Fibroblast growth factor 21 as a potential master regulator in metabolic disorders.

FGF21 is an endocrine hormone that controls key metabolic processes and induces the synthesis of glucose transporters, resulting in increased glucose absorption levels in fat cells. It is expressed in multiple metabolically active organs and tissues. FGF21 is also a powerful regulator of glucose homeostasis as a direct downregulating gene of peroxisome proliferator-activated receptor (PPAR), which plays a role in regulating the activity of glucose and lipids. Attempts were made to understand various aspects related to FGF21, including properties like receptor binding and genomic linkage map, along with the information about the genes that function in the upregulation of FGF21 and how it, directly and indirectly, downregulates the genes that are vital in various metabolic pathways. Furthermore, various gene regulatory analyses on the specific gene concerning unique micro RNAs and long non-coding RNAs that target FGF21 and alter its functioning along with single-nucleotide polymorphisms (SNPs) were observed, that are the common cause of cell dysregulation, leading to different metabolic diseases and pathogenesis of cancer. Unique protein-protein interaction and cross talk between FGF21 and PPARγ shed light on their combined role in metabolic disorder-related regulatory activities. Its potential and unique role as an effective biomarker for various cardiovascular and metabolic disorders have also been highlighted. This study attempts to highlight the pleiotropic role of FGF21 activity following its overexpression and inhibition of cascades that results in the induction of obesity from diet and simultaneously signals adipocytes to absorb glucose and decrease triglyceride and blood sugar levels in diabetic models (after administration), rendering it a promising treatment for several metabolic and cardiovascular disorders.

Genome-based reclassification of Bacillus acidicola, Bacillus pervagus and the genera Heyndrickxia, Margalitia and Weizmannia.

In the present study, the taxonomic positions of Bacillus acidicola, Bacillus pervagus and members of the genera Heyndrickxia, Margalitia and Weizmannia were evaluated. The 16S rRNA gene sequence similarity between Bacillus acidicola DSM 14745T, Bacillus pervagus DSM 23947T and members of the genera Heyndrickxia and Margalitia were above the cut-off level (>95 %) for genus delineation. Amino acid identity (AAI) values and the results of phylogenomic analysis suggested that B. acidicola and the members of the genera Heyndrickxia, Margalitia and Weizmannia belong to the same genus. Furthermore, the AAI and phylogenomic results also differentiate B. pervagus from B. acidicola and the members of the genera Heyndrickxia, Margalitia and Weizmannia. Based on the results, we propose to transfer Bacillus acidicola, Margalitia and Weizmannia to the genus Heyndrickxia. We also propose the reclassification of B. pervagus into a new genus Oikeobacillus gen. nov., with the type species Oikeobacillus pervagus comb. nov.

Genome-based reclassification of Picrophilus torridus Zillig et al. 1996 as a later heterotypic synonym of Picrophilus oshimae Schleper et al. 1996.

In the present study, we attempt to clarify the taxonomic positions of Picrophilus oshimae and Picrophilus torridus. The 16S rRNA gene sequence similarity between P. oshimae DSM 9789T and P. torridus DSM9790T (99.4 %) was above the threshold value (98.6 %) for bacterial species delineation. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between P. oshimae DSM 9789T and P. torridus DSM9790T were higher than the threshold values (95-96 % for ANI and 70 % for dDDH) for bacterial species delineation. The present results indicate that Picrophilus torridus Zillig et al. 1996 is a later heterotypic synonym of Picrophilus oshimae Schleper et al. 1996.

Description of Tellurirhabdus bombi sp. nov., Isolated from Bumblebee.

A Gram-stain-negative, aerobic, non-motile, and rod-shaped bacterium, designated IE-0392T, was isolated from a bumblebee. The 16S rRNA gene sequence (highest 16S rRNA gene sequence similarity with the type strain of Tellurirhabdus rosea (90.0%) and phylogenetic analysis suggest that strain IE-0392T was a member of the genus Tellurirhabdus. Strain IE-0392T optimally grew at 25 â„ƒ and pH 7.0. Menaquinone 7 (MK-7) was the only isoprenoid quinone present in strain IE-0392T. The major fatty acids (> 10%) of strain IE-0392T were iso-C15:0, C16:1 ω5c, and iso-C17:0 3-OH. The polar lipids of strain IE-0392T were phosphatidylethanolamine, phosphatidylserine, unidentified aminophospholipids, unidentified aminolipid, unidentified phospholipid, and unidentified lipids. The genomic DNA G + C content of strain IE-0392T was 48.8%. The amino acid identity (AAI) and the average nucleotide identity (ANI) values suggest that strain IE-0392T is a novel member of the genus Tellurirhabdus. The results suggest that strain IE-0392T represents a novel species of the genus Tellurirhabdus, for which the name Tellurirhabdus bombi sp. nov., is proposed. The type strain is IE-0392T (= GDMCC 1.2794T = JCM 35040T).

