Neighbourhood change in Genesee and Kent Counties,Michigan, 1970–2019

Michigan was an industrial powerhouse until the onset of deindustrialization in 1970. This paper compares socio-economic and demographic changes at the neighbourhood level between 1970 and 2019 in two medium-sized cities/counties in Michigan (Flint/Genesee County and Grand Rapids/Kent County) that underwent deindustrialization. Only 35% of neighbourhoods in the two counties were of the same class in 2019 as in 1970. Middle-class neighbourhoods declined while poor and upper-middle class neighbourhoods increased. The contemporary spatial structure of neighbourhoods in these two counties is a mixture of classic concentric ring/sectoral models interspersed with socio-economic downgrading inner-ring suburbs identified within other US cities since the 1990s.     

Mycobacterium tuberculosis Rv1916 is an Acetyl-CoA-Binding Protein

Isocitrate lyase (ICL) isoform 2 is an essential enzyme for some clinical Mycobacterium tuberculosis (Mtb) strains during infection. In the laboratory Mtb strain H37Rv, the icl2 gene encodes two distinct gene products – Rv1915 and Rv1916 – due to a frameshift mutation. This study aims to characterise these two gene products to understand their structure and function. While we were unable to produce Rv1915 recombinantly, soluble Rv1916 was obtained with sufficient yield for characterisation. Kinetic studies using UV-visible spectrophotometry and ¹H-NMR spectroscopy showed that recombinant Rv1916 does not possess isocitrate lyase activity, while waterLOGSY binding experiments demonstrated that it could bind acetyl-CoA. Finally, X-ray crystallography revealed structural similarities between Rv1916 and the C-terminal domain of ICL2. Considering the probable differences between full-length ICL2 and the gene products Rv1915 and Rv1916, care must be taken when using Mtb H37Rv as a model organism to study central carbon metabolism.     

Antifungal action of quaternary ammonium compounds against environmental molds isolated from food industries

Molds are ubiquitously found microorganisms that are usually present as contaminants in food industrial environments. It has been shown that Cladosporium and Aspergillus genera are two of the most abundant and widely distributed in these locations because they are highly resistant species to sanitizing treatments. Hence, the search of antimicrobial compounds that are effective to these types of fungal contamination becomes relevant. The aim of this report was to evaluate the antifungal capacity of two commercial preparations made both with benzalkonium chloride (a first generation QAC) alone and with the addition of glutaraldehyde at different concentrations and contact times. A suspension-neutralization test was performed employing spores of five strains of both Aspergillus section Nigri and Cladosporium cladosporioides, all isolated from food industries environments. Results have shown that benzalkonium chloride preparation was successful in destroying Cladosporium spores at 5% (v/v) concentration (average 4D value of 9.1 min) but failed in neutralizing Aspergillus propagules at the same conditions. On the other hand, the commercial mixture made of benzalkonium chloride and glutaraldehyde was effective in the inactivation of all food spoilage fungi spores at 1% (v/v) concentration (average 4D value of 1.8 and 8.8 min for Cladosporium and Aspergillus strains, respectively).