Corrigendum: Development of sandwich dot-ELISA for specific detection of Ochratoxin A and its application on to contaminated cereal grains originating from India.

[This corrects the article DOI: 10.3389/fmicb.2015.00511.].

Valorization of dragon fruit waste to value-added bioproducts and formulations: A review.

Owing to the increasing worldwide population explosion, managing waste generated from the food sector has become a cross-cutting issue globally, leading to environmental, economic, and social issues. Circular economy-inspired waste valorization approaches have been increasing steadily, generating new business opportunities developing valuable bioproducts using food waste, especially fruit wastes, that may have several applications in energy-food-pharma sectors. Dragon fruit waste is one such waste resource, which is rich in several value-added chemicals and oils, and can be a renewable resource to produce several value-added compounds of potential applications in different industries. Pretreatment and extraction processes in biorefineries are important strategies for recovering value-added biomolecules. There are different methods of valorization, including green extractions and biological conversion approaches. However, microbe-based conversion is one of the advanced technologies for valorizing dragon fruit waste into bioethanol, bioactive products, pharmaceuticals, and other valued products by reusing or recycling them. This state-of-the-art review briefly overviews the dragon fruit waste management strategies and advanced eco-friendly and cost-effective valorization technologies. Furthermore, various applications of different valuable bioactive components obtained from dragon fruit waste have been critically discussed concerning various industrial sectors. Several industrial sectors, such as food, pharmaceuticals, and biofuels, have been critically reviewed in detail.

Sustainable Phenylalanine-Derived SAILs for Solubilization of Polycyclic Aromatic Hydrocarbons.

The solubilization capacity of a series of sustainable phenylalanine-derived surface-active ionic liquids (SAILs) was evaluated towards polycyclic aromatic hydrocarbons-naphthalene, anthracene and pyrene. The key physico-chemical parameters of the studied systems (critical micelle concentration, spectral properties, solubilization parameters) were determined, analyzed and compared with conventional cationic surfactant, CTABr. For all studied PAH solubilization capacity increases with extension of alkyl chain length of PyPheOCn SAILs reaching the values comparable to CTABr for SAILs with n = 10-12. A remarkable advantage of the phenylalanine-derived SAILs PyPheOCn and PyPheNHCn is a possibility to cleave enzymatically ester and/or amide bonds under mild conditions, to separate polycyclic aromatic hydrocarbons in situ. A series of immobilized enzymes was tested to determine the most suitable candidates for tunable decomposition of SAILs. The decomposition pathway could be adjusted depending on the choice of the enzyme system, reaction conditions, and selection of SAILs type. The evaluated systems can provide selective cleavage of the ester and amide bond and help to choose the optimal decomposition method of SAILs for enzymatic recycling of SAILs transformation products or as a pretreatment towards biological mineralization. The concept of a possible practical application of studied systems for PAHs solubilization/separation was also discussed focusing on sustainability and a green chemistry approach.

Bacterial glycobiotechnology: A biosynthetic route for the production of biopharmaceutical glycans.

The recent advancement in the human glycome and progress in the development of an inclusive network of glycosylation pathways allow the incorporation of suitable machinery for protein modification in non-natural hosts and explore novel opportunities for constructing next-generation tailored glycans and glycoconjugates. Fortunately, the emerging field of bacterial metabolic engineering has enabled the production of tailored biopolymers by harnessing living microbial factories (prokaryotes) as whole-cell biocatalysts. Microbial catalysts offer sophisticated means to develop a variety of valuable polysaccharides in bulk quantities for practical clinical applications. Glycans production through this technique is highly efficient and cost-effective, as it does not involve expensive initial materials. Metabolic glycoengineering primarily focuses on utilizing small metabolite molecules to alter biosynthetic pathways, optimization of cellular processes for glycan and glycoconjugate production, characteristic to a specific organism to produce interest tailored glycans in microbes, using preferably cheap and simple substrate. However, metabolic engineering faces one of the unique challenges, such as the need for an enzyme to catalyze desired substrate conversion when natural native substrates are already present. So, in metabolic engineering, such challenges are evaluated, and different strategies have been developed to overcome them. The generation of glycans and glycoconjugates via metabolic intermediate pathways can still be supported by glycol modeling achieved through metabolic engineering. It is evident that modern glycans engineering requires adoption of improved strain engineering strategies for creating competent glycoprotein expression platforms in bacterial hosts, in the future. These strategies include logically designing and introducing orthogonal glycosylation pathways, identifying metabolic engineering targets at the genome level, and strategically improving pathway performance (for example, through genetic modification of pathway enzymes). Here, we highlight current strategies, applications, and recent progress in metabolic engineering for producing high-value tailored glycans and their applications in biotherapeutics and diagnostics.

