Search

Terpenoids are the largest class of natural products, found across all domains of life. One of the most abundant bacterial terpenoids is the volatile odorant 2-methylisoborneol (2-MIB), partially responsible for the earthy smell of soil and musty taste of contaminated water. Many bacterial 2-MIB biosynthetic gene clusters were thought to encode a conserved transcription factor, named EshA in the model soil bacterium Streptomyces griseus. Here, we revise the function of EshA, now referred to as Sg Enc, and show that it is a Family 2B encapsulin shell protein. Using cryo-electron microscopy, we find that Sg Enc forms an icosahedral protein shell and encapsulates 2-methylisoborneol synthase (2-MIBS) as a cargo protein. Sg Enc contains a cyclic adenosine monophosphate (cAMP) binding domain (CBD)-fold insertion and a unique metal-binding domain, both displayed on the shell exterior. We show that Sg Enc CBDs do not bind cAMP. We find that 2-MIBS cargo loading is mediated by an N-terminal disordered cargo-loading domain and that 2-MIBS activity and Sg Enc shell structure are not modulated by cAMP. Our work redefines the function of EshA and establishes Family 2B encapsulins as cargo-loaded protein nanocompartments involved in secondary metabolite biosynthesis. The volatile odorant 2- methylisoborneol is one of the most abundant terpenoid natural products found in nature. Here, the authors report biochemical and structural data showing that bacterial 2-methylisoborneol biosynthesis is compartmentalized inside a megadalton encapsulin protein compartment. [ABSTRACT FROM AUTHOR]

Simple Summary: Ruminal protein degradation of seven feedstuffs was estimated in sacco and in vitro by using a protease assay. In sacco protein degradation data were used as reference. The accuracy of the protease assay is reduced by two methodological aspects. During in vitro incubation, microbial activity induced by microbial colonization of the feedstuff may increase, requiring antibiotic solutions in protease assays. The protease alone cannot sufficiently hydrolyze protein–carbohydrate complexes. Therefore, a carbohydrase of fiber- or starch-hydrolyzing activity was added to the protease assay as a simultaneous incubation. The antibiotic solution reduced protein degradation by protease. The antibiotic solution is recommended to prevent microbial activity and improve standardization of the protease assay. Differences between in sacco and in vitro degradation data were not essentially reduced by additional carbohydrases. Unfavorable incubation conditions and the inhibitory effect of protease on the carbohydrase activity during simultaneous incubation may be responsible for the insufficient hydrolysis of protein–carbohydrate complexes by the carbohydrases. It does not seem promising to incubate protease and carbohydrase simultaneously. The objectives of the study were to examine the effect of an antibiotic solution applied in the Streptomyces griseus protease method (SGPM) and the effect of carbohydrases in SGPM on the effective crude protein (CP) degradation (ED) with reference to in sacco ED. For this purpose, the ruminal CP degradation of rapeseed meal, dried distillers' grains with solubles, wheat grain, corn grain, corn silage, grass silage and partial crop field pea silage was determined in sacco using three rumen-fistulated dairy cows and in vitro using SGPM. The impact of the antibiotic solution on CP degradation by S. griseus protease was investigated by supplementing SGPM with Penicillin–Streptomycin solution to reduce microbial mass proliferation during incubation. The carbohydrase α-amylase or Viscozym® L (cell wall-degrading enzyme mixture) was added to the SGPM at four different doses simultaneously as a co-incubation to improve feed protein accessibility. For most feedstuffs, ED was lower when the antibiotic solution was used in SGPM (p < 0.05). The use of an antibiotic solution in the SGPM is recommended to standardize the SGPM. The in sacco ED values were significantly underestimated by the SGPM and by the SGPM with co-incubated carbohydrase (p < 0.05). Co-incubation of S. griseus protease and carbohydrase was not successful in reducing the differences to the in sacco CP degradation. [ABSTRACT FROM AUTHOR]

Chemical compounds that affect microbial interactions have attracted wide interest. In this study, Streptomyces griseus showed enhanced growth when cocultured with the rice blast fungus Pyricularia oryzae on potato dextrose agar (PDA) medium. An improvement in S. griseus growth was observed before contact with P. oryzae, and no growth‐promoting effect was observed when the growth medium between the two microorganisms was separated. These results suggested that the chemicals produced by P. oryzae diffused through the medium and were not volatile. A PDA plate supplemented with phenol red showed that the pH of the area surrounding P. oryzae increased. The area with increased pH promoted S. griseus growth, suggesting that the alkaline compounds produced by P. oryzae were involved in this growth stimulation. In contrast, coculture with the soilborne plant pathogen Fusarium oxysporum and entomopathogenic fungus Cordyceps tenuipes did not promote S. griseus growth. Furthermore, DL‐α‐Difluoromethylornithine, a polyamine biosynthesis inhibitor, prevented the increase in pH and growth promotion of S. griseus by P. oryzae. These results indicated that P. oryzae increased pH by producing a polyamine. [ABSTRACT FROM AUTHOR]

Compost is a natural and sustainable way to improve soil fertility and enhance plant growth. Moringa leaves have high mineral, cytokinin, and vitamin content which are useful for growth so that they can be used as organic fertilizer. Azotobacter and Streptomyces are from soil and have many biological activities. This study aimed to detect the importance of bioagents formula with Moringa Compost (MC) to enhance plant growth in poor sterile soil and plants were irrigated with half strength of Hoagland nutrient solution. Moringa leaves were collected and cleaned, and organic compost was prepared and analyzed for microbial and chemical composition. The prepared MC was rich in nitrogen and minerals and had high content of bacteria and fungi. The two bioagents used were isolate MB5 and MB11 which were characterized and molecular identified as Azotobacter chroococcum MB5 and Streptomyces griseus MB11. The free-living A. chroococcum can fix atmospheric nitrogen while Streptomyces is a filamentous bacterium with a high ability to produce secondary metabolites. The addition of 20% MC to soil increased soil EC and microbial counts compared to MC-free soil. Moreover, inoculation of soil with either AZ or ST increased the microbial counts and soil EC and the clearest increase was in the case of inoculation of soil with MC+AZ+ST. It also found that MC extract alone with the bacterial filtrates increases seed germination of Phaseolus vulgaris L. (common bean), which is a herbaceous annual worldwide plant, grown for its edible dry seeds or green unripe pods. In this regard, inoculation of soil with inoculum of both A. chroococcum MB5, and S. griseus MB11, in the presence of MC has the most pronounced effect and enhances both the growth, fresh and dry weights, leaf number, plant height, and root length of P. vulgaris grown under greenhouse conditions for one month and chemical content of the plant protein carbohydrates, P, N, Ca++ and K+. In conclusion, the combined application A. chroococcum MB5 and S. griseus MB11, as a biofertilizers with Moringa compost is recommended to enhance P. vulgaris growth. The use of these biofertilizers can reduce the use of chemical fertilizers, which can have detrimental effects on soil and the environment. Therefore, further research on the inoculation and application of these microorganisms with MC is essential for sustainable agriculture.

Efficient delivery systems based on biopolymers offer new solutions to enhance food security by boosting crop yield and quality while decreasing agrochemical input and mitigating environmental impact. Herein, a novel Pickering emulsion fabrication method that utilizes antibody‐functionalized silk fibroin to enhance foliar adhesion upon application for efficient agrochemicals delivery is reported. Silk fibroin microparticles (SFMPs) stabilize both nonpolar and polar oil‐in‐water Pickering emulsions, revealing the cooperative function of both oil phase polarity and aqueous media pH in stabilization, where phytohormones addition influenced the stability and oil‐water contact angle. Phytohormone‐containing Pickering emulsions are functionalized with anti‐pectic polysaccharide (alpha‐1,5‐arabinan) antibody labeled SFMPs through adsorption, to enhance droplet adhesion to leaf cuticle surface. As a proof‐of‐concept, Pickering emulsion containing 0.1 mM jasmonic acid (JA) is applied to Arabidopsis thaliana via foliar spraying. Following washing, treatment with antibody‐functionalized Pickering emulsion increased trichome numbers on young leaves by 20% and 3%, when compared to nonencapsulated JA and nonfunctionalized emulsions, respectively. The functionalized Pickering emulsion stabilized by SFMPs exhibited no plant toxicity and biodegraded 50 wt.% in 7 days, catalyzed by Streptomyces griseus protease. Results highlight the potential of SFMP‐stabilized oleic acid‐in‐water Pickering emulsion as a sustainable and biodegradable solution to precisely deliver agrochemicals through foliar spray. [ABSTRACT FROM AUTHOR]

