Effects Of Environmental Stress Research Articles

LssR plays a positive regulatory role in acid and nisin tolerance response of Lactococcus lactis

In Lactococcus lactis, different regulation mechanisms can be activated to overcome the effects of adverse environmental stresses. Here, a TetR family regulator LssR was demonstrated as a positive regulator in the activation of the mechanisms involved in acid and nisin tolerance of L. lactis. The deletion of lssR led to the reduction of tolerance of L. lactis NZ9000 to nisin and acid stress, and the survival rates of NZ9000 under nisin and acid stress were roughly 20-fold, 10-fold (pH 3.0, hydrochloric acid), and 8.9-fold (pH 4.0, lactic acid) of the lssR mutant NZΔlssR, respectively. Moreover, the lssR mutant NZΔlssR also displayed a lower intracellular pH stability and a changed cell surface morphology. Subsequently, transcriptome analysis revealed that genes related to the arginine deiminase pathway, the surface polysaccharides biosynthesis, carbohydrates transport and metabolism, multidrug resistance, cell repair proteins and chaperones were predominantly down transcribed in NZΔlssR. The transcript levels of the arginine deiminase pathway and the surface polysaccharides biosynthesis-associated genes under acid and nisin stresses were compared between the wild type NZ9000 and NZΔlssR using real-time fluorescence quantitative PCR. It revealed that the arginine deiminase pathway genes (arcD1C1C2T) and the surface polysaccharides biosynthesis genes (cgT, gmhB, gmhA, hddA, tagH and tarS) were proposed to be the main regulatory mechanisms of LssR in response to the acid and nisin stresses. Overall, the important role of LssR in the acid and nisin stresses response was demonstrated and the putative regulation mechanism of LssR was revealed.

Within-subject variation of technical performance in elite Brazilian professional soccer players: the environmental stress, match location, and opposition’s ranking influences

ABSTRACT Recent research identified that the behaviour of players and teams varies depending on the match context affecting the players’ technical performance. Due to the high context variability of a soccer game, understanding the characteristics of technical performance in soccer can enable coaches to make better decisions. The present study aimed to evaluate the effects of environmental stress, match location, and opposition’s ranking on technical performance variation of elite soccer players from strong and weak teams from the Brasileirão Serie A (Brazilian First Division National Championship). Fourteen match actions were chosen as dependent variables in the analysis. Values of each action of each player per match were established. We compared the means of these values from the Top 4 and Bottom 4 teams across different match contexts (environment heat stress, match location, and opposition’s ranking). We calculated all comparisons using linear mixed models. The results showed better technical performance under low or medium environmental heat stress at home and against weak opposition (p < 0.05). Therefore, match context affects elite Brazilian soccer players’ technical performance from the first division championship.

Research on aging-related degradation of control rod drive system based on dynamic object-oriented Bayesian network and hidden Markov model

The control rod drive system is critical to the reactor's reliable operation. The performance of its control system and mechanical system will gradually deteriorate because of operational and environmental stresses, thus increasing the reactor's operational risk. Currently there are few researches on the aging-related degradation of the entire control rod drive system. Because it is difficult to quantify the effect of various environmental stresses and establish an accurate physical model when multiple mechanisms superimposed in the degradation process. Therefore, this paper investigates the aging-related degradation of a control rod drive system by integrating Dynamic Object-Oriented Bayesian Network and Hidden Markov Model. Uncertainties in the degradation of the control system and mechanical system are addressed by using fuzzy theory and the Hidden Markov Model respectively. A system which consists of eight control rod drive mechanisms divided into two groups is used to demonstrate the method. The aging-related degradation of the control rod drive system is analyzed by the Bayesian inference algorithm based on the accelerated life test data, and the impact of different operating schemes on the system performance is also investigated. Meanwhile, the components or units that have major impact on the system's performance are identified at different operational phases. Finally, several essential safety measures are suggested to mitigate the risk caused by the system degradation.

