We have increased the production of bovine chymosin in Aspergillus niger var. awamori to more than one gram per liter of secreted authentic enzyme by combining a mutagenesis protocol with a novel robotic screening program. Analysis of the superior chymosin producing strains indicated that they have enhanced capabilities to secrete extracellular proteins.
This study tested the importance of filter media, extraction and assay protocol, and bioaerosol source on the determination of endotoxin under field conditions in swine and poultry confinement buildings. Multiple simultaneous air samples were collected using glass fiber (GF) and polycarbonate (PC) filters, and these were assayed using two methods in two separate laboratories: an endpoint chromogenic Limulus amebocyte lysate (LAL) assay (QCL) performed in water and a kinetic chromogenic LAL assay (KQCL) performed in buffer with resistant-parallel line estimation analysis (KLARE). In addition, two aqueous filter extraction methods were compared in the QCL assay: 120 min extraction at 22 degrees C with vigorous shaking and 30 min extraction at 68 degrees C with gentle rocking. These extraction methods yielded endotoxin activities that were not significantly different and were very highly correlated. Reproducibility of endotoxin determinations from duplicate air sampling filters was very high (Cronbach alpha all > 0.94). When analyzed by the QCL method GF filters yielded significantly higher endotoxin activity than PC filters. QCL and KLARE methods gave similar estimates for endotoxin activity from PC filters; however, GF filters analyzed by the QCL method yielded significantly higher endotoxin activity estimates, suggesting enhancement of the QCL assay or inhibition of the KLARE asay with GF filters. Correlation between QCL-GF and QCL-PC was high (r = 0.98) while that between KLARE-GF and KLARE-PC was moderate (r = 0.68). Analysis of variance demonstrated that assay methodology, filter-type, barn-type, and interactions between assay and filter-type and between assay and barn-type were important factors influencing endotoxin exposure assessment.
Spergularia marina (L.) Griseb. is. a rapidly growing, annual, coastal halophyte. Because of its small size, it is suitable for isotope studies of ion transport well beyond the seedling stage. The purpose of this report is to establish the similarities and differences between 22Na+ and 42K+ uptake in S. marina and in more commonly used mesophytic crop species. Vegetative plants were used 18 days after transfer to solution culture. Plants were grown either on Na+‐free medium or on 0.2 × sea water. 22Na+ uptake was linear with time for several hours. The rate was relatively insensitive to external concentration between 1 and 180 mol Na+ m−3, particularly in Na+‐free plants. Transport to the shoot accounted for 40 to 70% of the total uptake, dependent on salinity but largely independent of time. 42K+ uptake decreased with increasing salinity in Na+‐free plants and increased in 0.2 × sea water plants. Both uptake and transport to the shoot were non‐linear with time, upward concavity suggesting recovery from a manipulative and/or osmotic injury. Steady state root contents were compared with predicted contents based on cortical cell electrical potentials using the Nernst equation. Reasonable agreement was found in all cases except Na+ content of 0.2 × sea water plants, in which active efflux was indicated. Uptake studies conducted in the presence of chemical modifiers (dicyclohexylcarbodiimide, dinitrophenol and fusicoccin) showed responses of 42K+ uptake as expected from studies on agronomic species, and implied the presence of a similar active uptake here despite the appearance of equilibrium. Active Na+ uptake was suggested at low Na+ levels. We conclude that S. marina is a promising experimental system combining the rapid nutrient acquisition strategy of agionomically important annuals with a high degree of salt tolerance.
Bioaerosol sampling for viable microorganisms was conducted in 25 dairy barns in summer and in winter to examine the relationship of sample storage and shipping in determining bioaerosol concentrations separately for yeasts, molds, mesophilic bacteria, and thermophilic organisms. The study also compared the performance of three sampling methods--(1) all-glass impinger (AGI) used with peptone solution in both seasons and (2) betaine solution in winter; and (3) the nuclepore filtration and elution (NFE) method, using air filtration with subsequent elution and culturing--which were studied in a pairwise fashion with duplicate, simultaneous, side-by-side sampling. For each sample, one duplicate was analyzed within two hours in a laboratory less than 50 km from the sampling site, while the other was express-mailed to the authors' laboratory. Concentrations of all microorganisms measured by the AGI peptone method were unaffected by mailing in winter, but mesophilic bacteria increased in summer. AGI betaine samples were unchanged except for increased concentrations of molds after mailing in winter. Yeasts and mesophilic bacteria significantly decreased after mailing of NFE samples. Pairwise comparison of the sampling methods in winter yielded no significant differences in airborne concentrations for the yeasts, mesophilic bacteria, and thermophilic bacteria. Both AGI betaine and NFE methods had significantly greater concentrations of molds than AGI peptone. In summer, concentrations of yeasts and mesophilic bacteria were significantly greater with AGI peptone, as were molds with the NFE method.(ABSTRACT TRUNCATED AT 250 WORDS)
Attributes of the coastal halophyte Spergularia marina (L.) Griseb. that make it useful for studies of the physiological basis for salt tolerance in fully autotrophic higher plants are discussed. Growth, morphological, and ion-content characteristics are presented to serve as a background for subsequent studies of transport physiology. Plants were grown in solution culture on dilutions of artificial seawater or on the same solution without NaCl ("fresh water") from the time at which they could be conveniently transferred as seedlings (about 2 weeks old) to the onset of flowering about 5 weeks later. Eighteen days after transfer, plants growing on 0.2 × seawater were larger, being nearly twice the size of plants on fresh water. A Na+ specific effect was indicated, as the major part of the growth stimulation (54%) resulted from a 1 mM NaCl supplementation of "fresh water." Succulence was not a consideration in the growth response: root length was directly proportional to weight as was leaf surface area and neither was affected by salinity. Total Na+ plus K+ per gram root or shoot showed little variation with salinity from 1 to 180 mM Na+ levels. In roots, the relative Na+ and K+ contents were also little affected by salinity, but in the shoots, increasing salinity resulted in higher Na+ and lower K+ contents. Distribution within the shoots of 0.2 × plants showed no regions either free of or exceptionally high in Na+. The ion content and distribution patterns are compared with those in a number of other halophytes.
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