Wan Azlina Ahmad

Pilot-scale removal of chromium from industrial wastewater using the ChromeBac system.

The enzymatic reduction of Cr(VI) to Cr(III) by Cr(VI) resistant bacteria followed by chemical precipitation constitutes the ChromeBac system. Acinetobacter haemolyticus was immobilized onto carrier material inside a 0.2m(3) bioreactor. Neutralized electroplating wastewater with Cr(VI) concentration of 17-81 mg L(-1) was fed into the bioreactor (0.11-0.33 m(3)h(-1)). Complete Cr(VI) reduction to Cr(III) was obtained immediately after the start of bioreactor operation. Together with the flocculation, coagulation and filtration, outflow concentration of less than 0.02 mg Cr(VI)L(-1) and 1mg total CrL(-1) were always obtained. Performance of the bioreactor was not affected by fluctuations in pH (6.2-8.4), Cr(VI) (17-81 mg L(-1)), nutrient (liquid pineapple waste, 1-20%v/v) and temperature (30-38 degrees C). Standby periods of up to 10 days can be tolerated without loss in activity. A robust yet effective biotechnology to remove chromium from wastewater is thus demonstrated.

Chryseobacterium artocarpi sp. nov., isolated from the rhizosphere soil of Artocarpus integer

A bacterial strain, designated UTM-3(T), isolated from the rhizosphere soil of Artocarpus integer (cempedak) in Malaysia was studied to determine its taxonomic position. Cells were Gram-stain-negative, non-spore-forming rods, devoid of flagella and gliding motility, that formed yellow-pigmented colonies on nutrient agar and contained MK-6 as the predominant menaquinone. Comparative analysis of the 16S rRNA gene sequence of strain UTM-3(T) with those of the most closely related species showed that the strain constituted a distinct phyletic line within the genus Chryseobacterium with the highest sequence similarities to Chryseobacterium lactis NCTC 11390(T), Chryseobacterium viscerum 687B-08(T), Chryseobacterium tructae 1084-08(T), Chryseobacterium arthrosphaerae CC-VM-7(T), Chryseobacterium oncorhynchi 701B-08(T), Chryseobacterium vietnamense GIMN1.005(T), Chryseobacterium bernardetii NCTC 13530(T), Chryseobacterium nakagawai NCTC 13529(T), Chryseobacterium gallinarum LMG 27808(T), Chryseobacterium culicis R4-1A(T), Chryseobacterium flavum CW-E2(T), Chryseobacterium aquifrigidense CW9(T), Chryseobacterium ureilyticum CCUG 52546(T), Chryseobacterium indologenes NBRC 14944(T), Chryseobacterium gleum CCUG 14555(T), Chryseobacterium jejuense JS17-8(T), Chryseobacterium oranimense H8(T) and Chryseobacterium joostei LMG 18212(T). The major whole-cell fatty acids were iso-C15 : 0 and iso-C17 : 1ω9c, followed by summed feature 4 (iso-C15 : 0 2-OH and/or C16 : 1ω7t) and iso-C17 : 0 3-OH, and the polar lipid profile consisted of phosphatidylethanolamine and several unknown lipids. The DNA G+C content strain UTM-3(T) was 34.8 mol%. On the basis of the phenotypic and phylogenetic evidence, it is concluded that the isolate represents a novel species of the genus Chryseobacterium, for which the name Chryseobacterium artocarpi sp. nov. is proposed. The type strain is UTM-3(T) ( = CECT 8497(T) = KCTC 32509(T)).

