Current Biotechnology - Volume 1, Issue 4, 2012

Listeria monocytogenes is a foodborne pathogen that can cause listeriosis, an invasive infection in humans with a fatality rate of 20-30%. Listeriosis is a global public health concern, with an increasing incidence in Europe, especially among elderly persons. Cases of listeriosis are, for the most part, associated with ‘ready-to-eat’ foods, including deli meats, smoked fish, unpasteurised milk, soft cheeses, fresh-cut fruit and vegetables. Research on various biotechnological approaches for the control of L. monocytogenes in foods has attracted much attention in recent years, as consumers demand more natural ‘clean-label’ foods. Protective cultures and/or their microbial products (e.g. bacteriocins) have been investigated as potential controls of L. monocytogenes in various food systems and processes. More recently, bacteriophage technology has seen a revival of interest and a number of phage preparations, e.g. Listex P100 and Listshield, have been approved for use in the control of L. monocytogenes on ready-to-eat foods by the United States Food and Drug Administration and in the European Union. Their application offers a highly attractive option in Food Safety Management Systems, to aid in the management of this pathogen; however, debate continues as to whether such preparations should be used at all and whether they should be considered as processing aids or food additives. This review will assess the potential of using biotechnological approaches to control L. monocytogenes in ready-to-eat foods. While the use of such ‘natural’ controls in food should not replace proper controls and hygiene practices, there is undoubtedly a role for their strategic development and intelligent use in combating L. monocytogenes.

High-resolution episcopic microscopy (HREM) is a recently developed technique, which permits the rapid generation of digital volume data from biological material. Typical HREM data have a resolution of approximately 2×2×2 µm3 and are comprised of a stack of inherently aligned images, which resemble the quality of digital images of histological sections. This study aims at recapitulating technical details of the HREM method, providing information on recent modifications and briefly discussing the current and future fields of application.

This review presents the advantages of biogenic synthesis of metallic sulfide nanoparticles, compared to chemical synthesis processes. The impact of biogenically synthesized sulfide nanoparticles is discussed from ecological point of view. This review also discusses the morphological characteristics and mechanistic aspects of sulfide nanoparticles synthesized by the biogenic process. By revising recent publications, it is evident that it would be a great advantage to use a nonpathogenic biological system to produce sulfide nanoparticles for commercialization purposes. This new area of nanobiotechnological processes is more attractive compared to traditional physical and chemical methods of nanoparticles synthesis, since microbial biosynthesis of nanoparticles does not involve hazardous chemicals and it is considered to be a cost-effective and eco-friendly approach.

Biopharmaceuticals and their generic counterparts referred to as biosimilars represent the fastest growing segment of the pharmaceutical market. In contrast to conventional small molecule therapeutics, myriad additional considerations need to be addressed during the regulatory approval process. Key issues surrounding these protein based agents stem from their biosynthesis from living cells, and include post translational modification, propensity to aggregate, and variation in three dimensional structure. Though existing regulatory pathways in the USA have successfully managed the approval of a number of blockbuster biopharmaceuticals, they did not specifically address generic versions of these agents. Given the importance of this class, the US FDA recently followed suit with other global regulatory agencies and issued guidelines for their introduction and approval. As the market for biosimilars is set to grow rapidly and the technology for their production is continually evolving, herein we review the state of the art in 2012 for their production, and likely areas for growth and innovation in the sector.

In all likelihood, the management of solid and liquid wastes will become one of the most important environmental problems of the 21st Century. A major priority is thus to develop new strategies for the reduction, reuse, recycling, and valorization of this waste in order to reduce its negative impact on the environment. European Union countries are currently required to treat urban wastewater in all the cities, and consequently a significant increase in the generation of sewage sludge has been produced. However, the toxic substances in this kind of sludge have created a new environmental problem. Composting is an aerobic process, during which organic waste is biologically degraded by microorganisms to humus-like material. The microbiota and its physico-chemical changes during the composting process have received much attention during the last years. In this context, different culture dependent and culture independent techniques have been used to describe the constant and shifting biodiversity present in the composting process. In this paper several aspects related to sewage sludge are analyzed: origin, composition and microbial structure. Moreover, the use of sludge to produce biofuels is also reviewed as a novel biotechnology.

Rhodanese is an ubiquitous enzyme active in all living organisms from bacteria to man. It is multifunctional enzyme but plays central role in cyanide detoxification. This enzyme is also widely distributed in plants. It functions through double displacement (ping pong) mechanism. The activity of rhodanese in a particular tissue reflect the ability of that tissue to detoxify cyanide. The level of rhodanese in different tissues of animals is correlated with the level of exposure to cyanide. Mitochondrial bovine rhodanese is the best characterized rhodanese which is 293 amino acids long consisting of inactive N-terminal and catalytic C-terminal domain. It comprises of single polypeptide chain of 32,900 Da folded into two domains of about equal size. Active site of rhodanese has essential sulfhydryl and aromatic groups in close proximity. In addition to this, competitive inhibition of rhodanese by aromatic ions suggests the presence of tryptophanyl residue at the active center. Sequence analysis of rhodanese-like proteins highlights their heterogeneity to form rhodanese superfamily presenting variably arranged rhodanese domains as single or tandem domains, or combined with other protein domains. Many methods for rhodanese assay have been reported but the most common one is colorimetric estimation of thiocyanate formed from the reaction of cyanide with thiosulphate catalyzed by rhodanese.

This paper reports molecular characterization and cellulase activity profiling of thermotolerant Aspergillus strains isolated from composting soils/ degrading paper waste. A. terreus strain AN1 was found to be a good source of cellulases that showed efficient biodeinking of mixed office waste paper. The culture was optimized for production of endoglucanase, β-glucosidase, FPase and xylanase on rice straw containing solidified culture medium employing Box Behnken design of experiments to study the influence of pH, moisture content and corn steep liquor on enzyme production. A. terreus under optimized conditions produced 162, 955, 6.6, 3027 (units/g of substrate) of endoglucanase, β- glucosidase, Fpase, and xylanase corresponding to 5.7, 5.4, 2.5 and 1.1 folds higher enzyme activities when compared to those obtained under unoptimized conditions. Isoelectric focusing (IEF) profiling of the crude extract showed that A. terreus produced three endoglucanase isoforms corresponding to pI values of 3.0, 3.9 and 5.9 that were functionally distinct and showed differences in their substrate specificity. Furthermore, four isoforms of β-glucosidase and eleven multiple forms of xylanase distributed over a wide range of pI were also detected.

The aim of this paper is to recommend a kinetic model related to UV disinfection of the secondary treated wastewater. Results revealed that application of the model of Chick-Watson in its original form is not representative of the kinetics of disinfection. Modification considering the speed change during the disinfection has not significantly improved the results. According to the parameter ε representing, the difference between the experimental and the calculated values using the model of Chick-Watson in its original form appeared feeble for all bacterial strains studied. Thus, we see therefore that the model of Collins-Selleck was most effective in considering the change in the kinetics of inactivation during the disinfection. Also, we found for the most strains of Pseudomonas aeruginosa tested that the model of Hom showed a great agreement to describe the kinetics of UV disinfection. Modeling the reactivation at the range of temperature of 7.5-50°C was presented. First-order saturation model does not fit the obtained data of photoreactivation; a modification of the model is recommended which coincides with the classical logistic equation.