Moderate heat stress prevented the observed biomass and yield stimulation caused by elevated CO2 in two well-watered wheat cultivars

Key messageHeat stress (HS) under well-watered conditions was not detrimental to leaf photosynthesis or yield but modified the elevated CO2 response of photosynthesis and yield in two contrasting wheat cultivars.Climate change is increasing the frequency of extreme events such as heat waves, adversely affecting crop productivity. While positive impacts of elevated carbon dioxide (eCO2) on crop productivity are evident, the interactive effects of eCO2 and environmental stresses are still unclear. To investigate the interactive effects of elevated CO2 and heat stress (HS), we grew two contrasting wheat cultivars, early-maturing Scout and high-tillering Yitpi, under non-limiting water and nutrients at ambient (aCO2, 450 ppm) or elevated (eCO2, 650 ppm) CO2 and 22 °C in the glasshouse. Plants were exposed to two 3-day HS cycles at the vegetative (38.1 °C) and/or flowering (33.5 °C) stage. At aCO2, both wheat cultivars showed similar responses of photosynthesis and mesophyll conductance to temperature and produced similar grain yield. Relative to aCO2, eCO2 enhanced photosynthesis rate and reduced stomatal conductance and maximal carboxylation rate (Vcmax). During HS, high temperature stimulated photosynthesis at eCO2 in both cultivars, while eCO2 stimulated photosynthesis in Scout. Electron transport rate (Jmax) was unaffected by any treatment. eCO2 equally enhanced biomass and grain yield of both cultivars in control, but not HS, plants. HS reduced biomass and yield of Scout at eCO2. Yitpi, the cultivar with higher grain nitrogen, underwent a trade-off between grain yield and nitrogen. In conclusion, eCO2 improved photosynthesis of control and HS wheat, and improved biomass and grain yield of control plants only. Under well-watered conditions, HS was not detrimental to photosynthesis or growth but precluded a yield response to eCO2.

Effect of nutritional and environmental conditions on biofilm formation of avian pathogenic Escherichia coli.

To study the effects of environmental stress and nutrient conditions on biofilm formation of avian pathogenic Escherichia coli (APEC). The APEC strain DE17 was used to study biofilm formation under various conditions of environmental stress (including different temperatures, pH, metal ions, and antibiotics) and nutrient conditions (Luria-Bertani [LB] and M9 media, with the addition of different carbohydrates, if necessary). The DE17 biofilm formation ability was strongest at 25°C in LB medium. Compared to incubation at 37°C, three biofilm-related genes (csgD, dgcC, and pfs) were significantly upregulated and two genes (flhC and flhD) were downregulated at 25°C, which resulted in decreased motility. However, biofilm formation was strongest in M9 medium supplemented with glucose at 37°C, and the number of live bacteria was the highest as determined by confocal laser scanning microscopy. The bacteria in the biofilm were surrounded by a thick extracellular matrix, and honeycomb-like or rough surfaces were observed by scanning electron microscopy. Moreover, biofilm formation of the DE17 strain was remarkably inhibited under acidic conditions, whereas neutral and alkaline conditions were more suitable for biofilm formation. Biofilm formation was also inhibited at specific concentrations of cations (Na+ , K+ , Ca2+ , and Mg2+ ) and antibiotics (ampicillin, chloramphenicol, kanamycin, and spectinomycin). The real-time quantitative reverse transcription PCR showed that the transcription levels of biofilm-related genes change under different environmental conditions. Nutritional and environmental factors played an important role in DE17 biofilm development. The transcription levels of biofilm-related genes changed under different environmental and nutrient conditions. The findings suggest that nutritional and environmental factors play an important role in APEC biofilm development. Depending on the different conditions involved in this study, it can serve as a guide to treating biofilm-related infections and to eliminating biofilms from the environment.

Negative schizotypal traits predict the reduction of reward motivation in effort-reward imbalance.

The schizotypy construct is useful for studying the effects of environmental stress on development of subclinical negative symptoms. The relationship among self-report motivation, effort-reward imbalance (ERI), and schizotypal features has seldom been studied. We aimed to examine the possible moderation effect of schizotypal traits on ERI and reward motivation. Eight-hundred-and-forty-three college students were recruited online to complete a set of self-reported measures capturing schizotypal traits, effort-reward imbalance and reward motivation, namely the Schizotypal Personality Questionnaire (SPQ), the Effort-Reward Imbalance-School Version Questionnaire (C-ERI-S) and the Motivation and Pleasure Scale-Self Report (MAP-SR). We conducted multiple linear regression to construct models to investigate the moderating effects of schizotypal traits on the relationship between ERI and reward motivation. Stressful ERI situation predicted the reduction of reward motivation. Negative schizotypal traits showed a significant negative moderating effect on the relationship between ERI and reward motivation, while positive and disorganized schizotypal traits had significant positive moderating effects. Schizotypal traits subtypes differently moderate the relationship between ERI and reward motivation. Only negative schizotypal traits and stressful ERI situation together have negative impact on reward motivation.

