BackgroundInorganic polyphosphate (poly P) plays an important role in stress tolerance and virulence in many bacteria. PPK1 is the principal enzyme involved in poly P synthesis, while PPK2 uses poly P to generate GTP, a signaling molecule that serves as an alternative energy source and a precursor for various physiological processes. Campylobacter jejuni, an important cause of foodborne gastroenteritis in humans, possesses homologs of both ppk1 and ppk2. ppk1 has been previously shown to impact the pathobiology of C. jejuni.Methodology/Principal FindingsHere, we demonstrate for the first time that the deletion of ppk2 in C. jejuni resulted in a significant decrease in poly P-dependent GTP synthesis, while displaying an increased intracellular ATP:GTP ratio. The Δppk2 mutant exhibited a significant survival defect under osmotic, nutrient, aerobic, and antimicrobial stresses and displayed an enhanced ability to form static biofilms. However, the Δppk2 mutant was not defective in poly P and ppGpp synthesis suggesting that PPK2-mediated stress tolerance is not ppGpp-mediated. Importantly, the Δppk2 mutant was significantly attenuated in invasion and intracellular survival within human intestinal epithelial cells as well as in chicken colonization.Conclusions/SignificanceTaken together, we have highlighted the role of PPK2 as a novel pathogenicity determinant that is critical for C. jejuni survival, adaptation, and persistence in the host environments. PPK2 is absent in humans and animals; therefore, can serve as a novel target for therapeutic intervention of C. jejuni infections.

The food control and regulatory system in China is beset by several challenges. While firms have to reduce their costs in pursuit of benefits, customers are increasingly focusing on safety and quality of food products. Although the Chinese government has developed more stringent regulatory measures, food safety incidents still occur, including abuse of food additives, adulterated products as well as contamination by pathogenic microorganisms, pesticides, veterinary drug residues, and heavy metals, and use of substandard materials. A national food safety strategy has been proposed to assure food safety from “farm to table.” This paper begins with the analysis of current food regulatory systems and then discusses cogovernance of food safety management in China. We explore the practice in the city of Shenzhen where government intervention has strengthened food control, thereby creating an opportunity to form a coregulatory system. The review highlights that the current food safety regulatory system of multi‐agency structure can inevitably lead to insufficient incentives for business entities. Due to asymmetric information, lack of regulatory resources, and consumer advocacy, coregulation has been developed and is increasingly being promoted as an important instrument of food regulation.

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Composition and ensilage performance of giant reed harvested in August, October, November, and December, were evaluated and compared. Generally, late-harvested giant reed had higher dry matter content, lower nitrogen content, and higher water soluble carbohydrates (WSC) content than early-harvested giant reed. During 90days of ensilage, giant reed harvested in October, November, and December showed dry matter losses of about 1%, while giant reed harvested in August showed a higher dry matter loss of about 8%. During the ensilage process, more lactic acid was produced in late-harvested giant reed than in early-harvested giant reed. Late-harvested giant reed had a higher lignin content and lower enzymatic digestibility than early-harvested giant reed. However, enzymatic digestibility of all the giant reed biomass was improved by the 90-day ensilage process, reaching levels of 43-46%. In summary, ensilage could be used for storing giant reed biomass harvested at different times and for improving its digestibility.