Biobased natural deep eutectic system as versatile solvents: Structure, interaction and advanced applications.

The increasing emphasis on the development of green replacements to traditional organic solvents and ionic liquids (ILs) can be attributed to the rising concerns over human health and detrimental impacts of conventional solvents towards the environment. A new generation of solvents inspired by nature and extracted from plant bioresources has evolved over the last few years, and are referred to as natural deep eutectic solvents (NADES). NADES are mixtures of natural constituents like sugars, polyalcohols, sugar-based alcohols, amino acids and organic acids. Interest in NADES has exponentially grown over the last eight years, which is evident from an upsurge in the number of research projects undertaken. NADES are highly biocompatible as they can be biosynthesized and metabolized by nearly all living organisms. These solvents pose several noteworthy advantages, such as easy synthesis, tuneable physico-chemical properties, low toxicity, high biodegradability, solute sustainability and stabilization and low melting point. Research on the applicability of NADES in diverse areas is gaining momentum, which includes as - media for chemical and enzymatic reactions; extraction media for essential oils; anti-inflammatory and antimicrobial agent; extraction of bioactive composites; as chromatographic media; preservatives for labile compounds and in drug synthesis. This review gives a complete overview of the properties, biodegradability and toxicity of NADES which we propose can assist in further knowledge generation on their significance in biological systems and usage in green and sustainable chemistry. Information on applications of NADES in biomedical, therapeutic and pharma-biotechnology fields is also highlighted in the current article along with the recent progress and future perspectives in novel applications of NADES.

Tetrahydrocannabinols: potential cannabimimetic agents for cancer therapy.

Tetrahydrocannabinols (THCs) antagonize the CB1 and CB2 cannabinoid receptors, whose signaling to the endocannabinoid system is essential for controlling cell survival and proliferation as well as psychoactive effects. Most tumor cells express a much higher level of CB1 and CB2; THCs have been investigated as potential cancer therapeutic due to their cannabimimetic properties. To date, THCs have been prescribed as palliative medicine to cancer patients but not as an anticancer modality. Growing evidence of preclinical research demonstrates that THCs reduce tumor progression by stimulating apoptosis and autophagy and inhibiting two significant hallmarks of cancer pathogenesis: metastasis and angiogenesis. However, the degree of their anticancer effects depends on the origin of the tumor site, the expression of cannabinoid receptors on tumor cells, and the dosages and types of THC. This review summarizes the current state of knowledge on the molecular processes that THCs target for their anticancer effects. It also emphasizes the substantial knowledge gaps that should be of concern in future studies. We also discuss the therapeutic effects of THCs and the problems that will need to be addressed in the future. Clarifying unanswered queries is a prerequisite to translating the THCs into an effective anticancer regime.

The Colloquy between Microbiota and the Immune System in Colon Cancer: Repercussions on the Cancer Therapy.

Colorectal cancer is the second leading cause of cancer deaths worldwide and has engrossed researchers' attention toward its detection and prevention at early stages. Primarily associated with genetic and environmental risk factors, the disease has also shown its emergence due to dysbiosis in microbiota. The microbiota not only plays a role in modulating the metabolisms of metastatic tissue but also has a keen role in cancer therapy. The immune cells are responsible for secreting various chemokines and cytokines, and activating pattern recognition receptors by different microbes can lead to the trail by which these cells regulate cancer. Furthermore, mixed immune reactions involving NK cells, tumor-associated macrophages, and lymphocytes have shown their connection with the microbial counterpart of the disease. The microbes like Bacteroides fragilis, Fusobacterium nucleatum, and Enterococcus faecalis and their metabolites have engendered inflammatory reactions in the tumor microenvironment. Hence the interplay between immune cells and various microbes is utilized to study the changing metastasis stage. Targeting either immune cells or microbiota could not serve as a key to tackling this deadly disorder. However, harnessing their complementation towards the disease can be a powerful weapon for developing therapy and diagnostic/prognostic markers. In this review, we have discussed various immune reactions and microbiome interplay in CRC, intending to evaluate the effectiveness of chemotherapy and immunotherapy and their parallel relationship.

