Genomic and physiological characterization of beer spoiling Megasphaera spp.

During winemaking, malolactic fermentation (MLF) is usually induced by Oenococcus oeni owing to its high resistance to wine stress factors. To ensure a controlled and efficient MLF process, starter cultures are inoculated in wine. In previous studies, O. oeni strains with sub-lethal acid or ethanol stresses showed higher freeze-drying vitality and better MLF performance. To explore the mechanisms involved, influences of acid and ethanol stresses on O. oeni SD-2a were investigated in this study to gain a better understanding of the cross-protection responses. The results showed that acid and ethanol stresses both caused damage to cell membranes and decreased cellular adenosine triphosphate concentration. At the same time, acid stress increased the uptake of glutathione, while ethanol stress led to cell depolarization. The results of comparative proteomic analysis highlighted that heat shock protein was induced with almost all acid and ethanol stresses. In addition, the expression of stress-relevant genes (hsp20, clpP, trxA, ctsR, recO, usp) increased greatly with ethanol and acid stress treatments. Finally, the viability of O. oeni was improved with acid and ethanol pretreatments after freeze-drying. This study demonstrated that acid and ethanol stresses had mixed influences on O. oeni SD-2a. Some physiological and molecular changes would contribute to a more stress-tolerant state of O. oeni, thereby improving the viability of lyophilized cells. © 2020 Society of Chemical Industry.

Groundrules, advantages, and disadvantages to using systems modeling to address stress management questions are discussed. A systems model designed to explore the effects of multiple climatic stresses on potential site productivity is presented as an example of systems modeling applied to stress management research. Predictions from this model are used to examine the effect of multiple versus single climatic stresses on seasonal stand productivity. The model is also used to explore the possible effect of changing climates on future loblolly pine plantation productivity.

Response of ecological indices to nutrient and chemical contaminant stress factors in Eastern Mediterranean coastal waters

Crop tolerance to multiple abiotic stresses has long been pursued as a Holy Grail in plant breeding efforts that target crop adaptation to tropical soils. On tropical, acidic soils, aluminum (Al) toxicity, low phosphorus (P) availability and drought stress are the major limitations to yield stability. Molecular breeding based on a small suite of pleiotropic genes, particularly those with moderate to major phenotypic effects, could help circumvent the need for complex breeding designs and large population sizes aimed at selecting transgressive progeny accumulating favorable alleles controlling polygenic traits. The underlying question is twofold: do common tolerance mechanisms to Al toxicity, P deficiency and drought exist? And if they do, will they be useful in a plant breeding program that targets stress-prone environments. The selective environments in tropical regions are such that multiple, co-existing regulatory networks may drive the fixation of either distinctly different or a smaller number of pleiotropic abiotic stress tolerance genes. Recent studies suggest that genes contributing to crop adaptation to acidic soils, such as the major Arabidopsis Al tolerance protein, AtALMT1, which encodes an aluminum-activated root malate transporter, may influence both Al tolerance and P acquisition via changes in root system morphology and architecture. However, trans-acting elements such as transcription factors (TFs) may be the best option for pleiotropic control of multiple abiotic stress genes, due to their small and often multiple binding sequences in the genome. One such example is the C2H2-type zinc finger, AtSTOP1, which is a transcriptional regulator of a number of Arabidopsis Al tolerance genes, including AtMATE and AtALMT1, and has been shown to activate AtALMT1, not only in response to Al but also low soil P. The large WRKY family of transcription factors are also known to affect a broad spectrum of phenotypes, some of which are related to acidic soil abiotic stress responses. Hence, we focus here on signaling proteins such as TFs and protein kinases to identify, from the literature, evidence for unifying regulatory networks controlling Al tolerance, P efficiency and, also possibly drought tolerance. Particular emphasis will be given to modification of root system morphology and architecture, which could be an important physiological “hub” leading to crop adaptation to multiple soil-based abiotic stress factors.

Multiple stress factors and the emission of plant VOCs

In practical applications, products are usually exposed to multiple stress factors (including environmental stresses and operating stresses) simultaneously. However, existing work on accelerated degradation test mainly focuses on the case of a single stress factor. This motivates the need to develop a reliability assessment model for accelerated degradation test involving multiple stress factors. Therefore, this paper proposes a Wiener process-based accelerated degradation test model that simultaneously considers multiple stress factors, random effects and measurement errors. Then the explicit expression for the lifetime distribution under normal operating conditions of the proposed Wiener accelerated degradation test model is obtained, along with its approximate mean lifetime. In addition, the maximum likelihood estimates of model parameters are derived using the profile likelihood approach, and maximum likelihood estimates for some reliability metrics under normal operating conditions are also obtained. Besides, we construct confidence intervals for model parameters and some reliability metrics using the bias-corrected and accelerated percentile bootstrap method. Finally, the performance of the proposed method is demonstrated by extensive simulation studies, and a numerical example.