Compost is a natural and sustainable way to improve soil fertility and enhance plant growth. Moringa leaves have high mineral, cytokinin, and vitamin content which are useful for growth so that they can be used as organic fertilizer. Azotobacter and Streptomyces are from soil and have many biological activities. This study aimed to detect the importance of bioagents formula with Moringa Compost (MC) to enhance plant growth in poor sterile soil and plants were irrigated with half strength of Hoagland nutrient solution. Moringa leaves were collected and cleaned, and organic compost was prepared and analyzed for microbial and chemical composition. The prepared MC was rich in nitrogen and minerals and had high content of bacteria and fungi. The two bioagents used were isolate MB5 and MB11 which were characterized and molecular identified as Azotobacter chroococcum MB5 and Streptomyces griseus MB11. The free-living A. chroococcum can fix atmospheric nitrogen while Streptomyces is a filamentous bacterium with a high ability to produce secondary metabolites. The addition of 20% MC to soil increased soil EC and microbial counts compared to MC-free soil. Moreover, inoculation of soil with either AZ or ST increased the microbial counts and soil EC and the clearest increase was in the case of inoculation of soil with MC+AZ+ST. It also found that MC extract alone with the bacterial filtrates increases seed germination of Phaseolus vulgaris L. (common bean), which is a herbaceous annual worldwide plant, grown for its edible dry seeds or green unripe pods. In this regard, inoculation of soil with inoculum of both A. chroococcum MB5, and S. griseus MB11, in the presence of MC has the most pronounced effect and enhances both the growth, fresh and dry weights, leaf number, plant height, and root length of P. vulgaris grown under greenhouse conditions for one month and chemical content of the plant protein carbohydrates, P, N, Ca++ and K+. In conclusion, the combined application A. chroococcum MB5 and S. griseus MB11, as a biofertilizers with Moringa compost is recommended to enhance P. vulgaris growth. The use of these biofertilizers can reduce the use of chemical fertilizers, which can have detrimental effects on soil and the environment. Therefore, further research on the inoculation and application of these microorganisms with MC is essential for sustainable agriculture. [ABSTRACT FROM AUTHOR]

The present study aims to obtain manganese ferrite nanoparticles functionalized with chitosan (C-MNP) or ethylenediamine (E-MNP) by coprecipitation and polyol one-step methods, characterize their interaction with S. griseus demonstrating cell immobilization, and evaluate the antimicrobial activity of the free cell extracts obtained from immobilized S. griseus fermentation in the presence of different concentrations of MNP. The adsorption isotherms were analyzed mathematically using Langmuir and Freundlich models. The highest coefficient of determination (R2) for the S. griseus cell adsorption isotherm with C-MNP was observed with a linear function of the Langmuir model. The adsorption isotherm of S. griseus cells with E-MNP was better fitted to the Freundlich model. Cell immobilization by adsorption on magnetic nanoparticles was demonstrated in both cases. Different concentrations of C-MNP and E-MNP were used in fermentations to prepare cell-free extracts with antifungal activity. The best results were obtained with E-MNP, with a 91.5% inhibition of radial fungal growth. Magnetic nanoparticles offer potential applications in different fields and easy biomass separation. [ABSTRACT FROM AUTHOR]

Indolizidines have long been recognized for their valuable bioactivities, their common feature being a bicyclic structure connected via a nitrogen atom. Traditionally, plants have been identified as the primary producers. However, recent discoveries have revealed that certain bacterial strains belonging to the genus of actinomycetes also possess the ability to synthesize various indolizidine-based compounds. Among these strains, Streptomyces sp. HNA39, Saccharopolyspora sp. RL78, and Streptomyces NCIB 11649 have been identified as producers of cyclizidines, characterized by their distinctive cyclopropyl moiety. Additionally, Streptomyces griseus OS-3601 synthesizes a unique class of indolizidine derivatives known as iminimycins, distinguished by their rare imine-cation structure. Protoplast fusion of a Streptomyces griseus strain with Streptomyces tenjimariensis resulted in a new indolizidine named indolizomycin. This review aims to provide an overview of known bacterial indolizidine producers, summarize current knowledge regarding the biosynthesis of cyclizidines and iminimycins, and assess their respective bioactivities. [ABSTRACT FROM AUTHOR]

Some of the most metabolically diverse species of bacteria (e.g., Actinobacteria) have higher GC content in their DNA, differ substantially in codon usage, and have distinct protein folding environments compared to tractable expression hosts like Escherichia coli. Consequentially, expressing biosynthetic gene clusters (BGCs) from these bacteria in E. coli often results in a myriad of unpredictable issues with regard to protein expression and folding, delaying the biochemical characterization of new natural products. Current strategies to achieve soluble, active expression of these enzymes in tractable hosts can be a lengthy trial-and-error process. Cell-free expression (CFE) has emerged as a valuable expression platform as a testbed for rapid prototyping expression parameters. Here, we use a type III polyketide synthase from Streptomyces griseus, RppA, which catalyzes the formation of the red pigment flaviolin, as a reporter to investigate BGC refactoring techniques. We applied a library of constructs with different combinations of promoters and rppA coding sequences to investigate the synergies between promoter and codon usage. Subsequently, we assess the utility of cell-free systems for prototyping these refactoring tactics prior to their implementation in cells. Overall, codon harmonization improves natural product synthesis more than traditional codon optimization across cell-free and cellular environments. More importantly, the choice of coding sequences and promoters impact protein expression synergistically, which should be considered for future efforts to use CFE for high-yield protein expression. The promoter strategy when applied to RppA was not completely correlated with that observed with GFP, indicating that different promoter strategies should be applied for different proteins. In vivo experiments suggest that there is correlation, but not complete alignment between expressing in cell free and in vivo. Refactoring promoters and/or coding sequences via CFE can be a valuable strategy to rapidly screen for catalytically functional production of enzymes from BCGs, which advances CFE as a tool for natural product research. [ABSTRACT FROM AUTHOR]

Simple Summary: Given the imperative need to control Salmonella in animal production, and the escalating problem of antimicrobial resistance, there is a paramount requirement for alternative strategies that can uphold both animal productivity and health. In this context, the utilization of probiotics is an important option that needs to be further studied. This research encompassed a comprehensive analysis to assess the probiotic potential of Bacillus and Streptomyces griseus. The strains used exhibited significant inhibitory activity against Salmonella and the production of antimicrobial metabolites, and demonstrated robust survivability throughout gastrointestinal transit. Consequently, it is inferred that these bacterial strains hold substantial promise as a biotechnological solution for Salmonella control in animal production. Probiotics are increasingly recognized for their potential in managing bacterial challenges in animal production. This study aimed to evaluate the probiotic potential of Bacillus and Streptomyces strains, specifically their bioprotective ability against Salmonella. In agar inhibition assays, these bacteria supported Salmonella-inhibition zones, ranging from 2.5 ± 0.5 to 6.3 ± 2.0 mm. Analyses of antimicrobial metabolites revealed their capacity to produce compounds with anti-Salmonella properties, except for Bacillus subtilis MLB2. When Salmonella was exposed to lyophilized metabolites, inhibition occurred in both liquid (at concentrations between 250 and 500 g/L) and solid cultures (at 500 g/L). To confirm their probiotic potential, the S. griseus and Bacillus strains underwent evaluations for antimicrobial resistance, bile salt tolerance, auto- and co-aggregation, pH resistance, and their ability to adhere to and inhibit Salmonella in Caco-2 cells. These assessments confirmed their probiotic potential. The probiotic strains were further encapsulated and subjected to simulated swine and poultry digestion. They demonstrated survival potential through the gastrointestinal tract and significantly reduced the Salmonella population. Thus, these strains exhibit considerable promise for producing biotechnological products aimed at controlling Salmonella in animal production. This approach ensures the health and hygiene of farming facilities, mitigates the spread of zoonotic bacteria, and contributes positively to public health. [ABSTRACT FROM AUTHOR]

