Identifying hyphal fragments in the atmosphere.

Hyphal fragments were collected with a Kramer-Collins spore sampler at a prairie and at a woodland site near Manhattan, Kansas, from July to October, 1970. Colonies developed from isolated hyphal fragments included, in order of occurrence, Cladosporim (62.9%), Alternaridg (30.69), sterile mycelial types (2.2 f,), Helminthoxporim (1.7%,), Penicillizzm (1.79), and Carvsxl4Xflia (0.99h). Introduction The presence of hyphal fragments as a major component of the air spora had been largely overlooked until Pady and Kramer (1960), Pady and Gregory (1963), and Harvey (1970) included in their studies considerable information on concentrations and viability of hyphal fragments irl the atmosphere. Even so, little has been done to identify specifically these fragments. The results of such a study are reported here. Materials and Methods Two stampling sites were selected for this study, 6.6 miles north of Manhattan, Kansas, and approximately 1 mile east of Tuttle Creek Reservoir. One site, designated the woodland site, is at the base of a ravine approximately 2,500 ft east of (and downwind of the direction of prevailing winds from) the main body of the reservoir. Dominant tree species in the ravine are oak and elm. The other site, designated the prairie site, is on the crest of a hill in a typical tall-grass prairie, 1,500 ft southeast of and overlooking the woodland site. Samples were taken regularly, usually in a series of 4 to 5 consecutive days each week, during a 4-month period from July to October, 1970. Two Kramer-Collins Spore Samples (Kramer and Pady, 1966 ) were used. Slides were changed daily between 10 :00 and 10: 30 AM . Exposed slides were kept dry in a plastic slide box until hyphal fragments could be isolated, which was during the afternoon of the day on which the slides were changed. This content downloaded from 157.55. 39.17 on Wed, 31 Aug 2016 05:06:11 UTC All use subject to http://about.jstor. org/terms Hyphal fragments, particularly ematiaceous forms (which were easiest to see with the dissecting microscope) were picked from the slides with a microneedle and transferred to a petri dish containing freshly poured water agar. Each fragment was moved over the surface of ie agar until it appeared to be free of contaminating spores. Fragments then were transferred to a petri dish containing Difco Potato-Dextrose Medium with . 019o Streptomycin where they were allowed to germinate and develop into colonies. Usually 12 to 24 hyphal fragments were isolated from each slide every day. After 48 hours of incubation at room temperature, each fragment was examined under the microscope to determine if germination had occurred and to check for contamination. SpeciSc determinations were made after each colony began sporulating. Results Finre genera of fungi were identified from isolated hyphal fragments. As indicated in Table 1, they were Clvdosporigm, identiSed either as C. cladoporzoides (Fres.) DeVries or C. herbargm (Pers.) Link, 62.9go of the total; Alternaria, 30.69,; sterile mycelial colonies, 2.2So; Helminthosporigm, 1.7%;Penicilligm, 1.7So; and Cgrvglariv, 0.9fi0. Therewere no significant differences in the occurrence of any of the genera isolated at the two sites. Hyphal fragments generally ranged in length from 5 to 40ju; a few, however, were l0Oju or more long. Many were branched and either septate or nonseptate. The majority were dematiaceous but hyaline Table 1. Fungal colonies identified from isolated hyphal fragments in woodland (W) and prairie (P) sites, near Manhattan, Kansas, July-October, lf70. Percentage Total of total July August September October colonies colonies W P W P W P W P isolated identified Clvdosporium 10 16 2 1 35 39 19 22 144 62.9% (C. cladosporioides) (3) (13) (2) (1) (30) (35) (17) (19) (C. herbarum) (2) (3) (5) (4) (2) (3) Alternariv . 6 3 21 10 15 15 70 30.6% Helminthosporium 1 2 1 4 1.7% Penirillium 2 1 1 4 1.7% Cursularia 1 1 2 0.9% Sterile colonies 2 1 2 5 2.2% TOTAL: Germinated hyphal fragnaents 22 19 3 4 58 52 34 37 229 100.0% Total numbers of hyphal fragments isolated each 140 120 96 96 160 152 137 139 1,040 month at each location Identifying Hyphal Fragments in the Atmosphere 49 This content downloaded from 157.55. 39.17 on Wed, 31 Aug 2016 05:06:11 UTC All use subject to http://about.jstor. org/terms Tx anctioslx of the Wanax Accgd emy of Science fragments also were present. Most were thought to be portions of conidiophores. Germination occurred at one or both ends of the hyphal fragments, where germ tubes emerged through the septal walls. Lateral germination, with germ tubes emerging through the side walls as reported by Pady and Gregory (1963) was not observed here. The percentage of fragments germinating was lowest (3.69o) during Augtlst which was exceptionally hot and dry. In Ceptember, when a considerable amount of rainfall was received, the percentage of hyphal fragments germinating was much higher (356Se). Discussion Hyphal fragments, which are broken pieces of fungal mycelium primarily conidiophores, are present wherever fungal spores are present. They are most common in the atmosphere during the growing season, when climatic factors favor the development of fungi with aerial sporulating structures. In Kansas during hot summer months (July-August) and cold winter months (November-January), the concentration of these hypal fragments decreases considerably (Pady and Kramer, 1966). Harvey (1970) in recent studies at Cardiff mentioned the importance of such climatic factors as temperatUlre, rainfall, and wind in determining fluctuations in concentration. He emphasized that release of hyphal fragments intaD the air is entirely passive and that wind is principally responsible for eroding them from plant and soil surfaces. From the single hyphal-fragment isolations, Cladoxporizlm was the most frequently isolated fungus. That was consistent with air-spora studies done in the temperate parts of the world at ground level (Gregory and Hirst, 1957; Hyde and Williams, 1953; Kramer et 1., 1959a); at high altitudes (Pady and Kapica, 1953, 1955); and at surface level over theoceans (Sreeramulu, 1957). Twospecies,C.cladoxposioidex (Fres.) DeVries and C. helbrvz (Pers.) Link, consistently were identified from all isolates. Alte>varia, Helmislthospol izfm, Pe1zirilligm, and CzlsflvgldlSia, identified from the single-fragment isolations, also have been found to be common constituents of the air spora by numerous workers throughout the world (Gregory and Hirst, 1957; Hyde and Williams, 1946; Kramer and Pady, 1960; and Kramer et 1., 1959b, 1960).