Morphological aspects of adaptation of the alkalophilic bacteria Bacillus aequororis to high salinity and alkalinity of the medium

AFM-images were obtained and the morphometric parameters of cells of the facultative alkalophile Bacillus aequororis 5-DB and neutrophilic Bacillus subtilis ATCC 6633 were calculated after incubation in an alkaline medium with a high concentration of sodium chloride. It was shown that adaptation of B. aequororis 5-DB is not accompanied by significant changes in morphometric parameters, while the volume of cells slightly (by 1–1.5 times) decreases and their surface roughness increases. Neutrophilic bacillus, on the contrary, reacts to an increase in salt concentration and pH (50 g/l, pH 11) by significant changes in the cell: the cell volume decreases 2–3 times, and with daily adaptation to 50 g/l salt with pH 8 increases by 2.4 times due to the increase in cell length. Cells of an alkalophilic bacillus, in contrast to those of a neutrophilic bacillus, do not undergo significant changes in morphology with a high mineralization of the environment, both under direct exposure and after daily adaptation.

Byproducts from cassava industry: alternative substrates for cyclodextrin glycosyltransferase production by alkalophilic Bacillus trypoxylicola SM–02

Bioproductos de la industria de la yuca: sustratos alternativos para la producción de ciclodextrina glucosiltransferasa por alcalófilo Bacillus trypoxylicola SM-02 En el presente trabajo estudiamos el uso licor de maíz fermentado (LMF), harina de cáscara de yuca (HCY) y aguas residuales de yuca para la producción de ciclodextina glicosiltransferasa (CGTase) por un nuevo aislado alcalófilo de Bacillus trypoxylicola SM-02 en fermentación sumergida. Los experimentos se realizaron por Diseño Central Compuesto Rotativo 22 totalizando 11 ensayos. La mayor actividad enzimática de 352.53 U/mL se obtuvo con 1.5 g de HCY y 0.6 g de LMF. La temperatura y el pH óptimos fueron 55 ºC y pH 8.0, respectivamente. CGTase mostró una actividad relativa superior al 50% durante 120 min. a la temperatura óptima. Solo el CaCl2 mostró actividad positiva para CGTasa. Los resultados apuntaron a un buen potencial de B. trypoxylicola SM-02 para la producción de CGTasa usando substratos residuales. In the present work was studied the use of cassava peel flour (CPF), corn steep liquor (CSL), and cassava wastewater as substrates to produce cyclodextrin glycosyltransferase (CGTase) from a new alkalophilic isolate of Bacillus trypoxylicola SM-02 by submerged fermentation. The experiments were performed as a Central Composite Design 22, totalizing 11 assays. An enzymatic activity of 352.53 U/mL was obtained using 1.5 g of CPF and 0.6 g of CSL. The optimum temperature and pH of CGTase was 55 °C and 8.0, respectively. The CGTase depicted a relative activity of more than 50% for 120 min at the optimum temperature. The only salt that positively influenced the CGTase activity was CaCl2. The results are indicative of a potential role of B. trypoxylicola SM-02 in the production of CGTase using residual substrates.