The potential of using microorganisms as biological sources of industrially economic enzymes has stimulated interest in the exploitation of extracellular enzymatic activity in several microorganisms. The aim of this research is to assess the cellulose degrading potentials of two microorganisms, Aspergillus oryzae and Streptomyces griseus using cellulose Congo red agar media. Soil sample collected from waste dump was serially diluted and inoculated in starch casein agar and SDA to isolate S. griseus and A. oryzae respectively. To assess their potentials to utilize cellulose, each of the two microorganisms was inoculated on cellulose Congo-red media and incubated at 30 ℃ for 7days. A zone of clearing around the colonies after incubation confirms the secretion of extracellular cellulase, and was used as an indication for cellulose utilization. The zone of clearing was measured with a meter rule. In the results obtained, both microorganisms demonstrated cellulose utilization ability with Aspergillus oryzae showing a zone of clearing of 30.50 ± 0.50 mm while Streptomyces griseus showed a wider zone of clearing of 60.00 ± 1.00 mm. The results indicate that both microorganisms can be potent producers of the enzyme cellulase, with Streptomyces griseus having a higher cellulase-producing ability. [ABSTRACT FROM AUTHOR]

Amino acid‐based surfactants are valuable compounds for cosmetic formulations. The chemical synthesis of acyl amino acids is conventionally performed by the Schotten–Baumann reaction using fatty acyl chlorides, but aminoacylases have also been investigated for use in biocatalytic synthesis with free fatty acids. Aminoacylases and their properties are diverse; they belong to different peptidase families and show differences in substrate specificity and biocatalytic potential. Bacterial aminoacylases capable of synthesis have been isolated from Burkholderia, Mycolicibacterium, and Streptomyces. Although several proteases and peptidases from S. griseus have been described, no aminoacylases from this species have been identified yet. In this study, we investigated two novel enzymes produced by S. griseus DSM 40236T. We identified and cloned the respective genes and recombinantly expressed an α‐aminoacylase (EC3.5.1.14), designated SgAA, and an ε‐lysine acylase (EC3.5.1.17), designated SgELA, in S. lividans TK23. The purified aminoacylase SgAA was biochemically characterized, focusing on its hydrolytic activity to determine temperature‐ and pH optima and stabilities. The aminoacylase could hydrolyze various acetyl amino acids at the Nα‐position with a broad specificity regarding the sidechain. Substrates with longer acyl chains, like lauroyl amino acids, were hydrolyzed to a lesser extent. Purified aminoacylase SgELA specific for the hydrolysis of Nε‐acetyl‐l‐lysine was unstable and lost its enzymatic activity upon storage for a longer period but could initially be characterized. The pH optimum of SgELA was pH 8.0. While synthesis of acyl amino acids was not observed with SgELA, SgAA catalyzed the synthesis of lauroyl‐methionine.

Amino acid‐based surfactants are valuable compounds for cosmetic formulations. The chemical synthesis of acyl amino acids is conventionally performed by the Schotten–Baumann reaction using fatty acyl chlorides, but aminoacylases have also been investigated for use in biocatalytic synthesis with free fatty acids. Aminoacylases and their properties are diverse; they belong to different peptidase families and show differences in substrate specificity and biocatalytic potential. Bacterial aminoacylases capable of synthesis have been isolated from Burkholderia, Mycolicibacterium, and Streptomyces. Although several proteases and peptidases from S. griseus have been described, no aminoacylases from this species have been identified yet. In this study, we investigated two novel enzymes produced by S. griseus DSM 40236T. We identified and cloned the respective genes and recombinantly expressed an α‐aminoacylase (EC3.5.1.14), designated SgAA, and an ε‐lysine acylase (EC3.5.1.17), designated SgELA, in S. lividans TK23. The purified aminoacylase SgAA was biochemically characterized, focusing on its hydrolytic activity to determine temperature‐ and pH optima and stabilities. The aminoacylase could hydrolyze various acetyl amino acids at the Nα‐position with a broad specificity regarding the sidechain. Substrates with longer acyl chains, like lauroyl amino acids, were hydrolyzed to a lesser extent. Purified aminoacylase SgELA specific for the hydrolysis of Nε‐acetyl‐l‐lysine was unstable and lost its enzymatic activity upon storage for a longer period but could initially be characterized. The pH optimum of SgELA was pH 8.0. While synthesis of acyl amino acids was not observed with SgELA, SgAA catalyzed the synthesis of lauroyl‐methionine. [ABSTRACT FROM AUTHOR]

The present study investigated the copper tolerance and bioremediation potential of endophytic bacteria because endophytic bacteria are the most common bacterial strains associated with heavy metal bioremediation. The acute toxic effects of copper on living organisms were determined using two endophytic bacterial species, Bacillus sp. and Streptomyces griseus (S. griseus). After 4 days of acute toxicity test, changes in metal and bacteria concentrations in water, inhibition (%), bioaccumulation rate, and bioconcentration factors were evaluated. According to the evaluations, cell weights decreased, and inhibition rate (%) increased with increasing metal concentration after a certain level (10 mg/L Cu). With increasing metal concentrations from 5 to 25 mg/L , biosorption efficiency decreased from 35.94% to 20.73% for S. griseus and from 56.36% to 34.47% for Bacillus sp. The bioaccumulation quantities increased with increasing metal concentrations for both species. Based on the present findings, it is concluded that Bacillus sp. and S. griseus are suitable candidates for the bioremediation of copper ions from contaminated environments. These endophytic bacteria use hyperaccumulating plants for more effective bioremediation of heavy metals. [ABSTRACT FROM AUTHOR]

Phomopsis canker is one of the major devastating stem diseases that occur in tea plants caused by the fungal pathogen Phomopsis theae. Rapid development of this disease leads to a capital loss in the tea industry which demands an ecofriendly disease management strategy to control this aggressive pathogen. A total of 245 isolates were recovered from the tea rhizosphere and screened for in vitro plant growth promoting (PGP) traits and antagonism against P. theae. Among them, twelve isolates exhibited multifarious PGP traits including phytohormones, siderophore, hydrogen cyanide, salicylic acid production, phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and antifungal activity. In vitro studies on morphological, biochemical, and phylogenetic analyses classified the selected isolates as Pseudomonas fluorescens (VPF5), Bacillus subtilis (VBS3), Streptomyces griseus (VSG4) and Trichoderma viride (VTV7). Specifically, P. fluorescens VPF5 and B. subtilis VBS3 strains showed the highest level of PGP activities. On the other hand, VBS3 and VTV7 strains showed higher biocontrol efficacy in inhibiting mycelia growth and spore germination of P. theae. A detailed investigation on hydrolytic enzymes produced by antagonistic strains, which degrade the fungus cell wall, revealed that highest amount of chitinase and β-1,3- glucanase in VTV7 and VBS3 strains. Further, the key antifungal secondary metabolites from these biocontrol agents associated with suppression of P. theae were identified using gas chromatography mass spectrometry. The above study clearly recognized the specific traits in the isolated microbes, which make them good candidates as plant growth-promoting rhizobacteria (PGPR) and biocontrol agents to improve plant growth and health. However, greenhouse trials and field application of these beneficial microbes is required to further confirm their efficacy for the management of stem canker in tea cultivation. [ABSTRACT FROM AUTHOR]

Marine symbiotic actinomycetes play a key role in drug development and their ecological niches can influence a variety of natural product biosynthesis, providing potential defensive benefits. In this study, we report the whole-genome sequence analysis of marine gastropod mollusk Planaxis sp.-associated Streptomyces griseus SCSIO PteL053, which harbors 28 putative biosynthetic gene clusters (BGCs). Among them, two BGCs encoded by a hybrid non-ribosomal peptide (NRPS)/polyketide (PKS) synthetase and non-ribosomal peptide synthetase (NRPS) are responsible for the synthesis of the known therapeutic metabolites 2,2′-bipyridine and actinomycin analogs, respectively. Detailed bioinformatics analysis revealed the putative BGCs and the functions of the involved genes in the biosynthesis of the known compounds SF2738D (1), SF2738F (2), actinomycin D (3), and Actinomycin Xoβ (4). In the present study, complete-genome sequencing allowed us to rediscover known, clinically useful secondary metabolites in the newly isolated Streptomyces griseus SCSIO PteL053. [ABSTRACT FROM AUTHOR]