Isotherm kinetics of Cr(III) removal by non-viable cells of Acinetobacter haemolyticus

The potential use of non-viable biomass of a Gram negative bacterium i.e. Acinetobacter haemolyticus to remove Cr(III) species from aqueous environment was investigated. Highest Cr(III) removal of 198.80 mg g(-1) was obtained at pH 5, biomass dosage of 15 mg cell dry weight, initial Cr(III) of 100 mg L(-1) and 30 min of contact time. The Langmuir and Freundlich models fit the experimental data (R(2)>0.95) while the kinetic data was best described using the pseudo second-order kinetic model (R(2)>0.99). Cr(III) was successfully recovered from the bacterial biomass using either 1M of CH(3)COOH, HNO(3) or H(2)SO(4) with 90% recovery. TEM and FTIR suggested the involvement of amine, carboxyl, hydroxyl and phosphate groups during the biosorption of Cr(III) onto the cell surface of A. haemolyticus. A. haemolyticus was also capable to remove 79.87 mg g(-1) Cr(III) (around 22.75%) from raw leather tanning wastewater. This study demonstrates the potential of using A. haemolyticus as biosorbent to remove Cr(III) from both synthetic and industrial wastewater.

Bioaccumulation of silver and the isolation of metal-binding protein from P.diminuta

Um estudo sobre o crescimento de Pseudomonas diminuta em um meio contendo cloreto livre (CFM) e ions de prata na concentracao (50 µM) em uma cultura em batelada. Os resultados demonstraram que grandes quantidades de prata foram acumuladas dentro da celula durante a fase exponencial de crescimento comparada a uma quantidade limitada na superficie da celula. Isto sugeriu um mecanismo captacao do metal durante o crescimento bacteriano. Em vista disto, tentativas foram realizadas no sentido de isolar as proteinas relacionadas com a propriedade de se ligar a prata em cultura P.diminuta em um meio contendo ou nao ions prata. As proteinas foram extraidas das culturas bacterianas pela precipitacao com o sulfato do amonio seguido de sua purificacao utilizando um focalizador isoeletrico e SDS-PAGE. Os resultados desta experiencia mostraram a presenca de proteinas de alto e baixo peso molecular contendo prata com pI variando entre 2,0 a 9,0 quando as bacterias crescem na presenca da prata.

Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ((1)H NMR and (13)C NMR), UV-Vis, and LC-MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV-Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36μgmL(-1). This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent.

Current perspective on bacterial pigments: emerging sustainable compounds with coloring and biological properties for the industry - an incisive evaluation

The current inclination towards exploiting bacterial pigments for various coloring functions, like food, cloth, painting, cosmetics, pharmaceuticals, plastics etc. is a well-recognized aspect. Nevertheless, the current bacterial pigment productions are not effective to meet their industrial needs. Current research going on world over on bacterial pigments signify that genetic engineering for strain improvement, optimization of bioprocess modelling and utilizing cheap agro-industrial residues as substrates are key developmental strategies to maximize pigment production from bacteria. Incidentally the superior performance characteristics of the bacteria for producing differing colouring compounds and the environmental acceptability of bacterial pigments are very encouraging factors to promote higher pigment production taking advantage of the current developmental strategies. This paper evaluates the current advances in bacterial pigment production, its recovery and wide-ranging scope of its industrial applications and commercial viability.

Violet pigment production from liquid pineapple waste by Chromobacterium violaceum UTM5 and evaluation of its bioactivity

Synthetic pigments have been utilized in numerous industries including textile, cosmetic, food and pharmaceuticals. However, the drawbacks of these pigments, namely toxicity problems have kindled interest in natural pigments. In view of this, the use of natural pigments such as those from a bacterial origin offers an interesting alternative for industrial application. However, large scale applications of natural pigments are often hindered by the high production cost. This study evaluates the feasibility of using liquid pineapple waste for the production of violacein by a locally isolated Chromobacterium violaceum UTM5 both in a shake flask and a 50 L bioreactor. The use of optimized growth parameters including culture conditions, concentration of liquid pineapple waste and supplementation of L-tryptophan resulted in a violacein yield of 16 256 ± 440 mg L−1. Post treatment of the effluent effectively reduced the COD, turbidity and TSS contents to less than 1 mg L−1, 1.57 ± 0.2 NTU and 2.7 ± 0.6 mg L−1 respectively. The violet pigment exhibited good stability during the entire storage period of 30 days at pH 7, temperature 25–30 °C and under dark conditions. The violet pigment has a good antimicrobial activity against selected microorganisms. Of interest, the pigment was active against Staphylococcus aureus ATCC 29213 and methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 with a MIC value of 7.8 and 15.6 μg mL−1, respectively. However, the pigment is toxic to the V79-4 Chinese hamster lung cells with low selectivity index. The purified compounds were determined as violacein and deoxyviolacein respectively using FT-IR, LC-MS and NMR. The results confirmed the feasibility of using liquid pineapple waste as a potential low cost growth medium for the large-scale cultivation of violet pigment using C. violaceum UTM5.

