Extreme Alkaline Research Articles

Occultella gossypii sp. nov., an alkali-resistant isolate from soil sampled in a cotton field.

A non-spore-forming, motile and alkali-resistant actinobacterium, designated N2-46T, was isolated from an alkaline soil sample collected from a cotton field in the Xinjiang region of PR China. Strain N2-46T formed creamy colonies on tryptone soy agar and managed to survive in extreme alkaline conditions at a pH value of 11. Strain N2-46T displayed the highest 16S rRNA gene similarity of 99.65 % to Haloactinobacterium kanbiaonis HY164T, followed by Occultella aeris F300T (99.61%) and Occultella glacieicola T3246-1T (98.54 %). 16S rRNA-directed phylogenetic analysis showed that strain N2-46T was embedded in a subclade with O. aeris F300T with a bootstrap value of 71.8 %. The phylogenetic tree based on core genes of genome sequences showed that strain N2-46T formed a unique subclade next to H. kanbiaonis HY164T and O. aeris F300T with a bootstrap value of 100 %. Digital DNA-DNA hybridization and the average nucleotide identity analyses showed that strain N2-46T displayed the highest values of 67.1 % (63.2-70.7 %) and 91.82 % with H. kanbiaonis HY164T, respectively. Comparative genomic analysis indicated that strain N2-46T and its three closest neighbours exhibited comparable distribution patterns in heavy metal resistance genes and biosynthetic gene clusters, while displaying distinctions probably related to ecological adaptation. MK-8(H4) was identified as the predominant isoprenoid quinone. The main fatty acids were identified as iso-C14 : 0 and anteiso-C15 : 0. Polar lipids are composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, mono and diacylated phosphatidylinositol dimannosides, as well as several uncharacterized polar lipid, glycolipid, and phospholipids. Genotypic and physiological analyses support the view that strain N2-46T (=JCM 34413T=CGMCC 1.18819T) should be classified as a novel species of the genus Occultella, for which the name Occultella gossypii sp. nov. is proposed.

Highly Reversible “Off‐On‐Off” Dual‐channel Fluorescence Probe Based on Amino Pyrazole and Phenothiazine for Sensing Extremely Alkaline Solution

AbstractAcid‐base balance is related to many cell functions, and its disorders can lead to many diseases. Real‐time detection of intracellular pH fluctuation is very important to prevent many diseases and environmental water samples. Here, we report a dual‐channel fluorescence probe PTZ‐aminopyrazole based on low‐cost phenothiazine and 3‐aminopyrazole, which can detect pH fluctuation highly sensitively through protonation under acidic condition and deprotonation under alkaline condition. The probe exhibits a fluorescence intensity and UV absorbance characteristics in the extreme acidity range of 2.6‐5.5 and especially in the extreme alkaline range of 11.1‐13.8, respectively. In addition, PTZ‐ aminopyrazole has high pH‐selective reaction to metal ions, good reversibility and excellent photostability. Furthermore, PTZ‐aminopyrazole can be fixed on a test paper, which shows a rapid and reversible colorimetric response to HCl/NaOH vapor with naked‐eye.

Effect of Microbial Cell-Free Supernatants Extracted From a Range of pH Levels on Corn (Zea mays L.) and Tomato (Solanum lycopersicum L.) Seed Germination and Seedling Growth

