Seasonal Variability in Abundance and Diversity of Soil Gymnamoebae Along a Short Transect in Southeastern USA

Abstract

The abundance and diversity of gymnamoebae in three subsoils varying in compaction and water retention along a 1.2 m transect were documented as the local climatic conditions changed from late summer 1999 through mid-summer 2000. The mean density of gymnamoebae for the loose soil (1,655/g) was greater than either the most compact (1,468/g) or moderately compact soil (851/g). Minimum densities occurred in middle and late summer for all soils while significant (F = 38.803, < or = 0.0002) density peaks at 3.212/g occurred in early summer in the most compact soil, 2.928/g in the least compact, and 2,209/g in the moderately compact soil. Limax non-eruptive gymnamoebae (mt 2) correlated (r = 0.49, p < or = 0.016) with moisture while eruptive limax gymnamoebae ( 3) correlated with temperature (r = 0.07, p < or = 0.024), moisture (r = 0.58, p < or = 0.001) and precipitation (r = 0.46, p < or = 0.029). Flattened or discoid amoebae (mt 4) dominated throughout most of the survey, and the two limax groups showed inverse relationships. Chi-square analyses showed significant differences in the numbers of limax eruptive gymnamoebae compared to all other morphotypes on all but one sampling period.

Metatranscriptomic census of active protists in soils

“…Applying the most recent taxonomy and a newly built reference database allowed us to detect a large diversity within all amoebozoan classes. The general dominance of the classes Tubulinea and Discosea confirmed former cultivation-based studies (for example, Finlay et al, 2000;Bass and Bischoff, 2001), whereas the high abundance of Variosea is novel. This class was only constructed in 2004, hosting mostly large plasmodial, branching or reticulate amoebae Smirnov et al, 2008;Smirnov et al, 2011).…”

Acanthamoeba castellaniiPromotion of In Vitro Survival and Transmission of Coxsackie B3 Viruses

“…In these experiments, trophozoites at 6 days postinfection were washed, suspended in 10 ml of PYG medium (1.5 ϫ 10 5 cell/ml), and incubated in 25-cm 2 sterile plastic flasks at 25°C. At selected time intervals (2,4,6,8,10, and 12 days), amoebas were counted with a hemacytometer (Nageotte chamber). Cell viability was determined by the nigrosin dye exclusion method.…”

“…Free-living amoebas of the genus Acanthamoeba are ubiquitous in nature (34); they have been isolated from air (19,32,33), soil (2,3,6,29), and water environments, including chlorinated swimming pools (10), drinking water (17,28), cooling towers (5), natural thermal water (31), hospital water networks (35), and marine water (4). Acanthamoeba is characterized by a feeding and replicating trophozoitic stage which under adverse conditions can develop to a dormant cyst stage (34).…”

Microorganisms Resistant to Free-Living Amoebae

“…Their abundance and diversity in the environment are strongly dependent on season, temperature, moisture, precipitation, pH, and nutrient availability (9,21,204). In soil, free-living amoebae are more abundant at plant-soil interfaces since plants allow the growth of a variety of plant parasites (bacteria and fungi) on which amoebae feed (204).…”

“…Free-living amoebae are present worldwide (reviewed in reference 204) and have been isolated from soil (9,10,21,188), water (11,104,108,111,144,145), air (138,(202)(203)(204)(205), and the nasal mucosa of human volunteers (7,179). Their abundance and diversity in the environment are strongly dependent on season, temperature, moisture, precipitation, pH, and nutrient availability (9,21,204).…”