The biosorption of Co(II) on three fungal biomasses:Paecilomycessp.,Penicilliumsp., andAspergillus niger, was studied in this work. The fungal biomass ofPaecilomycessp. showed the best results, since it removes 93% at 24 h of incubation, while the biomasses ofPenicilliumsp. andAspergillus nigerare less efficient, since they remove the metal 77.5% and 70%, respectively, in the same time of incubation, with an optimum pH of removal for the three analyzed biomasses of 5.0 ± 0.2 at 28°C. Regarding the temperature of incubation, the most efficient biomass was that ofPaecilomycessp., since it removes 100%, at 50°C, while the biomasses ofPenicilliumsp. andAspergillus nigerremove 97.1% and 94.1%, at the same temperature, in 24 hours of incubation. On the contrary, if the concentration of the metal is increased, the removal capacity for the three analyzed biomasses decreases; if the concentration of the bioadsorbent is increased, the removal of the metal also increases. It was observed that, after 4 and 7 days of incubation, 100%, 100%, and 96.4% of Co(II) present in naturally contaminated water were removed, respectively.

Due to the increase in contamination of aquatic niches by different heavy metals, different technologies have been studied to eliminate these pollutants from contaminated aquatic sources. So the objective of this work was to determine the removal of cobalt (II) in aqueous solution by the biomass of the aquatic lily or water hyacinth (Eichhornia crassipes) which, is one of the main weeds present in fresh water, due to its rapid reproduction, growth, and high competitiveness, by the colorimetric method of the methyl isobutyl ketone. The removal was evaluated at different pHs (4.0–8.0) for 28 h. The effect of temperature in the range from 20 °C to 50 °C and the removal at different initial concentrations of cobalt (II) of 100 to 500 mg/L was also studied. The highest bioadsorption (100 mg/L) was at 28 h, at pH 5.0 and 28 °C, with a removal capacity of 73.1%, which is like some reports in the literature. Regarding the temperature, the highest removal was at 50 °C, at 28 h, with a removal of 89%. At the metal and biomass concentrations analyzed, its removal was 82% with 400–500 mg/L, and 100% with 5 g of natural biomass at 20 h. In addition, this completely removes the metal in situ (100 mg/L in contaminated water, at 7 days of incubation, with 10 g of natural biomass in 100 mL). So, the natural biomass can be used to remove it from industrial wastewater, even if in vivo, only eliminate 17.3% in 4 weeks.

The objective of this work was to study the resistance and removal capacity of heavy metals by the yeast Candida albicans. The resistance of some heavy metals was analyzed: the yeast grows in 2000 ppm of chromium, zinc, lead, and copper, 1500 ppm of arsenic (III), 500 ppm of silver, and little bit in cobalt (300 ppm) and mercury and cadmium (200 ppm). Analyzing its potential to remove heavy metals, it can efficiently remove is as follows: Cr(VI) (76%), lead (57%), silver (51%), cadmium (46%), fairly arsenic(III) (40% with the modified biomass), cobalt (37%), mercury (36%), copper (31%), little bit zinc (22%), and fluoride (10%). We determine the optimal characteristics for chromium(VI) removal in living cells and death biomass. The ideal conditions for the removal of 50 mg/L of Cr(VI) in living cells were 28°C, pH 7.0, and 10 × 106 yeast/mL, with glycerol-like carbon source. In dead yeast biomass, the ideal conditions for removal of metal are 200 mg/L of Cr(VI), 60°C, pH 1.0, 20 h, and 5 g of biomass.

Industrial effluents from chromium-based products lead to chromium pollution in the environment. Several technologies have been employed for the removal of chromium (Cr) from the environment, including adsorption, ion-exchange, bioremediation, etc. In this study, we isolated a Cr (VI)-resistant fungus, Purpureocillium lilacinum, from contaminated soil, which could reduce chromium. We also characterized a reductant activity of dichromate found in the cellular fraction of the fungus: optimal pH and temperature, effect of enzymatic inhibitors and enhancers, metal ions, use of electron donors, and initial Cr (VI) and protein concentration. This study also shows possible mechanisms that could be involved in the elimination of this metal. We observed an increase in the reduction of Cr (VI) activity in the presence of NADH followed by that of formate and acetate, as electron donor. This reduction was highly inhibited by EDTA followed by NaN₃ and KCN, and this activity showed the highest activity at an optimal pH of 7.0 at 37 °C with a protein concentration of 3.62 µg/mL.

Authors: Ismael Acosta-Rodríguez, Juan F. Cárdenas-González, María de Guadalupe Moctezuma-Zárate and Víctor M. Martínez-Juárez

The maguey mezcalero potosino (Agave salmiana) is a natural resource of great regional importance, used for the manufacture of mezcal and other alcoholic beverages by fermentation of simple sugars and sugars released by fructans hydrolysis. For this, only the stem and base of leaves is used, which results on wasting the other sections that represent up to 40% of weight of the complete plant. The objective of this study was to identify and quantify the fermentable carbohydrates present in raw and hydrolysed juices of the stem and four sections of the whole leaves (base, neck, wings and apex) of maguey plants with representative specimens of three stages of maturity with industrial importance. For carbohydrate characterization, high resolution liquid chromatography (HLPC) was used. The sugars found as fructose, glucose, sucrose, xylose and maltose coincide with those identified in other Agave species, significant differences are observed depending on the section and the state of maturity of the plant, the sugar concentration in the discarded sections of the plant (fructose: 5.79 – 4.80 mg mL-1) are considerable and statistically similar to those found in the stem (fructose: 2.49 mg mL-1) and the base of the leaf (fructose: 3.16 mg mL-1) (structure used in the mezcal production process). The results obtained can promote the integral use of the plant and diversification towards other industries such as pharmaceuticals, biofuels or foods.