Holm oak decline is determined by shifts in fine root phenotypic plasticity in response to belowground stress.

Summary Climate change and pathogen outbreaks are the two major causes of decline in Mediterranean holm oak trees (Quercus ilex L. subsp. ballota (Desf.) Samp.). Crown‐level changes in response to these stressful conditions have been widely documented but the responses of the root systems remain unexplored. The effects of environmental stress over roots and its potential role during the declining process need to be evaluated.We aimed to study how key morphological and architectural root parameters and nonstructural carbohydrates of roots are affected along a holm oak health gradient (i.e. within healthy, susceptible and declining trees).Holm oaks with different health statuses had different soil resource‐uptake strategies. While healthy and susceptible trees showed a conservative resource‐uptake strategy independently of soil nutrient availability, declining trees optimized soil resource acquisition by increasing the phenotypic plasticity of their fine root system.This increase in fine root phenotypic plasticity in declining holm oaks represents an energy‐consuming strategy promoted to cope with the stress and at the expense of foliage maintenance. Our study describes a potential feedback loop resulting from strong unprecedented belowground stress that ultimately may lead to poor adaptation and tree death in the Spanish dehesa.

Effects of Alkali Stress on the Growth and Menaquinone-7 Metabolism of Bacillus subtilis natto.

Menaquinone-7 (MK-7) is an important vitamin K2, synthesized from the menaquinone parent ring and seven isoprene side chains. Presently, the synthesis of MK-7 stimulated by environmental stress primarily focuses on oxygen stress, while the effect of alkali stress is rarely studied. Therefore, this study researched the effects of alkali stress on the fermentation performance and gene expression of Bacillus subtilis natto. The organism’s growth characteristics, biomass, sporogenesis, MK-7 biosynthesis, and gene expression were analyzed. After a pH 8.5 stress adaptation treatment for 0.5 h and subsequent fermentation at pH 8.5, which promoted the growth of the strain and inhibited the spore formation rate. In addition, biomass was significantly increased (P < 0.05). The conversion rate of glycerol to MK-7 was 1.68 times higher than that of the control group, and the yield of MK-7 increased to 2.10 times. Transcriptomic analysis showed that the MK-7 high-yielding strain had enhanced carbon source utilization, increased glycerol and pyruvate metabolism, enhanced the Embden-Meyerhof pathway (EMP), tricarboxylic acid (TCA) circulation flux, and terpenoid biosynthesis pathway, and promoted the accumulation of acetyl-CoA, the side-chain precursor of isoprene. At the same time, the up-regulation of transketolase increased the metabolic flux of the pentose phosphate (HMP) pathway, which was conducive to the accumulation of D-erythrose 4-phosphate, the precursor of the menadione parent ring. This study’s results contribute to a better understanding of the effects of environmental stress on MK-7 fermentation by Bacillus subtilis natto and the molecular regulatory mechanism of MK-7 biosynthesis.

Pre-Growth Environmental Stresses Affect Foodborne Pathogens Response to Subsequent Chemical Treatments.

Foodborne pathogens such as Salmonella, E. coli O157:H7, and Listeria monocytogenes are known to survive under different environmental stresses with an effect on their physiological properties. The purpose of this study was to determine the effect of different environmental stresses on the foodborne pathogens response to subsequent chemical treatments. Three types of pathogens Salmonella, E. coli O157:H7, and Listeria monocytogenes were subjected to different environmental stresses: (i) Desiccation (ii) high salt (iii) low pH, and (iv) temperatures (14, 23, and 37 °C) during their growth. The cells harvested at their early stationary growth phase were subsequently subjected to chlorine (100 or 200 ppm), peracetic acid (40 or 80 ppm), and 0.5% lactic acid treatments. The results showed that pre-growth stress conditions have significant effect on the reduction of tested pathogens depending upon the type of chemical treatment. Salmonella showed the highest sensitivity against all these treatments when compared to E. coli O157:H7 and Listeria monocytogenes. In addition, Listeria monocytogenes showed the highest percentage of sub-lethally injured cells. These findings highlighted the need to consider pre-growth conditions as an important factor for the validation of physical and chemical intervention treatments.

