which the mechanism of resistance was not associated with reduced binding) and an unselected control strain, were exposed to sublethal doses of pure Cry1A crystal proteins. A histopathological study was conducted to determine the epithelial damage caused by ingestion of Cry1Ac. Tissue sections of the midgut were obtained after 20, 40 and 60 min of toxin ingestion. Histopathological changes were observed primarily in columnar cells and were time-dependent. However, essentially the same level of damage was observed in the two strains. Toxin feeding tests with Cry1Ac and Cry1Ab, indicated that the toxins retarded growth and inhibited food intake of susceptible larvae, but did not significantly affect larvae of the resistant strain. Since the histopathological damage was similar in both strains, it appears that resistant larvae could repair (or substitute) more readily the damaged cells.     

Properties of Simian Virus 40 Rescued from Cell Lines Transformed by Ultraviolet-Irradiated Simian Virus 40

Simian virus 40 (SV40) strains have been rescued from various clonal lines of mouse kidney cells that had been transformed by ultraviolet (UV)-irradiated SV40. To learn whether some of the rescued SV40 strains were mutants, monkey kidney (CV-1) cells were infected with the rescued virus strains at 37 C and at 41 C. The SV40 strains studied included strains rescued from transformed cell lines classified as "good," "average," "poor," and "rare" yielders on the basis of total virus yield, frequency of induction, and incidence of successful rescue trials. Four small plaque mutants isolated from "poor" yielder lines and fuzzy and small plaque strains isolated from an "average" and a "good" yielder line, respectively, were among the SV40 strains tested. Virus strains rescued from all classes of transformed cells were capable of inducing the transplantation antigen, and they induced the intranuclear SV40-T-antigen, thymidine kinase, deoxyribonucleic acid (DNA) polymerase, and cellular DNA synthesis at 37 C and at 41 C. With the exception of four small plaque strains rescued from "poor" yielders, the rescued SV40 strains replicated their DNA and formed infectious virus with kinetics similar to parental SV40 at either 37 or 41 C. The four exceptional strains did replicate at 37 C, but replication was very poor at 41 C. Thus, only a few of the rescued virus strains exhibited defective SV40 functions in CV-1 cells. All of the virus strains rescued from the "rare" yielder lines were similar to parental SV40. Several hypotheses consistent with the properties of the rescued virus strains are discussed, which may account for the significant variations in virus yield and frequency of induction of the transformed cell lines.     

Variation of cassiicolin genes among Chinese isolates of <Emphasis Type="Italic">Corynespora cassiicola</Emphasis>

Corynespora cassiicola is a species of fungus that is a plant pathogen of many agricultural crop plants, including severe target spot disease on cucumber. Cassiicolin is an important effector of pathogenicity of this fungus. In this study, we collected 141 Corynespora isolates from eighteen hosts, and the casscolin gene was detected in 82 C. cassiicola strains. The deduced protein sequences revealed that 72 isolates contained the Cas2 gene, two strains from Gynura bicolor harboured the Cas2.2 gene, and 59 isolates without a cassiicolin gene were classified as Cas0. Phylogenetic analyses was performed for the 141 isolates using four loci (ITS, ga4, caa5, and act1) and revealed two genetic clusters. Cluster A is composed of four subclades: subcluster A1 includes all Cas2 isolates plus 18 Cas0 strains, subcluster A2 includes the eight Cas5 isolates and one Cas0 isolate, and subclusters A3 and A4 contain Cas0 strains. Cluster B consists of 21 Cas0 isolates. Twenty-two C. cassiicola strains from different toxin classes showed varying degrees of virulence against cucumber. Cas0 or Cas2 strains induced diverse responses on cucumber, from no symptoms to symptoms of moderate or severe infection, but all Cas5 isolates exhibited avirulence on cucumber.     

Hydrocarbon degradation and enzyme activities of cold-adapted bacteria and yeasts

The potential of 89 culturable cold-adapted isolates from uncontaminated habitats, including 61 bacterial and 28 yeast strains, to utilize representative fractions of petroleum hydrocarbons (n-alkanes, monoaromatic and polycyclic aromatic hydrocarbons) for growth and to produce various enzymes at 10°C was investigated. The efficiency of bacterial and yeast strains was compared. The growth temperature range of the yeast strains was significantly smaller than that of the bacterial strains. Sixty percent of the yeasts but only 8% of the bacteria could be classified as true psychrophiles, showing no growth above 20°C. A high percentage (89%) of the yeast strains showed lipase activity. More than one-third of the 61 bacterial strains produced amylase, -lactamase, -galactosidase or lipase; more than two-thirds were protease producers. Only 6% of the bacterial strains but 79% of the yeast strains utilized n-hexadecane for growth; 13% of the bacterial strains and 21–32% of the yeast strains utilized phenol, phenanthrene or anthracene for growth. Only four yeast strains but none of the bacterial strains could grow with all hydrocarbons tested. The biodegradation of phenol was investigated in fed-batch cultures at 10°C. Three yeast strains degraded phenol concentrations as high as 10 mm (one strain) or 12.5 mm (two strains). Of eight bacterial strains, two strains degraded up to 10 mm phenol. The optimum temperature for phenol degradation was 20°C for all eight bacterial strains and for two yeast strains. Biodegradation by five yeast strains was optimal at 10°C and faster at 1°C than at 20°C. All phenol-degrading strains produced catechol 1,2 dioxygenase activity.Communicated by K. Horikoshi     

Growth pattern of four strains of a Bdelloid rotifer species: egg size and numbers

Life-history traits and growth patterns of four strains of Macrotrachela quadricornifera (Rotifera, Bdelloidea) were studied to assess the influence of maternal traits on egg size. There were two small (S, Va) and two large strains (H, G) with similar patterns of life cycle and body growth. They allocated to reproduction similar relative amounts of resources partitioned into eggs of similar relative size. All strains started reproduction while growing and, although their final sizes differed, at maturity had similar large or small sizes but different ages. Their egg sizes were unaffected by the clutch size, but were positively correlated with mother's body size.     

Pyrolysis-gas-liquid chromatography of fungi: Numerical characterization of species variation among members of the Aspergillus glaucus group

Principles of numerical analysis were applied to the interpretation of pyrolysis-gas-liquid chromatography (PGLC) data for characterizing species variation among three strains each of four species of theAspergillus glaucus group. Similarity values for the strains were calculated by comparing the number of peaks in which two strains agreed or disagreed. These data indicate that numerical analyses of pyrochromatograms were closely correlated with conventional taxonomic placement of the taxa with the exception of several intergrading or interbridging forms. Thus, a fundamental unity of these strains can be discerned at the chemical level by PGLC analysis. This unity stems from the similar chemical composition of these organisms, and deviation from this basic composition imparts to these strains their uniqueness and thus permits their delineation into distinct entities or pyrotypes based on the peak pattern of the pyrochromatograms.