Spore concentration

The experiments were intended to clarify the question as to whether transmission of spores from Mars to Earth could be feasible. To do this, a Mars meteorite was simulated, i.e., the spores were mixed with powdered rock and the mixture pressed together to give a small cube about 1 cm3 in size. The spore concentration was about the same as in normal soil on Earth. The samples were in orbit for around 2 weeks, and their survival ability was determined on their return to Earth, compared with the corresponding samples which had been left on Earth (control experiment). 

The integrated system has been tested for enhancement of bacterial capturing by introducing a solution of bacteria spores (concentration of 106 cells per mL) at 200 pL min 1 flow rate into the flow cell. Here, a small number of spore clumps were observed forming in the central region of the chamber when the ultrasound (0.5 V at 1.92-MHz frequency) was turned on. The clumps were held stationary... 

The BR-test has been modified several times (37, 38). One of its versions, known as the BR-test AS, contains antifolates that make it possible to detect sulfones and sulfonamides in addition to the usual inhibitory substances. Another version, which is called BR-test Blue Star, has been officially accepted and used in Canada. By decreasing the spore concentration in the detection medium, a sensitivity of less than 40 ng sulfamethazine/ml milk is possible with this test (38). 

Results of the titer showed a viable B. subtilis spore concentration of 6.65xl08 spores per ml in the original suspension. Inoculation of 9.9 ml of disinfectant with 100 pi of this suspension produced an initial concentration of 6.65x10 spores per ml in the assay tube. 

Effects of Colletotrichum truncatum spore concentration on shoot elongation of dark-grown hemp sesbania seedlings in a pathogen-weed bioassay. Diamond symbols = control (H20), squares = 102, triangles = 103, and cross marks = 5 x 105 spores/ml respectively. (From Hoagland, R. E. 1995, Biocontrol Sci. Technol., 5, 251-259. With permission.)... 

The pathogens (103 to 104 spores mL 1) caused significant shoot growth inhibition within 25 to 30 h and seedling death within 40 to 50 h. Stem collapse time, as a function of various spore concentrations, was also a useful bioassay parameter. Nonlinear regression analysis86 was used to model stem collapse time as a function of spore concentration (Fig. 16.2, solid lines). The trend used for this model was an exponential decay model of the form ... 

Meteorological factors are also responsible for seasonal variability in the air spora. In most temperate areas, spore concentrations tend to increase in late spring often showing a significant correlation with increasing temperatures [13]. Many studies have shown highest levels of airborne spores typically... 

Troutt C, Levetin E Correlation of spring spore concentrations and meteorological conditions in Tulsa, Oklahoma. Int J Biometeor 2001 45 64-74. 

Delfino RJ, Zieger RS, Seltzer JM, Street DH, Matteucci RM, Anderson PR, Koutrakis P The effect of outdoor fungal spore concentrations on daily asthma severity. Environm Health Perspect 1997 105 622-635. 

Low concentrations of HCl were required to dramatically reduce the spore concentration of Bacillus subtilus. Concentrations as low as 6mgl can inhibit some plant stem growth. 

Different strains of the same mold may make differing amounts and types of mycotoxins. Certain strains may not always produce mycotoxins, making it impossible to predict mycotoxin levels based solely on spore concentrations in air. 

II. Toxic dose. Because mycotoxins are not volatile, exposure would require inhalation of aerosolized spores, mycelial fragments, or contaminated substrates. The toxic inhaled dose of mycotoxin for humans is not known. Based on experimental data from single-dose in vivo studies, Stachybotrys chartarum spores (in-tranasally in mice or intratracheally in rats) high doses (more than 30 million spores/kg) can produce pulmonary inflammation and hemorrhage. The no-effect dose in rats (3 million ores/kg) corresponds to a continuous 24-hour exposure to 2.1 million spores/m for infants, 6.6 million spores/m for a school-age child, or 15.3 million spores/m for an adult. These spore concentrations are much higher than those measured in building surveys. 

Oliveira M, Riheiro H, Delgado J, Abreu I (2009) The effects of meteorological factors on airborne fungal spore concentration in two areas differing in urbanisation level. Int J Biometeorol 53 61... 

Stimulate formation of small spherical cell pellets (Zhou 1999). Roa Engel et al. (2011) showed from measurements with a microsensor that 0.25 mm inside a pellet the level was less than 5% of the concentration outside the pellet. Zhou et al. (2011) demonstrated that smaller pellets produce more fumaric acid, which could have been caused by the absence of oxygen limitation inside the pellets. By reducing clumps formation the viscosity of the broth is also reduced, even if CaCOj is present. Moreover, pellets can facilitate biomass retention. For R. oryzae a large number of factors have been optimized to favor pellet formation during cell cultivation (Zhou et al. 2000, 2011 Liu et al. 2008 Roa Engel et al. 2011). These include pH, temperature, nutrients, spore concentration and age, stirring frequency, and culture volume. 

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