The negative effects of more extreme pH conditions (soil acidity and alkalinity) are increasingly challenging crop production. Managing acidity and alkalinity in soils has been achieved through techniques such as the use of lime, afforestation, tillage, and addition of organic matter. The use of microbes to address this challenge is new and could increase agroecosystem sustainability while helping plants survive more extreme acidity and alkalinity, among other stresses. Use of plant growth promoting microbes (PGPM) has recently gained attention as these microbes afford plants several benefits, including nutrient acquisition and stress tolerance, both biotic and abiotic. Several methods of microbe application have been developed, all intended to maximize the benefits of plant-microbial interactions. The current study assessed the potential of changing microbial culture pH during production, followed by removal of cells to produce supernatant that enhances plant growth, specifically under acidity and alkalinity stresses. The study included L. helveticus. (EL2006H) and B. subtilis (EB2004S) which were cultured at three pH levels (5, 7, and 8) incubated for 24–48 h then centrifuged at 12 000 g to remove the cells. The cell-free supernatants obtained were used for seed germination and early seedling growth assays. The results indicated significant increase in seed germination rate, for both corn and tomato, compared to experimental controls. Supernatants produced at pH 5, for both strains, had greater effect than those produced at pHs 7 and 8. Similarly, the positive effect of these supernatants was observed in seedling growth as increased root length and volume. Their results indicate that there is potential in stressing microbes below or above optimum pH (~7) to induce production and excretion of favorable materials into the growth medium, as was evident in this study. To the best of our knowledge this would be the first attempt to look at this pH change to increase potential benefits related to plant growth promotion by microbes. It was interesting to learn that using the CFS of microbes cultured at pH 5 increased germination rate and seedling growth. These results provide an initial indication that support broadened research into PGPM under pH stressed conditions.

Biomineralization-mimetic growth of ultrahigh-load metal-organic frameworks on inert glass fibers to prepare hybrid membranes for collecting organic hazards in unconventional environment

• Pristine and ultrahigh-load metal-organic frameworks on inert glass fibers. • Hybrid membranes to collect organic hazardous substances in unconventional environs. • Presented ultrahigh-adsorption abilities to substances that included dyes and antibiotics. • Extraordinary robustness to high temperature, organic solvent, extreme alkaline solution. • Suitable for difficult environments, satisfactory recycling, and long-term operation abilities. Exploring new membrane matrices with demanding functions but inert surficial properties to prepare hybrid membranes is challenging. Inspired by biomineralization, we proposed a strategy to grow pristine and ultrahigh-load metal-organic frameworks (MOFs) on inert glass fibers (GF) to prepare GF@MOFs (ZIF-8) hybrid membranes to efficiently collect organic hazardous substance in conventional and unconventional solutions. Comparing with the poor coverage of the MOFs using the conventional method, this new method induced an ultra-high load of MOFs, and even interesting intergrown-particle-, sheet-flower-, and grain-like shapes. The GF@ZIFs exhibited adsorbability of malachite green up to 3964.8 mg g −1 , whereas that of the reported analogues only reached 1667 mg g −1 . The hybrid membranes also exhibited adsorption capability of 192.2 mg g −1 to tetracycline. More importantly, having benefited from the introduction of robust GF matrices, the robustness of the GF@ZIFs was significantly enhanced: synergetic effect derived from the GF and MOFs could be observed. Furthermore, all three types of GF@ZIFs presented well-maintained performance in 70-°C hot water, chloroform, and pH 14 NaOH solution, which are generally nonadoptive to conventional hybrid membranes. The GF@ZIF membranes were further developed as a filter device for rapid collection of over 95% malachite green (50 mg L −1 , 10 mL) in 1 h. The proposed method could create a new direction for exploring new types of matrices to fabricate hybrid materials.

Application of Affitins for Affinity Purification of Proteins.

Affinity chromatography is a powerful purification technique, as it allows proteins of interest to be obtained at a high degree of purity in a single step. This technique can be applied on a research laboratory scale as well as on an industrial scale. The interaction involved in affinity separation most often involves a natural ligand or an antibody specific for the protein of interest, or the recognition of a peptide tag artificially added to the recombinant protein. Unfortunately, natural ligands are not always available and it may be undesirable or impossible to add a purification tag, especially for the production of therapeutic proteins. We have developed Affitins as a new class of artificial affinity proteins that can be generated against virtually any protein of interest. Due to their very high selectivity, their remarkable robustness against extreme acid or alkaline conditions and their low production cost, Affitins are particularly suited to this technique. We describe here the production of Affitins and their immobilization on resin beads to prepare affinity chromatography columns. The protocol also describes the use of these columns.

