Yoram Gerchman | University of Haifa (original) (raw)

Papers by Yoram Gerchman

Carbohydrate Polymers, Jul 1, 2019

production from recycled paper mill sludge using ozonation pretreatment followed by recyclable ma... more production from recycled paper mill sludge using ozonation pretreatment followed by recyclable maleic acid hydrolysis,

protocols.io, Mar 11, 2021

Cellulose nanocrystals (CNCs) have gained increased interest worldwide for their unique propertie... more Cellulose nanocrystals (CNCs) have gained increased interest worldwide for their unique properties. CNC production by acid hydrolysis of cellulose-rich biomass is well established, but its' quantification is still complicated. In this study, a rapid method for the determination of CNC concentration using Calcofluor White (CW) fluorescence dye is demonstrated for both purified and homemade CNCs recovered from Whatman filter paper. The method is robust, selective for crystalline cellulose, suitable for routine measurement in CNC production and that the pH must be basic for staining using CW.

Waste and Biomass Valorization, Jun 15, 2020

Rising socioeconomic level and increasing popularity of e-commerce have dramatically increased th... more Rising socioeconomic level and increasing popularity of e-commerce have dramatically increased the use of cardboard packaging materials, and consequent related recycling and wastes. Large amounts of sludge (up to 40% of input mass) is formed through the recycling process, with sludge solids that are very rich in cellulose fibers (~ 75% w/w). To date this sludge is mostly disposed in landfills, resulting in added economic and environmental costs to the recycling process. Short ozonation pretreatment of RPS resulted in enzymatic release of ~ 34% of the cellulosic fraction of the sludge as sugar, and fermentation of these sugars by yeasts resulted in production of ~ 15 g/L ethanol. The solid remnants, were used as a bio-sorbent, efficiently removing dyes from textile wastewater. Recycled paper sludge waste was thus a good source for both energy and water-treatment applications, increasing sustainability and circular economy in the paper and cardboard recycling industry. Keywords Cardboard and paper recycling • Ethanol • Circular economy • Textile dye removal • Water treatment Statement of Novelty Paper and cardboard use and consequently recycling are increasing rapidly, resulting in large amounts of recycled paper sludge (RPS), a waste without an environmental solution. Here we show that short ozonation treated-RPS is an effective feedstock for the production of bioethanol and as well as a low-cost bio-sorbent for the textile wastewatertreatment sector. This process can reduce RPS dumping costs, while making recycling more circular.

Biology Methods and Protocols

Bacterial adhesion to tissue is the starting point for many pathogenic processes and beneficial i... more Bacterial adhesion to tissue is the starting point for many pathogenic processes and beneficial interactions. The dynamics and speed of adhesion (minutes) make high-resolution temporal kinetic data important, but this capability is absent from the current toolset. We present a high-throughput method with a second-to-minute kinetic resolution, testing the adhesion of Pseudomonas aeruginosa PAO1 wild-type, flagella-, pili-, and quorum-sensing mutants to human embryonic kidney (HEK293) cells. Adhesion rates were in good correlation with HEK293 confluence, and the ways in which various bacterial mutations modified adhesion patterns are in agreement with the published literature. This simple assay can facilitate drug screening and treatment development as well as provide a better understanding of the interactions of pathogenic and probiotic bacteria with tissues, allowing the design of interventions and prevention treatments.

The larvicidal potential of olive mill waste water (OMWW) extract against mosquito larvae was eva... more The larvicidal potential of olive mill waste water (OMWW) extract against mosquito larvae was evaluated. We exposed second instar Culex laticinctus (Edwards) and Aedes albopictus (Skuse) larvae to increasing OMWW concentrations. In addition, we tested the effects of long term exposure to a low OMWW concentration on larval development. The two mosquito species responded differently to OMWW extracts. Larval Cx. laticinctus showed higher vulnerability to increasing OMWW concentrations in comparison to Ae. albopictus. By contrast, Cx. laticinctus exposed to a low OMWW concentration until pupation did not exhibit survival differences, but rather sex-specific development responses. These trends were not observed in Ae. albopictus whose survival was significantly reduced following long exposer to OMWW extraction. These results showed that OMWW, which is known as agricultural byproduct waste, may be reused as a biopesticide.

