The results show that the supplementation of lipases at low concentration was enough to improve the assimilation of organic compounds through anaerobic biomass, in agreement to the results previously reported in the literature (Mendes et al. 2006, 2010; Rosa et al. 2009; Valladão et al. 2011).
M. extorquens does not possess a functioning glyoxylate cycle and therefore the assimilation of C2 compounds has remained enigmatic for a long time [12].
Another important regulatory system in the assimilation of nitrogen compounds is the NtrB/NtrC (Part of the nitrogen regulation system Ntr) two-component system [ 18, 19].
Finally, a complete glyoxylate bypass system (malate synthase and isocitrate lyase) was found in only AMDSBA1 and S. acidophilus, possibly permitting carbon assimilation of C2 compounds like acetate.
Additionally, we confirm the presence of bldB in S. lividans and deduce that S. lividans 66 and TK24, both deficient in the glyoxylate bypass, possess an alternative metabolic mechanism for the assimilation of C2 compounds.
The SHMT is coded by the glyA genes and act as the first enzyme in the assimilation of C1 compounds through the addition of formaldehyde to glycine, producing the principal intermediate in the pathway, serine [ 4].
Besides the classic morphological identification of molds there are some metabolic markers that are important for species/genus identification, such as the ability to grow within certain temperature ranges and assimilation of different compounds as a sole carbon source.
The previous analyses suggested that X. citri had two ABC systems for the transport and assimilation of organosulfur compounds, but it lacks a proper TauABCD system as observed in E. coli.
As the glyoxylate bypass is non-functional in both S. lividans strains due to the absence of the gene encoding isocitrate lyase it is likely that the ethylmalonyl-CoA pathway functions as the alternative mechanism for the assimilation of C2 compounds.
This includes the downregulation of glycolytic genes and the activation of glyoxylate cycle genes (ICL1, MLS1), which facilitate the assimilation of two-carbon compounds in concert with gluconeogenic genes (PCK1, FBP1).
Previous studies have shown that genes responsible for controlling the glyoxylate cycle and gluconeogenesis, which are used for the assimilation of two carbon compounds, are activated after C. albicans is exposed to macrophages.