Microbe-fabricated nanoparticles as potent biomaterials for efficient food preservation.

In recent years, cutting-edge nanotechnology research has revolutionized several facets of the food business, including food processing, packaging, transportation, preservation, and functioning. Nanotechnology has beginning to loom large in the food business as the industry's demand for biogenic nanomaterial grows. The intracellular and extracellular synthesis of metal, metal oxide, and other essential NPs has recently been explored in a variety of microorganisms, including bacteria, actinomycetes, fungi, yeasts, microalgae, and viruses. These microbes produce a variety extracellular material, exopolysaccharides, enzymes, and secondary metabolites which play key roles in synthesizing as well as stabilizing the nanoparticle (NPs). Furthermore, genetic engineering techniques can help them to improve their capacity to generate NPs more efficiently. As a result, using microorganisms to manufacture NPs is unique and has a promising future. Microbial-mediated synthesis of NPs has lately been popular as a more environmentally friendly alternative to physical and chemical methods of nanomaterial synthesis, which require higher prices, more energy consumption, and more complex reaction conditions, as well as a potentially dangerous environmental impact. It is critical to consider regulatory measures implemented at all stages of the process, from production through refining, packaging, preservation, and storage, when producing bionanomaterials derived from culturable microbes for efficient food preservation. The current review discusses the synthesis, mechanism of action, and possible food preservation uses of microbial mediated NPs, which can assist to minimize food deterioration from the inside out while also ensuring that food is safe and free of contaminants. Despite the numerous benefits, there are looming debates concerning their usage in food items, particularly regarding its aggregation in human bodies and other risks to the environment. Other applications and impacts of these microbe-fabricated NPs in the context of future food preservation prospects connected with regulatory problems and potential hazards are highlighted.

Targeting STAT3 signaling pathway in cancer by agents derived from Mother Nature.

Signal transducer and activator of transcription (STAT) proteins are latent transcription factors that reside in the cytoplasm of several types of cells. In canonical signaling, upon stimulation by cytokines and growth factors, STATs get activated and translocate into the nucleus to transcribe target genes. Among STATs, the STAT3 variant has been studied extensively and implicated in diverse human malignancies. Transcriptionally, STAT3 can upregulate the expression of genes associated with cell proliferation, antiapoptosis, prosurvival, angiogenesis, metastasis, and immune evasion. STAT3 can be constitutively activated in a broad range of human cancers including solid as well as hematological tumors and overexpression of STAT3 has been observed in a wide-range of patient-derived tumor tissue samples that may contribute to dismal prognosis. In contrast, blockade of STAT3 activation using inhibitors or knockdown systems can markedly suppress tumor progression, thus highlighting the significance of abrogating STAT3 signaling cascade in cancer therapy. In this review, we have provided a comprehensive overview of mechanisms of STAT3 signal transduction and its endogenous negative modulators, the role of STAT3 in oncogenesis, the interplay of miRNAs in STAT3 signaling, and mechanisms involved in persistent activation of STAT3. Furthermore, the review also provides a detailed overview of STAT3 signaling inhibition by selected natural compounds, which have displayed potent activity in various preclinical cancer model.

Mitigation of Salinity Stress in Wheat Seedlings Due to the Application of Phytohormone-Rich Culture Filtrate Extract of Methylotrophic Actinobacterium Nocardioides sp. NIMMe6.