Nature Communications

Many plants produce fleshy fruits, attracting fruit-eating animals that disperse the seeds in the... more Many plants produce fleshy fruits, attracting fruit-eating animals that disperse the seeds in their droppings. Such seed dispersal results in a conflict between the plant and the animal, as digestion of seeds can be highly beneficial to the animal but reduces plant fitness. The plant Ochradenus baccatus uses the myrosinase-glucosinolates system to protect its seeds. We show that hydrolysis of the O. baccatus fruit glucosinolates by the myrosinase enzyme inhibited digestive enzymes and hampered digestion in naïve individuals of the bird Pycnonotus xanthopygos. However, digestion in birds regularly feeding on O. baccatus fruits was unaffected. We find that Pantoea bacteria, dominating the gut of these experienced birds as well as the fruits, thrive on glucosinolates hydrolysis products in culture. Augmentation of Pantoea protects both naïve birds and plant seedlings from the effects of glucosinolates hydrolysis products. Our findings demonstrate a tripartite interaction, where the pla...

The mere presence of predators causes prey organisms to enact predation-avoidance strategies. Thi... more The mere presence of predators causes prey organisms to enact predation-avoidance strategies. This presence is often reveled through predator-released kairomones. It was previously suggested that in many cases, the predator’s microbiota composition plays an important role in the release of these kairomones, however this mechanism is still poorly understood. Ovipositing mosquito females of several species are repelled by kairomones released from larvivorous fish. In this study we looked into the effects of the microbiota originated byGambusia affinis(Baird and Girard) on the ovipisition behavior of gravid mosquito females in an outdoor mesocosm experiment. We show that interference with the fish microbiota significantly reduces its repellant effect. We further show that the bacteriumPantoea pleurotiisolated from the skin of the fish repels oviposition ofCulex laticinctus(Edwards) andCuliseta longiareolataMacquart mosquitoes similarly to the effect of live fish. These results highligh...

Lignocellulose biomass for bioethanol production is one way for solving the environmental problem... more Lignocellulose biomass for bioethanol production is one way for solving the environmental problems of the agricultural residues, besides the production of renewable fuel for the transportation sector, however, the bioethanol production is still inefficient due to a large amount of remnant waste left. So the anaerobic digestion (AD) of this remnant could be an effective solution to increase the overall energy output from the biomass. This study aims to explore the overall energy output and sustainability from the olive mill solid waste (OMSW) through bioethanol production and the utilization of the remnant residues for biogas production by exploiting the organic waste-energy nexus as a circular economy model. The used remnant for biogas production was obtained following bioethanol production from OMSW subjected to microwave-assisted maleic acid, formic acid, or distilled water which were used for the pretreatment, and was followed with enzymatic hydrolysis and fermentation process. T...

Microbiology Spectrum, 2021

Pseudomonas aeruginosa was shown previously to attack amoebae and other predators by adhering to ... more Pseudomonas aeruginosa was shown previously to attack amoebae and other predators by adhering to them and injecting them with virulent substances. In this work, we show that an active, coordinated group behavior is enacted by the bacteria to utilize these molecular components, responding to both predator and bacterial population density.

Liquid transportation fuel replacements are of global importance, first among them is ethanol tha... more Liquid transportation fuel replacements are of global importance, first among them is ethanol that can be used as drop-in fuel additive, resulting in lower emission. To-date ethanol is produced mainly from especially grown crops such as sugar cane, corn and sorghum, but interest in ethanol production from lignocellulose waste (second generation) is growing rapidly with some factories already working. This pursue is of especial importance for many Mediterranean countries where there is not enough land and water to grow specialized energy crops.

STAR Protocols, 2021

This protocol describes the culturing of the nematode Caenorhabditis elegans (C. elegans) in a st... more This protocol describes the culturing of the nematode Caenorhabditis elegans (C. elegans) in a sterol-defined experimental system and the subsequent quantitative analysis of C. elegans sterols through gas chromatography-mass spectrometry. Although studied primarily in mammals, sterols are essential biomolecules for most eukaryotes. C. elegans cannot synthesize sterols and thus relies on the uptake of dietary sterols. Therefore, C. elegans is a powerful system to study metabolism in sterol-defined conditions that are described in our protocol.

Mobbing, a group attack of prey on predator, is a strategy enacted by many animal species. Here w... more Mobbing, a group attack of prey on predator, is a strategy enacted by many animal species. Here we report bacterial mobbing carried out by the bacteriumPseudomonas aeruginosatowardsAcanthamoeba castellanii, a common bacterivore. This behavior consists of bacterial taxis towards the amoebae, adhesion en masse to amoebae cells, and eventual killing of the amoebae. Mobbing behavior transpires in second’s timescale and responds to predator population density. A mutant defective in the production of a specific quorum sensing signal displays reduced adhesion to amoeba cells. This deficiency ameliorated by external addition of the missing signal molecule. The same quorum sensing mutant also expresses long term deficiency in its ability to cause amoeba death and shows higher susceptibility to predation, highlighting the importance of group coordination to mobbing and predation avoidance. These findings portray bacterial mobbing as a regulated and dynamic group behavior.