Electrochemical Synthesis of Ferrate (FeO4 2–) in Extreme Alkaline Medium and its Application in Dye Degradation

Synthesis of ferrate (FeO4 2−) from iron plate of transformer waste electrochemically in high alkaline medium and its application for dye degradation has been carried out. The effect of parameters such as time, NaOH concentration, type of electrolyte solution and ferrate stability were studied. The ferrate solution formed is dark purple in colour with a maximum wavelength of 505 nm. The ferrate was compacted by fresh drying to produce Na2FeO4 crystals and characterized by XRF, XRD and FT-IR techniques. The ferrate was applied to degrade methylene blue, methyl orange, rhodamine and remazol black B dyes. The results showed the highest degradation of dyestuff in methylene blue by 98% and COD reduction by 73.69% at pH 8, ferrate dose of 1.1 mg and contact time of 70 min. This shows that ferrate is an environmentally friendly material which can be used to degrade toxic dyes.

Potential of plant growth-promoting rhizobacteria-plant interactions in mitigating salt stress for sustainable agriculture: A review

Soil salinization affecting different crops is one of the serious threats to global food security. Soil salinity affects 20% and 33% of the total cultivated and irrigated agricultural lands, respectively, and has been reported to caused a global crop production loss of 27.3 billion USD. The conventional approaches, such as using salt-tolerant varieties, saline soil scrapping, flushing, leaching, and adding supplements ( e.g ., gypsum and lime), often fail to alleviate stress. In this context, developing diverse arrays of microbes enhancing crop productivity under saline soil conditions without harming soil health is necessary. Various advanced omics approaches have enabled gaining new insights into the structure and metabolic functions of plant-associated beneficial microbes. Various genera of salt-tolerating rhizobacteria ameliorating biotic and abiotic stresses have been isolated from different legumes, cereals, vegetables, and oil seeds under extreme alkaline and saline soil conditions. Rapid progress in rhizosphere microbiome research has revived the belief that plants may be more benefited from their association with interacting diverse microbial communities as compared with individual members in a community. In the last decade, several salt-tolerating plant growth-promoting rhizobacteria (PGPR) that improve crop production under salt stress have been exploited for the reclamation of saline agrosystems. This review highlights that the interaction of salt-tolerating microbes with plants improves crop productivity under salinity stress along with potential salt tolerance mechanisms involved and will open new avenues for capitalizing on cultivable diverse microbial communities to strengthen plant salt tolerance and, thus, to refine agricultural practices and production under saline conditions.

Hydrolytic Degradation of Polylactic Acid Fibers as a Function of pH and Exposure Time.

Polylactic acid (PLA) is a widely used bioresorbable polymer in medical devices owing to its biocompatibility, bioresorbability, and biodegradability. It is also considered a sustainable solution for a wide variety of other applications, including packaging. Because of its widespread use, there have been many studies evaluating this polymer. However, gaps still exist in our understanding of the hydrolytic degradation in extreme pH environments and its impact on physical and mechanical properties, especially in fibrous materials. The goal of this work is to explore the hydrolytic degradation of PLA fibers as a function of a wide range of pH values and exposure times. To complement the experimental measurements, molecular-level details were obtained using both molecular dynamics (MD) simulations with ReaxFF and density functional theory (DFT) calculations. The hydrolytic degradation of PLA fibers from both experiments and simulations was observed to have a faster rate of degradation in alkaline conditions, with 40% of strength loss of the fibers in just 25 days together with an increase in the percent crystallinity of the degraded samples. Additionally, surface erosion was observed in these PLA fibers, especially in extreme alkaline environments, in contrast to bulk erosion observed in molded PLA grafts and other materials, which is attributed to the increased crystallinity induced during the fiber spinning process. These results indicate that spun PLA fibers function in a predictable manner as a bioresorbable medical device when totally degraded at end-of-life in more alkaline conditions.