Simple Summary: The objective of the present study was to assess the suitability of an enzymatic laboratory method to estimate ruminal protein degradation. In situ data were used as reference. Appropriate in vitro methods are important to overcome methodological and ethical shortcomings, associated with the use of experimental animals. A cluster analysis was performed on the basis of differences between in vitro and in situ protein degradation. Among the 40 feedstuffs we tested, this difference was lowest in legume grains and highest in cereal by-products and barley. The feedstuffs clustered unspecific, not relatable to nutrient composition, origin or treatment. However, it was often obvious that additional carbohydrate-degrading enzymes should be used to assist the laboratory method, based solely on protease, to make it more conform with the in situ reference data. Effective degradation (ED) of crude protein (CP) was estimated in vitro at 0.02, 0.05 and 0.08 h−1 assumed ruminal passage rates for a total of 40 feedstuffs, for which in situ ED was available and used as reference degradation values. For this, the Streptomyces griseus protease test was used. The differences between in vitro CP degradation and the in situ CP degradation values were lowest in legume grains and highest in cereal by-products and barley. The differences between in situ and in vitro ED were expressed using a degradation quotient (degQ), where degQ = (EDin vitro − EDin situ)/EDin situ. Among the tested feedstuffs, eight specific clusters were identified according to degQ for the assumed passage rates. The feedstuffs clustered in an unspecific way, i.e., feedstuffs of different nutrient composition, origin or treatment did not necessarily group together. Formaldehyde–treated rapeseed meal, soybean meal, wheat, a treated lupin, sunflower meal and barley could not be assigned to any of the clusters. Groupwise degradation (range of degQ for assumed passage rates are given in brackets) was detected in grass silages (−0.17, −0.11), cereal by-products together with sugar beet pulp (−0.47, −0.35) and partly in legume grains (−0.14, 0.14). The clustering probably based on different specific nutrient composition and matrix effects that influence the solubility of feed protein and limit the performance of the protease. The matrix can be affected by treatment (chemically, thermally or mechanically), changing the chemical and physical structure of the protein within the plant. The S. griseus protease test had reliable sensitivity to reflect differences between native feedstuffs and treatments (thermally or chemically) that were found in situ. The in situ results, however, are mostly underestimated. The clustering results do not allow a clear conclusion on the groupwise or feed-specific use of carbohydrate-degrading enzymes as pre- or co-inoculants as part of the S. griseus protease test and need to be tested for its potential to make this test more conform with in situ data. [ABSTRACT FROM AUTHOR]

Following the discovery of streptomycin from Streptomyces griseus in the 1940s by Selman Waksman and colleagues, aminoglycosides were first used to treat tuberculosis and then numerous derivatives have since been used to combat a wide variety of bacterial infections. These bactericidal antibiotics were used as first-line treatments for several decades but were largely replaced by ß-lactams and fluoroquinolones in the 1980s, although widespread emergence of antibiotic-resistance has led to renewed interest in aminoglycosides. The primary site of action for aminoglycosides is the 30 S ribosomal subunit where they disrupt protein translation, which contributes to widespread cellular damage through a number of secondary effects including rapid uptake of aminoglycosides via elevated proton-motive force (PMF), membrane damage and breakdown, oxidative stress, and hyperpolarisation of the membrane. Several factors associated with aminoglycoside entry have been shown to impact upon bacterial killing, and more recent work has revealed a complex relationship between metabolic states and the efficacy of different aminoglycosides. Hence, it is imperative to consider the environmental conditions and bacterial physiology and how this can impact upon aminoglycoside entry and potency. This mini-review seeks to discuss recent advances in this area and how this might affect the future use of aminoglycosides. [ABSTRACT FROM AUTHOR]

A novel strain, Streptomyces griseiviridis MUM 136JT was recovered from a mangrove forest soil in Malaysia. The Gram-positive bacterium forms strong yellow aerial mycelium and moderate yellow substrate mycelium on ISP 2 agar. A polyphasic approach was used to determine the taxonomy status of strain MUM 136JT . The strain showed a spectrum of phylogenetic and chemotaxonomic properties consistent with those of the members of the genus Streptomyces. The cell wall peptidoglycan was determined to contain LL-diaminopimelic acid. The predominant menaquinones were identified as MK-9(H8) and MK-9(H6), while the identified polar lipids consisted of lipid, aminolipid, phospholipid, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylinositolmannoside. The cell wall sugars consist of ribose, mannose, and galactose. The predominant cellular fatty acids (>10.0 %) were identified as iso-C16:0 (31.6 %), anteiso-C15:0 (14.8 %), iso-C15:0 (12.0 %), and anteiso-C17:0 (11.1 %). Phylogenetic analysis identified that closely related strains for MUM 136JT are Streptomyces leeuwenhoekii DSM 42122T (98.9 %), Streptomyces erythrogriseus JCM 9650T (98.4 %), Streptomyces griseoincarnatus JCM 4381T (98.5 %). The DNA-DNA relatedness values between MUM 136 JT and closely related type strains ranged from 13.3 ± 1.5 % to 17.4 ± 2.0 %. The name Streptomyces griseiviridis sp. nov. is proposed, and the type strain is MUM 136JT (= NBRC 114249T = MCCC 1K04199T ). [ABSTRACT FROM AUTHOR]

Chitosan was used in the sol-gel synthesis of zinc oxide nanoparticles (ZnO NPs) as a capping agent in order to control the size, morphology, optical bandgap, photocatalytic efficiency, and antimicrobial activity. Different chitosan sources were used for the sol-gel synthesis of ZnO NPs, namely chitosan of shrimp shells, crab shells, and Streptomyces griseus bacteria. The photocatalytic efficiency was studied by using the methylene blue (MB) photodegradation test, and the antibacterial activity of the different types of ZnO NPs was investigated by the agar well diffusion technique. The particle size of ZnO NPs varied between 20 and 80 nm, and the band gap energy ranged between 2.7 and 3.2 eV. Due to the different chitosan sources, the ZnO NPs showed different antibacterial activity against Listeria innocua, Bacillus Subtiliis, Staphylococcus Aureus, Salmonella Typhimurium and Pseudomonas Aeruginosa. The ZnO NPs with lower band gap values showed better antibacterial results compared to ZnO NPs with higher band gap values. The MB dye removal of ZnO (shrimp shells), ZnO (crab shells), and ZnO (Streptomyces griseus) reached 60%, 56%, and 44%, respectively, at a contact time of 60 min, a low initial MB dye concentration of 6 × 10−5 M, a solution temperature of 25 °C, and a pH = 7. [ABSTRACT FROM AUTHOR]

With this research, we aimed to determine the impact of grafting and rootstock seed treated with Streptomyces griseus (MT210913) (S. griseus) or shikimic acid (SA) at a 60 ppm concentration on tomato (Solanum lycopersicum L.) production grown under low-temperature conditions. Two open-field trials were performed during both winter seasons of 2020 and 2021 at the Experimental Farm, Faculty of Agriculture, Cairo University, Giza, Egypt. A tomato cultivar (Peto 86) was used as a scion and two tomato phenotypes were employed as rootstocks (Solanum cheesmaniae L. (line LA 524) and GS hybrid), as well as self-grafted as a control. Effects of sub-optimal temperature on vegetative growth, yield, and fruit quality were tested. The results indicate that, under cold stress, rootstock seed priming, especially with S. griseus, enhanced plant growth, total yield, and fruit quality properties. GS hybrid rootstock was more effective than that of S. cheesmaniae rootstock in terms of mitigating the negative effect of cold stress. GS hybrid, inoculated with S. griseus, increased the total yield per plant by 10.5% and 5.7% in the first and second seasons, respectively. Higher levels of GA3 and mineral content were noticed in leaves that were grafted and treated with S. griseus compared to the control treatment. Additionally, the great enhancing effects of all anatomical features of tomato plants were recorded with GS hybrid rootstock, inoculated by S. griseus. These results prove that grafting on GS hybrid rootstock treated with S. griseus is a potential choice to alleviate the cold stress of commercial tomato varieties. [ABSTRACT FROM AUTHOR]

The sugars streptose and dihydrohydroxystreptose (DHHS) are unique to the bacteria Streptomyces griseus and Coxiella burnetii, respectively. Streptose forms the central moiety of the antibiotic streptomycin, while DHHS is found in the O-antigen of the zoonotic pathogen C. burnetii. Biosynthesis of these sugars has been proposed to follow a similar path to that of TDP-rhamnose, catalyzed by the enzymes RmlA, RmlB, RmlC, and RmlD, but the exact mechanism is unclear. Streptose and DHHS biosynthesis unusually requires a ring contraction step that could be performed by orthologs of RmlC or RmlD. Genome sequencing of S. griseus and C. burnetii has identified StrM and CBU1838 proteins as RmlC orthologs in these respective species. Here, we demonstrate that both enzymes can perform the RmlC 3",5" double epimerization activity necessary to support TDP-rhamnose biosynthesis in vivo. This is consistent with the ring contraction step being performed on a double epimerized substrate. We further demonstrate that proton exchange is faster at the 3"-position than the 5"-position, in contrast to a previously studied ortholog. We additionally solved the crystal structures of CBU1838 and StrM in complex with TDP and show that they form an active site highly similar to those of the previously characterized enzymes RmlC, EvaD, and ChmJ. These results support the hypothesis that streptose and DHHS are biosynthesized using the TDP pathway and that an RmlD paralog most likely performs ring contraction following double epimerization. This work will support the elucidation of the full pathways for biosynthesis of these unique sugars. [ABSTRACT FROM AUTHOR]

