Influence of ammonium sulphate feeding time on fed-batch Arthrospira (Spirulina) platensis cultivation and biomass composition with and without pH control.

Previous work demonstrated that a mixture of NH(4)Cl and KNO(3) as nitrogen source was beneficial to fed-batch Arthrospira (Spirulina) platensis cultivation, in terms of either lower costs or higher cell concentration. On the basis of those results, this study focused on the use of a cheaper nitrogen source mixture, namely (NH(4))(2)SO(4) plus NaNO(3), varying the ammonium feeding time (T=7-15 days), either controlling the pH by CO(2) addition or not. A. platensis was cultivated in mini-tanks at 30°C, 156 μmol photons m(-2) s(-1), and starting cell concentration of 400 mg L(-1), on a modified Schlösser medium. T=13 days under pH control were selected as optimum conditions, ensuring the best results in terms of biomass production (maximum cell concentration of 2911 mg L(-1), cell productivity of 179 mg L(-1)d(-1) and specific growth rate of 0.77 d(-1)) and satisfactory protein and lipid contents (around 30% each)

New trends in biotechnological processes to increase the environmental protection

A sustainable development can be achieved by deepening into more effective and eco-friendly products and technologies. From this point of view, the development of biotechnological processes to increase the environmental protection could be included in the best available techniques reference documents, the so-called BREFs, that cover, as far as practicable, the industrial activities to achieve an integrated pollution prevention and control. Members of the European Union are required to take these documents into account when determining the best available techniques, generally or in specific cases under the European Commission Directives. In order to include biotechnological processes into the BREFs, for example, for obtaining food and pharmaceutical additives, these products have to be cost competitive with those synthesized by chemical ways. Biotechnological processes are advantageous compared to the chemical ones since various metabolites can be obtained simultaneously in the same process, and these metabolites are more eco-friendly than their chemical counterparts. Additionally, this feature also matches the increasing demand of consumers for natural products, which has intensified the biotechnological production of natural additives. This special issue reports advances in the use of biotechnological processes for the treatment of contaminated soil or water as well as the revalorization of agroindustrial residues through the production of valuable metabolites such as biosurfactants or antioxidants, with applications in biomedicine, food industry, pharmaceutical industry, or environmental bioremediation

Bacteriocin production by Lactobacillus plantarum ST16Pa in supplemented whey powder formulations

Whey, the main by-product of the dairy industry, is frequently disposed of in the environment without any treatment due to the high cost of this process. Alternatively, whey can be used as a medium to culture lactic acid bacteria and produce value-added products such as bacteriocins. In this work, we attempted to improve bacteriocin production by Lactobacillus plantarum ST16Pa in a whey powder formulation supplemented with additional sources of carbon, nitrogen, and vitamin B12 at different levels and varying the agitation intensity according to a Plackett-Burman experimental design. Only the addition of tryptone positively influenced the production of this bacteriocin. The results allowed us to identify a supplemented whey formulation, comprising 150 g/L of whey total solids plus 10 g/L of tryptone and soybean extract, whose fermentation by Lb. plantarum ST16Pa in shake flasks under agitation at 150 rpm led to a cell-free supernatant with an antimicrobial activity against Listeria innocua 6a CLIST 2865 (inhibition zone of 13.23 mm) close to that previously obtained in de Man, Rogosa and Sharpe medium by other authors. These results are significant considering that the same strain cultured in cheese whey did not previously display any antimicrobial activity

Effects of light intensity and dilution rate on the semicontinuous cultivation of Arthrospira (Spirulina) platensis. A kinetic Monod-type approach.

Abstract Semicontinuous cultures were carried out at different dilution rates (D) and light intensities (I) to determine the maximum productivity of Arthrospira platensis cultivated in helicoidal photobioreactor up to the achievement of pseudo-steady-state conditions. At I = 108 μmol photons m−2 s−1, the semicontinuous regime ensured the highest values of maximum cell concentration (Xm = 5772 ± 113 mg L−1) and productivity (PXS = 1319 ± 25 mg L−1 d−1) at the lowest (D = 0.1 day−1) and the highest (D = 0.3 day−1) dilution rates, respectively. A kinetic model derived from that of Monod was proposed to determine the relationship between the product of light intensity to dilution rate (ID) and the cell productivity, which were shown to exert a combined influence on this parameter. This result put into evidence that pseudo-steady-state conditions could be modified according to circumstances, conveniently varying one or other of the two independent variables

Texture profile and sensory acceptance of a symbiotic diet aerated mousse containing Lactobacillus acidophilus LA-5, inulin, and fructooligosaccharide

This work dealt with the texture profile and sensory acceptance of a symbiotic diet aerated mousse containing Lactobacillus acidophilus LA-5, inulin, and fructooligosaccharid

Doxycycline degradation by the oxidative Fenton process

Doxycycline is a broad-spectrum tetracycline occurring in domestic, industrial and rural effluents, whose main drawback is the increasing emergence of resistant bacteria. This antibiotic could be degraded by the so-called Fenton process, consisting in the oxidation of organic pollutants by oxygen peroxide (H2O2) in the presence of Fe2+. Experiments were performed according to an experimental Rotational Central Composite Design to investigate the influence of temperature (0 \u2013 40.0\ub0C), H2O2 concentration (100 \u2013 900 mg/L) and Fe2+ concentration (5 \u2013 120 mg/L) on residual doxycycline and total organic carbon concentrations. Whereas the final residual doxycycline concentration ranged from 0 to 55.8 mg/L, the oxidation process proved unable to reduce the total organic carbon by more than 30%. The best operating conditions were concentrations of H2O2 and Fe2+ of 611 and 25 mg/L, respectively, and temperature of 35.0\ub0C, but the analysis of variance revealed that only the first variable exerted a statistically-significant effect on the residual doxycycline concentration. These results suggest possible application of this process in the treatment of doxycycline-containing effluents and may be used as starting basis to treat tetracycline-contaminated effluents

