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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.128, #1)

Toward a new generation of therapeutics by Satya Prakash; Christopher Martoni (pp. 1-21).

Scientific evidence in the prevention and treatment of various disorders is accumulating regarding probiotics. The health benefits supported by adequate clinical data include increased resistance to infectious disease, decreased duration of diarrhea, management of inflammatory bowel disease, reduction of serum cholesterol, prevention of allergy, modulation of cytokine gene expression, and suppression of carcinogen production. Recent ventures in metabolic engineering and heterologous protein expression have enhanced the enzymatic and immunomodulatory effects of probiotics and, with time, may allow more active intervention among critical care patients. In addition, a number of approaches are currently being explored, including the physical and chemical protection of cells, to increase probiotic viability and its health benefits. Traditional immobilization of probiotics in gel matrices, most notably calcium alginate and κ-carrageenan, has frequently been employed, with noted improvements in viability during freezing and storage. Conflicting reports exist, however, on the protection offered by immobilization from harsh physiologic environments. An alternative approach, microencapsulation in “artificial cells,” builds on immobilization technologies by combining enhanced mechanical stability of the capsule membrane with improved mass transport, increased cell loading, and greater control of parameters. This review summarizes the current clinical status of probiotics, examines the promises and challenges of current immobilization technologies, and presents the concept of artificial cells for effective delivery of therapeutic bacterial cells.

Keywords: Artificial cells; biotherapy; probiotic; gastrointestinal tract; immobilization; microencapsulation; biopharmaceutics

Continuous biotreatment of copper-concentrated solutions by biosorption with Sargassum sp. by Francisca Pessôa de França; Flávia Pinto Padilha; Antonio Carlos Augusto da Costa (pp. 23-32).

Seaweed Sargassum sp. biomass proved to be useful for the recovery of ionic copper from highly concentrated solutions simulating effluents from semiconductor production. In the case of solutions containing copper in the form of chloride, sulfate, and nitrate salts, the best pH for the recovery of copper was 4.5. It was observed that copper biosorption from copper nitrate solutions was higher than the recovery of copper from copperchloride or copper sulfate solutions. The continuous system used was constituted of four column reactors filled with the biomass of Sargassum sp. and showed high operational stability. The biomass of Sargassum sp. in the reactors was gradually saturated from the bottom to the top of each column reactor. The biomass of Sargassum sp. in the first column saturated first, followed by a gradual saturation of the remaining columns owing to preconcentration performed by the biomass in the first column. The biomass of Sargassum in the bioreactors completely biosorbed the ionic copper contained in 63 L of copper sulfate solution, 72 L of copper chloride solution, and 72 L of copper nitrate solution, all the solutions containing copper at 500 mg/L. Effluents produced after biosorption presented copper concentrations <0.5 mg/L.

Keywords: Biosorption; Semiconductor effluents; Sargassum ; fixed-bed reactors

Contribution of cell-surface components to Cu²⁺ adsorption by Pseudomonas putida 5-x by L. Wang; F. T. Li; Q. Zhou (pp. 33-46).

The contribution of various cell-surface components to Cu²⁺ adsorption by a Gram-negative bacterium, Pseudomonas putida 5-x, that was isolated from local electroplating effluent with a high capability to accumulate heavy metal ions was studied. The cell superficial layer had a negative effect on Cu²⁺ adsorption of the bacterial cells. Cu²⁺ adsorption capacity of the separated cell envelopes was fivefold more than that of the intact cells, owing to the liberation of more and more binding sites during the separation process. Some main components in the cell envelope, such as the peptidoglycan (PEG) layer, outer membrane, and inner membrane, provide the capability for Cu²⁺ adsorption. The content of the components in the cell envelope is in the order inner membrane > outer membrane > PEG layer, and their Cu²⁺ adsorption capacity was in the order PEG layer > outer membrane > inner membrane. The total contribution of the separated PEG layer material to Cu²⁺ adsorption by the cell envelope was no more than 15%, and the outer membrane and inner membrane contributed about 30–35% and 25–30%, respectively. The relatively high phospholipid content in the outer membrane may be the major reason for the higher adsorption capacity of the outer membrane to Cu²⁺ and, hence, such a high Cu²⁺ adsorption capacity of P. putida 5-x cell envelope.

