Microbial exopolysaccharides: Main examples of synthesis, excretion, genetics and extraction

Microbial exopolysaccharides (EPS) are high molecular weight polymers having different sugar residues. EPS have potential applications in different fields, such as medicine, food and environment. Therefore, there is a growing interest in production, characterization and application of EPS from different microorganisms. The present study designed to investigate the production and characterization of EPS from Rhodotorula mucilaginosa YMM19 isolated from Morus nigra L. fruits as well as to examine their potential emulsifying properties. Effect of NaCl concentration, incubation period and pH on the production of EPS was studied. The maximum EPS production by yeast was achieved at 10% NaCl (9741.84mg/l). The best incubation time for production of EPS was 5days. Production of EPS decreased under neutral condition and increased at acidic and alkaline condition. The structural feature of EPS was examined by FT-IR and NMR spectral analysis and confirmed the presence of glucose, glucopyranose and galactose. The isolated EPS showed higher emulsification capacity with emulsification activity of 71% and emulsifying index of 60%. The EPS gave strong emulsification for farnesol and was more effective than sodium dodecyl sulphate, a reference emulsifier, in enhancing the herbicidal activity of farnesol against Melilotus indicus under greenhouse condition. The results suggest that the EPS produced by YMM19 strain has a potential to be used as emulsifying agent in pesticide formulations.

Current advances in the investigation of leaf rolling caused by biotic and abiotic stress factors

Crops are often simultaneously threatened by abiotic and biotic stress factors but the stress response of the plant holobiont is not well understood, despite the high importance of this response to ensure future plant production. Therefore, the aim of this study was to assess the impact of individual and combined abiotic (ionic and osmotic) and biotic ( Verticillium dahliae and Fusarium oxysporum) stress factors on plant performance and on the bacterial composition of the root endosphere in tomato. Structure and function of the microbiota was analyzed by 16S ribosomal RNA gene amplicon sequencing and a complementary cultivation approach, including in vitro and in vivo assays. Under all stress conditions, tomato growth and photosynthetic activity was reduced. Combined abiotic stressors with F. oxysporum but not with V. dahliae infection led to an additive negative effect on plant performance. All stress conditions induced a microbiome shift, and changed the relative abundance of phyla such as Firmicutes and classes of Proteobacteria. Endophytes identified as Bacillus, Paenibacillus, and Microbacterium spp. showed tolerance to abiotic stress conditions and plant beneficial effects. Stressor-specific enrichments of beneficial bacteria in the root were discovered (e.g., Paenibacillus in roots infected with F. oxysporum and Microbacterium in roots infected with V. dahliae). Interestingly, endophytes that were able to promote plant growth were obtained only from roots exposed to individual biotic and combined abiotic and biotic stress conditions but not individual abiotic stressors. Our study revealed stressor-specific enrichment of beneficial bacteria in tomato roots, which has implications for novel plant protection strategies.

Plants are constantly subjected to biotic and abiotic stress factors, from their planting time up to the harvesting, transport, storage and consumption of plant products. These stresses exert deleterious harmful effects on crop health as well as cause huge losses to their production worldwide. To combat these stress factors, researchers all around the globe are involved in procuring management practices ranging from traditional genetics and breeding techniques to present day available novel biotechnological tools. Use of microorganisms is one such method by which both abiotic and biotic stress can be tackled in an economical, ecofriendly and successful manner. Plant growth-promoting rhizobacteria (PGPR) are the bacteria living in rhizosphere region and promoting plant growth and suppressing stress components as well. Different microorganisms acquire different mechanisms to fight with these plant stresses. In this chapter, an effort has been made to impart the knowledge about the abiotic and biotic stress factors, their management in an efficient and novel way.