Effects of combined treatment with ultrasound and pH shifting on foaming properties of chickpea protein isolate

In this study, the foaming properties of chickpea protein isolate (CPI) subjected to different pH shifting treatment were investigated. It was found that the foaming ability (FA) of CPI, CPI subjected to treatment with pH shifting at pH 2 and pH 12 (CPI2 and CPI12), CPI subjected to combined treatment of ultrasound with pH shifting at pH 2 and pH 12 (CPI2–U and CPI12–U) were 81.1%, 180%, 225.5%, 212.1%, and 263.3%, respectively, while the foaming stability (FS) of these CPI did not change significantly. These results indicated that pH shifting under extreme acid or alkaline pH condition significantly enhanced the foaming properties of CPI, while the use of ultrasound further intensify this change. The best foaming properties of CPI12–U was ascribed to its smallest particle size, zeta potential, interfacial tension, the largest solubility and surface hydrophobicity. Besides, the free sulfhydryl content of CPI subjected to these treatments increased significantly, facilitating their adsorption to the air-liquid interface. Moreover, the increased content of α-helixes for CPI subjected to these treatments contributed to the formation of more stable interfaces. So this study provided a convenient means to significantly improve the foaming properties of CPI.

Effects of Bicarbonate Stress on Serum Ions and Gill Transporters in Alkali and Freshwater Forms of Amur Ide (Leuciscus waleckii).

The Amur ide (Leuciscus waleckii) is a fish in the Cyprinidae family. Compared with other Amur ide living in freshwater ecosystems, the Amur ide population in Lake Dali Nor of China is famous for its high tolerance to the alkaline conditions of 54 mM (pH 9.6). Yet, surprisingly, the ionoregulatory mechanism responsible for this remarkable alkaline adaptation remains unclear. Therefore, this study sought to investigate how bicarbonate affects the acid-base balancing and ionoregulatory responses of this animal. Here, using a comparative approach, the alkali form of Amur ide and its ancestral freshwater form living in other freshwater basins were each exposed to 50 mM (pH 9.59 ± 0.09), a level close to the alkalinity of Lake Dali Nor, and their physiological (AE1) adjustment of ions and acid-base regulation were investigated. This study highlighted differences in blood pH and serum ions (e.g., Na+, K+, Cl−, and Ca2+), Na+/K+ ATPase (NKA) activity and its mRNA level, and mRNA expression of gill transporters (Na+/H+ exchanger member 2 and/or 3, Na+/ cotransporter (NBC1), Cl−/ exchanger, Na+/Cl− cotransporter (NCC), Na+/K+/2Cl− (NKCC1), SLC26A5, and SLC26A6) for alkalinity adaptation between the two forms of Amur ide differing in alkalinity tolerance. Specifically, close relationships among the serum Na+ and mRNA levels of NCC, NKCC1, and NHE, and also NKA and NBC1, in addition to serum Cl− and bicarbonate transporters (e.g., SLC26A5 and SLC26A6), characterized the alkali form of Amur ide. We propose that this ecotype can ensure its transepithelial Cl− and Na+ uptake/base secretions are highly functional, by its basolateral NKA with NBC1 and apical ionic transporters, and especially NCC incorporated with other transporters (e.g., SLC26). This suggests an evolved strong ability to maintain an ion osmotic and acid-base balance for more effectively facilitating its adaptability to the high alkaline environment. This study provides new insights into the physiological responses of the alkaline form of the Amur ide fish for adapting to extreme alkaline conditions. This information could be used as a reference to cultivating alkaline-tolerant fish species in abandoned alkaline waters.

