Mehmet Ali Mazmanci

Chromium(VI) bioremoval by pseudomonas bacteria: role of microbial exudates for natural attenuation and biotreatment of Cr(VI) contamination

Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).

Thermophilic bacteria in cool temperate soils: are they metabolically active or continually added by global atmospheric transport?

Thermophilic soil geobacilli isolated from cool temperate geographical zone environments have been shown to be metabolically inactive under aerobic conditions at ambient temperatures (−5 to 25°C). It is now confirmed that a similar situation exists for their anaerobic denitrification activity. It is necessary therefore to determine the mechanisms that sustain the observed significant viable populations in these soils. Population analysis of thermophiles in rainwater and air samples has shown different species compositions which support the view that long distance global transport and deposition in rainwater is a possible source of replenishment of the soil thermophile populations. Survival experiments using a representative Geobacillus isolate have indicated that while cells lose viability rapidly at most temperatures, populations can increase only when the temperature allows growth to take place at a rate which exceeds death rate. Long term (9-month) experiments at 4°C show population increases which can be accounted for by very slow growth rates complemented by negligible death rates. These results are interpreted in the context of current hypotheses on the biogeography patterns of bacteria.

Evaluation of cytotoxic and mutagenic effects of Coriolus versicolor and Funalia trogii extracts on mammalian cells.

This study examined the in vitro cytotoxic activities of standardized aqueous bioactive extracts prepared from Coriolus versicolor and Funalia trogiiATCC 200800 on HeLa and fibroblast cell lines using a MTT (3-[4,5-dimetiltiazol-2-]-2–5-difeniltetrazolium bromide) cytotoxicity assay. F. trogii and C. versicolor extracts were cytotoxic to both cell lines. At 10 μL treatment level, F. trogii and C. versicolor extracts inhibited proliferation of HeLa cancer cells by 71.5% and 45%, respectively, compared with controls. Toxicity was lower toward normal fibroblasts. In the latter case, treatment at 10 μL level with F. trogii and C. versicolor extracts reduced cell proliferation by 51.3% and 38.7%, respectively. In separate experiments, the mitotic index (MI) obtained with 3 μL treatment level of unheated extracts of the two fungi was comparable to the MI value obtained by treatment with 4 μg/mL MMC (anticancer agent mitomycin-C). A significant induction of sister chromatid exchange (SCE) was observed in normal cultured lymphocytes treated with MMC (4 μg/mL). MMC treatment reduced replication index compared with treatment with unheated F. trogii extract and negative controls (p < 0.001). In contrast to MMC, F. trogii extracts did not affect the proliferation of human lymphocytes compared with controls (p > 0.05). Laccase and peroxidase enzyme activities in F. trogii extract were implicated in their inhibitory effect on cancer cells. F. trogii extract was concluded to have antitumor activity.

A study of anti-cancer effects of Funalia trogii in vitro and in vivo

Extracts of natural products have been used for many years for health benefits. We report on an in vitro and in vivo study into the anti-tumour efficacy of an aqueous extract of the mycelial form of basidiomycete, Funalia trogii. A variety of biological assays were used to show that a 4h exposure of HT29, LNCaP, PC3, MCF-7 and MDA-MB-231 tumour cells to extract (0.5-5.0 mg/ml) resulted in significant cytotoxicity. In a clonogenic assay, IC50 values were found to range from 0.4-0.72 mg/ml; exposing fibroblast cells to the extract resulted in no cell kill. The extract resulted in significant cell kill in proliferating endothelial cells but had no toxicity to quiescent cells, this is useful in targeting tumour tissue since endothelial cells in tumours proliferate more rapidly that those found in other parts of the body. When tumours grown in immune compromised mice were injected intratumourally with extract (5 mg/ml twice a week for two weeks), a 9 day tumour growth delay was observed. The results indicate that the mycelial extract of F. trogii has a promising anti-tumour property.

Ethanol production from Washingtonia robusta fruits by using commercial yeast

In order to reduce the cost and time of in vitro raised plants of Trichosanthes dioica Roxb., a minimal medium has been formulated by substituting costly growth regulators from the medium with a cost effective constituent, the coconut milk. A semisolid Murashige and Skoogs’s medium supplemented exclusively with 15% coconut milk showed the highest percentage of plantlet regeneration (99%) in the explants. When nodal, shoot-tip and immature leaf explants were cultured on this medium, rhizogenesis was observed in about 5 to 6 days of inoculation, followed by shoot formation in about 8 to 10 days. The fully developed plantlets, 10 to 12 cm in length with professed roots were obtained in about 20 days of inoculation in a single step without adding/changing growth regulators. After transplantation in the potted soil, these plantlets showed similar growth patterns as compared to the plants obtained from a conventional three-four step method of tissue culture experiments. Keywords: Coconut milk, tissue culture, Trichosanthes dioica Roxb

Decolorization of Azo Dyes by Immobilized Fungi

Decolorization has recently become an area of major scientific interest as indicated by the large quantity of related research reports. During the past two decades, several color removal techniques have been reported, few of which have been accepted by some industries. There is a need to find alternative technologies that are effective in decolorizing dyes from large volume of effluents. Alternative technologies such as decolorization with fungi are still in progress. Especially, ligninolytic fungi and their extracellular oxidative enzymes have been reported to be responsible for the decolorization of dyes. Immobilization applications seem to be more encouraging than those with free cells, because it allows using microbial cells and support materials repeatedly. This chapter reviews the widely used immobilization materials and the application of fungal immobilization to dye decolorization process.