Search Results (6)

Salinity poses a major threat to sustainable agriculture and coastal ecosystems, resulting in a substantial loss of plant productivity and biodiversity. Although some coastal grass species exhibit natural adaptation to saline conditions, the physiological mechanisms underlying salt tolerance remain incompletely understood, particularly regarding the contribution of plant-associated microorganisms. In a previous study, a commercial cultivar of red fescue (Festuca rubra ssp. rubra cv. Rafael) was shown to be salt sensitive when grown hydroponically, whereas wild populations of F. rubra commonly occur in coastal salt marshes (possibly ssp. litoralis). We hypothesized that this difference in salt tolerance is partly associated with beneficial fungal plant interactions. To test this hypothesis, we investigated whether inoculation with a fungal isolate designated Fusarium sp. 1 and isolated from F. rubra growing on a salt marsh along the Dutch Wadden Sea coast could improve the salinity tolerance of the commercial cultivar. The results showed that inoculation with Fusarium sp. 1 alleviated the salt-induced growth inhibition. At 100 mM NaCl, shoot and root biomass were partially restored relative to non-inoculated controls, accompanied by a significant increase in the shoot-to-root ratio. To investigate the physiological basis of this response, we applied the Microelectrode Ion Flux Estimation (MIFE) technique to quantify Na⁺ -induced K⁺ efflux in roots. Inoculated plants exhibited improved K⁺ homeostasis, characterized by a reduced instantaneous Na⁺-induced K⁺ efflux and a faster recovery of root fluxes. Moreover, inoculated plants grown at 50 and 100 mM NaCl displayed 333% and 397% greater net K⁺ influx, respectively, compared with non-inoculated controls. Our results indicated that inoculation with Fusarium sp. 1 improves the salinity tolerance of F. rubra, likely through enhanced root K⁺ retention. These findings suggest that commercial F. rubra cultivars remain responsive to beneficial microbial associations and highlight the potential of exploring plant–microbe interactions from naturally salt-adapted environments to improve salinity resilience in grasses and potentially other crops. Full article

Extreme environments foster phylogenetically diverse microorganisms and unique community assembly patterns. Plateau saline marsh lakes represent understudied extreme habitats characterized by dual stressors of high salinity and low temperature. Here, we analyzed the soil bacterial and archaeal diversity in three salt marshes of the Qaidam Basin on the Qinghai-Tibetan Plateau, China. While the bacterial and archaeal alpha diversity showed no significant differences among the three salt marshes, the community composition varied significantly. Notably, soil salinity (indicated by electric conductivity, EC) exerted opposing effects on microbial diversity—suppressing bacterial while promoting archaeal communities. Stochastic processes were the predominant mechanism for both bacterial and archaeal community assembly, where the weights were, in descending order, drift, homogeneous selection, and dispersal limitation. Network analysis revealed predominantly positive co-occurrence patterns within both bacterial and archaeal communities. We did not find a direct relationship between any bacterial or archaeal co-occurrence network properties and soil EC, but there was a significant correlation of network complexity to microbial diversity, which was influenced by EC. Our findings indicate distinct responses of bacterial and archaeal diversity to varying salinity levels, while the underlying assembly processes appear to be conserved in driving shifts in community diversity in plateau salt marsh wetlands. Full article

This study investigates the formation of a protective layer on a 5083 aluminum alloy surface induced by microorganisms from salt marsh. The influence of the initial surface roughness was examined to identify optimal conditions for maximum coverage and thickness of the protective layer. As two opposing effects are suspected, where high surface roughness enhances bacterial adhesion but reduces the resistance to abiotic corrosion, various degrees of roughness were tested. Using electrochemical experiments (OCP measurement, 1/Rp determination, and pitting sensitivity), SEM/TEM observation and EDX characterization, a compromise was found on the initial roughness to obtain a thick protective layer through good bacterial adhesion while minimizing abiotic corrosion. The optimal roughness, achieved through 240-grit grinding, facilitates a uniform distribution of microorganisms and the development of a dense, evenly thick protective layer that significantly enhances the alloy’s resistance to pitting corrosion. The passivity domain doubled when comparing the electrochemical behavior of electrodes immersed in the presence of microbial activity to those immersed without it. Full article