Changing environment has a huge impact on bio-resources and global agriculture. Abiotic stress factors are dramatically increasing along with these uncontrolled environmental changes. Rice (Oryza sativa) is the most important crop providing food toward more than half of the world populations, and India is one of the major rice growing country. This important crop plant experiences massive yield loss due to abiotic out-lashes, e.g., salinity, drought, heat stress, cold shock, UV damage, and mineral toxicity. The sessile nature of plants make them easy targets of several environmental odds, but long-term evolutionary interaction of plants with environment in turn shapes reprogramming of its defense signaling networks tightly. The subtle changes in the environment can be sensed by the plant very efficiently and are portrayed by their genetic orchestrations. Due to enormous development in modern genomics, technologies, and biotechnological applications, the minute changes in gene expression and modification of metabolic functions can now be precisely recorded. Besides, complex modulations in metabolic network through biotechnology are implicated to overcome the situations in a positive way. Studies focusing on specific abiotic stress and its protection have long been implicated in different plants including rice. Unfortunately, growing yield loss in rice due to multiple abiotic stress factors supersedes increasing demand of this crop. Recently, a versatile approach has been flourished to meet the yield–demand ratio against multiple abiotic stresses. The present chapter describes various important abiotic stresses in rice plants, their complex defense signaling mechanism, and recent developments to combat these multiple stress factors comprehensively.

General stress response of Bacillus subtilis and other bacteria

Pediococcus pentosaceus, an important lactic acid bacterium in the brewing of Chinese Baijiu (liquor), usually encounters environmental stresses including ethanol and lactic acid, which severely impact cellular growth and metabolism. In this study, a combined physiological and omics analysis was employed to elucidate the response mechanisms of P. pentosaceus under ethanol and lactic acid stress conditions. The results showed that the biomass of cells decreased by about 40% under single-stress conditions and 70% under co-stress conditions. Analysis of the differentially expressed genes revealed that the cells adjusted various cellular processes to cope with environmental stresses, including modifications in cell wall synthesis, membrane function, and energy production pathways. Meanwhile, the increased expression of genes involved in DNA repair system and protein biosynthesis ensured the normal physiological function of cells. Notably, under ethanol stress, P. pentosaceus upregulated genes involved in unsaturated fatty acid biosynthesis, enhancing membrane stability and integrity. Conversely, under lactic acid stress, cells downregulated F-type ATPase, reducing H+ influx to maintain intracellular pH homeostasis. The metabolomic analysis revealed DNA damage under co-stress conditions and further validated the transcriptomic results. Our findings elucidate the molecular and physiological strategies of P. pentosaceus under acid and ethanol stress, providing a foundation for optimizing fermentation processes and enhancing microbial resilience in industrial settings.

We deeply investigated the mechanism underlying metabolic regulation in response to consecutive monoculture (replanting disease) and different abiotic stresses that unfolded the response mechanism to consecutive monoculture problem through RNA-seq analysis. The consecutive monoculture problem (CMP) resulted of complex environmental stresses mediated by multiple factors. Previous studies have noted that multiple stress factors in consecutive monoculture soils or plants severely limited the interpretation of the critical molecular mechanism, and made a predict that the specifically responding factor was autotoxic allelochemicals. To identify the specifically responding genes, we compared transcriptome changes in roots of Rehamannia glutinosa Libosch using consecutive monoculture, salt, drought, and ferulic acid as stress factors. Comparing with normal growth, 2502, 2672, 2485, and 1956 genes were differentially expressed in R. glutinosa under consecutive monoculture practice, salt, drought, and ferulic acid stress, respectively. In addition, 510 genes were specifically expressed under consecutive monoculture, which were not present under the other stress conditions. Integrating the biological and enrichment analyses of the differentially expressed genes, the result demonstrated that the plants could alter enzyme genes expression to reconstruct the complicated metabolic pathways, which used to tolerate the CMP and abiotic stresses. Furthermore, most of the affected pathway genes were closely related to secondary metabolic processes, and the influence of consecutive monoculture practice on the transcriptome genes expression profile was very similar to the profile under salt stress and then to the profile under drought stress. The outlined schematic diagram unfolded the putative signal regulation mechanism in response to the CMP. Genes that differentially up- or down-regulated under consecutive monoculture practice may play important roles in the CMP or replanting disease in R. glutinosa.