The outbreak and spread of foodborne diseases is a serious concern for global healthcare and security. Finding novel antimicrobial agents with diverse mechanisms of action against the current spoilage and foodborne bacterial pathogens is a central strategy to overcome the problems of antibiotic resistance. Soil actinomycetes are the major antimicrobial producers with great biopreservative and medical value. This study was aimed at isolating Streptomyces from soil samples of northwestern Ethiopia against spoilage and foodborne bacterial pathogens. Thirty-six soil samples were collected at a depth of 5–10 cm in the rhizosphere and agricultural soils of soybean. A total of 118 actinomycete strains were isolated and screened primarily using the perpendicular streak plate method against 3 Gram-positive and 3 Gram-negative bacterial strains. Out of 118 isolates, 36/118 (30.50%) were active against at least two of the tested bacteria, of which 8 isolates were selected for their wide-spectrum antibacterial activities. During the disc diffusion assay, the eight in vitro ethyl acetate extract antibacterial activities range from 7 to 24 mm. The minimum inhibitory concentration and minimum bactericidal concentration values range from 0.10 to 0.25 μg/mL and 0.15 to 0.40 μg/mL, respectively. Following the morphological, physiological, biochemical, and molecular characteristics, eight potent isolates were identified as follows: Streptomyces fasciculus, Streptomyces roseochromogenes, Streptomyces ruber, Streptomyces glaucus, Streptomyces griseus, Streptomyces cellulosae, Streptomyces griseoflavus, and Streptomyces xanthophaeus. After the treatment of potent Streptomyces cell-free culture supernatant with proteinase K, papain, α-amylase, and lysozyme enzymes, their antagonistic effects were also observed. Most Streptomyces cell-free culture supernatant antibacterial activity was highly resistant to heat, acidity, organic solvents, and additives. Thus, the results of this investigation revealed that soil actinomycetes could be a valuable source for novel antibacterial agents applicable in food biopreservation and the treatment of spoilage and foodborne bacterial pathogens. [ABSTRACT FROM AUTHOR]

Using Fusarium oxysporum species (F. oxysporum), a green synthesis of super-paramagnet iron oxide @silver@ Chitosan (SPION@Ag@Cs) was achieved. The physico-chemical characteristics of the SPION@Ag@Cs nanocomposite revealed the development of superparamagnetic phases of iron oxide (Fe2O3), as well as fluorescence, Raman absorption, and biocompatibility. Drug and gene delivery, and diagnosis, are all possibilities for the nanocomposite. The uptake of nitric oxide by HT-29 colorectal cell lines is examined in this article, for up to 72 h, the cytotoxicity of the HCT116 cell line was investigated. These characteristics were compared to Streptomyces griseus fungal species (S. griseus) which develops Fe3O4 under the same preparation conditions. [ABSTRACT FROM AUTHOR]

Background: Bio-based aromatic compounds are of great interest to the industry, as commercial production of aromatic compounds depends exclusively on the unsustainable use of fossil resources or extraction from plant resources. γ-amino acid 3-amino-4-hydroxybenzoic acid (3,4-AHBA) serves as a precursor for thermostable bioplastics. Results: Under aerobic conditions, a recombinant Corynebacterium glutamicum strain KT01 expressing griH and griI genes derived from Streptomyces griseus produced 3,4-AHBA with large amounts of amino acids as by-products. The specific productivity of 3,4-AHBA increased with decreasing levels of dissolved oxygen (DO) and was eightfold higher under oxygen limitation (DO = 0 ppm) than under aerobic conditions (DO ≥ 2.6 ppm). Metabolic profiles during 3,4-AHBA production were compared at three different DO levels (0, 2.6, and 5.3 ppm) using the DO-stat method. Results of the metabolome analysis revealed metabolic shifts in both the central metabolic pathway and amino acid metabolism at a DO of < 33% saturated oxygen. Based on this metabolome analysis, metabolic pathways were rationally designed for oxygen limitation. An ldh deletion mutant, with the loss of lactate dehydrogenase, exhibited 3.7-fold higher specific productivity of 3,4-AHBA at DO = 0 ppm as compared to the parent strain KT01 and produced 5.6 g/L 3,4-AHBA in a glucose fed-batch culture. Conclusions: Our results revealed changes in the metabolic state in response to DO concentration and provided insights into oxygen supply during fermentation and the rational design of metabolic pathways for improved production of related amino acids and their derivatives. [ABSTRACT FROM AUTHOR]

Copyright of Arab Journal of Plant Protection is the property of Arab Society for Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study focuses on structural, molecular docking and simulation analysis of L-asparaginase protein belonging to Streptomyces iranensis (S. iranensis) (WP_044568095), Streptomyces himalayensis (S. himalayensis) (WP_181864635) and Streptomyces griseus (S. griseus) (WP_037680047). The three protein sequences retrieved from NCBI are also assessed for characteristic, secondary structure and localization studies. The analysis with BLAST tool predicted WP_044568095 to be 40.18% and 39.16% identical with D. chrysanthemi (P06608) and E. coli L-asparaginase II (P00805). Similarly WP_181864635 is identified to be 38.39% and 37.58% identical with P06608, P00805 respectively while no resemblance is observed with WP_037680047.1. The three Streptomyces proteins on subsequent studies by I-TASSER and GalaxyRefine are found to have 85.9%, 84.2% and 79.2% residues in the favoured zone for WP_044568095, WP_181864635 and WP_037680047 on validation by PROCHECK. Further, acceptable findings are obtained from studies by ERRAT and ProSA. Molecular docking performed by CB-Dock and PyRx resulted in similar predictions about the active site amino acids forming hydrogen bond with L-asparagine. WP_044568095 docked with Asn resulted in lowest energy of - 4.6 kcal/mol while - 4.4 kcal/mol is obtained for WP_181864635, WP_037680047 evaluated by AutoDock Vina of PyRx software. The docked structures of WP_044568095 and WP_181864635 under controlled conditions by CABS-Flex 2.0 are found stable in comparison with WP_037680047. As L-asparaginase possess high therapeutic application in various malignancies treatment, the evaluated proteins of S. iranensis, S. himalayensis and S. griseus are worth analysing further for in vitro enzyme activity and are considered to have promising therapeutic importance. [ABSTRACT FROM AUTHOR]

Isolation and identification of new microbial isolates capable of producing cholesterol oxidase enzyme (CHO) is of great potential in the field of biotechnology of industrial enzymes. Four producing strains of actinomycetes were isolated from Egyptian soils demonstrated high activity in cholesterol degradation compared to the other isolates. Based on different standard morphological, biochemical as well as molecular techniques using 16S rRNA sequencing, these actinomycetes were identified as Streptomyces sp. strain NHIA_CH3 MK680299, Streptomyces sp. strain NHIA_CH5 MK680300, Streptomyces griseus strain NHIA_CH6 MK680301 and Streptomyces drozdowiczii strain NHIA_CH10 MK680302. In order to optimize the CHO enzyme activity, different fermentation media were tested in submerged cultures at shake flask level. Maximum activity (23.7 U/mL) was observed in culture of Streptomyces sp. strain NHIA_CH5 which was scaled up to the 5L volume of the stirred tank bioreactor. Results of the batch fermentation showed an earlier production of CHO enzyme with 4% increase in activity compared to that obtained from shake flask cultures indicated that Streptomyces sp. strain NHIA_CH5 could be a potential source of CHO enzyme for commercial purpose. [ABSTRACT FROM AUTHOR]

With this research, we aimed to determine the impact of grafting and rootstock seed treated with Streptomyces griseus (MT210913) (S. griseus) or shikimic acid (SA) at a 60 ppm concentration on tomato (Solanum lycopersicum L.) production grown under low-temperature conditions. Two open-field trials were performed during both winter seasons of 2020 and 2021 at the Experimental Farm, Faculty of Agriculture, Cairo University, Giza, Egypt. A tomato cultivar (Peto 86) was used as a scion and two tomato phenotypes were employed as rootstocks (Solanum cheesmaniae L. (line LA 524) and GS hybrid), as well as self-grafted as a control. Effects of sub-optimal temperature on vegetative growth, yield, and fruit quality were tested. The results indicate that, under cold stress, rootstock seed priming, especially with S. griseus, enhanced plant growth, total yield, and fruit quality properties. GS hybrid rootstock was more effective than that of S. cheesmaniae rootstock in terms of mitigating the negative effect of cold stress. GS hybrid, inoculated with S. griseus, increased the total yield per plant by 10.5% and 5.7% in the first and second seasons, respectively. Higher levels of GA3 and mineral content were noticed in leaves that were grafted and treated with S. griseus compared to the control treatment. Additionally, the great enhancing effects of all anatomical features of tomato plants were recorded with GS hybrid rootstock, inoculated by S. griseus. These results prove that grafting on GS hybrid rootstock treated with S. griseus is a potential choice to alleviate the cold stress of commercial tomato varieties.