Evaluating the Effects of Environmental Stress on Leaf Chlorophyll Content as an Index for Tree Health

Chlorophyll content plays a vital role in photosynthetic and biomass production in all plants. Because chlorophyll shows a greater sensitivity to changes in external conditions than do other pigments in foliage, such as carotenoids for example, chlorophyll content in leaves may be a good surrogate for environmental stress, changes in temperature and humidity, as well as in pollutant levels both in the air and in the soil. This paper reviews the potential for chlorophyll content in the leaves of trees as a measure of tree health, resistance to stress and environmental conditions. Because chlorophyll content is shown to decrease dramatically with increases in pollution, non-destructive methods for evaluating the amount of chlorophyll in leaves and its changes over a time may be a sufficient indicator for environmental pollutant levels in the air, in the soil and in the water used by a tree.

Titanium and Zinc Based Nanomaterials in Agriculture: A Promising Approach to Deal with (A)biotic Stresses?

Abiotic stresses, such as those induced by climatic factors or contaminants, and biotic stresses prompted by phytopathogens and pests inflict tremendous losses in agriculture and are major threats to worldwide food security. In addition, climate changes will exacerbate these factors as well as their negative impact on crops. Drought, salinity, heavy metals, pesticides, and drugs are major environmental problems that need deep attention, and effective and sustainable strategies to mitigate their effects on the environment need to be developed. Besides, sustainable solutions for agrocontrol must be developed as alternatives to conventional agrochemicals. In this sense, nanotechnology offers promising solutions to mitigate environmental stress effects on plants, increasing plant tolerance to the stressor, for the remediation of environmental contaminants, and to protect plants against pathogens. In this review, nano-sized TiO2 (nTiO2) and ZnO (nZnO) are scrutinized, and their potential to ameliorate drought, salinity, and xenobiotics effects in plants are emphasized, in addition to their antimicrobial potential for plant disease management. Understanding the level of stress alleviation in plants by these nanomaterials (NM) and relating them with the application conditions/methods is imperative to define the most sustainable and effective approaches to be adopted. Although broad-spectrum reviews exist, this article provides focused information on nTiO2 and nZnO for improving our understanding of the ameliorative potential that these NM show, addressing the gaps in the literature.

Individual and Interactive Effects of Multiple Abiotic Stress Treatments on Early-Season Growth and Development of Two Brassica Species

Potential global climate change-related impacts on crop production have emerged as a major research priority and societal concern during the past decade. Future changes, natural and human-induced, projected in the climate have implications for regional and global crop production. The simultaneous occurrence of several abiotic stresses instead of stress conditions is most detrimental to crops, and this has been long known by farmers and breeders. The green leafy vegetables of the Brassicaceae family have especially gained attention due to their many health benefits. However, little information is available about abiotic stress’s effects on Brassica vegetables’ growth and development. An experiment was conducted on two Brassica species: B. oleracea L. var. acephala WINTERBOR F1 (hybrid kale) and B. juncea var. GREEN WAVE OG (mustard greens). Seven treatments were imposed on the two brassica species in soil–plant–atmosphere–research (SPAR) units under optimum moisture and nutrient conditions, including a control treatment (optimal temperature and UV-B conditions at ambient CO2 levels), and six treatments where stresses were elevated: CO2, UV-B, temperature (T), CO2+UV-B, CO2+T, and CO2+UV-B+T. Above- and below-ground growth parameters were assessed at 26 d after sowing. Several shoot and root morphological and developmental traits were evaluated under all the treatments. The measured growth and development traits declined significantly under individual stresses and under the interaction of these stresses in both the species, except under elevated CO2 treatment. All the traits showed maximum reductions under high IV-B levels in both species. Leaf area showed 78% and 72% reductions, and stem dry weight decreased by 73% and 81% in kale and mustard, respectively, under high UV-B levels. The increased CO2 concentrations alleviated some deleterious impacts of high temperature and UV-B stresses. The results of our current study will improve our understanding of the adverse effects of environmental stresses on the early-season growth and development of two Brassica species.

Studying biodiversity-ecosystem function relationships in experimental microcosms among islands.