Transfer of Bacillus tepidiphilus Narsing Rao et al. 2021 to the genus Peribacillus as Peribacillus tepidiphilus comb. nov.

In the present study, the taxonomic position of Bacillus tepidiphilus was re-evaluated. Bacillus tepidiphilus (B. tepidiphilus) SYSU G01002T showed the highest 16S rRNA gene sequence similarity with the type strain Peribacillus alkalitolerans (P. alkalitolerans) (97.7%). In the phylogenetic (based on 16S rRNA sequence) and phylogenomic (based on 71 bacterial single-copy genes) trees, B. tepidiphilus SYSU G01002T clade with the members of the genus Peribacillus. The amino acid identity (AAI) value of B. tepidiphilus SYSU G01002T was highest with P. alkalitolerans KCTC 33631T (73.6%). The AAI value between B. tepidiphilus SYSU G01002T and P. alkalitolerans KCTC 33631T was above the cutoff level for genus delineation. The average nucleotide identity (ANI) between B. tepidiphilus and P. alkalitolerans KCTC 33631T was 74.1%, which was below the ANI value (95-96%) for species delineation. Based on the phylogenetic, phylogenomic, AAI, and ANI analysis, Bacillus tepidiphilus is proposed to transfer to the genus Peribacillus as Peribacillus tepidiphilus comb. nov. The type strain is SYSU G01002T (= KCTC 43131T = CGMCC 1.17491T).

Proposal to transfer Bacillus lacisalsi Dong et al. 2021 to the genus Alteribacter as Alteribacter lacisalsi comb. nov.

In the present study, the taxonomic position of Bacillus lacisalsi YSP-3T was evaluated using phylogenetic and genome-based comparison. B. lacisalsi YSP-3T showed the highest 16S rRNA gene sequence similarity to Alteribacter natronophilus M30T (98.4 %), followed by Alteribacter aurantiacus K1-5T (97.5 %) and Alteribacter populi FJAT-45347T (97.2 %). In phylogenetic (based on 16S rRNA gene sequences) and phylogenomic (based on 71 bacterial single-copy genes) trees, B. lacisalsi YSP-3T clustered with the members of the genus Alteribacter. The amino acid identity (AAI) values between B. lacisalsi YSP-3T and the members of the genus Alteribacter were >65 %, which is above the cut-off level (65-95 %) for genus delineation. The average nucleotide identity (ANI) values between B. lacisalsi YSP-3T and the members of the genus Alteribacter were <95 %, which is lower than the threshold value (95-96 %) for bacterial species delineation. The AAI value suggested that B. lacisalsi YSP-3T was a member of the genus Alteribacter while the ANIb value suggested it as a novel species of the genus Alteribacter. Based on the results, we propose to transfer Bacillus lacisalsi to the genus Alteribacter as Alteribacter lacisalsi comb. nov.

Comparative occurrence of ESBL/AmpC beta-lactamase-producing Escherichia coli and Salmonella in contract farm and backyard broilers.

The present study was conducted to detect the occurrence of beta-lactamase and biofilm-producing Escherchia coli and Salmonella in apparently healthy broiler birds reared in household and contract poultry farms. In total, 150 cloacal swabs were collected from apparently healthy broiler birds of various age groups reared in backyard (n = 100) and contract farms (n = 50) in West Bengal (India). The isolation rate of ESBL producers was significantly more (P < 0·05) reared in contract poultry farms than those reared in backyard. Majority of the E. coli isolates possessed blaCTX-M followed by blaSHV and blaTEM . Majority of the Salmonella strains possessed blaTEM followed by blaCTX-M , and no blaSHV was detected. The selected sequences of the PCR products were found cognate with blaCTX-M-1 , blaCTX-M-2 , blaCTX-M-9 , blaCTX-M-14 , blaCTX-M-15 , blaSHV-12 and blaTEM-52 . The study detected 46·8% of E. coli and 42·5% of Salmonella strains as biofilm producers. Beta-lactamase-producing Enterobacteriaceae strains showed resistance against tetracycline, chloramphenicol, doxycycline, co-trimoxazole and ampicillin and sensitivity to imipenem-EDTA, colistin and gentamicin. The study revealed the partial clonal relationship of ESBL sequences possessed by the poultry isolates of the present study and local clinical isolates available in the database. The study made consumer awareness about careful handling of live birds or poultry meat to avoid the zoonotic transmission of antimicrobial-resistant Enterobacteriaceae.

