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Head of Institute: Prof. Oren Tirosh

Administrative manager: Rakefet Kalev

Office Address:
Institute of Biochemistry, Food Science and Nutrition,
Robert H. Smith Faculty of Agriculture, Food and Environment,
The Hebrew University of Jerusalem, 
Herzl 229, Rehovot 7610001, ISRAEL

Tel: +972 - (0)8-9489385
Fax: +972 - (0)8-9363208
Email Address: rakefetk@savion.huji.ac.il

Publications

2021
Sivakala, K. K. ; Jose, P. A. ; Matan, O. ; Zohar-Perez, C. ; Nussinovitch, A. ; Jurkevitch, E. In vivo predation and modification of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) gut microbiome by the bacterial predator Bdellovibrio bacteriovorus. JOURNAL OF APPLIED MICROBIOLOGY 2021, 131, 2971-2980.Abstract
Aims The Mediterranean fruit fly (the medfly) causes major losses of agricultural fruits. Its microbiome is mainly composed of various Enterobacteriaceae that contribute to nutrient acquisition and are associated with the fly's development. Moreover, the performance of males produced by the sterile insect technique is improved by providing mass-reared insects with specific gut bacteria. Bdellovibrio and like organisms (BALOs) are obligate predators of Gram-negative bacteria that efficiently preys upon diverse Enterobacteriaceae, making it a potential disruptor of the fly's microbiome. We hypothesized that the fly's microbiome can be targeted to control the insect. Methods and Results Inoculation of B. bacteriovorus as free-swimming or encapsulated cells into gut extracts significantly reduced gut bacterial abundance, sustaining predator survival. Similar treatments applied to adult flies showed that the predators also survived in the gut environment. While addition of the predators did not affect total gut bacterial abundance and end-point fly mortality, a shift in the gut community structure, measured by high-throughput community sequencing was observed. Conclusions The bacterial predator of bacteria B. bacteriovorus can prey and survive in vivo in the medfly gut. Significance and Impact of the Study This study establishes the potential of BALOs to affect the microbiome of insect hosts.
Azaria, S. ; Nussinovitch, A. ; Nir, S. ; Mordechai, S. ; van Rijn, J. Removal of geosmin and 2-methylisoborneol from aquaculture water by novel, alginate-based carriers: Performance and metagenomic analysis. JOURNAL OF WATER PROCESS ENGINEERING 2021, 42.Abstract
Hydrophobic carriers were examined for geosmin and 2-methylisoborneol removal from water derived from an aquaculture system. A combination of adsorption and biodegradation was found to underlie the removal of the off-flavor compounds. Adsorption of these compounds by the carriers was unaffected by the presence of organic matter in the water to be treated. A model based on adsorption/desorption and first-order degradation kinetics provided an accurate prediction for experimentally determined 2-methylisoborneol removal rates. Steady removal of geosmin and 2-methylisoborneol as well as nitrate reduction were observed during long-term operation of the plug-flow reactors with water derived from an aquaculture facility. Metagenomic analysis of the microbial community on the carriers during long-term operation of the reactors revealed a predominance of denitrifying bacteria. It was found that geosmin and 2-methylisoborneol led to statistically significant changes in the abundances of 21 contigs that contained genes involved in terpene degradation. This study shows that at low ambient concentrations of geosmin and 2-methylisoborneol in nitrate and organic-rich water, such as found in aquaculture systems, their biodegradation can be accomplished by terpene-degrading denitrifiers that develop on hydrophobic carriers used for filtration of the contaminated water.
2020
Sason, G. ; Nussinovitch, A. Selective protective coating for damaged pomegranate arils. FOOD HYDROCOLLOIDS 2020, 103.Abstract
This is the first report on a method to create a selective protective coating (i.e., ``bandage'') to treat only the damaged part of pomegranate arils for shelf-life extension of these ready-to-eat chilled fruit. Implementation of a specific sequence of steps enabled the formation of an edible alginate-based protective gel layer only on the damaged surface of the aril. The consecutive steps included immersion of the arils in a solution containing a crosslinking agent, followed by immersion in an aqueous solution consisting of a polysaccharide, and then drying of the arils at ambient temperature. The selective coating method relies on the difference between the hydrophobic natural aril skin and the hydrophilic damaged parts of the aril. The formed coating was thin, transparent and sensorially undetectable, as demonstrated by triangle test. The formed coating helped preserve product quality and decreased fluid exudation during storage. The straightforward method for creating this selective coating may also be valid for any injured or cut plant tissue.