Streptomyces griseofuscus DSM 40191 is a fast growing Streptomyces strain that remains largely underexplored as a heterologous host. Here, we report the genome mining of S. griseofuscus, followed by the detailed exploration of its phenotype, including the production of native secondary metabolites and ability to utilise carbon, nitrogen, sulphur and phosphorus sources. Furthermore, several routes for genetic engineering of S. griseofuscus were explored, including use of GusA-based vectors, CRISPR-Cas9 and CRISPR-cBEST-mediated knockouts. Two out of the three native plasmids were cured using CRISPR-Cas9 technology, leading to the generation of strain S. griseofuscus DEL1. DEL1 was further modified by the full deletion of a pentamycin BGC and an unknown NRPS BGC, leading to the generation of strain DEL2, lacking approx. 500 kbp of the genome, which corresponds to a 5.19% genome reduction. DEL2 can be characterized by faster growth and inability to produce three main native metabolites: lankacidin, lankamycin, pentamycin and their derivatives. To test the ability of DEL2 to heterologously produce secondary metabolites, the actinorhodin BGC was used. We were able to observe a formation of a blue halo, indicating a potential production of actinorhodin by both DEL2 and a wild type. [ABSTRACT FROM AUTHOR]

Streptomyces genomes harbor numerous, biosynthetic gene clusters (BGCs) encoding for drug-like compounds. While some of these BGCs readily yield expected products, many do not. Biosynthetic crypticity represents a significant hurdle to drug discovery, and the biological mechanisms that underpin it remain poorly understood. Polycyclic tetramate macrolactam (PTM) antibiotic production is widespread within the Streptomyces genus, and examples of active and cryptic PTM BGCs are known. To reveal further insights into the causes of biosynthetic crypticity, we employed a PTM-targeted comparative metabologenomics approach to analyze a panel of S. griseus clade strains that included both poor and robust PTM producers. By comparing the genomes and PTMproduction profiles of these strains, we systematically mapped the PTM promoter architecture within the group, revealed that these promoters are directly activated via the global regulator AdpA, and discovered that small promoter insertion-deletion lesions (indels) differentiate weaker PTM producers from stronger ones. We also revealed an unexpected link between robust PTMexpression and griseorhodin pigment coproduction, withweaker S. griseus-clade PTM producers being unable to produce the latter compound. This study highlights promoter indels and biosynthetic interactions as important, genetically encoded factors that impact BGC outputs, providing mechanistic insights that will undoubtedly extend to other Streptomyces BGCs. We highlight comparative metabologenomics as a powerful approach to expose genomic features that differentiate strong, antibiotic producers from weaker ones. This should prove useful for rational discovery efforts and is orthogonal to current engineering and molecular signaling approaches now standard in the field. [ABSTRACT FROM AUTHOR]

A new actinomycete strain designated TBG19NRA1, exhibiting antimicrobial activities against Gram-positive and Gram-negative bacteria, was isolated from forest soil of Neyyar Wild Life Sanctuary, Thiruvananthapuram, Kerala. Cultural characteristics strongly suggested that this isolate belongs to the genus Streptomyces. Polyphasic taxonomic studies including phylogenetic analysis based on 16S rDNA sequence suggests that the isolate is a strain of S. griseus. Studies on the effect of different nutritional compounds on antibiotic activity revealed that the highest antibacterial activity was obtained when 1% starch (w/v) was used as the sole carbon source along with mineral trace elements. Extraction and purification of TBG19NRA1 culture supernatant led to the isolation of a pure molecule with good antibacterial activity. The compound has been identified as the cyclic polyether lasalocid A on the basis IR, MS and 13C NMR data interpretation and comparison with reference data from literature. [ABSTRACT FROM AUTHOR]

Streptomyces species a genus in Actinobacteria phylum were isolated from the rhizosphere of some plants in Los Angeles. Some plant growth promotion properties of isolates were determined, such as: indole acetic acid, siderophore production and phosphate solubilization. The colonization ability of Streptomyces species was investigated under in vitro conditions on spinach seeds. Maximum likelihood approach was applied to 16S rRNA gene sequences to draw a phylogenetic tree of the best identified isolates, according to their measured properties. A total of ten isolates were characterized as Actinobacteria according to their morphological properties. Of those, four isolates possessing some traits related to plant growth promotion were identified as Streptomyces griseus strain 52-1 (Step1) and Streptomyces albogriseolus strain DSM 4 (Step-2) from tomatoes, Streptomyces aurantiacus strain 4683 (Step-5) and Streptomyces kanamyceticus strain 22-5 (Step-8) from sunflowers’ rhizosphere. The identified isolates showed the maximum indole acetic acid production, 95.67, 110.14, 94.12 and 105.04 mg L-1, respectively. The maximum siderophore production (22.23, 19.34, 10.12 and 33.24 mg mL-1) and mineral phosphate solubilization (61.8, 69.32, 61.6 and 68.4 mg 100 mL-1) were obtained using Strep-1, Strep-2, Strep-5 and Strep-8 isolates, respectively. None of the isolates could grow on nitrogen free media. The results of spinach root colonization test with the isolates indicated the potential of Strep-1, Strep-2, Strep-5 and Strep-8 isolates to colonize spinach roots. [ABSTRACT FROM AUTHOR]

Dihydropyriculol is a major secondary metabolite of Pyricularia oryzae. However, the biological activity of dihydropyriculol has not been reported. Here, we showed that dihydropyriculol has inhibitory activity against Streptomyces griseus. Localization analysis of dihydropyriculol revealed that dihydropyriculol could reach to S. griseus under confrontation culture. These results suggest that dihydropyriculol can be used as a chemical weapon against S. griseu s. [ABSTRACT FROM AUTHOR]

16α-Hydroxylated steroids are important precursors in the synthesis of high value steroidal drugs such as glucocorticoids in the pharmaceutical industry. In this study, an innovative biotechnological method based on enzymatic catalysis was presented for the high-efficient production of 16α-hydroxyl-testosterone. CYP154C, a cytochrome P450 from Streptomyces griseus ATCC 13273, was identified to carry out a one-step regio- and stereoselective hydroxylation of testosterone along with putidaredoxin reductase (PDR) and putidaredoxin (Pdx) as the redox partner. The Km and kcat values of CYP154C for testosterone were 23.40 ± 3.69 μM and 4.75 min−1, respectively. The catalytic efficiency (kcat/Km) for testosterone was 12.18 s−1·μM−1. Using a CYP154-based whole-cell system in E. coli BL21(DE3), high efficiency of hydroxylation of testosterone for production of 16α-hydroxyl-testosterone was achieved. The bioconversion rate of testosterone (50 mg/L) by the whole cell system came up to 75 ± 2.87% within 24 h. These results demonstrated the high potential of CYP154-based biocatalytic system for 16α-hydroxyl-testosterone production. [ABSTRACT FROM AUTHOR]

