Effect of fermentation temperature on hydrogen production from cow waste slurry by using anaerobic microflora within the slurry.

We examined hydrogen production from a dairy cow waste slurry (13.4 g of volatile solids per liter) by batch cultures in a temperature range from 37 to 85 degrees C, using microflora naturally present within the slurry. Without the addition of seed bacteria, hydrogen was produced by simply incubating the slurry, using the microflora within the slurry. Interestingly, two peaks of fermentation temperatures for hydrogen production from the slurry were observed at 60 and 75 degrees C (392 and 248 ml H2 per liter of slurry, respectively). After the termination of the hydrogen evolution, the microflora cultured at 60 degrees C displayed hydrogen-consuming activity, but hydrogen-consuming activity of the microflora cultured at 75 degrees C was not detected, at least for 24 days. At both 60 and 75 degrees C, the main by-product was acetate, and the optimum pH of the slurry for hydrogen production was around neutral. Bacteria related to hydrogen-producing moderate and extreme thermophiles, Clostridium thermocellum and Caldanaerobacter subterraneus, were detected in the slurries cultured at 60 and 75 degrees C, respectively, by denaturing gradient gel electrophoresis analyses, using the V3 region of 16S rDNA.

Reduction of nitrous oxide emission from pig manure composting by addition of nitrite-oxidizing bacteria.

Nitrous oxide (N2O) is emitted from pig manure composting, and the emission correlates with nitrite (NO2-) accumulation in the composting material. In the present study, we added nitrite-oxidizing bacteria (NOB)to inhibit NO2- accumulation and evaluated its effect on N2O emission in a laboratory-scale composting experiment. Mature pig manure compost (MPMC) containing NOB at 10(6) MPN g(-1) WM or cultured MPMC (cul-MPMC) NOB at 10(11) MPN g(-1) WM was added after the thermophilic phase of composting. The addition of these materials prevented NO2- accumulation, promoting oxidation to nitrate (NO3-), whereas the accumulation of NO2- occurred in the material to which NOB was not added as the result of the delayed growth of indigenous NOB compared with that of ammonia-oxidizing bacteria (AOB). The pattern of NO2- in the material agreed with that of N2O emission; therefore, N2O emission ceased rapidly when NOB was added. Emission rates of N2O were 88.5 (no addition), 17.5 (MPMC addition), and 20.2 (cul-MPMC addition) g N-N2O kg(-1) TNinitial, respectively. Improving composition of nitrifying communities for complete nitrification promotion would be useful to establish a composting method with low N2O emission.

Effect of addition of organic waste on reduction of Escherichia coli during cattle feces composting under high-moisture condition.

To ensure Escherichia coli reduction during cattle feces composting, co-composting with a variety of organic wastes was examined. A mixture of dairy cattle feces and shredded rice straw (control) was blended with organic wastes (tofu residue, rice bran, rapeseed meal, dried chicken feces, raw chicken feces, or garbage), and composted using a bench-scale composter under the high-moisture condition (78%). The addition of organic waste except chicken feces brought about maximum temperatures of more than 55 degrees C and significantly reduced the number of E. coli from 10(6) to below 10(2)CFU/g-wet after seven days composting, while in the control treatment, E. coli survived at the same level as that of raw feces. Enhancements of the thermophilic phase and E. coli reduction were related to the initial amount of easily digestible carbon in mass determined as BOD. BOD value more than 166.2 mg O2/DMg brought about significant E. coli reduction.

Transferrin and inhibin mRNA in mature pig Sertoli cells.

Aims: There is increasing concern about the effect of environmental toxins and endocrine disrupters on human spermatogenesis but ethical considerations prohibit direct research. Therefore, we developed a method of isolating mature pig Sertoli cells and studying the levels of mRNA of transferrin and inhibin, markers of Sertoli cell function, using real-time polymerase chain reaction analysis. Methods: Sertoli cells from mature Meishan boars were isolated and cultured. The mRNA was isolated from the cells after 3 days of treatment with follicle-stimulating hormone (FSH), testosterone and ß-estradiol. The amounts of transferrin and inhibin mRNA were analyzed by real-time polymerase chain reaction and the relative level of mRNA was calculated. Results: FSH tended to increase the levels of transferrin and inhibin mRNA, as did the combinations of FSH and the steroids. The effect of testosterone and ß-estradiol alone on the level of mRNA was less than that of FSH. Beta-estradiol treatment resulted in a dose-dependent decrease in mRNA. Conclusion: The Sertoli cell culture used in the present study appears to have a normal secretory function because the mRNA levels of both markers increased after FSH treatment. The suppressive effect of ß-estradiol on inhibin mRNA level suggests that ß-estradiol has an effect on the function of Sertoli cells. (Reprod Med Biol 2005; 4: 259 -264).

Isolation of thermophilic ammonium-tolerant bacterium and its application to reduce ammonia emission during composting of animal wastes.

A thermophilic bacterium, strain TAT105, was isolated from compost made of animal wastes. TAT105 had high tolerance to ammonium nitrogen up to 1200 mM, and highly assimilated nitrogen during the growth on swine feces. The strain was classified into Bacillus, close to Bacillus pallidus. To evaluate the effect of adding TAT105 to ammonia (NH3) emission during the composting process of animal wastes, laboratory scale composting was done. NH3 emission tended to be lower and nitrogen loss was smaller in the TAT105-added material than in the control material to which TAT105 was not added. Thermophilic ammonium-tolerant bacteria in the TAT105-added material increased to about 8x10(9) CFU/g of dry matter on the average during the tests, and most of them were judged to be TAT105 from morphological colony discrimination. These results suggested the possibility of reducing NH3 emission from composting of animal wastes by adding TAT105.

Patterns and quantities of NH(3), N(2)O and CH(4) emissions during swine manure composting without forced aeration--effect of compost pile scale.

To evaluate the NH(3), N(2)O, and CH(4) emissions from composting of livestock waste without forced aeration in turned piles, and to investigate the possible relationship between the scale of the compost pile and gas emission rates, we conducted swine manure composting experiments in parallel on small- and large-scale compost piles. Continuous measurements of gas emissions during composting were carried out using a chamber system, and detailed gas emission patterns were obtained. The total amount of each gas emission was computed from the amount of ventilation and gas concentration. NH(3) emission was observed in the early period of composting when the material was at a high temperature. Sharp peaks in CH(4) emission occurred immediately after swine manure was piled up, although a high emissions level continued after the first turning only in the large-scale pile. N(2)O emissions started around the middle stage of the composting period when NH(3) emissions and the temperature of the compost material began to decline. The emission rates of each gas in the small and large piles were 112.8 and 127.4 g NH(3)-N/kg T-N, 37.2 and 46.5 g N(2)O-N/kg T-N, and 1.0 and 1.9 g CH(4)/kg OM, respectively. It was found that changing the piling scale of the compost material was a major factor in gas emission rates.