Production of bacteriocin-like inhibitory substances (BLIS) by Bifidobacterium lactis using whey as a substrate

The objective of this work was to evaluate the production of bacteriocin-like inhibitory substances (BLIS) by Bifidobacterium animalis subsp. lactis in whey supplemented with yeast extract, inulin, Tween 80 or L-cysteine. Cell growth, acidification, glucose and lactose consumption as well as BLIS production were measured during fermentations carried out in shake flasks. The best additive for both cell growth and BLIS production was shown to be yeast extract, which gave the highest concentrations of biomass (9.9 log CFU/mL) and BLIS (800 AU/mL). In a bench-scale fermenter, B. lactis growth and BLIS production were between 6 and 25 % higher than in flasks depending on the conditions assayed

Selection of Co-Substrate and Aeration Conditions for Vanillin Production by Escherichia coli JM109/pBB1

Yeast extract, Luria-Bertani medium and tryptone were tested as co-substrates for vanillin production from ferulic acid by resting cells of Escherichia coli JM109/pBB1. Yeast extract proved to be the best component for sustaining such a bioconversion, which is not self-sustained from the bioenergetic point of view. Tests were also performed under variable aeration conditions by simultaneously varying the ratio of medium to vessel volume and the agitation speed. The results of these tests suggest that, under excess aeration, a non-specific oxidase activity was very likely responsible for the oxidation of a significant portion of vanillin to vanillic acid, thus reducing the vanillin yield

Simultaneous Effects of Total Solids Content, Milk Base, Heat Treatment Temperature and Sample Temperature on the Rheological Properties of Plain Stirred Yogurt

Metodom odzivnih površina utvrđen je utjecaj ukupne čvrste tvari, mliječne baze, temperature obrade i temperature uzorka na indeks konzistencije, indeks tečenja i prividnu viskoznost tekućeg jogurta. Statističkom obradom razvijeni su matematički modeli. Svi su uzorci pokazali osobine smičnog naprezanja. Povećanje udjela ukupne čvrste tvari (9,3-22,7 %) i temperature obrade mliječne baze (81,6-98,4 %) dovelo je do smanjenja indeksa konzistencije i povećanja indeksa tečenja. Prividna viskoznost izravno je ovisila o udjelu ukupne čvrste tvari u jogurtu. Reološka svojstva jogurta uvelike su ovisila o udjelu ukupne čvrste tvari u mlijeku.Response surface methodology was used to establish a relationship between total solids content, milk base, heat treatment temperature, and sample temperature, and consistency index, flow behaviour index, and apparent viscosity of plain stirred yogurts. Statistical treatments resulted in developments of mathematical models. All samples presented shear thinning fluid behaviour. The increase of the content of total solids (9.3–22.7 %) and milk base heat treatment temperature (81.6–98.4 °C) resulted in a significant increase in consistency index and a decrease in flow behaviour index. Increase in the sample temperature (1.6–18.4 °C) caused a decrease in consistency index and increase in flow behaviour index. Apparent viscosity was directly related to the content of total solids. Rheological properties of yogurt were highly dependent on the content of total solids in milk

Biosurfactants as Multifunctional Remediation Agents of Environmental Pollutants Generated by the Petroleum Industry

Fuel and oil spills during the exploration, refining, and distribution of oil and petrochemicals are primarily responsible for the accumulation of organic pollutants in the environment. The reduction in contamination caused by hydrocarbons, heavy metals, oily effluents, and particulate matter generated by industrial activities and the efficient recovery of oil at great depths in an environmentally friendly way pose a challenge, as recovery and cleaning processes require the direct application of surface-active agents, detergents, degreasers, or solvents, often generating other environmental problems due to the toxicity and accumulation of these substances. Thus, the application of natural surface-active agents is an attractive solution. Due to their amphipathic structures, microbial surfactants solubilize oil through the formation of small aggregates (micelles) that disperse in water, with numerous applications in the petroleum industry. Biosurfactants have proven their usefulness in solubilizing oil trapped in rock, which is a prerequisite for enhanced oil recovery (EOR). Biosurfactants are also important biotechnological agents in anti-corrosion processes, preventing incrustations and the formation of biofilms on metallic surfaces, and are used in formulations of emulsifiers/demulsifiers, facilitate the transport of heavy oil through pipelines, and have other innovative applications in the oil industry. The use of natural surfactants can reduce the generation of pollutants from the use of synthetic detergents or chemical solvents without sacrificing economic gains for the oil industry. Therefore, investments in biotechnological processes are essential. It is predicted that, in the not-too-distant future, natural surfactants will become viable from an economic standpoint and dominate the world market. The application of biosurfactants in these settings would lead to industrial growth and environmental sustainability. The main goal of this paper is to provide an overview of diverse applications of biosurfactants on environmental remediation, petroleum biotechnology, and the oil industry through a scientific literature review