The chitin-assimilating gram-negative bacterium, Lysobacter sp. MK9-1, was isolated from soil and was the source of a glycoside hydrolase family 19-type chitinase (Chi19MK) gene that is 933-bp long and encodes a 311-residue protein. The deduced amino acid sequence of Chi19MK includes a signal peptide, an uncharacterized sequence, a carbohydrate-binding module family 12-type chitin binding domain, and a catalytic domain. The catalytic domain of Chi19MK is approximately 60% similar to those of ChiB from Burkholderia gladioli CHB101, chitinase N (ChiN) from Chitiniphilus shinanonensis SAY3T, ChiF from Streptomyces coelicolor A3(2), Chi30 from Streptomyces olivaceoviridisis , ChiA from Streptomyces cyaneus SP-27, and ChiC from Streptomyces griseus HUT6037. Chi19MK lacking the signal and uncharacterized sequences (Chi19MKΔNTerm) was expressed in Escherichia coli Rosetta-gami B(DE3), resulting in significant chitinase activity in the soluble fraction. Purified Chi19MKΔNTerm hydrolyzed colloidal chitin and released disaccharide. Furthermore, Chi19MKΔNTerm inhibited hyphal extension in Trichoderma reesei and Schizophyllum commune. Based on quantitative antifungal activity assays, Chi19MKΔNTerm inhibits the growth of Trichoderma viride with an IC 50 value of 0.81 μM. [ABSTRACT FROM AUTHOR]

Deep Eutectic Solvents (DES) are ionic liquid analogs that have attracted considerable attention as green solvents for biocatalytic transformations. The use of DES as part of a ‘solvent engineering’ approach to enhance enzyme stability holds great promise since they are biodegradable, relatively inexpensive and environmentally safe media for enzyme reactions. However, the behaviour of specific enzymes in such solvents is complex; some enzymes are inhibited in DES, while others appear to be activated.Glucosidases are among the most widely used enzymes for commercial chemoenzymatic synthesis. In particular, their application in the synthesis of biodegradable alkyl glucosides by reverse hydrolysis is of great interest. Previous work in this laboratory identified Streptomyces griseus glucosidase (Sgβgl) as an interesting enzyme for biotechnological applications. In this study, we examined its behaviour in the presence of DES as a co-solvent using choline chloride as hydrogen bond donor and using glycerol, glucose and urea as hydrogen bond acceptors. We show that Sgβgl activity depends on both the nature of DES components, and their ratio in the eutectic mixture, as well as the water content of the reaction medium. A choline chloride/glycerol DES mixture at a level of 40% (v/v) caused activation of Sgβgl and increased its optimum temperature from 70 to 80 ​°C: it also led to a striking increase in its thermostability, doubling its half-life at 60 ​°C and almost tripling its half-life at 80 ​°C.The synthesis of alkyl glucosides was explored using DES as a co-solvent. In the presence of DES, Sgβgl catalysed the formation of a range of alkyl glucosides. The presence of DES resulted in enhanced product yield, which was observed to increase with increasing temperature, up to 60 ​°C.These studies show that the application of DES at relatively low % (v/v) levels can dramatically effect enzyme activity and stability. Specifically, enhanced thermostability can significantly increase the operating range for glucosidases for biocatalytic applications. Solvent engineering offers a simple and effective way to enhance glucosidase stability and will be useful as an alternative and/or adjunct to more complex methods such as immobilisation or protein engineering.

• S. griseus was selected by screening as new AurF-like source. • pNBA was obtained by N -oxygenation of pABA using S. griseus whole cells. • A simple culture media for Streptomyces was formulated to improve biomass formation. • S. griseus and B. cereus co-cultures enhance N -oxygenase activity. Aromatic nitro compounds are key building blocks for many industrial syntheses and are also components of explosives, drugs and pesticides. Due to the environmentally unfriendly experimental conditions involved in their chemical syntheses, industrial processes would benefit from the use of biocatalysts. Among potentially useful enzymes, N -oxygenases, whose role is to oxygenate primary amines, are becoming relevant. These enzymes are involved in different secondary metabolic pathways in Streptomyces and in few other bacteria, forming part of the enzyme pools implicated in antibiotic synthesis. In this work, a group of Streptomyces strains, whose biomass was obtained from simple and novel culture media, were identified as new sources of N -oxygenase activity. Furthermore, the use of unspecific metabolic stimulation strategies allowed substantial improvements in the activity of whole cells as biocatalysts. It is remarkable the 6 to 50-fold increase in nitro compound yields compared to the biotransformation under standard conditions when Streptomyces griseus was the biocatalyst. In addition, biocatalyst substrate acceptance was studied in order to determine the biocatalytic potential of this enzyme. [ABSTRACT FROM AUTHOR]

Tea is an important beverage with several health benefits to human beings, but increase in tea diseases is of much concern in recent days. Amongst several stem and root diseases of tea plants, Poria hypolateritia causing red root-rot and Phomopsis theae causing Phomopsis canker diseases are very important in terms of heavy crop loss in young as well as mature tea plantations, respectively. In the present study, indigenous biocontrol agents such as bacteria, fungi and actinomycetes were isolated from southern Indian tea soils collected from different agroclimatic regions and subjected to biosynthesis of copper and silica nanoparticles. Copper and silica nanoparticles were produced using selected indigenous biocontrol agents such as Pseudomonas fluorescens, Trichoderma atroviride and Streptomyces griseus and then characterise for their nature, size, shape, elemental analysis, distribution and functional groups. The results showed that copper and silica nanoparticles were inhibited the growth of P. hypolateritia and P. theae. Nanocopper and nanosilica were subjected to prepare various nanoformulations using suitable inert and eco-friendly carrier materials. Toxicity of nanoformulations was done using zebrafish model. It was confirmed that there was no toxicity of nanocopper and nanosilica when exposed to 0.5, 3 and 30 µg concentrations in terms of viability percentage of embryo, hatching rate, body mass index and heartbeat counts. The present investigation could be a novel approach for the management of root and stem diseases in tea plantations which in turn useful to enhance tea quality parameters. [ABSTRACT FROM AUTHOR]

Plants are good source of antimicrobial agents and may be used for alternative drug formation in future. In the present study, comparative antimicrobial analysis of four species of family Asteraceae in southern Rajasthan has been investigated. Acanthospermum hispidum, Pentanema indicum, Sphaeranthus indicus, and Tridax procumbens of family Asteraceae were collected from southern Rajasthan. Antimicrobial activity was carried out of dried leaves extract in methanol and ethyl acetate against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Streptomyces griseus bacteria and Aspergillus niger, Candida albicans, Fusarium oxysporium and Trichoder-ma reesei fungi. Antibacterial and antifungal activities of all four species were measured in the form of zone of inhibition.The highest zone of inhibition was observed on E. coli in S. indicus i.e. 26.00±0.59 mm in ethyl acetate extract and lowest zone of inhibition was observed on B. subtilis in T. procumbens i.e. 5.00±0.21 mm in methanol extract. While the highest zone of inhibition was observed on S. griseus in A. hispidium i.e. 30.00±0.50 mm in ethyl acetate extract and lowest zone of inhibition was observed on C. albicans in A. hispidum i.e. 10.00±0.49 mm in methanol extract. The results of the present study suggest the use of natural antimicrobial agent against studied microorganism. [ABSTRACT FROM AUTHOR]

Ultrahigh-resolution (< 1.0 Å) structures have revealed unprecedented and unexpected details of molecular geometry, such as the deformation of aromatic rings from planarity. However, the functional utility of such energetically costly strain is unknown. The 0.83 Å structure of α-lytic protease (αLP) indicated that residues surrounding a conserved Phe side-chain dictate a rotamer which results in a ~6° distortion along the side-chain, estimated to cost 4 kcal/mol. By contrast, in the closely related protease Streptomyces griseus Protease B (SGPB), the equivalent Phe adopts a different rotamer and is undistorted. Here, we report that the αLP Phe side-chain distortion is both functional and conserved in proteases with large pro regions. Sequence analysis of the αLP serine protease family reveals a bifurcation separating those sequences expected to induce distortion and those that would not, which correlates with the extent of kinetic stability. Structural and folding kinetics analyses of family members suggest that distortion of this side-chain plays a role in increasing kinetic stability within the αLP family members that use a large Pro region. Additionally, structural and kinetic folding studies of mutants demonstrate that strain alters the folding free energy landscape by destabilizing the transition state (TS) relative to the native state (N). Although side-chain distortion comes at a cost of foldability, it suppresses the rate of unfolding, thereby enhancing kinetic stability and increasing protein longevity under harsh extracellular conditions. This ability of a structural distortion to enhance function is unlikely to be unique to αLP family members and may be relevant in other proteins exhibiting side-chain distortions.