Plants encounter several biotic and abiotic stresses, usually in combination. This results in major economic losses in agriculture and forestry every year. Climate change aggravates the adverse effects of combined stresses and increases such losses. Trees suffer even more from the recurrence of biotic and abiotic stress combinations owing to their long lifecycle. Despite the effort to study the damage from individual stress factors, less attention has been given to the effect of the complex interactions between multiple biotic and abiotic stresses. In this review, we assess the importance, impact, and mitigation strategies of climate change driven interactions between biotic and abiotic stresses in forestry. The ecological and economic importance of biotic and abiotic stresses under different combinations is highlighted by their contribution to the decline of the global forest area through their direct and indirect roles in forest loss and to the decline of biodiversity resulting from local extinction of endangered species of trees, emission of biogenic volatile organic compounds, and reduction in the productivity and quality of forest products and services. The abiotic stress factors such as high temperature and drought increase forest disease and insect pest outbreaks, decrease the growth of trees, and cause tree mortality. Reports of massive tree mortality events caused by “hotter droughts” are increasing all over the world, affecting several genera of trees including some of the most important genera in plantation forests, such as Pine, Poplar, and Eucalyptus. While the biotic stress factors such as insect pests, pathogens, and parasitic plants have been reported to be associated with many of these mortality events, a considerable number of the reports have not taken into account the contribution of such biotic factors. The available mitigation strategies also tend to undermine the interactive effect under combined stresses. Thus, this discussion centers on mitigation strategies based on research and innovation, which build on models previously used to curb individual stresses.

Secondary metabolites (SMs) play vital roles in plant defence mechanisms, adaptation to environmental conditions, and interactions with other organisms. Biotic and abiotic stress factors can significantly influence the production, accumulation, and composition of SMs in plants. Understanding the intricate relationship between stress and SM production is crucial for enhancing plant resilience, agricultural productivity, and the development of novel phytopharmaceuticals. This research provides current knowledge regarding the impact of biotic and also abiotic stress on SMs in plants. Biotic stress factors such as pathogen infection, and herbivore attacks, as well as abiotic stress factors like drought, along with temperature extremes, and also salinity, can profoundly influence the biosynthesis and accumulation of SMs in plants. We discussed the methodology based on secondary sources underlying physiological, biochemical, and molecular mechanisms involved in stress-induced SM synthesis and highlight the potential implications for plant biology, agriculture, and human health. The study also emphasizes the functions of SMs in plants including defence against herbivores, pathogens, and abiotic stresses. The mechanism by which thesecompounds act as allelochemicals and signalling molecules is also discussed.

The increased demand for natural polymers has spurred interest in microbial exopolysaccharide (EPS) production for various industrial applications, and as EPS production is influenced by medium composition and environmental conditions, the study of these factors has become a crucial focus in recent years. This study focused on screening, production, and optimization of process parameters to achieve a high EPS yield. Industrial effluent samples were collected from Valsad, Vapi, Daman, Silvassa and Surat region. Total 100 Bacteria were isolated from which 58 were screened positive in primary screening and 34 were screened positive in secondary screening. Maximum EPS producing strain was subjected to optimization of various process parameters such as incubation temperature, incubation time, medium pH, carbon source and its concentration, nitrogen source and its concentration. Maximum EPS 3.4 g/L was produced by bacterial strain N-95 and 16s rRNA sequencing of these bacteria show 98.89% similarity with Bacillus licheniformis strain KP062r. Optimum EPS production was achieved at temperature 300C, pH 7, sucrose as a carbon source at 3% concentration, urea as nitrogen source at 0.075% concentration with inoculum concentration 2.5%. Through process optimization, EPS production increased from 3.4 g/L to 7.1 g/L, reflecting a 2.08-fold enhancement compared to previous conditions. This demonstrates that changes in environmental factors have significant effect on EPS production.