Ecological studies on islands have provided fundamental insights into the mechanisms underlying biodiversity of larger organisms, but we know little about the factors affecting island microbial biodiversity and ecosystem function. We conducted a field experiment on five Baltic Sea islands where we placed aquatic microcosms with different levels of salinity mimicking environmental stress and allowed diatoms to colonize the microcosms via the air. Using structural equation models (SEM), we investigated the interconnections among environmental and dispersal‐related factors, diatom biodiversity, and ecosystem productivity (represented by chlorophyll a concentration). We also tested whether the body size structure of the community influences productivity together with biodiversity. In SEMs, we found no relationship between species richness or evenness and productivity. However, productivity increased with increasing mean body size of species in the communities. The effects of environmental stress on both biodiversity and ecosystem productivity were highlighted as species richness and evenness declined, whereas productivity increased at the highest salinity levels. In addition to salinity, wind exposure affected both biodiversity metrics and productivity. This study provides new insights into microbial community assembly in a field experimental setting and the relationship between biodiversity and ecosystem function. Our results indicate that salinity presents a strong abiotic filter, leading to communities that may be species poor, yet comprise salinity‐tolerant and relatively productive species at high salinity. Our findings also emphasize the importance of mean community body size in mediating the effects of environmental conditions on productivity and suggest that this trait should be considered more broadly in biodiversity–ecosystem function studies.

High Environmental Temperature: Insights into Behavioural, Neurodevelopmental and Gut Microbiome Changes Following Gestational Exposure in Rats

Adverse effects of changing climate have been associated with increase average global temperature resulting in environmental changes. We set out to investigate effects of environmental stress due to increased heat exposure on developmental milestones, behaviour, gut microbiota and neuroarchitecture in rat pups.Pregnant Wistar rats were held in standard temperature (ST) (26 ± 2 °C; control) or high temperature (HT) (40 ± 2 °C) housing. After parturition, a cohort of the HT group and their pups were moved to the control/ST housing (gestational-only-exposed pup [GE]) while the other subset remained in the HT housing (gestational and postnatal exposed pups [GE + PE]). At different time points, we examined neurodevelopmental milestones and behaviour in the pups. Following sacrifice changes in gut microbiota, neuroarchitecture, cytokine levels (TNF-α, IL-4, IL-10), SOD, MDA, expression of MBP, NeUN and GFAP were determined.We observed impaired positioning and placing of paws, prolonged righting reflex, delayed ear opening and significant decreased body weight gain in HT pups when compared with control. We identified Firmicutes and Proteobacteria and noted a significant difference in Firmicutes count between GE and GE + PE pups at P15. Furthermore, TNF-α, IL-4, IL-10 and MDA levels were increased in GE and GE + PE pups. There was also a reduction in MBP expression in the HT pups.Taken together, our results revealed a delay in neurodevelopmental milestones in pups exposed to high HT during gestation and post natal life. Pups whose dam were exposed to high HT during gestation also showed some set back but improved over the course of testing.

Decay and damage of therapeutic phage OMKO1 by environmental stressors.

Antibiotic resistant bacterial pathogens are increasingly prevalent, driving the need for alternative approaches to chemical antibiotics when treating infections. One such approach is bacteriophage therapy: the use of bacteria-specific viruses that lyse (kill) their host cells. Just as the effect of environmental conditions (e.g. elevated temperature) on antibiotic efficacy is well-studied, the effect of environmental stressors on the potency of phage therapy candidates demands examination. Therapeutic phage OMKO1 infects and kills the opportunistic human pathogen Pseudomonas aeruginosa. Here, we used phage OMKO1 as a model to test how environmental stressors can lead to damage and decay of virus particles. We assessed the effects of elevated temperatures, saline concentrations, and urea concentrations. We observed that OMKO1 particles were highly tolerant to different saline concentrations, but decayed more rapidly at elevated temperatures and under high concentrations of urea. Additionally, we found that exposure to elevated temperature reduced the ability of surviving phage particles to suppress the growth of P. aeruginosa, suggesting a temperature-induced damage. Our findings demonstrate that OMKO1 is highly tolerant to a range of conditions that could be experienced inside and outside the human body, while also showing the need for careful characterization of therapeutic phages to ensure that environmental exposure does not compromise their expected potency, dosing, and pharmacokinetics.