Keywords: Biosorption; cell envelope; inner membrane; outer membrane; peptidoglycan layer

The future of coproducts from corn processing by Kent D. Rausch; Ronald L. Belyea (pp. 47-86).

Increased demand for ethanol as a fuel additive has resulted in dramatic growth in ethanol production. Ethanol is produced from corn by either wet milling or dry-grind processing. In wet milling, the corn kernel is fractionated into different components, resulting in several coproducts. Wet-milling plants are capital intensive because of equipment requirements; they produce large volumes of ethanol and are corporate owned. In dry-grind processing, the corn kernel is not fractionated and only one coproduct, distillers’ dried grains with solubles (DDGS), is generated. Dry-grind plants require less equipment and capital than wet mills. They generate smaller volumes of ethanol, are producer owned, and add direct benefits to rural economies. Most of the increase in ethanol production during the past decade is attributed to growth in the dry-grind industry. The marketing of coproducts provides income to offset processing costs. For dry-grind plants, this is especially important, because only one coproduct is available. Several issues could affect DDGS marketing. The increasing volume of DDGS accompanying ethanol production could reduce market value; high phosphorous content could limit the use of DDGS, because of animal waste disposal issues. Water removal is a costly processing step and affects the economics of ethanol processing. Technologies to remove germ and fiber from DDGS could produce a new coproduct suitable for feeding to nonruminants; this would expand the markets for DDGS. Reducing phosphorus in DDGS would sustain markets for conventional DDGS. The development of more efficient methods of water removal would increase the efficiency of ethanol processing and reduce the costs of processing. New technologies could contribute to greater stability of dry-grind plants.

Keywords: Distillers’ dried grains with solubles; dry-grind process; wet milling; dry milling; ruminants; pericarp; endosperm

Effect of copper and manganese ions on activities of laccase and peroxidases in three Pleurotus species grown on agricultural wastes by Mirjana Stajić; Limor Persky; Yitzhak Hadar; Dana Friesem; Sonja Duletić-Laušević; Solomon P. Wasser; Eviatar Nevo (pp. 87-96).

Copper (Cu²⁺) and manganese (Mn²⁺) ions influenced laccase (Lac) and peroxidase production in Pleurotus eryngii, Pleurotus ostreatus, and Pleurotus pulmonarius. In P. eryngii, the optimum Cu²⁺ concentration for Lac production was 1 mM and for peroxidases 10mM, and Mn²⁺ concentration of 5mM led to peaks of Lac and peroxidase activity. In P. ostreatus HAI 493, the highest level of Lac activity was at Cu²⁺ concentrations of 1 and 10 mM and Mn²⁺ concentration of 1mM, respectively. The absence of Cu²⁺ and Mn²⁺ caused the highest levels of peroxidase production. In P. ostreatus HAI 494, the highest level of Lac activity was at a Cu²⁺ concentration of 5 mM and at Mn²⁺ concentration of 1 mM, respectively. High levels of peroxidase activity were found in the medium without and with 1mM Cu²⁺, and at 1 and 5 mM Mn²⁺, respectively. In P. pulmonarius, the highest Lac activity was found in the presence of 5 mM Cu²⁺ and 5 mM Mn²⁺, respectively. The absence of Cu²⁺ and Mn²⁺ as well as their presence at a concentration of 1 mM led to the peaks of peroxidase activities.

Keywords: Pleurotus eryngii ; Pleurotus ostreatus ; Pleurotus pulmonarius ; laccase; peroxidases; copper; manganese

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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.128, #1)

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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.128, #1)