Salinity stress is an important plant growth limiting factor influencing crop productivity negatively. Microbial interventions for salinity stress mitigation have invited significant attention due to the promising impacts of interactive associations on the intrinsic mechanisms of plants. We report the impact of microbial inoculation of a halotolerant methylotrophic actinobacterium (Nocardioides sp. NIMMe6; LC140963) and seed coating of its phytohormone-rich bacterial culture filtrate extract (BCFE) on wheat seedlings grown under saline conditions. Different plant-growth-promoting (PGP) attributes of the bacterium in terms of its growth in N-limiting media and siderophore and phytohormone [indole-3-acetic acid (IAA) and salicylic acid] production influenced plant growth positively. Microbial inoculation and priming with BCFE resulted in improved germination (92% in primed seeds at 10 dS m-1), growth, and biochemical accumulation (total protein 42.01 and 28.75 mg g-1 in shoot and root tissues at 10 dS m-1 in BCFE-primed seeds) and enhanced the activity level of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase) to confer stress mitigation. Biopriming with BCFE proved impactful. The BCFE application has further influenced the overexpression of defense-related genes in the seedlings grown under salinity stress condition. Liquid chromatography-mass spectrometry-based characterization of the biomolecules in the BCFE revealed quantification of salicylate and indole-3-acetate (Rt 4.978 min, m/z 138.1 and 6.177 min, 129.1), respectively. The high tolerance limit of the bacterium to 10% NaCl in the culture media suggested its possible survival and growth under high soil salinity condition as microbial inoculant. The production of a high quantity of IAA (45.6 µg ml-1 of culture filtrate) by the bacterium reflected its capability to not only support plant growth under salinity condition but also mitigate stress due to the impact of phytohormone as defense mitigators. The study suggested that although microbial inoculation offers stress mitigation in plants, the phytohormone-rich BCFE from Nocardioides sp. NIMMe6 has potential implications for defense against salinity stress in wheat.

Engineered Microbes for Pigment Production Using Waste Biomass.

Agri-food waste biomass is the most abundant organic waste and has high valorisation potential for sustainable bioproducts development. These wastes are not only recyclable in nature but are also rich sources of bioactive carbohydrates, peptides, pigments, polyphenols, vitamins, natural antioxidants, etc. Bioconversion of agri-food waste to value-added products is very important towards zero waste and circular economy concepts. To reduce the environmental burden, food researchers are seeking strategies to utilize this waste for microbial pigments production and further biotechnological exploitation in functional foods or value-added products. Microbes are valuable sources for a range of bioactive molecules, including microbial pigments production through fermentation and/or utilisation of waste. Here, we have reviewed some of the recent advancements made in important bioengineering technologies to develop engineered microbial systems for enhanced pigments production using agri-food wastes biomass/by-products as substrates in a sustainable way.

Stage-dependent concomitant microbial fortification improves soil nutrient status, plant growth, antioxidative defense system and gene expression in rice.

Stage-dependent concomitant fortification of rice (Oryza sativa L.) varieties PB1612 and CO51 with microbial inoculants Trichoderma asperellum and Pseudomonas fluorescens as seed coating, seedling root inoculation and soil application enhanced growth, activated antioxidant enzymes and modulated defence-related genes in plants. Microbial inoculants improved shoot height, tiller numbers, fresh weight and dry biomass. Co-inoculation was more impactful in enhancing plant growth and development as compared to single inoculation. Single and co-inoculation improved organic carbon (OC) and N, P and K content in the soil substantially. Mean values between control and co-inoculation varied significantly for OC in PB1612 (p0.001) and CO51 (p0.019) and phosphorus content in PB1612 (p0.044) and CO51 (p0.021). Microbial inoculation enhanced soil nutrients and increased their bioavailability for the plants. Total polyphenolics, flavonoids and protein content increased in the leaves following microbial inoculation. Enhanced non-enzymatic antioxidant parameters (ABTS, DPPH, Fe-ion reducing power and Fe-ion chelation) was found in microbe inoculated rice reflecting high free radical scavenging activity in polyphenolics-rich leaf extracts. Increased enzyme activity of superoxide dismutase (SOD), glutathione reductase (GR), phenylalanine ammonia-lyase (PAL), peroxidase (PO), glutathione peroxidase (GPX), ascorbate peroxidase (APX) and catalase (CAT) showed improved ROS scavenging in rice plants having co-inoculation. Over-expression of PAL, cCuZn-SOD and CAT genes in microbial inoculated rice plants was recorded. The study concludes that plant stage-wise concomitant fortification by microbial inoculants could play multi-pronged manifestations at physiological, biochemical and molecular level in rice to positively influence growth, development and defense attributes in plants.

