V. cholerae may be distributed between continents by waterfowl (Figure 1, Halpern et al., 2008). (In collaboration with Ido Izhaki and Gadi Kazir, Univ. of Haifa, Israel).
Novel insights into Haemagglutinin Protease (HAP) gene regulation in Vibrio cholerae
Quorum-sensing (QS) signals of V. cholerae and HAP gene regulation should be understood with regard to their role in chironomids rather than humans (Figure 2, Halpern, 2010). Further research is needed to understand the role of cholera toxin in the environmental existence of V. cholerae. Currently, we are focusing on studying the role of QS signals in the production of HAP by V. cholerae in environmental mixed species consortium on chironomid egg masses (in collaboration with Brian K. Hammer, Georgia Institute of Technology, USA; funded by the BSF).
Endogenous bacteria in chironomids
Using Koch's postulates we were able to demonstrate that the endogenous bacteria in chironomids enable the insect to survive in polluted environments (Senderovich and Halpern 2013). We aim at exploring the role of intrinsic physiological factors of chironomids vs. its endogenous microbiota in maintaining homeostasis under stress conditions. (In collaboration with Bimalendu B. Nath, India; funded by Joint UGC – ISF grant)
2. The ecology and virulence of Legionella spp. populations in freshwater We use an integrated molecular approach based on high-resolution diagnostics of environmental and clinical isolates to determine the abundance, activity and virulence of Legionella populations' in-situ. (In collaboration with Manfred Höfle, National Research Center for Biotechnology, Braunschweig, Germany and Dina Bahader Bitar, El Quds University, Jerusalem; funded by the DFG).
3. Bacterial community composition of floral nectar and their role in plant fitness We showed for the first time, that bacterial communities in nectar are abundant and diverse (Fridman et al., 2012, EMR). Using NGS we are studying bacterial communities of floral nectar and their pollinators (e.g. bees, Aizenberg Gershtein et al., 2013) and visitors, along a spatial climatic gradient across the globe (Figure 3) (In collaboration with Ido Izhaki, Univ. of Haifa, Israel; funded by the ISF).
Figure 3. Asphodelus aestivus. (A) Flower and a consumer fly (Eempidoidea). (B) Flower collection. (C). Nectar collection. (D) Bagged inflorescences
4. Taxonomy In my research, novel bacterial species are being isolated from
different environments that were not explored before (e.g. chironomid egg
masses, raw milk, floral nectar).
The following list represents novel bacterial species that I, together with
my students have isolated, named and characterized: