Biology subjects

Shlosberg, Y.

Publications and source records attributed to Shlosberg, Y..

5 recordsLinked to original sources

bioRxiv2022

Trichodesmium Erythraeum produces a higher photocurrent than other cyanobacterial species in bio-photo electrochemical cells.

In recent years, the increase in world energy consumption, and the worries from potential future disasters that may derive from climate change have inspired the motivation to develop renewable energy technologies. One of the promising methods is the utilization of whole bacterial cells to produce photocurrent in a bio-photo electrochemical cell (BPEC). The photocurrent derives from the photosynthesis pathway, while the redox couple NADP+/NADPH perform cyclic electron mediation between photosystem I inside the cells, and the anode. Over the years, various cyanobacterial species were utilized in diverse BPECs setups, while the photocurrent was enhanced by the addition of natural electron mediators such as NAD+, NADP+, Cytochrome C, Vitamin B1, and the artificial mediator potassium ferricyanide. The cyanobacterium Trichodesmium Erythraeum (Te) is a marine species that consist of high content of Phycocyanin and Phycoerythrin pigments that play a major role in photosynthesis enhancement. In this work, we produce for the first-time photocurrent from Te. We apply 2D-fluorescence measurements to detect its NADPH secretion and show that its photocurrent production is enhanced as a function of increasing electrolyte salinity. Finally, we produce photocurrent from additional cyanobacterial species: Synechocystis sp. PCC6803, Synechococcus elongatus PCC 7942, Acaryochloris marina MBIC 11017, and Spirulina, using their cultivation medium as electrolytes in the BPEC. We show that TE produces a photocurrent intensity that is significantly greater than all other species with and without the addition of exogenous electron mediators. The utilization of TE may pave the way toward the establishment of marine clean energy technologies.

microbiology↗

bioRxiv2021

Identification of bacteria by poly-aromatic hydrocarbons biosensors

Human health is consistently threatened by different species of pathogenic bacteria. To fight the spread of diseases, it is important to develop rapid methods for bacterial identification. Over the years, different kinds of biosensors were developed for this cause. Another environmental risk are poly-aromatic hydrocarbons (PAHs) that may be emitted from industrial facilities and pollute environmental water and soil. One of the methods for their purification is conducted by the addition of bacteria that can degrade the PAHs, while the bacteria itself can be filtrated at the end of the process. Although many studies reported monitoring of the PAHs degradation by fluorescence, not much attention was dedicated to studying the influence of the PAHs on the intrinsic fluorescence of the degrading bacteria. In this work, we apply synchronous fluorescence (SF) measurements to study the ability of the 5 PAHs: 9-Antracene carboxylic acid (9ACA), Pyrene, Perylene, Pentacene, and Chrysene to interact with bacteria and change its fluorescence spectra. We show that upon incubation of each PAH with the bacterium E.coli only the 2 PAHs 9ACA and Perylene cause an intensity decrease in the emission at {lambda} = 300 - 375 nm, which derives from the emission of Tyrosine and Tryptophane (TT). Also, we show that upon incubation of 9ACA and Perylene with 5 different pathogenic bacteria, the intensity increase or decrease in the TT emission is unique to each bacterial species. Based on this observation, we suggest that the PAHs 9ACA and Perylene can be utilized as biosensors for bacterial identification.

microbiology↗

bioRxiv2021

A new replication medium enables a rapid identification of {varphi}x-174 virus by synchronous fluorescence of Tryptophan.

Development of rapid methods for detection of virus particles based on their intrinsic fluorescence is challenging. Pure viruses may be detected in filtered solutions, based on the strong fluorescence of the amino acid Tryptophan (Trp) in their proteins. Nevertheless, Trp also exists in high quantities in the hosts and host cultivation media. In this work, we show that a separation of the bacteriophage{varphi} x-174 from its E. coli host (grown on the standard cultivation medium "Nutrient Agar") by simple extraction and filtration is not sufficient for its detection based on the intrinsic fluorescence since ~70 % of the Trp fluorescence is derived from impurities. We formulate a new cultivation medium with very low Trp concentration. We apply synchronous fluorescence measurements to show that no Trp fluorescence is detected in the extract solution upon incubation of this medium substrate with ammonium acetate extraction buffer. Finally, we detect{varphi} x-174 based on the spectral fingerprint of its intrinsic Trp content by synchronous fluorescence measurements. The concept of coupling intrinsic fluorescence-based methods to impurities reduction in the source, may pave the way towards future development of simple, cheap, and rapid methods for detection of viral pathogens.

microbiology↗

bioRxiv2021

Harvesting electrical current from intact plant leaves

Here, we show that it is possible to harvest photocurrent directly from unprocessed plant tissues from terrestrial or aquatic environments in bio-photoelectrochemical cells (BPECs) and use the current to produce molecular H2. The source of electrons is shown to originate from the Photosystem II water-oxidation reaction and utilizes exported mediating molecules, especially NADPH. The photocurrent production is dependent on the concentration of the photosynthetic complexes, as an increase in total chlorophyll and oxygen evolution rates lead to increased photocurrent rates. The permeability of the outer leaf surface is another important factor in photocurrent harvesting. Different tissues produce photocurrent densities in the range of [~] 1 - 10 mA / cm2 which is significantly higher than microorganism-based BPECs. The relatively high photocurrent and the simplicity of the plants BPEC may pave the way toward the development of future applicative photosynthetic based energy technologies.

bioengineering↗

bioRxiv2021

Bioelectricity generation from live marine photosynthetic macroalgae

Conversion of solar energy into electrical current by photosynthetic organisms has the potential to produce clean energy. Previously reported bio-photoelectrochemical cells (BPECs) have utilized unicellular photosynthetic microorganisms. In this study, we describe for the first time BPECs that utilize intact live marine macroalgae (seaweeds) in natural seawater or saline buffer or natural seawater. The BPECs produce electrical currents from of >50mA/cm2, from both light-dependent (photosynthesis) and light independent processes. These values are significantly greater than the current densities that have been reported for single-cell microorganisms. The photocurrent is inhibited by the Photosystem II inhibitor DCMU, indicating that the source of light-driven electrons is from water oxidation via NADPH and other reduced molecules. We show here that intact seaweed cultures can be used in a large-scale BPEC containing seawater that produces bias-free photocurrent. The ability to produce bioelectricity from intact seaweeds may pave the way to future development of a low-cost energy technology using BPECs.

bioengineering↗