American Journal of Physiology-Renal Physiology, 2018

Atherosclerosis and cardiovascular complications are prevalent among patients undergoing chronic ... more Atherosclerosis and cardiovascular complications are prevalent among patients undergoing chronic hemodialysis (HD). In this population, peripheral polymorphonuclear leukocytes (PMNLs) are primed, releasing proinflammatory mediators such as elastase. Elastase is normally inhibited by a specific inhibitor, avoiding undesirable degradation of cellular and extracellular components. This study tested the hypothesis that in states of noninfectious inflammation, elastase is released by PMNLs and acts in an uncontrolled manner to inflict vascular damage. Blood was collected from patients undergoing HD and healthy controls (HC). PMNL intracellular and surface expressions of elastase were determined by quantitative real-time PCR, Western blotting, and flow cytometry. The elastase activity was evaluated using a fluorescent substrate. The levels of serum α1-antitrypsin (α1-AT), the natural elastase inhibitor, were determined by Western blot. Free active elastase was elevated in HD sera, whereas...

Bioresource Technology, 2017

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Basic and Applied Ecology, 2016

Flower-color polymorphisms are well-documented, but how color morph frequencies change over time ... more Flower-color polymorphisms are well-documented, but how color morph frequencies change over time is usually unknown. We studied this question using the milk thistle, Silybum marianum (Asteraceae). Purple flowers commonly occur in Israel, but an infrequent white morph has been recorded since the 1920s, at first from the south of the country. Over seven years, we recorded the frequencies of the two color morphs in 17 populations along a 156 km south-north transect with a steep rainfall gradient. The proportion of white inflorescences per population consistently decreased from south to north, and their mean proportion decreased from 24% to 12% over the study period. Four of the populations went extinct, but two were recolonized, and two additional populations decreased to <10 individuals. To test whether the color morphs differ in fitness, we collected the ripe inflorescences shortly before seed dispersal from all dimorphic populations in two flowering seasons. The numbers of developed, partially eaten and aborted seeds did not differ between color morphs. There was also no geographical trend in the numbers of developed, aborted and partially eaten seeds in either morph. Insect pollinators did not discriminate against the white morph. Thus, the decline of white-flowering plants over the course of the study cannot be attributed to negative interactions with pollinators or with seed herbivores, two potentially important agents affecting seed output. Our findings are compatible with genetic drift, mediated through population bottlenecks and founder effects, but this interpretation was not directly tested. Our study contributes to the ongoing discussion of the role of natural selection vs. random events in maintaining flower-color polymorphisms. Zusammenfassung Farbpolymorphismus bei Blüten ist gut dokumentiert, aber wie die Häufigkeiten der Blütenmorphen sich mit der Zeit verändern, ist normalerweise unbekannt. Wir untersuchten diese Frage an der Mariendistel Silybum marianum (Asteraceae). Purpurfarbene Blüten treten in Israel weithin auf, aber eine seltene weiße Morphe wird seit den 1920iger Jahren nachgewiesen, zuerst im Südteil des Landes. Sieben Jahre lang registrierten wir die Häufigkeiten der beiden Farbmorphen in 17 Populationen entlang eines Nord-Süd-Transekts (156 km), das einen steilen Niederschlagsgradienten bildet. Der Anteil der weißen Blüten je Population nahm von Süden nach Norden ab, und der mittlere Anteil fiel im Laufe der Untersuchung von 24% auf 12%. Vier Populationen starben aus, aber zwei wurden wiederbegründet und zwei weitere Populationen gingen auf weniger als zehn Individuen zurück. Um mögliche Unterschiede in der Fitness der beiden Morphen festzustellen, sammelten wir in zwei Jahren reife Blütenstände kurz vor der Ausbreitung der Samen in allen dimorphen Populationen. Es gab keine Unterschiede zwischen den Farbmorphen hinsichtlich der Zahl der voll entwickelten, befressenen und verkümmerten Samen. Es gab auch keinen geographischen Trend. Bestäuber-Insekten mieden die weiße Morphe nicht. Damit konnte die Abnahme der weißen Morphe im Untersuchungszeitraum nicht durch negative Interaktionen mit Bestäubern oder Samenfressern erklärt werden.

