Effects of hydrothermal pretreatment on the mono- and co-digestion of waste activated sludge and wheat straw.

The refractory properties of waste activated sludge and wheat straw inhibit their bioenergy recovery by anaerobic digestion. This paper attempted to estimate the digestive performance, energy conversion efficiency and economic feasibility of wheat straw mono-digestion and its co-digestion with sludge by hydrothermal pretreatment at different temperature gradients (125, 150 and 175 °C). The results illustrated that the hydrolysis of both wheat straw and sludge were improved with the temperature increasing. It is noted that after pretreatment at 175 °C, wheat straw mono-digestion obtained the cumulative specific methane yield of 168.8 mL/g·VS, 6.9% reduction compared to the unpretreated straw (181.4 mL/g·VS) due to the inhibition by by-products (furfural and 5-hydroxymethylfurfural, 5-HMF) formed at high temperatures. The highest cumulative specific methane yield of 225.7 mL/g·VS was achieved by the co-digestion of pretreated wheat straw and pretreated sludge under 175 °C, indicating that the participation of sludge in co-digestion improved the buffer capacity of the system to relieve the inhibition. In addition, the co-digestion of sludge and wheat straw both pretreated at 175 °C obtained the maximum energy production of 7901.1 MJ/t, 52% promotion compared to the mono-digestion without pretreatment. The results of economic analysis showed that the mono-digestion of wheat straw obtained relatively low net profits and the mono-digestion of sludge pretreated at 175 °C achieved the highest net profit of 31.44 US$/t. These results suggest that the co-digestion of both pretreated wheat straw and sludge can achieve the highest biogas production and energy conversion efficiency.

A Novel Vav3 Homolog Identified in Lamprey, Lampetra japonica, with Roles in Lipopolysaccharide-Mediated Immune Response.

Vav guanine nucleotide exchange factor 3 (Vav3), a Rho family GTPase, regulates multiple cell signaling pathways including those of T- and B-cell receptors in vertebrates through mediating the activities of the Rho family members. Whether the lamprey possesses Vav3 homolog and what role it plays in immune response remain unknown. Gene cloning, recombinant expression, antibody production and expression pattern analyses were performed to characterize the lamprey Vav3 in the current study. The lamprey Vav3 is closer to jawed vertebrates' Vav3 molecules (about 53% identities in general) than to Vav2 molecules of jawless and jawed vertebrates (about 51% identities in general) in sequence similarity. Conserved motif analysis showed that the most distinguished parts between Vav3 and Vav2 proteins are their two Src-homology 3 domains. The relative expression levels of lamprey vav3 mRNA and protein were significantly up-regulated in lamprey lymphocytes and supraneural myeloid bodies after mixed-antigens stimulation, respectively. In addition, lamprey Vav3 were up-regulated drastically in lymphocytes and supraneural myeloid bodies after lipopolysaccharide (LPS) rather than phytohemagglutinin (PHA) stimulation. Lamprey Vav3 distributed in the cytoplasm of variable lymphocyte receptor B positive (VLRB⁺) lymphocytes, and the number of plasmacytes (VLRB and lamprey Vav3 double positive) in blood lymphocytes also increased after LPS stimulation. Our results proved that lamprey Vav3 was involved in the LPS-mediated immune reaction of lamprey and provided a clue for the further study of the precise role lamprey Vav3 played in the signaling pathway of lamprey VLRB⁺ lymphocytes.