Bioactive Pectin-Murta (Ugni molinae T.) Seed Extract Films Reinforced with Chitin Fibers.

This study investigated the biocomposite pectin films enriched with murta (Ugni molinae T.) seed polyphenolic extract and reinforced by chitin nanofiber. The structural, morphological, mechanical, barrier, colorimetric, and antioxidant activity of films were evaluated. The obtained data clearly demonstrated that the addition of murta seed extract and the high load of chitin nanofibers (50%) provided more cohesive and dense morphology of films and improved the mechanical resistance and water vapor barrier in comparison to the control pectin film. The antioxidant activity ranged between 71% and 86%, depending on the film formulation and concentration of chitin nanofibers. The presented results highlight the potential use of chitin nanofibers and murta seed extract in the pectin matrix to be applied in functional food coatings and packaging, as a sustainable solution.

Green polymeric nanomaterials for the photocatalytic degradation of dyes: a review.

Pure and drinkable water will be rarer and more expensive as the result of pollution induced by industrialisation, urbanisation and population growth. Among the numerous sources of water pollution, the textile industry has become a major issue because effluents containing dyes are often released in natural water bodies. For instance, about two years are needed to biodegrade dye-derived, carcinogenic aromatic amines, in sediments. Classical remediation methods based upon physicochemical reactions are costly and still generate sludges that contain amine residues. Nonetheless, recent research shows that nanomaterials containing biopolymers are promising to degrade organic pollutants by photocatalysis. Here, we review the synthesis and applications of biopolymeric nanomaterials for photocatalytic degradation of azo dyes. We focus on conducting biopolymers incorporating metal, metal oxide, metal/metal oxide and metal sulphide for improved biodegradation. Biopolymers can be obtained from microorganisms, plants and animals. Unlike fossil-fuel-derived polymers, biopolymers are carbon neutral and thus sustainable in the context of global warming. Biopolymers are often biodegradable and biocompatible.

Molecular and Genomic Characterization of PFAB2: A Non-virulent Bacillus anthracis Strain Isolated from an Indian Hot Spring.

BACKGROUND: Thermophilic bacilli in both aerobic or facultative anaerobic forms have been isolated for over a hundred years from different mesophilic or thermophilic environments as they are potential source of bioactive secondary metabolites. But the taxonomic resolution in the Bacillus genus at species or at strain level is very challenging for the insufficient divergence of the 16S rRNA genes. One such recurring problem is among Bacillus anthracis, B. cereus and B. thuringiensis. The disease-causing B. anthracis strains have their characteristic virulence factors coded in two well-known plasmids, namely pXO1 (toxin genes) and pXO2 (capsule genes). OBJECTIVE: The present study aimed at the molecular and genomic characterization of a recently reported thermophilic and environmental isolate of B. anthracis, strain PFAB2. METHODS: We performed comparative genomics between the PFAB2 genome and different strains of B. anthracis, along with closely related B. cereus strains. RESULTS: The pangenomic analysis suggests that the PFAB2 genome harbors no complete prophage genes. Cluster analysis of Bray-Kurtis similarity resemblance matrix revealed that gene content of PFAB2 is more closely related to other environmental strains of B. anthracis. The secretome analysis and the in vitro and in vivo pathogenesis experiments corroborate the avirulent phenotype of this strain. The most probable explanation for this phenotype is the apparent absence of plasmids harboring genes for capsule biosynthesis and toxins secretion in the draft genome. Additional features of PFAB2 are good spore-forming and germinating capabilities and rapid replication ability. CONCLUSION: The high replication rate in a wide range of temperatures and culture media, the non-pathogenicity, the good spore forming capability and its genomic similarity to the Ames strain together make PFAB2 an interesting model strain for the study of the pathogenic evolution of B. anthracis.

Structural and Functional Properties of Exopolysaccharide Excreted by a Novel Bacillus anthracis (Strain PFAB2) of Hot Spring Origin.

