Rhodococcus erythropolis ATCC 4277 behavior against different metals and its potential use in waste biomining.

Rhodococcus erythropolis bacterium is known for its remarkable resistance characteristics that can be useful in several biotechnological processes, such as bioremediation. However, there is scarce knowledge concerning the behavior of this strain against different metals. This study sought to investigate the behavior of R. erythropolis ATCC 4277 against the residue of chalcopyrite and e-waste to verify both resistive capacities to the metals present in these residues and their potential use for biomining processes. These tests were carried out in a stirred tank bioreactor for 48 h, at 24ºC, pH 7.0, using a total volume of 2.0 L containing 2.5% (v/v) of a bacterial pre-culture. The pulp density of chalcopyrite was 5% (w/w), and agitation and oxygen flow rates were set to 250 rpm and 1.5 LO2 min-1, respectively. On the other hand, we utilized a waste of computer printed circuit board (WPCB) with a pulp density of 10% (w/w), agitation at 400 rpm, and an oxygen flow rate of 3.0 LO2 min-1. Metal concentration analyses post-fermentation showed that R. erythropolis ATCC 4277 was able to leach about 38% of the Cu present in the chalcopyrite residue (in ~ 24 h), and 49.5% of Fe, 42.3% of Ni, 27.4% of Al, and 15% Cu present in WPCB (in ~ 24 h). In addition, the strain survived well in the environment containing such metals, demonstrating the potential of using this bacterium for waste biomining processes as well as in other processes with these metals.

Transcriptional profiling of a fungal granuloma reveals a low metabolic activity of Paracoccidioides brasiliensis yeasts and an actively regulated host immune response.

Granulomas are important immunological structures in the host defense against the fungus Paracoccidioides brasiliensis, the main etiologic agent of Paracoccidioidomycosis (PCM), a granulomatous systemic mycosis endemic in Latin America. We have performed transcriptional and proteomic studies of yeasts present in the pulmonary granulomas of PCM aiming to identify relevant genes and proteins that act under stressing conditions. C57BL/6 mice were infected with 1x106 yeasts and after 8- and 12-weeks of infection, granulomatous lesions were obtained for extraction of fungal and murine RNAs and fungal proteins. Dual transcriptional profiling was done comparing lung cells and P. brasiliensis yeasts from granulomas with uninfected lung cells and the original yeast suspension used in the infection, respectively. Mouse transcripts indicated a lung malfunction, with low expression of genes related to muscle contraction and organization. In addition, an increased expression of transcripts related to the activity of neutrophils, eosinophils, macrophages, lymphocytes as well as an elevated expression of IL-1ß, TNF-α, IFN-γ, IL-17 transcripts were observed. The increased expression of transcripts for CTLA-4, PD-1 and arginase-1, provided evidence of immune regulatory mechanisms within the granulomatous lesions. Also, our results indicate iron as a key element for the granuloma to function, where a high number of transcripts related to fungal siderophores for iron uptake was observed, a mechanism of fungal virulence not previously described in granulomas. Furthermore, transcriptomics and proteomics analyzes indicated a low fungal activity within the granuloma, as demonstrated by the decreased expression of genes and proteins related to energy metabolism and cell cycle.

Biofilm formation by Candida albicans is inhibited by 4,4-dichloro diphenyl diselenide (pCl-PhSe)2.

Candida species are the fourth most common cause of nosocomial bloodstream infections. An increase in the frequency of infections which have become refractory to standard antifungal therapyhave been observed. Recently, the effect of different organochalcogenide compounds reducing both growth and germ tube formation by Candida albicans was demonstrated. This work studied the effect of the organochalcogenide compound (pCl-PhSe)2 on both growth and biofilm formation by Candida albicans. A decrease in C. albicans growth in the presence of crescent concentrations of (pCl- PhSe)2 was observed, in a cell density dependent manner. The inhibition of Candida growth by 10µM (pCl-PhSe)2 was ~60, 57, 47 and 24%, in cell densities of 10(3), 10(4), 10(5) and 10(6) cells/ml, respectively. The compound (pCl-PhSe)2 was able to inhibit biofilm formation by Candida albicans, when biofilm was performed using a cell density of 10(6) cells/ml. In addition, an increase in both ROS production (96%) and cell membrane permeability (1.107-fold) by 10 µM (pCl-PhSe)2 was observed in C. albicans.These results demonstrate that the organochalcogenide compound (pCl-PhSe)2 presents a great potential to inhibit both growth and biofilm formation by C. albicans.