A UAV-derived thermal infrared remote sensing three-temperature model and estimation of various vegetation evapotranspiration in urban micro-environments

The large-scale and single-point observations on urban vegetation easily cause the difficulty to quantitatively study the evapotranspiration of vegetation in urban micro-environments. In this content, the three-temperature (3T) model by combining the UAV-derived thermal infrared data was applied to estimate the evapotranspiration of different urban vegetation types at the microscale in Nanjing city, China accurately. The diurnal variation characteristics of the evapotranspiration rates of the different vegetation types such as arbors, shrubs and grasslands in different seasons were quantitatively analysed. The results showed that the estimated vegetation evapotranspiration rate was between 0–1.4 mm/h. The highest evapotranspiration rate among the different vegetation types was that of arbors, followed by shrubs and grasslands. The evapotranspiration rate on the sunny side was significantly higher than that on the shady side. There were obvious seasonal differences in vegetation evapotranspiration, which gradually decreased from spring to winter. The transpiration transfer coefficients of vegetation in summer and winter were significantly higher than those in other seasons, which indicated that the effects of water deficits or environmental stress were the largest at these times. The UAV-derived thermal infrared remote sensing three-temperature (3T) can simplify the complexity of the calculations and ensure the accuracy of the estimation results, which may provide the high spatio-temporal resolution urban vegetation evapotranspiration.

New technology of pre-treating processing of grain crops seeds by protective-incentive means

As the result analysis of known materials in the field of seed preparation, patent search and their systematization, an innovative approach is proposed, on the basis of which a conceptual model of a new technology for pre-sowing seeds of cereals by working solutions of chemical and biological protective-stimulating agents with preliminary dust cleaning in a continuous hermetic single technological flow. According to the proposed technology pre-sowing preparation is carried out directly at the seed storage site, which excludes energy-consuming and labor-intensive loading-unloading and transportation operations. The basis of the new technology is a combined machine for pre-sowing treatment with pneumatic loading and dust separating device, which works as follows. Seeds, from a boot by a pneumatic loader, where the seed surface is cleaned of dust, are fed into the dust separator. In the dust separator there is a separation of seeds and a dust-air mixture. In this case, the cleaned seeds without contact with the dusty medium are sent to the treatment zone where the fine particles of the working fluid (less than 40 microns), moving in the air flow, are applied to the surface of the seeds, which ensures the accuracy of the rate of application and the uniformity of the working solution distribution by the weight of the seeds and on the surface of each grain. When pre-sowing seed treatment with biopesticides, a temperature regime is maintained that ensures the vitality and effectiveness of the biopesticides action. The processed seeds are packed in sacks and sent for sowing. The proposed technology will provide increased productivity and reduced energy intensity of the technological process, reducing the seeds trauma, eliminating the over expenditure of expensive protective and stimulating agents and improving the quality of processing, high life activity and effectiveness of biopesticides exposure, reducing environmental stress and harmful effects on humans.

Stability of oil-in-water emulsions with eggplant flesh pulp (Solanum melongena L.) emulsifier: Effects of storage time, pH, ionic strength, and temperature.

In this study, we investigated the stability of oil-in-water emulsions prepared using eggplant flesh pulp (EFP) as natural emulsifier. The effects of time and environmental stresses on the stability of emulsions with different EFP concentrations were evaluated using the creaming indices (CIs), particle sizes, and zeta potentials of the emulsions. The emulsions with EFP concentrations of up to 1.50% remained stable for at least 90 days. The CIs, mean particle diameters (MPDs ]d3,2 ]), and zeta potentials of the emulsions with adequate EFP concentrations remained unchanged in the pH range of 3-9. Microstructure observations revealed that flocculation occurred for the emulsion with an EFP concentration of 1.50% at pH 3, whereas flocculation and coalescence occurred in the emulsion with a low EFP concentration of 0.50%. Upon increasing the concentration of NaCl from 0 to 0.5M, the MPDs (d3,2 ) of the emulsions with EFP concentrations of 1.00% and 1.50% remained nearly constant (57 and 48µm, respectively). Moreover, the MPDs (d3,2 ) and zeta potentials of the emulsions with EFP concentrations of 1.00% and 1.50% did not change significantly upon increasing temperature from 4 to 100°C. Hence, the emulsions with adequate EFP concentrations presented long storage times and were stable under various environmental stresses. Our results indicate that EFP is an effective and inexpensive emulsifier that can confer emulsions long-term storage stability and good resistance to environmental stresses. PRACTICAL APPLICATION: Eggplant, which is a common crop, is a rich source of natural materials. In this study, eggplant flesh pulp (EFP) was prepared via mechanical homogenization and its emulsifying properties for oil-in-water emulsions were evaluated. Our results demonstrated that the EFP-stabilized oil-in-water emulsions featured long storage times and were stable under environmental stresses (pH, ionic strength, and temperature). These properties render EFP-stabilized emulsions suitable as delivery systems for encapsulating and releasing nonpolar active ingredients in food products.

