Selma Gomes Ferreira Leite

CONTINUOUS BIOSORPTION OF CU AND ZN BY IMMOBILIZED WASTE BIOMASS SARGASSUM SP

Biosorption of copper and zinc by the residual biomass of the alga Sargassum sp. was investigated in a mini packed-bed column. The biomass was immobilized in a polymeric matrix to improve its physicochemical properties for continuous biosorption of heavy metals from aqueous solutions. Adsorption breakthrough curves obtained at different flow rates indicated that an increase in flow rate decreased the volume treated until the breakthrough point as well as the service time of the bed and the dynamic capacity of the column. At the lowest flow rate of 1.0 ml/min per cm2 it was possible to treat 446 and 414 bed volumes of copper and zinc up to their respective breakthrough points. At this flow rate, the dynamic capacity of the column was 11.9 mg Cu/g and 21.0 mg Zn/g.

Metals biosorption by sodium alginate immobilizedChlorella homosphaera cells

SummaryCadmium and zinc biosorption, alone or in combination, was investigated with sodium alginate immobilizedChlorella homosphaera cells. Concentrations ranging from 20.0 to 41.0mg/l cadmium, 75.0 and 720.0mg/l zinc were tested and, in all cases, the metal removal achieved values near 100%. When these metals were put in combination a decrease in the rate of absorption was detected. Gold was also tested in the immobilized system and 90% of the initial metal added was recovered in a solution containing 213.0mg/l of the metal, the alginic matrix being responsible for 40% gold uptake.

Selection of tannase-producing Aspergillus niger strains

The aim of this work was to select strains of Aspergillus niger for tannase production. Growth of colonies in plates with tannic acid-containing medium indicated their ability to synthesize tannase. Tannase activity was also measured in solid-state fermentation. A. niger 11T25A5 was the best tannase producer (67.5 U.g-1/72 hours of fermentation).

Gasoline biodegradation in different soil microcosms

The objective of this study was to evaluate gasoline biodegradation in batch soil microcosms. Microorganisms able to grow in the presence of gasoline were isolated from soil. Several treatment systems were performed using both isolated strains and Pseudomonas putida obtained from a culture collection. The treatment system using only autochthonous microflora (system 1) presented an average value of degradation of 50%. The association of Pseudomonas putida, Burkholderia cepacia, Pseudomonas alcaligenes and the native soil microflora (system 13) presented significant percentage of removal of n-undecane (88.7), n-dodecane (61.3) and n-tridecane (66.7). According to these results, systems 1 and 13 revealed considerable potential for application in bioremediation treatments.

Development and validation of automatic HS-SPME with a gas chromatography-ion trap/mass spectrometry method for analysis of volatiles in wines.

An automated headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed in order to quantify a large number of volatile compounds in wines such as alcohols, ester, norisoprenoids and terpenes. The procedures were optimized for SPME fiber selection, pre-incubation temperature and time, extraction temperature and time, and salt addition. A central composite experimental design was used in the optimization of the extraction conditions. The volatile compounds showed optimal extraction using a DVB/CAR/PDMS fiber, incubation of 5 ml of wine with 2g NaCl at 45 °C during 5 min, and subsequent extraction of 30 min at the same temperature. The method allowed the identification of 64 volatile compounds. Afterwards, the method was validated successfully for the most significant compounds and was applied to study the volatile composition of different white wines.

Lipase-catalyzed diacylglycerol production under sonochemical irradiation☆

The present paper describes a protocol for production of diacylglycerol by the partial hydrolysis of soybean oil catalyzed by lipase under ultrasound irradiation. Better yields and shorter reaction times were obtained under sonication as compared to the thermal process.

Repeated removal of cadmium and zinc from an industrial effluent by waste biomass Sargassum sp.

Waste biomass Sargassum sp. biosorbed 100% of Cd2+ and 99.4% of Zn2+ from a 3 and 98 mg l−1 solution (pH 4.5), respectively, at the end of four serial experiments. Of the five desorbents studied in consecutive adsorption/desorption cycles, CaCl2 0.05 M eluted nearly 40% of both metals and decreased the biosorption in only 8% and 17% of Cd2+ and Zn2+, respectively. Although NaOH desorbent improved the heavy metal uptake from the second cycle onwards, it did not elute metals from the pre-loaded biomass.

Cadmium and zinc biosorption byChlorella homosphaera

SummaryCadmium and zinc biosorption byChlorella homosphaera cells were tested under laboratory conditions, in a range of concentrations from 0.5 to 14.0 mg/l. The results indicated two distinct phases for cadmium biosorption: a rapid phase probably associated with metal adsorption around the cell wall and a slower phase associated with the metal transport into the interior of the cells. For zinc biosorption these phases were not well defined probably due to the metabolic use of this metal by the cells.

Degradation of gasoline aromatic hydrocarbons by two N2-fixing soil bacteria

Two bacterial strains, 3A and 5A, isolated from soil, were selected for their ability to degrade gasoline aromatic compounds and to fix N2. Strains 3A and 5A have been ascribed to the genera Agrobacterium and Alcaligenes, respectively. Using gasoline as the sole carbon source these strains were as effective at degrading benzene, toluene and xylene as Pseudomonas putida ATCC12236, a reference biodegrading strain.

Bioemulsifier production by Microbacterium sp. strains isolated from mangrove and their application to remove cadmiun and zinc from hazardous industrial residue

The contamination of ecosystems with heavy metals is an important issue in current world and remediation technologies should be in according to environmental sustainability concept. Bioemulsifier are promising agents to be used in metal removal and could be effective to many applications in environmental industries. The aims of this work was screening the potential production of bioemulsifier by microorganisms isolated from an oil contaminated mangrove, and evaluate cadmium and zinc removal potential of those strains from a hazardous industrial residue. From that, bioemulsifier-producing bacteria were isolated from urban mangrove sediments. Four isolates were identified as Microbacterium sp by 16S rRNA analysis and were able to reduce up to 53.3% of culture medium surface tension (TS) when using glucose as carbon and energy source and 20.2% when sucrose was used. Suspensions containing bioemulsifier produced by Microbacterium sp. strains show to be able to remove cadmium and zinc from contaminated industrial residue, and its ability varied according carbon source. Significant differences in metal removal were observed by all strains depending on the carbon source. When glucose was used, Cd and Zn removal varied from 17 to 41%, and 14 to 68%, respectively. However, when sucrose was used it was observed only 4 to a maximum of 15% of Cd removal, and 4 to 17% of Zn removal. When the same tests were performed after ethanol precipitation, the results were different: the percentages of removal of Zn (7-27%) and Cd (14-32%) were higher from sucrose cultures. This is the first report of heavy metals removal by bioemulsifier from Microbacterium sp.