2019
Achmon, Y. ; Dowdy, F. R. ; Simmons, C. W. ; Zohar-Perez, C. ; Rabinovitz, Z. ; Nussinovitch, A. Degradation and bioavailability of dried alginate hydrocolloid capsules in simulated soil system. Journal of Applied Polymer Science 2019, 136. Publisher's VersionAbstract
Hydrocolloid capsules are common chemical carriers used in many types of applications in foods, biotechnology, and agriculture. Alginate microbeads and macrobeads are some of the more prevalent types of hydrocolloid capsules. Most studies to date have focused on alginate carrier applications but only a few have looked at their bioavailability after use. In this study, alginate carriers were subjected to simulated field conditions and their biodegradation in the soil was evaluated by respiration measurements, visualization, and volatile solids reduction. Using respiration rate, the degradation rate was calculated at 32 ± 3.1% (w/w) after 2 months. The visually estimated volume and volatile solids reduction gave degradation rates of 40 ± 8.6% (v/v) and 22.5 ± 2.5% (w/w), respectively. Moreover, water-loss calculations suggested that the carriers can serve as a stand-alone soil amendment for water retention. These findings emphasize the importance of studying hydrocolloid bioavailability in the soil and alginate carrier suitability for future applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48142. © 2019 Wiley Periodicals, Inc.
2018
Sason, G. ; Nussinovitch, A. Characterization of κ-carrageenan gels immersed in ethanol solutions. Food Hydrocolloids 2018, 79, 136-144. Publisher's VersionAbstract
Studying the influence of water–ethanol mixtures on the properties of κ-carrageenan gels could serve as a tool for the development of innovative semi-solid alcohol-containing food products. The changes in κ-carrageenan gels upon immersion in solutions with various concentrations of ethanol were characterized. κ-Carrageenan gels immersed in high ethanol concentrations lost considerable weight. At lower ethanol concentrations (50%–70%), weight loss was only moderate. However, at ethanol concentrations lower than 50%, the gels swelled and gained weight. The swelling/deswelling of κ-carrageenan gels immersed in ethanol solutions was dependent on their hydrocolloid concentration. All gels became stronger with increasing concentration of ethanol in the surrounding solvent. This change in gel strength following immersion did not stem solely from the changes in hydrocolloid concentration upon swelling/deswelling. Cryo-scanning electron microscopy of the gels revealed microstructures consistent with the observed mechanical properties. The residual potassium concentration in gels immersed in the various ethanol solutions was found to be lower than that required for gelation, constituting possible evidence of changed interactions upon immersion. © 2017 Elsevier Ltd
Shpaizer, A. ; Nussinovitch, A. ; Kanner, J. ; Tirosh, O. S-Nitroso-N-acetylcysteine Generates Less Carcinogenic N-Nitrosamines in Meat Products than Nitrite. J Agric Food Chem 2018, 66, 11459-11467.Abstract
Nitrite reacts with secondary amines to form N-nitrosamines (N-NA), which lead to gastrointestinal cancers. The aim of this study was to compare nitrite with S-nitrosocysteine (Cys-SNO) and S-nitroso-N-acetylcysteine (NAC-SNO) with respect to N-NA formation, which was evaluated by determining the conversion of N-methylaniline to N-nitrosomethylaniline. Under neutral and acidic pH conditions, N-NA formation rate was nitrite > Cys-SNO > NAC-SNO. In the presence of copper or nucleophiles, NAC-SNO generated much less N-NA than Cys-SNO. Nitrite and Cys-SNO produced higher amounts of N-NA in the presence of oxygen, whereas NAC-SNO was almost oxygen insensitive. In meat in the stomach medium, NAC-SNO produced much lower amounts of N-NA than other additives. In heated meat, Cys-SNO and NAC-SNO generated the nitrosyl-hemochrome pink pigment, better than nitrite. In conclusion, NAC-SNO was much less reactive for N-NA formation than nitrite and Cys-SNO in conditions relevant to meat production and stomach digestion.
2017
Belkin, S. ; Yagur-Kroll, S. ; Kabessa, Y. ; Korouma, V. ; Septon, T. ; Anati, Y. ; Zohar-Perez, C. ; Rabinovitz, Z. ; Nussinovitch, A. ; Agranat, A. J. Remote detection of buried landmines using a bacterial sensor. Nature Biotechnology 2017, 35, 308-310. Publisher's Version