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Currently for bacterial identification and classification the rrs gene encoding 16S rRNA is used as a reference method for the analysis of strains of the genus Nocardia. However, it does not have enough polymorphism to differentiate them at the species level. This fact makes it necessary to search for molecular targets that can provide better identification. The sodA gene (encoding the enzyme superoxide dismutase) has had good results in identifying species of other Actinomycetes. In this study the sodA gene is proposed for the identification and differentiation at the species level of the genus Nocardia. We used 41 type species of various collections; a 386 bp fragment of the sodA gene was amplified and sequenced, and a phylogenetic analysis was performed comparing the genes rrs (1171 bp), hsp65 (401 bp), secA1 (494 bp), gyrB (1195 bp) and rpoB (401 bp). The sequences were aligned using the Clustal X program. Evolutionary trees according to the neighbour-joining method were created with the programs Phylo_win and MEGA 6. The specific variability of the sodA genus of the genus Nocardia was analysed. A high phylogenetic resolution, significant genetic variability, and specificity and reliability were observed for the differentiation of the isolates at the species level. The polymorphism observed in the sodA gene sequence contains variable regions that allow the discrimination of closely related Nocardia species. The clear specificity, despite its small size, proves to be of great advantage for use in taxonomic studies and clinical diagnosis of the genus Nocardia.

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Abstract:The health benefits of nutrients provided by edible insects are not properly studied, even though insect intake in Latin American and Asia is a cultural tradition since ancient times. Insects from the giant water bug (Belostomidae family) are consumed both in Mexico and Thailand, and are known as "Cucarachon de agua" (Lethocerus americanus) and "Mangda" (Lethocerus indicus), respectively. Raw samples of these insects were collected on 2014 at Xochimilco channels from Mexico and from Warorot night market in Chiang Mai, Thailand to further analyze nutrient composition of samples according to official methods of analysis (AOAC) techniques. The nutrient compositions were as following: proteins 60.12% and 53.11%; lipids 5.72% and 8.15%; minerals 5.46% and 6.75%; fiber 10.95 % and 12.23%; soluble carbohydrates 17.75% and 19.74%, for insects obtained from Mexico and Thailand, respectively. Giant water bug shows differences in nutrient composition. It may be the consequence of differences in the environment where they acquire the nutrients necessary for growth and reproduction. However, giant water bugs are available all year around and are a good source of proteins that could help people to obtain a cheaper source of this important macronutrient.

Nocardia species are aerobic, Gram-positive bacteria with branched filaments reported as opportunistic microorganisms associated with infectious diseases of the skin. We report the isolation of N. wallacei in Mexico from a 43-year-old man, an HIV-positive construction worker who sought care for difficulty breathing and abundant sputum.