Optimization of culture conditions for flexirubin production by Chryseobacterium artocarpi CECT 8497 using response surface methodology

Flexirubins are the unique type of bacterial pigments produced by the bacteria from the genus Chryseobacterium, which are used in the treatment of chronic skin disease, eczema etc. and may serve as a chemotaxonomic marker. Chryseobacterium artocarpi CECT 8497, an yellowish-orange pigment producing strain was investigated for maximum production of pigment by optimizing medium composition employing response surface methodology (RSM). Culture conditions affecting pigment production were optimized statistically in shake flask experiments. Lactose, l-tryptophan and KH2PO4 were the most significant variables affecting pigment production. Box Behnken design (BBD) and RSM analysis were adopted to investigate the interactions between variables and determine the optimal values for maximum pigment production. Evaluation of the experimental results signified that the optimum conditions for maximum production of pigment (521.64 mg/L) in 50 L bioreactor were lactose 11.25 g/L, l-tryptophan 6 g/L and KH2PO4 650 ppm. Production under optimized conditions increased to 7.23 fold comparing to its production prior to optimization. Results of this study showed that statistical optimization of medium composition and their interaction effects enable short listing of the significant factors influencing maximum pigment production from Chryseobacterium artocarpi CECT 8497. In addition, this is the first report optimizing the process parameters for flexirubin type pigment production from Chryseobacterium artocarpi CECT 8497.

Development of formaldehyde detection method using onion juice as chromogenic agent

AbstractThis work reports an initial study on the use of natural compound, i.e. onion juice, as a novel environmental-friendly chromogenic agent to determine the concentration of formaldehyde. The method is based on the reaction of formaldehyde with yellow onion juice to produce a pink solution which absorb strongly at 514 nm. Factors affecting the extent of reaction between formaldehyde and onion juice such as temperature, pH of onion juice and reaction time were optimized using the response surface methodology approach via the Box–Behnken design. The experimental values obtained were close to the predicted values indicating good approximation of the model. The optimum response was obtained by heating the onion juice at 60°C, pH 4.9, reaction temperature of 103°C and reaction time of 17 min. A linear calibration curve was obtained using formaldehyde concentrations ranging from 0.5 to 15 mg L−1. This study demonstrates the potential application of onion juice as a simple, safe and environmental friendly t...

Isolation of Pigment-Producing Bacteria and Characterization of the Extracted Pigments

Bacteria produce pigments for various reasons and it plays an important role. Some bacteria such as cyanobacteria have phycobilin pigments to carry out photosynthesis. Other example for pigment-producing bacterial strains includes Serratia marcescens that produces prodigiosin, Streptomyces coelicolor (prodigiosin and actinorhodin), Chromobacterium violaceum (violacein) and Thialkalivibrio versutus (natronochrome and chloronatronochrome). These bacteria can be isolated/cultured/purified from various environmental sources such as water bodies, soil, on plant, in insects and in man or animal. Various growth mediums can be used to isolate different types of bacteria. However, due to the high cost of using synthetic medium, there is a need to develop new low cost process for the production of pigments as well as during the isolation procedure. The use of agro-industrial residues for example, would provide a profitable means of reducing substrate cost. Pigment produced by the bacteria can be isolated using solvent extraction. These pigments can be further purified and characterized for physical and chemical characteristics using various instrumental-based analytical techniques such as TLC, UV–vis Spectroscopy, FTIR, ESI–MS, NMR HPLC and Gel Permeation Chromatography.