Exopolysaccharide produced by a unique avirulent Bacillus anthracis strain PFAB2 of hot spring origin has been characterized and its functional properties are investigated which is a first report. Maximum yield of EPS is 7.66 g/l with 2% glucose and 1% peptone as optimum carbon and nitrogen source respectively. The EPS is found to be a homopolymer consisting of only glucose as principle monosaccharide component. Through 1H NMR study, different dextran-like proton peaks are observed. Molecular weight of the EPS resembles low molecular weight bacterial origin polysaccharides. Melting transition of the EPS has started after 276 °C which indicates good thermal stability. The EPS also shows potent antioxidant activity in terms of DPPH and ABTS mediated free radical scavenging property compared to standard ascorbic acid. Emulsifying property of the EPS is also observed and has shown good emulsification of vegetable oils. The polysaccharide forms a thermo resistant gel during the heating phase, with G' higher than G″ indicating excellent shear-thinning behaviour and viscoelastic nature of the EPS.

Structural and Functional Properties, Biosynthesis, and Patenting Trends of Bacterial Succinoglycan: A Review.

The exopolysaccharide succinoglycan is produced mainly by a large number of soil microbes of Agrobacterium, Rhizobium or Pseudomonas genera etc. Structural properties of succinoglycan are unique in terms of its thermal stability and superior viscosifying property. Unlike the other highly commercialized bacterial exopolysaccharides like dextran or xanthan, mass scale application of succinoglycan has not been that much broadly explored yet. Bacterial succinoglycan is found suitable as a viscosifying and emulsifying agent in food industry, in gravel packing or fluid-loss control agent etc. In this present review, the key aspects of succinoglycan study, in particular, developments in structural characterizations, exo/exs operon system involved in biosynthesis pathway, commercial applications in food and other industries and patenting trends have been discussed.

Genome-based approach to evaluate the metabolic potentials and exopolysaccharides production of Bacillus paralicheniformis CamBx3 isolated from a Chilean hot spring.

In the present study, a thermophilic strain designated CamBx3 was isolated from the Campanario hot spring, Chile. Based on 16S rRNA gene sequence, phylogenomic, and average nucleotide identity analysis the strain CamBx3 was identified as Bacillus paralicheniformis. Genome analysis of B. paralicheniformis CamBx3 revealed the presence of genes related to heat tolerance, exopolysaccharides (EPS), dissimilatory nitrate reduction, and assimilatory sulfate reduction. The pangenome analysis of strain CamBx3 with eight Bacillus spp. resulted in 26,562 gene clusters, 7,002 shell genes, and 19,484 cloud genes. The EPS produced by B. paralicheniformis CamBx3 was extracted, partially purified, and evaluated for its functional activities. B. paralicheniformis CamBx3 EPS with concentration 5 mg mL-1 showed an optimum 92 mM ferrous equivalent FRAP activity, while the same concentration showed a maximum 91% of Fe2+ chelating activity. B. paralicheniformis CamBx3 EPS (0.2 mg mL-1) demonstrated ß-glucosidase inhibition. The EPS formed a viscoelastic gel at 45°C with a maximum instantaneous viscosity of 315 Pa.s at acidic pH 5. The present study suggests that B. paralicheniformis CamBx3 could be a valuable resource for biopolymers and bioactive molecules for industrial applications.

Characterization of Chilean hot spring-origin Staphylococcus sp. BSP3 produced exopolysaccharide as biological additive.

A type of high molecular weight bioactive polymers called exopolysaccharides (EPS) are produced by thermophiles, the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures. Over time, EPS became important as natural biotechnological additives because of their noncytotoxic, emulsifying, antioxidant, or immunostimulant activities. In this article, we unravelled a new EPS produced by Staphylococcus sp. BSP3 from an acidic (pH 6.03) San Pedro hot spring (38.1 °C) located in the central Andean mountains in Chile. Several physicochemical techniques were performed to characterize the EPS structure including Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), 1D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). It was confirmed that the amorphous surface of the BSP3 EPS, composed of rough pillar-like nanostructures, is evenly distributed. The main EPS monosaccharide constituents were mannose (72%), glucose (24%) and galactose (4%). Also, it is a medium molecular weight (43.7 kDa) heteropolysaccharide. NMR spectroscopy demonstrated the presence of a [→ 6)-⍺-D-Manp-(1 → 6)-⍺-D-Manp-(1 →] backbone 2-O substituted with 1-⍺-D-Manp. A high thermal stability of EPS (287 °C) was confirmed by TGA analysis. Emulsification, antioxidant, flocculation, water-holding (WHC), and oil-holding (OHC) capacities are also studied for biotechnological industry applications. The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes, like flocculation and natural additives in product formulation.