Haloarchaea are a group of moderate and extreme halophilic microorganisms, belonging to the Archaea domain, that constitute relevant microbial communities in salty environments like coastal and inland salted ponds, marshes, salty lagoons, etc. They can survive in stress conditions such as high salinity and, therefore, high ionic strength, high doses of ultraviolet radiation (UV), high temperature, and extreme pH values. Consequently, most of the species can be considered polyextremophiles owing to their ability to respond to the multiple extreme conditions characterizing their natural habitats. They cope with those stresses thanks to several molecular and metabolic adaptations. Thus, some of the molecules produced by haloarchaea show significantly different biological activities and physicochemical properties compared to their bacterial counterparts. Recent studies have revealed promising applications in biotechnology and medicine for these biomolecules. Among haloarchaeal biomolecules, rare natural pigments (C₅₀ carotenoids) and small peptides called halocins and microhalocins have attracted attention worldwide due to their effects on animal and human commercial tumoral cells, apart from the role as antibiotics described for halocins or the immunomodulatory activity reported from C₅₀ carotenoids like bacterioruberin. This review summarizes recent knowledge on these two types of biomolecules in connection with cancer to shed new light on the design of drugs and new therapies based on natural compounds. Full article

In the context of global warming and carbon neutrality, reducing greenhouse gas emissions is fundamental to achieving sustainable development. As an important greenhouse gas, methane has a much stronger warming effect than CO₂, and studies have demonstrated that anaerobic oxidation of methane (AOM) is important for global methane emissions. This paper systematically investigated the AOM potential and microbial community response to the input of SO₄²⁻ in the three typical salt marsh soils of the Yellow River Delta: Reed, Suaeda salsa, and Tamarisk, using SO₄²⁻ as the electron acceptor and a combination of indoor anaerobic culture and high-throughput sequencing. The results showed that after adding an appropriate concentration of SO₄²⁻, the AOM potential was significantly promoted in Tamarix soil (p < 0.05) and significantly inhibited in Reed and Suaeda salsa soil (p < 0.05); soil AOM potential and SO₄²⁻ input concentration and background values were correlated. At the microbial level, SO₄²⁻ input affected the abundance of some microorganisms. At the phylum level, the relative abundance of Proteobacteria was increased in Suaeda salsa soil, decreased in Tamarisk soil, and did not change significantly in Reed soil; that of Crenarchaeota and Desulfobacterota was significantly increased in Tamarisk soil. At the genus level, Methylophaga, Methylotenera, and Methylomonaceae became the dominant populations, and it can be inferred that these bacteria are involved in the anaerobic oxidation of methane after the input of SO₄²⁻. This study will be of great significance to the mechanistic study of AOM and the conservation of microbial diversity in the Yellow River Delta Coastal Wetland, as well as provide a scientific basis for CH₄ reduction in coastal wetlands. Full article

Currently, microplastic pollution poses a great threat to diverse ecosystems. Microplastics can potentially change soil characteristics and impact soil microorganisms, and then affect the production of CO₂, CH₄ and other greenhouse gases. However, experimental study on different ecological soils is lacking. Herein, we experimentally analyzed the CO₂ and CH₄ production potential affected by four types of microplastics in freshwater (Poyang Lake in Jiangxi province, paddy soil in Hunan province) and saltwater (Salt marsh in Shandong province, mangrove soil in Fujian province) ecosystems. Microplastics promoted CO₂ production, of which polyethylene terephthalate (PET) had the greatest impact. In our study, the microplastics that had the greatest impact on CH₄ concentration emissions were high-density polyethylene (1276 umol·g⁻¹·L⁻¹), followed by polyvinyl chloride (384 umol·g⁻¹·L⁻¹), polyethylene terephthalate (198 umol·g⁻¹·L⁻¹), and polyamide (134 umol·g⁻¹·L⁻¹). In addition, the largest impact on CO₂ concentration emissions was displayed by polyethylene terephthalate (2253 umol·g⁻¹·L⁻¹), followed by polyvinyl chloride (2194 umol·g⁻¹·L⁻¹), polyamide (2006 umol·g⁻¹·L⁻¹), and high-density polyethylene (1522 umol·g⁻¹·L⁻¹). However, the analysis results based on one-way ANOVA showed that CO₂ emission was most significantly affected by soil properties rather than microplastics types. In comparison, the influencing factor on CH₄ production changed from soil types to the interaction between soil types and microplastics, and finally to the microplastics with the increase in incubation time. Further, by comparing CO₂ and CH₄ production and Global Warming Equivalent (GWE) affected by microplastics, freshwater ecosystems were more sensitive than saltwater. For all the soil types used in this study, high-density polyethylene had the greatest impact on CH₄ production potential. In conclusion, our study provided basic data for further understanding the effects of microplastics on soil greenhouse gas emissions from different sources. Full article