Microbial exopolysaccharides (EPS) provide a broad range of applications. Thus, there is an increasing interest in the production, characterization, and use of EPS derived from various microorganisms. Extremophile polysaccharides have unique properties and applications due to its unique structures. The importance of exopolysaccharides synthesized by a new bacterial strain, Alkalibacillus sp. w3, was highlighted in this study. Alkalibacillus sp. w3, a haloalkalitolerant firmicute that was recovered from a salt lake, was optimized for EPS production, and its biological activities were studied. Exopolysaccharide synthesis was observed in Horikoshi I broth medium. The optimal culture conditions for achieving the highest exopolysaccharide production were a 7-day incubation period, pH 10, and 250 g/L of NaCl. The most effective carbon and nitrogen sources for EPS production were glucose and a combination of yeast extract and peptone. Additionally, Plackett-statistical Burman’s design showed that all factors tested had a favorable impact, with glucose having the greatest significance on the production of EPS. The model’s best predictions for culture conditions resulted in a two-fold improvement in EPS production compared to the original yield before optimization. The recovered EPS contained 65.13% carbohydrates, 30.89% proteins, and 3.98% lipids. Moreover, EPS produced by Alkalibacillus sp. w3 demonstrated anticancer activity against hepatocellular carcinoma (HepG2) and human colon carcinoma (HCT-116) cell lines, with IC50 values as low as 11.8 and 15.5 µg/mL, respectively, besides antibacterial activity against various Gram-positive, Gram-negative bacteria, and yeast. Based on these results, EPS made by Alkalibacillus sp. w3 has many useful properties, which make it suitable for use in the medical field.

Background. This review systematizes current scientific data on the influence of abiotic (pH, temperature, hypoxia, ammonia, nitrite) and biotic (viral and bacterial infections) stress factors on gene expression in crustaceans of the order Decapoda. Molecular responses affecting key functional groups of genes associated with immunity, osmoregulation, antioxidant defense, chitin metabolism, and cellular homeostasis are analyzed. Stress-induced changes in gene expression are complex, tissue-specific, and time-dependent, representing key adaptive mechanisms. The results of this analysis have important practical implications for aquaculture, opening up prospects for identifying molecular markers of stress resistance and developing strategies for optimizing the maintenance conditions of commercially important species. Purpose. This review aims to systematize and analyze current scientific data on the influence of abiotic (such as pH, temperature, hypoxia, ammonia, nitrites) and biotic (viral and bacterial infections) stress factors on expression of genes associated with immunity, osmoregulation, antioxidant defense, chitin metabolism and cellular homeostasis in crustaceans of the order Decapoda. Materials and methods. The research was conducted in the scientific research laboratory "Center of Agrobiotechnology" of the Don State Technical University in 2024-2025. Results. Complex changes in the expression of key genes regulating immunity, osmoregulation, antioxidant protection, chitin metabolism, and cellular homeostasis have been identified. It has been shown that these tissue-specific and time-dependent changes in expression are the central mechanism of the adaptive response to stress. Conclusion. An analysis of current scientific data has allowed us to systematize information on the influence of abiotic and biotic stress factors on gene expression in crustaceans, particularly in members of the order Decapoda. It has been established that changes in key environmental parameters (such as temperature, pH, ammonia and nitrite concentrations) and exposure to pathogens (viruses, bacteria) trigger complex molecular responses affecting genes associated with immunity, osmoregulation, antioxidant defense, chitin metabolism, and cellular homeostasis. Sponsorship information. The study was supported by a grant within the framework of the “Nauka-2030”. EDN: RCUGTX

EDITORIAL article Front. Microbiol., 11 March 2016Sec. Microbiotechnology Volume 7 - 2016 | https://doi.org/10.3389/fmicb.2016.00308

Legumes represent one of the most valuable crops all over the world because of their high content of protein, carbohydrates, fibers and minerals. Legumes significantly affect animal and human health along with soil fertility enhancement. Despite large areas under legume cultivation, the per year legume produces are insufficient due to crop losses induced by several biotic and abiotic stress factors. Abiotic stress factors include numerous environmental parameters like temperature, soil compaction, soil contamination, chilling, frost, drought, humidity, and soil water content. Biotic stress factors involve parasites like nematodes, weeds, insects, viruses, bacteria, and fungi. Fungal plant pathogens are considered one of the major reasons of legume crop losses because of their high spreading instances and aggressive infection via seeds or entire plant body. Fungal diseases can even lead to 100% legume yield losses. Various natural, chemical and biological control methods of regulating fungal diseases have been reported. The most common fungal diseases include rust, powdery mildew, wilt, ascochyta blight, chocolate spot and root rot disease. Present article focuses on various biotic stress inducers of legumes with attention to fungal diseases and its management strategies.

