Medium alkalization due to carbon metabolism is largely responsible for inhibition of bacterial growth by Vibrio cholerae supernatants

Vibrio cholerae is the causative agent of the diarrheal disease cholera. Many Vibrio species secrete antimicrobial factors, though the identity of such a factor has not been determined for any V. cholerae strain. Such an antimicrobial factor could be relevant to pathogenesis of cholera, which disrupts the intestinal microbiome. In this study, we investigated the antimicrobial effects of supernatant from 72 hour old cultures of V. cholerae C6706 on Shigella flexneri CFS100. Inhibition of S. flexneri growth was found to be dependent on the alkaline pH of the supernatant. A 1:1 mixture of pH-adjusted supernatant and LB was found to inhibit S. flexneri growth at alkaline but not neutral pH, as was pH-adjusted LB alone. In minimal medium, elevation of supernatant pH by V. cholerae was dependent on nutritional factors, and this elevation of medium pH also correlated with increased S. flexneri growth inhibition. Though medium alkalization in LB is often attributed to amino acid catabolism and the consequent production of ammonia, supplementation of V. cholerae cultures in minimal medium with amino acids had a weaker effect on alkalization and inhibition than did supplementation with selected carbon sources. This suggests that some feature of carbon metabolism causes medium alkalization and the resultant antimicrobial activity. Several V. cholerae mutants in potentially relevant pathways were screened for alkalization and S. flexneri growth inhibition, but none had any effect.Complicating this picture is the finding that V. cholerae grown under microaerobic conditions produce a less alkaline supernatant with stronger S. flexneri growth inhibition. The significance of this is unknown.Molecular Bioscience

Scepticism and the genealogy of knowledge: situating epistemology in time

My overarching purpose is to illustrate the philosophical fruitfulness of expanding epistemology not only laterally across the social space of other epistemic subjects, but at the same time vertically in the temporal dimension. I set about this by first presenting central strands of Michael Williams' diagnostic engagement with scepticism, in which he crucially employs a Default and Challenge model of justification. I then develop three key aspects of Edward Craig's ‘practical explication' of the concept of knowledge so that they may be seen to resonate positively with Williams's epistemological picture: the admixture of internalist and externalist features; the proto-contextualism; and, finally, the distinctively genealogical antisceptical impetus. In this way I aim to support and augment the socialized anti-sceptical case mounted by Williams, and so to show that expanding epistemology in the temporal dimension can be a productive move in central debates in epistemology

Understanding Judicial Independence in Vanuatu

This paper is intended to fill a gap in the literature concerning the Vanuatu judiciary, as this topic is rarely addressed other than in reports by international non-government organisations, such as Transparency International and its local chapter, Transparency International (Vanuatu), or bilateral donors and multilateral organisations engaged in law and justice work (which is often unpublished). The paper also identifies potential sources of influence that threaten judicial independence, and reflects upon what insights Vanuatu's experiences may provide into the influence of informal networks on judicial independence more broadly. The paper also raises a number of unanswered questions relating to broader questions about the sources of respect for the judiciary in Vanuatu and the role of culture in relation to this respect.AusAI

Carnapian Explication and the Canberra Plan’s Conceptual Analysis: a Comparison and Critique

Conceptual analysis has been a traditional methodology within analytic philosophy, but it also has been the target of numerous attacks. On the other hand, explication has been undergoing a revival as a methodological alternative due to the revisionary element associated with it. This allows for a scientific reconstruction of our ordinary notions, which would share virtues associated with scientific concepts. However, there is now a popular variant of conceptual analysis which resembles closely the explicative methodology: the two-step methodology advanced by the advocates of the Canberra Plan. Although explication is a wider and more ambitious program, I will argue that both methodologies can be regarded as attempts to bring philosophical methodology and its products closer to scientific ones. However, I will also point out that, although the goal is advantageous, there still remain some theoretical problems

Streams in the Wilderness

Miranda Beale analyzes two award-winning novels by Marilynne Robinson, Gilead (2004) and Home (2008), identifying their major themes as the necessity of balancing parental responsibility and God\u27s loving guidance and redemptive power in raising children

The Musician\u27s Walk: An Ethical Labyrinth

The article reviews the book The Musician\u27s Walk: An Ethical Labyrinth, by James Jordan