Bioengineered

Various subspecies (ssp.) of Bacillus thuringiensis (Bt) are considered the best agents known so far to control insects, being highly specific and safe, easily mass produced and with long shelf life.1 The para-crystalline body that is produced during sporulation in the exosporium includes polypeptides named δ-endotoxins, each killing a specific set of insects. The different entomopathogenic toxins of various Bt ssp. can be manipulated genetically in an educated way to construct more efficient transgenic bacteria or plants that express combinations of toxin genes to control pests.2 Joint research projects in our respective laboratories during the last decade demonstrate what can be done by implementing certain ideas using molecular biology with Bt ssp. israelensis (Bti) as a model system. Here, we describe our progress achieved with Gram-negative bacterial species, including cyanobacteria, and some preliminary experiments to form transgenic plants, mainly to control mosquitoes (Dipte...

Bifidobacteria and lactobacilli are widely exploited as health-promoting bacteria in many functional foods. However, the molecular mechanisms as to how these bacteria positively impact on host health are far from completely understood. For this reason these microorganisms represent a growing area of interest with respect to their genomics, molecular biology and genetics. Recent genome sequencing of a large number of strains of bifidobacteria and lactobacilli has allowed access to the complete genetic makeup of representative members of these bacteria. Here, we will discuss how the analysis of genomic data has helped us to understand the mechanisms by which these bacteria adapt to the specific environment of the gastrointestinal tract, while also revealing genetic functions that mediate specific host-microbe interactions.

The aims of this study were to investigate the incidence of different resistance mechanisms to phage K in a bank of Irish Staph aureus hospital strains; and to develop a broad host-range phage cocktail with enhanced lytic activity against those strains which were previously phage resistant. A bank of 180 Staph aureus strains, which included all the sequence types currently in existence in Ireland, were tested for sensitivity to phage K. Twenty nine strains were identified, which did not permit plaque formation. The phage resistance systems in the 29 strain were investigated and it was found that restriction modification (r-m) was evident in 24, an adsorption inhibition mechanism was evident in three, while two were resistant by an unidentified mechanism. Seventeen modified derivatives of phage K were developed which could circumvent all the r-m systems. Nevertheless, six of the modified phage were considered superior in terms of their individual host ranges. These six were pooled as...

We recently evaluated the relationship between abiotic environmental stresses and lutein biosynthesis in the green microalga Dunaliella salina and suggested a rational design of stress-driven adaptive evolution experiments for carotenoids production in microalgae. Here, we summarize our recent findings regarding the biotechnological production of carotenoids from microalgae and outline emerging technology in this field. Carotenoid metabolic pathways are characterized in several representative algal species as they pave the way for biotechnology development. The adaptive evolution strategy is highlighted in connection with enhanced growth rate and carotenoid metabolism. In addition, available genetic modification tools are described, with emphasis on model species. A brief discussion on the role of lights as limiting factors in carotenoid production in microalgae is also included. Overall, our analysis suggests that light-driven metabolism and the photosynthetic efficiency of microal...

Thioredoxin (TRX) is small ubiquitous protein, which regulates cellular redox status and scavenges reactive oxygen species (ROS). TRX has been shown to exert suppressive effect on skin inflammation where oxidative stress is involved in its pathogenesis. We investigated the effect of TRX on UVB response. Ear swelling after UVB irradiation was significantly reduced in TRX-transgenic mouse compared with wild-type mouse. Furthermore, we have demonstrated that intraperitoneal administration of recombinant human thioredoxin (rhTRX) also reduced acute skin inflammatory reaction, such as skin erythema and edema. Histologically, inflammatory cells including neutrophils and lymphocytes were significantly reduced and average size of the caliber of blood vessels were also reduced in rhTRX-injected mice. The number of apoptotic keratinocytes, were significantly reduced in rhTRX-injected mice. Immunohistochemical intensity of 8-hydroxy-2'-deoxyguanosine was strikingly reduced in rhTRX-injecte...

Members of the genus Clostridium are of both medical and industrial importance. The molecular tools necessary to study and exploit their wide ranging physiological diversity through directed mutational analysis have until recently been lacking. The situation was transformed in the mid-2000s with the specific adaptation of intron re-targeting technology to the genus, through the development of the ClosTron. By making a handful of nucleotide changes to the group II intron encoding region, the intron can be directed to insert into almost any region within the genome. Through the use of a retrotransposition-activated marker (RAM), based on the ermB gene, successful insertion is selected on the basis of acquisition of resistance to erythromycin. The re-targeted region is designed using an online re-targeting algorithm (www.clostron.com), and then an order is placed with DNA2.0 for both the synthesis of the re-targeted region and its custom cloning into the ClosTron vector. Re-targeted Cl...

A total of 220 lactic acid bacteria isolates were screened for antifungal activity using Aspergillus fumigatus and Aspergillus niger as the target strains. Four Lactobacillus strains exhibited strong inhibitory activity on agar surfaces. All four were also identified as having strong inhibitory activity against the human pathogenic fungi Microsporum canis, Microsporum gypseum and Epidermophyton floccosum. One of the four lactobacilli, namely Lb. reuteri ee1p exhibited the most inhibition against dermatophytes. Cell-free culture ...

Various subspecies (ssp.) of Bacillus thuringiensis (Bt) are considered the best agents known so far to control insects, being highly specific and safe, easily mass produced and with long shelf life.1 The para-crystalline body that is produced during sporulation in the exosporium includes polypeptides named δ-endotoxins, each killing a specific set of insects. The different entomopathogenic toxins of various Bt ssp. can be manipulated genetically in an educated way to construct more efficient transgenic bacteria or plants that express combinations of toxin genes to control pests.2 Joint research projects in our respective laboratories during the last decade demonstrate what can be done by implementing certain ideas using molecular biology with Bt ssp. israelensis (Bti) as a model system. Here, we describe our progress achieved with Gram-negative bacterial species, including cyanobacteria, and some preliminary experiments to form transgenic plants, mainly to control mosquitoes (Diptera), but also a particular Lepidopteran and Coleopteran pest species. In addition, a system is described by which environment-damaging genes can be removed from the recombinants thus alleviating procedures for obtaining permits to release them in nature.