Advances in nanomaterials induced biohydrogen production using waste biomass.

Recent advances on biohydrogen production using different types of waste biomass with the implementation of nanomaterials are summarized. Inspired by exceptional physicochemical and catalytic properties of nanomaterials, the present review focuses on several approaches including impact of nanomaterials on cellulosic biohydrogen production, possible pretreatment technology, as well as improved enzyme & sugar production in order to enhance the biohydrogen yield. Particularly, impacts of nanomaterial are elaborated in detail on different pathways of biohydrogen production (e.g. dark fermentation, photo-fermentation and hybrid-fermentation) using variety of waste biomass. Additionally, emphases are made on the feasibility of nanomaterials for making the biohydrogen production process more economical and sustainable and hence to develop advanced techniques for biohydrogen production using waste biomass.

Microbial inoculation in rice regulates antioxidative reactions and defense related genes to mitigate drought stress.

Microbial inoculation in drought challenged rice triggered multipronged steps at enzymatic, non-enzymatic and gene expression level. These multifarious modulations in plants were related to stress tolerance mechanisms. Drought suppressed growth of rice plants but inoculation with Trichoderma, Pseudomonas and their combination minimized the impact of watering regime. Induced PAL gene expression and enzyme activity due to microbial inoculation led to increased accumulation of polyphenolics in plants. Enhanced antioxidant concentration of polyphenolics from microbe inoculated and drought challenged plants showed substantially high values of DPPH, ABTS, Fe-ion reducing power and Fe-ion chelation activity, which established the role of polyphenolic extract as free radical scavengers. Activation of superoxide dismutase that catalyzes superoxide (O2-) and leads to the accumulation of H2O2 was linked with the hypersensitive cell death response in leaves. Microbial inoculation in plants enhanced activity of peroxidase, ascorbate peroxidase, glutathione peroxidase and glutathione reductase enzymes. This has further contributed in reducing ROS burden in plants. Genes of key metabolic pathways including phenylpropanoid (PAL), superoxide dismutation (SODs), H2O2 peroxidation (APX, PO) and oxidative defense response (CAT) were over-expressed due to microbial inoculation. Enhanced expression of OSPiP linked to less-water permeability, drought-adaptation gene DHN and dehydration related stress inducible DREB gene in rice inoculated with microbial inoculants after drought challenge was also reported. The impact of Pseudomonas on gene expression was consistently remained the most prominent. These findings suggested that microbial inoculation directly caused over-expression of genes linked with defense processes in plants challenged with drought stress. Enhanced enzymatic and non-enzymatic antioxidant reactions that helped in minimizing antioxidative load, were the repercussions of enhanced gene expression in microbe inoculated plants. These mechanisms contributed strongly towards stress mitigation. The study demonstrated that microbial inoculants were successful in improving intrinsic biochemical and molecular capabilities of rice plants under stress. Results encouraged us to advocate that the practice of growing plants with microbial inoculants may find strategic place in raising crops under abiotic stressed environments.

Metagenome dataset of wheat rhizosphere from Ghazipur region of Eastern Uttar Pradesh.

Wheat is the major crop in India and like other crops also subjected to influence by microbial communities of the rhizospheric region which are extremely diverse and undoubtedly play a central role in the nutrient cycle, plant productivity and growth promotion. In order to know how changes in the rhizospheric microbial community can make an impact on overall crop function, wheat rhizospheric soil samples from Ghazipur (25.913824 N 83.529715 E) regions of Eastern Uttar Pradesh (Eastern Indogangatic Plain), were collected and analyzed. Full length 16S rRNA gene amplification sequencing was performed to reveal the bacterial community in wheat rhizosphere. A total of 51,909 read were analyzed, out of that only 44,125 reads were classified and 7784 were unclassified using oxford nanopore sequencing and EPI2ME data analysis platform. MinION oxford nanopore sequencing uncovered that dominant phyla were Proteobacteria (68%), followed by firmicutes (13%), bacteroidetes (3%), actinobacteria (3%) and acidobacteria (3%). The data is available at the NCBI - Sequence Read Archive (SRA) with accession number: SRX5275271.