Polysaccharides are renewable resources representing an important class of polymeric materials of biotechnological interest, offering a wide variety of potentially useful products to mankind. Exopolysaccharides (EPSs) of microbial origin with a novel functionality, reproducible physico-chemical properties, stable cost and supply, became a better alternative to polysaccharides of algal origin. EPSs are believed to protect bacterial cells from desiccation, heavy metals or other environmental stresses, including hostimmune responses, and to produce biofilms, thus enhancing the cells chances of colonising special ecological niches. One of the most important stress factor is salt stress for microorganisms. The present investigation is aimed to determine correlation between salt resistance and EPS production by three cyanobacterial isolates (Synechocystis sp. BASO444, Synechocystis sp. BASO507 and Synechocystis sp. BASO511). It is also aimed to investigate the effect of salt concentrations on EPS production by cyanobacteria and effect of salt on monosaccharide composition of EPS. Cyanobacterial isolates were identified by 16 S rRNA analysis. Its salt (NaCl) tolerance and association with exopolysaccharides (EPSs) production in three cyanobacterial isolates were investigated. Also, EPS was analysed by HPLC for monomer characterization. Increased EPS production was associated with NaCl tolerance. The most tolerant isolate, Synechocystis sp. BASO444, secreted the most EPS (500 mg/L). EPS production by Synechocystis sp. BASO444, Synechocystis sp. BASO507 and Synechocystis sp. BASO511 was investigated following exposure to 0.2 and 0.4 M NaCl. Also, flasks containing medium without NaCl were inoculated in the same manner to serve as controls. The monosaccharide compositions of EPS produced by the three isolates following exposure to 0.2 M NaCl were analysed by HPLC. Control EPS of BASO444 was composed of glucose (97%) and galacturonic acid (3%). The composition of BASO511 (control) was glucose (95%), xylose (4.80%), arabinose (0.13%), glucuronic acid (0.03%) and galacturonic acid (0.04%). However, the composition of BASO507 (control) was glucose (0.98%), xylose (98.00%), arabinose (1.00%), glucuronic acid (0.01%) and galacturonic acid (0.01%). In the presence of 0.2 M NaCl, EPS compositions and ratios of three cyanobacterial isolates changed. Although hyperproduction of EPS in response to starvation, antiviral activity, thickening agent and cosmetic industry for product formulations has been reported for cyanobacteria, the effect of NaCl on EPS production in cyanobacteria is not a popular area of study. There are no clear reports correlating EPS production and NaCl tolerance. The gap in the data about the effect of NaCl on cyanobacterial EPS production was filled by this investigation, and the results of our study have important implications in both the industrial and environmental arenas. Our results indicate that 1) exposure to elevated concentrations of NaCl affects the composition of EPS produced by Synechocystis sp. BASO444, Synechocystis sp. BASO507 and Synechocystis sp. BASO511, and 2) there is a correlation between NaCl tolerance and EPS production in some cyanobacteria. Differences in the monosaccharide composition and ratios of EPS may promote NaCl tolerance in these microorganisms. As well, these alternative composition polysaccharides may be important for industrial applications.