Kinetics on the Oxidation of Aminoiminomethanesulfonic Acid by Hypochlorous Acid: A Novel Product in the Chlorination of Aminoiminomethanesulfonic Acid

AbstractThe oxidation of aminoiminomethanesulfonic acid (AIMSOA) by HOCl is too fast to be traced in both acidic and neutral solutions, while extreme alkalinity will hasten the decomposition of AIMSOA. Nonetheless, in weakly alkaline solutions the oxidation kinetics were monitored successfully by stopped flow at 25 °C. The results show that the rate law is first order with respect to both [HOCl]tot and [AIMSOA] but shows an inverse dependence on [OH−]. The calculated kHOCl values of (9.2±0.2)×106 M−1 s−1 and a statistically insignificant kOCl‐ value indicate that the conjugate acid HOCl is regarded as the primary oxidant. The reaction is supposed to be a Cl+ transfer mechanism followed by the formation of a novel unreported oxidation product, AIMSOA‐chloramine. Various technologies were employed to investigate the structure and decomposition of AIMSOA‐chloramine. The above evidence showed that the product, a kind of chloramine rather than sulfate, was characterized by a distinct structure consisting of N−Cl bond. The chloramine could also slowly decompose to sulfate and chloride due to the cleavage of both C−S and N−Cl bonds. Based on the results, the mechanism involving the production of chloride and sulfate from the oxidation of AIMSOA in Cl‐containing oxides ‐ thiourea system should be excluded. In addition, the results also provide additional insights into the bromination for the HOBr‐AIMSOA reaction, in which priority may be given to the formation of bromamine.

Molecular structural modification of egg white protein by pH-shifting for improving emulsifying capacity and stability

The effect of pH-shifting on the molecular structure and emulsifying properties of egg white protein (EWP) was investigated. EWP was subjected to extreme alkaline pH treatment (11, 11.5, 12, 12.5, and 13) and then adjusted to neutral (pH 7.0). The results showed that the emulsifying activity and emulsion stability of EWP were enhanced under pH-shifting, especially at pH 13. The surface hydrophobicity of EWP13 increased significantly from 306.94 to 11653.67 (p < 0.05), and the free sulfhydryl content of EWP13 increased significantly from 15.106 μmol/g to 121.86 μmol/g (p < 0.05). Also, the size and turbidity of EWP13 were minimal, producing EWP soluble aggregates with an average size of 52.90 nm (p < 0.05). Moreover, circular dichroism (CD) and intrinsic fluorescence spectra showed that the secondary and tertiary structures changed. At EWP12.5 and EWP13, it showed a decrease of α-helix and an increase of β-sheet. The intrinsic fluorescence spectra suggested that Phe, Tyr, and Trp were exposed to a polar environment due to EWP unfolding. In conclusion, the EWP structure was changed by pH-shifting, resulting in more exposed hydrophobic groups, thus increasing the emulsion stability. Correspondingly, the emulsion of EWP13 showed the best stability under the conditions of oxidation, heating, and salt than native EWP. This work may provide an effective method and theoretical basis for molecular modification to improve the functional properties of EWP by pH-shifting treatment.

Systematic Exploration of the Synthetic Parameters for the Production of Dynamic VO2(M1).

Thermochromic dynamic cool materials present a reversible change of their properties wherein by increasing the temperature, the reflectance, conductivity, and transmittance change due to a reversible crystalline phase transition. In particular, vanadium (IV) dioxide shows a reversible phase transition, accompanied by a change in optical properties, from monoclinic VO2(M1) to tetragonal VO2(R). In this paper, we report on a systematic exploration of the parameters for the synthesis of vanadium dioxide VO2(M1) via an easy, sustainable, reproducible, fast, scalable, and low-cost hydrothermal route without hazardous chemicals, followed by an annealing treatment. The metastable phase VO2(B), obtained via a hydrothermal route, was converted into the stable VO2(M1), which shows a metal–insulator transition (MIT) at 68 °C that is useful for different applications, from energy-efficient smart windows to dynamic concrete. Within this scenario, a further functionalization of the oxide nanostructures with tetraethyl orthosilicate (TEOS), characterized by an extreme alkaline environment, was carried out to ensure compatibility with the concrete matrix. Structural properties of the synthesized vanadium dioxides were investigated using temperature-dependent X-ray Diffraction analysis (XRD), while compositional and morphological properties were assessed using Scanning Electron Microscopy, Energy Dispersive X-ray Analysis (SEM-EDX), and Transmission Electron Microscopy (TEM). Differential Scanning Calorimetry (DSC) analysis was used to investigate the thermal behavior.

