Metabolic performance of anaerobic digestion of chicken manure under wet, high solid, and dry conditions.

The anaerobic digestion (AD) of chicken manure as a solo substrate has been challenging due to the ammonium inhibition effects when adopting a high organic loading rate (OLR). In this study, through increasing both the total solid in the feeding materials from 5% to 20%, and the OLR from 1.7 to 7.1 g-volatile solids (VS)/(L·d), the AD of chicken manure under wet, high solid, and dry conditions, with a fixed hydraulic retention time of 20 days, was investigated. The results obtained indicated that the wet AD system could achieve a methane yield of 0.28 L/g-VS and a low volatile fatty acid level. However, the process deteriorated under dry conditions, and methane formed mainly through acetate oxidation and methanogenesis. Methanosarcina and Methanoplasma were found to be more tolerant But, whether the dry AD of chicken manure can survive an ammonia-stressed environment when the OLR is lowered, still needs investigation.

Enhanced methanogenic performance and metabolic pathway of high solid anaerobic digestion of chicken manure by Fe2+ and Ni2+ supplementation.

High solid anaerobic digestion (AD) is a promising technology for the treatment of organic waste in terms of efficient bioenergy production and digestate volume reduction. However, the high solid AD of chicken manure has been a challenge due to the inhibition effects caused by high ammonia levels. In this study, the addition of 280 mg/L Fe2+ and 2 mg/L Ni2+ has been proven to enhance the microbial activity and to overcome inhibition under the stressed environment. The mesophilic digesters feeding with total solid around 150 g/kg operated at an organic loading rate of 4.8 g/(L d) based on volatile solid and a 20-day hydraulic retention time. The total ammonia-nitrogen reached around 6.8 g/L in control and Fe-Ni digesters. The results from the 147-day continuously-fed experiment provided an increment of 34% methane production and a 29% reduction of volatile fatty acids against control. The acetoclastic and hydrogenotrophic methanogenic activity was increased by 89% and 40% respectively. The high throughout sequencing results showed an increased percentage of Methanosarcina sp., which may have contributed to the shifting of the methanogenic pathway towards acetoclastic methanogenesis. The positive effects of Fe2+ and Ni2+ supplementation obtained in this study lay the foundation for its use in AD of nitrogen rich materials.

[Effects of extracellular heat shock protein 70 on intestinal immune function of rats with severe scald injury].

OBJECTIVE: To explore the change in the expression of extracellular heat shock protein 70 (eHSP70) and interleukin 2 (IL-2) and their correlation in intestine of rats with severe scald injury, and to observe the effects of eHSP70 on CD3(+) T lymphocytes in Peyer's patch of intestine in rats with severe scald injury in vitro. METHODS: (1) Sixty male SD rats were divided into normal control group (NC, n=10, only anesthetized) and scald group (S, n=50) according to the random number table. Rats in scald group were inflicted with 30% total body surface area full-thickness scald on the back. Ten rats from group NC immediately after anesthetization and 10 rats from group S at post injury hour (PIH) 3, 6, 12, 24, 48 were sacrificed to harvest their small intestines. The expressions of eHSP70 and IL-2 were determined with enzyme-linked immunosorbent assay (ELISA), and their correlation was analyzed. (2) Another 2 male SD rats were inflicted with the same injury as above. At PIH 12, CD3(+) T lymphocytes in Peyer's patch of small intestine were isolated and cultured with RPMI 1640 nutrient solution containing 10% fetal bovine serum. Cells were divided into blank control group (BC) and 5, 10, 20 µg/mL eHSP70 groups according to the random number table, with 6 wells in each group. Cells in group BC didn't receive any other treatment, while cells in the latter three groups were treated with corresponding mass concentration of recombinant rat eHSP70. After being cultured for 48 hours, the proportions of Th1 and Th2 in CD3(+) T lymphocytes, and the apoptosis rate of CD3(+) T lymphocytes were detected with flow cytometer, while the expressions of IL-2 and IL-10 in culture supernatant of cells were determined with ELISA. The cell experiments were repeated for 10 times. Data were processed with one-way analysis of variance, Kruskal-Wallis rank sum test, SNK-q test, and Pearson correlation analysis. RESULTS: (1) Compared with those in group NC [(1 278±135) and (48.6±4.9) ng/mg], the levels of eHSP70 [(728±93), (412±31), (314±21), (528±40), (1 028±97) ng/mg] and IL-2 [(38.6±2.3), (32.3±1.0), (25.3±3.6), (33.9±4.1), (44.3±2.6) ng/mg] in intestine of rats in group S obviously decreased at PIH 3, 6, 12, 24, 48 (with q values from 3.48 to 5.32, P values below 0.05), reaching the nadir both at PIH 12, with a significantly positive correlation between the level of IL-2 and the level of eHSP70 (r=0.920, P<0.01). (2) Compared with those in group BC [(8.6±1.1)% and (3.75±0.45)%], the proportion of Th1 obviously increased [(11.3±2.1)%, (15.7±1.8)%, (10.8±1.5)%, with q values from 2.97 to 4.57, P values below 0.05], while the proportion of Th2 obviously decreased [(2.39±0.38)%, (1.05±0.23)%, (2.67±0.26)%, with q values from 2.48 to 4.32, P values below 0.05] in CD3(+) T lymphocytes of rats in 5, 10, 20 µg/mL eHSP70 groups. Compared with those in group BC [(34.3±2.2)% and (254±16) pg/mL], the apoptosis rate of CD3(+) T lymphocytes obviously decreased [(26.1±2.6)%, (20.7±1.5)%, (31.5±2.4)%, with q values from 3.47 to 4.95, P values below 0.05], while the level of IL-2 obviously increased [(417±22), (587±19), (307±27) pg/mL, with q values from 3.02 to 4.98, P values below 0.05] in culture supernatant of CD3(+) T lymphocytes of rats in 5, 10, 20 µg/mL eHSP70 groups. There was no significant difference in the level of IL-10 in culture supernatant of CD3(+) T lymphocytes of rats among the four groups (F=2.12, P>0.05). CONCLUSIONS: The expressions of eHSP70 and IL-2 in intestine of rats are decreased after severe scald, with a obviously positive correlation between them. eHSP70 can promote the differentiation of CD3(+) T lymphocytes in Th1 orientation, decrease the apoptosis rate of the cells, and promote the release of IL-2 of cells in Peyer's patch of intestine in rats with severe scald injury in vitro.