Microbial exopolysaccharides (EPSs) are very important because they are used in biotechnological applications in different industrial areas. The aim of the study was to determine the best EPS producer Pleurotus sp., to optimize EPS production and to perform partial purification and characterization of the produced EPS. After the production conditions were optimized, the EPS was isolated and partially purified. EPS was characterized by HP-TLC, 1H-NMR, FT-IR, and TGA. Hydroxyl, superoxide, and DPPH radical scavenging activities of the EPS were also investigated spectrophotometrically. The best EPS producer and its incubation period in submerged fermentation were determined as Pleurotus sajor caju and on 5 days, respectively. Culture conditions to increase EPS production were optimized as follows (in per liter): 90 g of glucose, 10 g of yeast extract, 10 g of peptone, and 100 mM of Mg2+. The optimal initial pH, temperature, and an agitation rate of culture were determined as 5.0, 25 °C, and 150 rate min−1, respectively. The highest EPS production was determined as 33.32 ± 1.6 g L−1. After isolation of EPS, one active fraction was obtained by gel filtration chromatography. EPS is composed mainly of glucose according to HP-TLC analysis. To the results, EPS had a complex structure by having carbohydrate and protein contents. The produced EPS had high degradation temperature as well as high antioxidant activity.

The method to analyze both eukaryotic and prokaryotic microorganisms without preliminary microbial information of sample seemed to be useful not only for research and investigation of microorganisms but also for industry using microorganisms. In the present manuscript, preparation of a new DNA primers, new reference database for 18S rDNA for our newly developed method [1]- [3], and analyses of eukaryotic and prokaryotic microorganisms in fermentation products were presented. In komekouji, Aspergillus spp., was enumerated to be 46.5 × 106 MPN g-1, and Penicillium spp., was enumerated to be 1.5 × 106 MPN g-1. In dry yeast, Saccharomyces group, were enumerated to be 8600 × 106 MPN g-1. In komekouji-miso, no eukaryotic microorganism was detected, while the other Bacillus spp., was numerically dominant (21.5 × 106 MPN g-1) as prokaryotic microorganisms, followed by B. subtilis group (4.65 × 106 MPN g-1), and the other Firmicutes (3.7 × 106 MPN g-1). The komekouji-miso included lower number of Actinobacteria (0.15 × 106 MPN g-1), Burkhokderia sp. (1.5 × 106 MPN g-1), and the other α,β,γ-proteobacteria (0.12 × 106 MPN g-1). In sake-kasu, both prokaryote and eukaryote were not detected by the method. Present results indicated that using both universal primers for eukaryotic and prokaryotic microorganisms, each groups of prokaryotic and eukaryotic microorganisms were enumerated without any preliminary information nor setting up standard curve, which were required for real time PCR.

Microbial exopolysaccharides (EPS) are increasingly recognized as effective, biodegradable, and low-toxicity biomaterials for the remediation of heavy metal-contaminated environments. Their high metal-binding capacity, chemical tunability, and microbial renewability make EPS attractive alternatives to conventional physicochemical adsorbents. Although numerous studies have reported the application of EPS in the removal of heavy metals and other toxic pollutants, existing literature remains fragmented, with limited integration of EPS production pathways, structure-function relationships, comparative adsorption performance and limited guidance on scalable production strategies.A key contribution is a consolidated comparative analysis of adsorption capacities of EPS, derived from different microbial taxa against major heavy metals, enabling informed selection of high-performing EPS systems for remediation applications. Furthermore, the review systematically categorizes the major metabolic pathways involved in EPS biosynthesis and identifies key microorganisms utilizing these pathways, highlighting regulatory factors influencing EPS yield and composition. Special emphasis is placed on bioreactor-based EPS production strategies, including batch, fed-batch, and continuous systems, and their role in improving productivity, consistency, and scalability.Emerging approaches such as EPS-based nanocomposites, hybrid materials, and bioengineered microbial systems are also discussed as promising solutions to overcome these limitations. This article provides a comprehensive and critical synthesis of microbial EPS in environmental remediation, focusing on their biosynthesis pathways, physicochemical characteristics, and adsorption mechanisms governing pollutant sequestration. By integrating microbial physiology with performance-oriented remediation outcomes, this review identifies critical bottlenecks and future research priorities required to advance microbial EPS from laboratory demonstrations toward cost-effective and scalable environmental remediation technologies.