Inactivation of stressed Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes in hummus using low dose gamma irradiation.

Hummus is a popular dip in the Middle East region prepared by mixing the boiled chickpeas with tahini and other ingredients, and because its consumption has increased world-wide some notoriety has developed following an increase in the incidence of hummus-related illness outbreaks and recalls. The objectives of the current research were (i) to study the efficiency of low dose gamma irradiation to inhibit Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in hummus, and (ii) to assess the effect of environmental stresses namely cold, heat, and desiccation on the resistance of these pathogens to gamma irradiation. The samples of hummus were prepared and then individually inoculated with approximately 7.0 log CFU/g of unstressed or cold-, heat-, or desiccated-stressed cocktail cultures of each of E. coli O157:H7, S. enterica, and L. monocytogenes. The inoculated samples were then exposed to gamma irradiation at doses of 0.1 to 0.6 kGy. The numbers of unstressed E. coli O157:H7, S. enterica, and L. monocytogenes were decreased by 0.6-3.9, 0.7-2.9, and 1.0-3.0 log CFU/g, respectively, by irradiation treatment. The resistance of E. coli O157:H7 to gamma irradiation was not affected by desiccation, heat, and cold stresses. However, the pre-exposure of S. enterica and L. monocytogenes cells to these stresses reduced their resistance toward gamma irradiation. PRACTICAL APPLICATION: Gamma irradiation is a non-thermal treatment that can be used in food processing to ensure food safety and quality. The current study proved that low levels (≤0.6 kGy) of gamma irradiation can effectively decrease the risk of unstressed and cold-, heat-, or desiccation-stressed Salmonella enterica, Listeria monocytogenes, or Escherichia coli O157:H7 in hummus.

Effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers of industrial hemp (Cannabis sativa L.)

BackgroundsCannabis sativa L. produces at least 120 cannabinoids. Although genetic variation is the main factor in cannabinoid production, the effects of short-term environmental stresses in the early flowering stage remains largely unknown.MethodsTo investigate the effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers, a hemp variety, Green-Thunder (5–8% CBD/mg of dry weight), was treated with mechanical damage, insect herbivory, extreme heat, or drought stress for 5–7 days during the first 2 weeks of flowering. Three hemp tissues, including flowers, leaves, and stems, were collected from hemp grown under these stress conditions at multiple time points during the first 2 weeks after transition to the short photoperiod and analyzed using high pressure liquid chromatography to quantify phytocannabinoids including cannabigerolic acid (CBGA), cannabigerol (CBG), cannabidiolic acid (CBDA), cannabidiol (CBD), Δ-tetrahydrocannabinolic acid (THCA), Δ-tetrahydrocannabinol (THC), and cannabinol (CBN).ResultsThe 5 days of mechanical wounding did not affect the production of any of the cannabinoids during the initial stage of flowering. However, after 5 days of herbivore treatment, there was a significant difference in concentration between day 1 and day 6 of CBGA (control: 308 μg/g; treatment – 24 μg/g), CBG (control: 69 μg/g; treatment: 52 μg/g), and CBD (control: 755 μg/g; treatment: 194 μg/g) between the control and treatment plants. The 7 days of heat treatment at 45–50 oC significantly reduced the production of CBGA during this observed window (control: 206 μg/g; treatment: 182 μg/g) and CBG (control: 21 μg/g; treatment: − 112 μg/g). Notably, the largest change was observed after 7 days of drought stress, when plants showed a 40% greater accumulation of CBG (control: 336 μg/g; treatment: 622 μg/g), and a significant decrease (70–80%) in CBD (control: 1182 μg/g; treatment: 297 μg/g) and THC amounts (control: 3927 μg/g; treatment: 580 μg/g).ConclusionsAlthough this observation is limited in the early flowering stage, the common field stresses are adequate to induce changes in the cannabinoid profiles, particularly drought stress being the most impactful stress for hemp flower initiation with the altering the cannabinoid production by decreasing CBD and THC accumulation while increasing CBG by 40%.