How can mycorrhizal symbiosis mediate multiple abiotic stresses in woody plants?

Developmental initiation of plant vascular tissue, including xylem and phloem, from the vascular cambium depends on environmental factors, such as temperature and precipitation. Proper formation of vascular tissue is critical for the transpiration stream, along with photosynthesis as a whole. While effects of individual environmental factors on the transpiration stream are well studied, interactive effects of multiple stress factors are underrepresented. As expected, climate change will result in plants experiencing multiple co-occurring environmental stress factors, which require further studies. Also, the effects of the main climate change components (carbon dioxide, temperature, and drought) on vascular cambium are not well understood. This review aims at synthesizing current knowledge regarding the effects of the main climate change components on the initiation and differentiation of vascular cambium, the transpiration stream, and photosynthesis. We predict that combined environmental factors will result in increased diameter and density of xylem vessels or tracheids in the absence of water stress. However, drought may decrease the density of xylem vessels or tracheids. All interactive combinations are expected to increase vascular cell wall thickness, and therefore increase carbon allocation to these tissues. A comprehensive study of the effects of multiple environmental factors on plant vascular tissue and water regulation should help us understand plant responses to climate change.

Many studies have focused on natural stress factors that shape the spatial and temporal distribution of calanoid copepods, but bioassays have shown that copepods are also sensitive to a broad range of contaminants. Although both anthropogenic and natural stress factors are obviously at play in natural copepod communities, most studies consider only one or the other. In the present investigation, we modeled the combined impact of both anthropogenic and natural stress factors on copepod populations. The model was applied to estimate Eurytemora affinis densities in the contaminated Scheldt estuary and the relatively uncontaminated Darß-Zingst estuary in relation to temperature, salinity, chlorophyll a, and sediment concentrations of cadmium, copper, and zinc. The results indicated that temperature was largely responsible for seasonal fluctuations of E. affinis densities. Our model results further suggested that exposure to zinc and copper was largely responsible for the reduced population densities in the contaminated estuary. The model provides a consistent framework for integrating and quantifying the impacts of multiple anthropogenic and natural stress factors on copepod populations. It facilitates the extrapolation of laboratory experiments to ecologically relevant end points pertaining to population viability.

Previously undiscovered failure modes in photovoltaic (PV) modules continue to emerge in field installations despite passing protocols for design qualification and quality assurance. Failure to detect these modes prior to widespread use could be attributed to the limitations of present‐day standard accelerated stress tests (ASTs), which are primarily designed to identify known degradation or failure modes at the time of development by applying simultaneous or sequential stress factors (usually two at most). Here, we introduce an accelerated testing method known as the combined‐accelerated stress test (C‐AST), which simultaneously combines multiple stress factors of the natural environment. Simultaneous combination of multiple stress factors allows for improved identification of failure modes with better ability to detect modes not known a priori. A demonstration experiment was conducted that reproduced the field‐observed cracking of polyamide‐ (PA‐) and polyvinylidene fluoride (PVDF)–based backsheet films, a failure mode that was not detected by current design qualification and quality assurance testing requirements. In this work, a two‐phase testing protocol was implemented. The first cycle (“Tropical”) is a predominantly high‐humidity and high‐temperature test designed to replicate harsh tropical climates. The second cycle (“Multi‐season”) was designed to replicate drier and more temperate conditions found in continental or desert climates. Testing was conducted on 2 × 2‐cell crystalline‐silicon cell miniature modules constructed with both ultraviolet (UV)–transmitting and UV‐blocking encapsulants. Cracking failures were observed within a cumulative 120 days of the Tropical condition for one of the PA‐based backsheets and after 84 days of Tropical cycle followed by 42 days of the Multi‐season cycle for the PVDF‐based backsheet, which are both consistent with failures seen in fielded modules. In addition to backsheet cracking, degradation modes were observed including solder/interconnect fatigue, various light‐induced degradation modes, backsheet delamination, discoloration, corrosion, and cell cracking. The ability to simultaneously apply multiple stress factors may allow many of the test sequences within the standardized design qualification procedure to be performed using a single test setup.

Transcriptomic analysis of bacteriocin synthesis and stress response in Lactobacillus paracasei HD1.7 under acetic acid stress