Genomic Signature of Shifts in Selection and Alkaline Adaptation in Highland Fish.

Understanding how organisms adapt to aquatic life at high altitude is fundamental in evolutionary biology. This objective has been addressed primarily related to hypoxia adaptation by recent comparative studies, whereas highland fish has also long suffered extreme alkaline environment, insight into the genomic basis of alkaline adaptation has rarely been provided. Here, we compared the genomes or transcriptomes of 15 fish species, including two alkaline tolerant highland fish species and their six alkaline intolerant relatives, three alkaline tolerant lowland fish species, and four alkaline intolerant species. We found putatively consistent patterns of molecular evolution in alkaline tolerant species in a large number of shared orthologs within highland and lowland fish taxa. Remarkably, we identified consistent signatures of accelerated evolution and positive selection in a set of shared genes associated with ion transport, apoptosis, immune response, and energy metabolisms in alkaline tolerant species within both highland and lowland fish taxa. This is one of the first comparative studies that began to elucidate the consistent genomic signature of alkaline adaptation shared by highland and lowland fish. This finding also highlights the adaptive molecular evolution changes that support fish adapting to extreme environments at high altitude.

Novel mechanisms of epithelial ion transport: insights from the cryptonephridial system of lepidopteran larvae.

Lepidopterans are among the most widespread and easily recognized insects. Whereas adult lepidopterans are known for their beauty and ecological importance as pollinators and sources of food for other animals, larvae are economically important pests of forests and agricultural crops. In the larval body, rapid growth while feeding on plant-based diet is associated with extreme alkalinity (up to pH = 11) of the midgut lumen that helps digest plant proteins. Additionally, the presence of plant secondary metabolites which serve as anti-herbivory agents requires uninterrupted excretory function, accomplished primarily by the Malpighian tubules (MTs). The so-called cryptonephridial condition, along with extreme regional heterogeneity of the MTs, and the ability to rapidly and reversibly alter the direction of epithelial ion transport are features that allow uninterrupted MT functioning and recycling of base equivalents. Studies of MTs in lepidopteran larvae have revealed that rapid adjustments in epithelial ion transport include unexpected roles for voltage-gated, ligand-gated and mechanosensitive ion channels, as well as gap junctions. These molecular components are present in epithelia of a variety of vertebrates and invertebrates and thus are likely to constitute a universal epithelial toolkit for rapid autonomous regulation of epithelial function.

Contribution of the Locus of Heat Resistance to Growth and Survival of Escherichia coli at Alkaline pH and at Alkaline pH in the Presence of Chlorine.

The locus of heat resistance (LHR) confers resistance to extreme heat, chlorine and oxidative stress in Escherichia coli. This study aimed to determine the function of the LHR in maintaining bacterial cell envelope homeostasis, the regulation of the genes comprising the LHR and the contribution of the LHR to alkaline pH response. The presence of the LHR did not affect the activity of the Cpx two-component regulatory system in E. coli, which was measured to quantify cell envelope stress. The LHR did not alter E. coli MG1655 growth rate in the range of pH 6.9 to 9.2. However, RT-qPCR results indicated that the expression of the LHR was elevated at pH 8.0 when CpxR was absent. The LHR did not improve survival of E. coli MG1655 at extreme alkaline pH (pH = 11.0 to 11.2) but improved survival at pH 11.0 in the presence of chlorine. Therefore, we conclude that the LHR confers resistance to extreme alkaline pH in the presence of oxidizing agents. Resistance to alkaline pH is regulated by an endogenous mechanism, including the Cpx envelope stress response, whereas the LHR confers resistance to extreme alkaline pH only in the presence of additional stress such as chlorine.