Re-addressing the biosafety issues of plant growth promoting rhizobacteria.

To promote agronomic sustainability, extensive research is being carried out globally, investigating biofertilizer development. Recently, it has been realized that some microorganisms used as biofertilizers behave as opportunistic pathogens and belong to the biosafety level 2 (BSL-2) classification. This poses serious risk to the environmental and human health. Evidence presented in various scientific forums is increasingly favoring the merits of using BSL-2 microorganisms as biofertilizers. In this review, we emphasize that partial characterization based on traditional microbiological approaches and small subunit rRNA gene sequences/conserved regions are insufficient for the characterization of biofertilizer strains. It is advised herein, that research and industrial laboratories developing biofertilizers for commercialization or environmental release must characterize microorganisms of interest using a multilateral polyphasic approach of microbial systematics. This will determine their risk group and biosafety characteristics before proceeding with formulation development and environmental application. It has also been suggested that microorganisms belonging to risk-group-1 and BSL-1 category should be used for formulation development and for field scale applications. While, BSL-2 microorganisms should be restricted for research using containment practices compliant with strict regulations.

Microbial Beta Glucosidase Enzymes: Recent Advances in Biomass Conversation for Biofuels Application.

The biomass to biofuels production process is green, sustainable, and an advanced technique to resolve the current environmental issues generated from fossil fuels. The production of biofuels from biomass is an enzyme mediated process, wherein ß-glucosidase (BGL) enzymes play a key role in biomass hydrolysis by producing monomeric sugars from cellulose-based oligosaccharides. However, the production and availability of these enzymes realize their major role to increase the overall production cost of biomass to biofuels production technology. Therefore, the present review is focused on evaluating the production and efficiency of ß-glucosidase enzymes in the bioconversion of cellulosic biomass for biofuel production at an industrial scale, providing its mechanism and classification. The application of BGL enzymes in the biomass conversion process has been discussed along with the recent developments and existing issues. Moreover, the production and development of microbial BGL enzymes have been explained in detail, along with the recent advancements made in the field. Finally, current hurdles and future suggestions have been provided for the future developments. This review is likely to set a benchmark in the area of cost effective BGL enzyme production, specifically in the biorefinery area.

Comparative genomic analysis of monosporidial and monoteliosporic cultures for unraveling the complexity of molecular pathogenesis of Tilletia indica pathogen of wheat.

Tilletia indica (Ti) - a quarantined fungal pathogen of wheat and its pathogenesis is chiefly governed by pathogen effectors secreted inside the host plant. The de novo genome sequencing of several field isolates and stages available could be used for understanding the molecular pathogenesis. The presence of gaps and low coverage of assembled genomes poses a problem in accurate functional annotation of such functions. In the present study attempts were made to improve the Ti draft genome through reconciliation of globally available datasets of three highly virulent monoteliospore cultures of Ti field isolates. It has sequence depth of 107x and N50 scaffold size of 80,772 (more than 26 times as large as achieved in the draft assembly) with highest sequence contiguity, more accurate and nearly complete. Functional annotation revealed that Ti genome contains 9209 genes evolved with many expanded gene families and arranged mostly in a cluster. About 79% of Ti genes were orthologous to other basidiomycetes fungi, Around 7.93% proteins were having secretary signals and 6.66% were identified as highly virulent pathogenicity genes. Using improved Ti genome as a reference, the genomic variation was assessed with respect to repeats, SNPs/InDel, gene families and correct set of virulence associated genes during its life cycle. The comparative intra-species, inter-stage and inter-species genomic variation will have broader implications to understand the gene regulatory networks involved in growth, mating and virulence behaviour of Tilletia f. spp. and also for better appreciation of fungal biology and disease management.