This research intends to reduce the crystallinity of chitin with physical methods so as to improve the enzymatic hydrolysis efficiency of chitin. Scanning electron microscopy showed that both steam explosion and high‐pressure homogenization significantly enlarged the pores in shrimp shells, which are made up of chitin, but γ radiation did not. X‐ray diffraction showed that the crystallinity index of chitin decreased by 23.2% in the (110) plane and 24.7% in the (020) plane after three rounds of steam explosion and decreased by 12.4% in the (110) plane and 28.7% in the (020) plane after three rounds of high‐pressure homogenization. After γ radiation, however, there was no significant change. The corresponding deacetylation degrees of the chitin treated with steam explosion and high‐pressure homogenization increased by 13.2 and 5.7%, respectively. The natural, steam‐exploded and high‐pressure homogenized chitins respectively produced 0.251, 0.145, and 0.407 mg/ml reducing sugars with the hydrolysis of Streptomyces griseus chitinase. However, when hydrolyzed by Paenibacillus sp. A1 chitinase the steam‐exploded and the high‐pressure homogenized chitin respectively released 40 and 300% more reducing sugars than the natural chitin. The results found that steam explosion and high‐pressure homogenization can reduce the crystallinity of chitin, and make it prone to enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

Lytic polysaccharide monooxygenases (LPMOs) are enzymes that degrade polysaccharides with an oxidative mechanism and contributed to the efficiency in biomass degradation by glycoside hydrolases (GHs). In this study, the substrate and reaction specificity of Sg LPMO10A that was an auxiliary activity family 10 (AA10) enzyme with a carbohydrate binding module family 2 (CBM2) domain from Streptomyces griseus , was analyzed. This enzyme produced oxidized cello-oligosaccharides from cellulose and boosted cellulose degradation by cellulases. Detailed study of the AA10 and CBM2 domains revealed that the binding ability of Sg LPMO10A depended on CBM2 and that only the AA10 domain functions more effectively in the presence of a certain amount of substrates. • Sg LPMO10A that bind two polysaccharide biomass, cellulose and chitin • Sg LPMO10A produced oxidized cello-oligosaccharides from cellulose. • Sg LPMO10A boosted cellulose degradation by cellulases. • Two domains of Sg LPMO10A were studied in details. • AA10 domain is best used in application for efficient enzymatic solubilization. [ABSTRACT FROM AUTHOR]

Due to their excellent mechanical strength and biocompatibility, silk fibroin(SF) hydrogels can serve as ideal scaffolds. However, their slow rate of natural degradation limits the space available for cell proliferation, which hinders their application. In this study, litchi-like calcium carbonate@hydroxyapatite (CaCO3@HA) porous microspheres loaded with proteases from Streptomyces griseus (XIV) were used as drug carriers to regulate the biodegradation rate of SF hydrogels. The results showed that litchi-like CaCO3@HA microspheres with different phase compositions could be prepared by changing the hydrothermal reaction time. The CaCO3@HA microspheres controlled the release of Ca ions, which was beneficial for the osteogenic differentiation of mesenchymal stem cells (MSCs). The adsorption and release of protease XIV from the CaCO3@HA microcarriers indicated that the loading and release amount can be controlled with the initial drug concentration. The weight loss test and SEM observation showed that the degradation of the fibroin hydrogel could be controlled by altering the amount of protease XIV-loaded CaCO3@HA microspheres. A three-dimensional (3D) cell encapsulation experiment proved that incorporation of the SF hydrogel with protease XIV-loaded microspheres promoted cell dispersal and spreading, suggesting that the controlled release of protease XIV can regulate hydrogel degradation. SF hydrogels incorporated with protease XIV-loaded microspheres are suitable for cell growth and proliferation and are expected to serve as excellent bone tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

Conventional refolding methods are associated with low yields due to misfolding and high aggregation rates or very dilute proteins. In this study, we describe the optimization of the conventional methods of reverse dilution and affinity chromatography for obtaining high yields of a cysteine rich recombinant glycoside hydrolase family 19 chitinase from Streptomyces griseus HUT6037 (SgChiC). SgChiC is a potential biocontrol agent and a reference enzyme in the study and development of chitinases for various applications. The overexpression of SgChiC was previously achieved by periplasmic localization from where it was extracted by osmotic shock and then purified by hydroxyapatite column chromatography. In the present study, the successful refolding and recovery of recombinant SgChiC (r-SgChiC) from inclusion bodies (IB) by reverse dilution and column chromatography methods is respectively described. Approximately 8 mg of r-SgChiC was obtained from each method with specific activities of 28 and 52 U/mg respectively. These yields are comparable to that obtained from a 1 L culture volume of the same protein isolated from the periplasmic space of E. coli BL21 (DE3) as described in previous studies. The higher yields obtained are attributed to the successful suppression of aggregation by a stepwise reduction of denaturant from high, to intermediate, and finally to low concentrations. These methods are straight forward, requiring the use of fewer refolding agents compared with previously described refolding methods. They can be applied to the refolding of other cysteine rich proteins expressed as inclusion bodies to obtain high yields of actively folded proteins. This is the first report on the recovery of actively folded SgChiC from inclusion bodies. [ABSTRACT FROM AUTHOR]

The study involved the isolation and identification of a member of Streptomyces griseorubens and the identification of its secondary metabolite content. Two extract samples were prepared by using butanol and chloroform. In the analyses of the extracts TLC, FT-IR, and GC-MS were employed. Butanol extract appeared to be dominated by three different pyrrole compounds (43.59%), while two fatty acids, linoleicand erucic acids, were the most abundant secondary metabolites in the chloroform extract, 27.57% and 12.34%, respectively. Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-compound was represented by a single and distinct band on the thin layer chromatography plate. In GC-MS spectra, it also constituted 13.50% of the butanol extract. [ABSTRACT FROM AUTHOR]

Symbiotic microbes help a myriad of insects acquire nutrients. Recent work suggests that insects also frequently associate with actinobacterial symbionts that produce molecules to help defend against parasites and predators. Here we explore a potential association between Actinobacteria and two species of fungus-farming ambrosia beetles, Xyleborinus saxesenii and Xyleborus affinis. We isolated and identified actinobacterial and fungal symbionts from laboratory reared nests, and characterized small molecules produced by the putative actinobacterial symbionts. One 16S rRNA phylotype of Streptomyces (XylebKG-1) was abundantly and consistently isolated from the galleries and adults of X. saxesenii and X. affinis nests. In addition to Raffaelea sulphurea , the symbiont that X. saxesenii cultivates, we also repeatedly isolated a strain of Nectria sp. that is an antagonist of this mutualism. Inhibition bioassays between Streptomyces griseus XylebKG-1 and the fungal symbionts from X. saxesenii revealed strong inhibitory activity of the actinobacterium toward the fungal antagonist Nectria sp. but not the fungal mutualist R. sulphurea. Bioassay guided HPLC fractionation of S. griseus XylebKG-1 culture extracts, followed by NMR and mass spectrometry, identified cycloheximide as the compound responsible for the observed growth inhibition. A biosynthetic gene cluster putatively encoding cycloheximide was also identified in S. griseus XylebKG-1. The consistent isolation of a single 16S phylotype of Streptomyces from two species of ambrosia beetles, and our finding that a representative isolate of this phylotype produces cycloheximide, which inhibits a parasite of the system but not the cultivated fungus, suggests that these actinobacteria may play defensive roles within these systems. [ABSTRACT FROM AUTHOR]

This study examined the in vitro crude protein (CP) degradability of wilted, dried for hay and ensiled Medicago sativa, Trifolium pratense and Sorghum sudanense, as well as of ensiled legume-sudan grass mixtures. The rumen degradable protein (RDP) was estimated using the latest Cornell net carbohydrate and protein system (CNCPS v6.5) and with the Streptomyces griseus protease assay (48 h of incubation). Sudan grass forages were the lowest in moderately degradable CP and the highest in CP fraction C, while red clover showed the least values for the soluble true protein like alfalfa forages for slowly degradable protein bound in neutral detergent fibre (NDF). Ensiling of legume-sudan grass mixtures decreases N-NH3 content by 12.2 and 5.1% in comparison with alfalfa and red clover silages, respectively. The RDP values for sudan grass (fresh, wilted, hay) were lower by 7.2 to 7.9% or 10.4 to 15.7% (CNCPS or S. griseus procedure) and up to 0.8 or 5.3 to 9.7% in comparison with alfalfa and red clover, respectively. The reduction of protein degradability in ensiled legume-sudan grass mixtures was 5.5 or 6.1% and 1.5 or 3% compared to alfalfa and red clover silages, respectively. Due to higher rumen undegradable protein content, the sudan grass and legume-sudan grass mixtures may be efficiently used to improve the protein utilization in ruminant nutrition. [ABSTRACT FROM AUTHOR]