Hot-pressed polyelectrolyte complexes as novel alkaline stable monovalent-ion selective anion exchange membranes

Polymeric ion-exchange membranes have come a long way since their invention, benefiting a wide range of processes, ranging from desalination to fuel cells. However, challenges such as alkaline stability, monovalent ion selectivity, cost-effectivity, and process sustainability largely persist. This work showcases alkaline stable anion-exchange membranes made by hot-pressing of a polyelectrolyte complex of poly(styrenesulfonate) (PSS) and poly(diallyldimethylammonium) (PDADMA). This completely aqueous production approach leads to especially dense (non-porous) saloplastic films with an excess of cationic groups, demonstrating good stability even at high salinities (up to 2 M NaCl). On key performance indicators for anion exchange membranes, such as water uptake (~40%), permselectivity (up to 97%), ion exchange capacity (1.01 mmol g−1), and resistance (2.3 O·cm2) the membranes show comparable values to commercial membranes. A drop in permselectivity at high salinities, however, indicates that the charge density of the membranes could be further improved. Still, what really sets these membranes apart is their natural long term (up to 60 days) stability at extreme acidic (pH 0) and alkaline conditions (pH 14) and a relevant monovalent selectivity of up to 6.3 for Cl− over SO42−. Overall this work showcases PDADMA/PSS based saloplastics as highly promising and stable anion-exchange membranes, that can be produced by a simple, scalable, and sustainable approach.

Engineering stable carbonic anhydrases for CO2 capture: a critical review.

Targeted inhibition of misregulated protein-protein interactions (PPIs) has been a promising area of investigation in drug discovery and development for human diseases. However, many constraints remain, including shallow binding surfaces and dynamic conformation changes upon interaction. A particularly challenging aspect is the undesirable off-target effects caused by inherent structural similarity among the protein families. To tackle this problem, phage display has been used to engineer PPIs for high-specificity binders with improved binding affinity and greatly reduced undesirable interactions with closely related proteins. Although general steps of phage display are standardized, library design is highly variable depending on experimental contexts. Here in this review, we examined recent advances in the structure-based combinatorial library design and the advantages and limitations of different approaches. The strategies described here can be explored for other protein-protein interactions and aid in designing new libraries or improving on previous libraries.

Isolation of a novel strain of Cyanobacterium sp. with good adaptation to extreme alkalinity and high polysaccharide yield

Isolation of a novel strain of Cyanobacterium sp. with good adaptation to extreme alkalinity and high polysaccharide yield

Characterizationharacterization of Extremophilic Actinomycetes Strains as Sources of Antimicrobial Agents.

Extremophilic actinomycetes strains can survive extreme saline and alkaline environments and produce antimicrobial agents. In this chapter, we discuss laboratory methods that can be used to isolate and characterize actinomycetes strains capable of potentially producing novel antimicrobial agent(s) when cultured in conditions that mimic the environments from which they were isolated. Methods used to screen for antibacterial and antiviral activities from these producer strains, and microbiological and molecular approaches used to identify these strains are described. Here we describe three methods. Method 1 focuses on the strategy to select optimal conditions to synthesize and accumulate the antibiotics from the studied actinomycetes strains by preparing crude extracts. In Method 2, we describe the screening strategies used to test the actinomycetes strains against gram-negative and gram-positive bacteria, antifungal agents, multidrug-resistant pathogens (MDR), and viral pathogens. Thus, the specific techniques to test for MDR pathogens such as the disk diffusion assay and wells assay are outlined. We also describe the antiviral activity screening of the selected actinomycetes extracts in Method 2 of this chapter. Specifically, we concentrate on methods used to test for antiviral activities such as primary hemolytic, hemagglutination, neuraminidase, and specific virus-inhibitory activities. Finally, the Method 3 section reveals the microbiological techniques used to morphologically characterize the actinomycetes strains that depend on the culture medium utilized for growth. Additionally, the method used to perform a detailed characterization of the morphology that actinomycetes strains possess is specified by the protocol for sample preparation and visualization using the scanning electron microscopy (SEM). Finally, we summarize the molecular approaches used to characterize actinomycetes strains, focusing specifically on the PCR and sequencing techniques.