The utilization of actinomycetes as potential soybean (Glycine max (L.)) co-inoculants was evaluated. Soil samples from Carbondale and Belleville, Ill., were used to inoculate pre-germinated soybean plants to determine antibiotic sensitivity in the native Bradyrhizobium japonicum population. Sensitivity was in the order kanamycin > tetracycline > oxytetracycline > rifampicin > neomycin. Antagonism by five actinomycete cultures toward seven test strains of B. japonicum was also assessed. The ranking average inhibition (across all seven B. japonicum strains) by these actino mycetes was Streptomyces kanamyceticus = Streptomyces coeruleoprunus > Streptomyces rimosus > Streptomyces sp. > Amy colatopsis mediterranei. Ten antibiotic combinations were used to isolate antibiotic-resistant mutants of B. japonicum I-110 and 3I1B-110 via successive cycles of mutation. Eighty-one antibiotic-resistant strains were isolated and tested for symbiotic competency; nine of which were selected for further characterization in a greenhouse pot study. Few differences in nodule number were caused by these treatments. Nodule occupancy varied from 0% to 18.3% when antibiotic-resistant strains of B. japonicum were used as the sole inoculants. However, when three mutant strains of B. japonicum were co-inoculated with S. kanamyceticus, significant increases in nodule occupancy (up to 55%) occurred. Increases in shoot nitrogen composition (27.1%-40.9%) were also caused by co-inoculation with S. kanamyceticus.
Background Vermicomposts (VC) improve plant growth and development beyond that normally observed from just soil nutrient transformation and availability. These increases in plant productivity have been attributed to improved soil structure and soil microbial populations that have higher levels of activity and greater production of biological metabolites, such as plant growth regulators. Although there have been many studies on the benefits of VC as a fertilizer source, little research has focused on the effects and/or interactions of soil type and VC application rates on vegetable crop productivity. This paper identifies optimum application rate(s) of VC on tomato growth responses for three different textural classes of soils (loamy sand, silt loam, and silty clay).Results Soils with high VC rates (0.4 and 0.8 g/g) produced taller plants with more leaf and flower numbers, higher leaf chlorophyll content, greater plant biomass, and more total leaf area compared to soils with low VC rates (0.05, 0.1, and 0.2 g/g). Tomato growth increases were also observed at the low VC soil amendment rates compared to the nontreated control. Tomatoes grown in the sandy soil amended with VC generally had the greatest growth responses (plant height, leaf and flower number, and leaf chlorophyll content) compared to the clay or silt loam soils, with the silt loam soil generally providing the least response. Conclusions This research indicated that VC is a suitable alternative fertilizer for tomato, with approximately 0.5-0.6 g/g VC added to soil resulting in optimal tomato plant growth. Moreover, this rate provided tomato growth results similar to the standard inorganic fertility program. The sandy soil with VC amendments generally increased tomato plant growth parameters the most compared to the clay and loam soils, with the loam soil generally providing the least.
The acidulation effects of the prolonged use of nitrogenous fertilizers on selected chemical and microbiological properties of a silt loam soil (Typic Ochraqualf) were assessed.Soil samples were collected from experimental plots initially established in 1971 that were annually treated with ten N fertilizer treatments and planted to corn. Residual soil acidity found to be associated with 9 annual applications of the N fertilizers was of the order: (NH 4 ) 2 SO 4 > NH 4 C1 > anhydrous NH 3 (at 300 kg N/ha) = NH 4 NO 3 > urea = ureaform = anhydrous NH 3 (at 150 kg N/ha) > Ca(NO 3 ) 2 NaNO 3 . Extractable P, Fe, Mn and Al followed a pattern of increasing availability with a decrease in soil pH. Exchangeable Ca and Mg levels were significantly higher in those treatments that did not show a significant decrease in soil pH over the 9-year duration.Significant differences by N treatment among selected microbial groups were also determined. The annual mean counts of soil 1377 1378 KHONJE, VARSA, AND KLUBEK fungi were significantly higher for the most and least acidifying treatments, namely ammonium sulfate and sodium nitrate.However, the mean counts of soil bacteria and actinomycetes were non-significant for any of the fertilizer treatments although the counts of both microbial groups declined with the addition of N.Significant differences in the mean counts of nitrifying and denitrifying bacteria were obtained with the ammonium sulfate treatment showing the greatest reduction in MPN counts. Microbial diversity (H') indices were also determined and correlated with soil pH. A quadratic relationship was determined for phyleal diversity (the total population of bacteria, actinomycetes and fungi) with soil pH, while a linear function best described physiological diversity (the nitrifying and denitrifying bacteria) versus soil pH.
The purpose of this study was to determine the microbial status of tofu sold in a rural Illinois county and assess the factors contributing to the safety of tofu. Six brands of tofu from eight different stores (60 total samples) were purchased and analyzed for temperature, pH, total aerobic bacteria, and the presence of coliforms. Relationships between age, temperature, pH of tofu, and total aerobic bacteria were tested. An analysis of variance was also performed to test for differences in total bacterial counts among the brands. Mean aerobic bacterial counts ranged from 0 to 7.76 x 10(7) CFU/g. Fifty-five percent of the tofu tested fell within the excellent range for freshness as delineated by the standards developed by the Soyfoods Association of North America, 6.7% fell within the acceptable range, 6.7% within the marginal range, and 28% within the unacceptable range. Sixteen percent of the samples contained coliform bacteria. No significant correlation was found between variables, except pH with total aerobic bacterial counts (r = -0.51) and pH with eosin-methylene blue agar counts (r = -0.67). Most of the tofu was displayed at unsafe temperatures (>5 degrees C) for potentially hazardous foods. This study confirmed the concerns regarding safety of tofu sold in the grocery stores. Based on these results, special training on tofu storage and handling is recommended for grocery stores selling this food product.
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