PloS one, 2014

In contrast to most other plant tissues, fleshy fruits are meant to be eaten in order to facilita... more In contrast to most other plant tissues, fleshy fruits are meant to be eaten in order to facilitate seed dispersal. Although fleshy fruits attract consumers, they may also contain toxic secondary metabolites. However, studies that link the effect of fruit toxins with seed dispersal and predation are scarce. Glucosinolates (GLSs) are a family of bitter-tasting compounds. The fleshy fruit pulp of Ochradenus baccatus was previously found to harbor high concentrations of GLSs, whereas the myrosinase enzyme, which breaks down GLSs to produce foul tasting chemicals, was found only in the seeds. Here we show the differential behavioral and physiological responses of three rodent species to high dose (80%) Ochradenus' fruits diets. Acomys russatus, a predator of Ochradenus' seeds, was the least sensitive to the taste of the fruit and the only rodent to exhibit taste-related physiological adaptations to deal with the fruits' toxins. In contrast, Acomys cahirinus, an Ochradenus se...

Journal of Experimental Biology, 2013

Summary Fleshy, ripe fruits attract seed dispersers but also seed predators. Although many fruit ... more Summary Fleshy, ripe fruits attract seed dispersers but also seed predators. Although many fruit consumers (legitimate seed dispersers as well as seed predators) are clearly exposed to plant secondary compounds (PSCs), their impact on the consumers’ physiology and foraging behaviour has been largely overlooked. Here, we document the divergent behavioural and physiological responses of three congeneric rodent species in the Middle East, seed dispersers versus seed predators, to fruit consumption. The fruit pulp of the desert plant Ochradenus baccatus contains high concentrations of glucosinolates (GLSs). These GLSs are hydrolyzed into active toxic compounds upon contact with the myrosinase enzyme released from seeds crushed during fruit consumption. Acomys russatus and A. cahirinus share a desert habitat. Acomys russatus acts as an O. baccatus seed predator, and A. cahirinus circumvents the activation of the GLSs by orally expelling vital seeds. We found that between the three specie...

Oikos, 2009

The vertical inflorescences of the Mediterranean annual Salvia viridis carry many small, colorful... more The vertical inflorescences of the Mediterranean annual Salvia viridis carry many small, colorful flowers, and are frequently terminated by a conspicuous tuft of colorful leaves ('flag') that attracts insect visitors. Insects may use the flags as indicators of food rewards in the inflorescences below, as long-distance cues for locating and choosing flowering patches, or both. Clipping of all flags from patches of inflorescences in the field reduced the number of arriving insects, but not the total number of inflorescences and flowers visited by them. The number of flowers visited per inflorescence increased with inflorescence size, and inflorescence and flower visits rates significantly increased with patch size. Six percent of the plants in the study population did not develop any flag during blooming, yet suffered no reduction in seed set as compared to flag-bearing neighboring individuals. Removal of flags from all inflorescences in a patch reduced seed set in comparison with untreated controls, while flag clipping from ten randomly selected inflorescences in a patch did not decrease seed production. These results suggest that flags signal long-distance information to potential pollinators (possibly indicating patch location or size), while flower-related cues may indicate inflorescence quality. Plants that do not develop flags probably benefit from the flag signals displayed by their neighbors, without bearing the costs of signal production. Greenhouse-grown S. viridis plants allocated a low proportion of their biomass to flags. Plants grown under water stress did not reduce biomass allocation to flags as compared to irrigated controls. Water loss rates of picked flags were lower than those of picked leaves. These findings suggest that the expenses of flag production and maintenance are modest, reducing the selective advantage of individuals that do not carry flags. We discuss additional potential evolutionary mechanisms that may select for flag production.

Evolutionary Ecology, 2013

Food and water resources are limiting factors for animals in desert ecosystems. Fleshy fruits are... more Food and water resources are limiting factors for animals in desert ecosystems. Fleshy fruits are a rare water source in deserts and when available they tend to attract a wide variety of organisms. Here we show that two congeneric rodent species, Acomys cahirinus and A. russatus, employ different fruit eating strategies that result in either dispersal or predation of the small seeds of the desert plant Ochradenus baccatus. The nocturnal A. cahirinus leaves intact seeds when consuming O. baccatus fruits and thus, acts mainly as a seed disperser; whereas the diurnal A. russatus consumes the whole fruit and digests the seeds and thus, acts mainly as a seed predator. Acomys russatus is subjected to the toxic products of the glucosinolates-myrosinase system found in O. baccatus fruits. Acomys cahirinus avoids the toxic compounds by consuming the pulp only, which contains glucosinolates but not the seeds that contain the enzyme that activates them. We suggest that the behavioral responses exhibited by A. russatus are the result of physiological adaptations to whole fruit consumption that are absent in A. cahirinus. Our results shed new light on the ecological divergence of the two congeneric species.