Preparation and Characterization of Lignin Nanoparticles from Different Plant Sources.

This article presents new research on producing lignin nanoparticles (LNPs) using the antisolvent nanoprecipitation method. Acetone (90%) served as the lignin solvent and water (100%) as the antisolvent, using five types of lignins from various sources. Comprehensive characterization techniques, including NMR, GPC, FTIR, TEM, and DLS, were employed to assess both lignin and LNP properties. The antioxidant activity of the LNPs was evaluated as well. The results demonstrated the successful formation of spherical nanoparticles below 100 nm with initial lignin concentrations of 1 and 2%w/v. The study highlighted the crucial role of lignin purity in LNP formation and colloidal stability, noting that residual carbohydrates adversely affect efficiency. This method offers a straightforward, environmentally friendly approach using cost-effective solvents, applicable to diverse lignin sources. The innovation of this study lies in its demonstration of a cost-effective and eco-friendly method to produce stable, nanometric-sized spherical LNPs. These LNPs have significant potential as reinforcement materials due to their reinforcing capability, hydrophilicity, and UV absorption. This work underscores the importance of starting material purity for optimizing the process and achieving the desired nanometric dimensions, marking a pioneering advancement in lignin-based nanomaterials.

Bacterial Polysaccharide-Stabilized Silver Nanoparticles Photocatalytically Decolorize Azo Dyes.

Bacterial polysaccharide is advantageous over plant, algal, and fungal polysaccharides in terms of stability, non-toxicity, and biodegradable nature. In addition, bacterial cell wall polysaccharide (CPs) is very little explored compared to exopolysaccharide. In this study, CPs have been isolated from thermotolerant Chryseobacterium geocarposphaerae DD3 (CPs3) from textile industry dye effluent. Structural characterization of the CPs was done by different techniques, viz., scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). CPs3 demonstrated compact non-porous amorphous surface composed of evenly distributed macromolecular lumps. TGA revealed a high thermostability (~ 350 °C) of the polysaccharide. FTIR and NMR confirm the polysaccharidic nature of the polymer, consisting of glucose units linked by both ß-(1 → 3) and ß-(1 → 4) glycosidic bonds. The functional properties of CPs3 were evaluated for industrial use as additive, especially antibacterial, emulsification, and flocculation capacities. A single-step green synthesis of silver nanoparticle (AgNP) was performed using CPs3. AgNP was characterized using ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), AFM, and particle size analyses. The CPs3-stabilized AgNP exhibited potential photocatalytic activity against a broad range of azo dyes, congo red (88.33 ± 0.48%), methyl red (76.81 ± 1.03%), and malachite green (47.34 ± 0.90%) after only 3 h of reaction. According to our knowledge, this is the first report on CPs from C. geocarposphaerae. The results demonstrated multifunctionality of CPs3 in both prospective, CPs3 as additive in biotechnology industry as well as Cps3-stabilized AgNP for bioremediation of azo dye.

Biological properties of exopolysaccharides produced by Bacillus spp.

There is currently a constant search for ecofriendly bioproducts, which could contribute to various biomedical applications. Among bioproducts, exopolysaccharides are prominent contemporary extracellular biopolymers that are produced by a great variety of bacterial species. These homo- or heteropolymers are composed of monomeric sugar units linked by glycosidic bonds, which are secreted to the external medium. Bacillus spp. are reported to be present in different ecosystems and produce exopolysaccharides with different biological properties such as antioxidant, antibacterial, antiviral anti-inflammatory, among others. Since a great diversity of bacterial strains are able to produce exopolysaccharides, a great variation in the molecular composition is observed, which is indeed present in some of the chemical structures predicted until date. These molecular characteristics and their relations with different biological functions are discussed in order to visualize future applications in biomedical section.

The role of bacterial exopolysaccharides (EPS) in the synthesis of antimicrobial silver nanomaterials: A state-of-the-art review.

The emergence of multi-drug resistant (MDR) pathogens poses a significant global health concern due to the failure of conventional medical treatment. As a result, the development of several metallic (Ag, Au, Zn, Ti, etc.) nanoparticles, has gained prominence as an alternative to conventional antimicrobial therapies. Among these, green-synthesized silver nanoparticles (AgNPs) have gained significant attention due to their notable efficiency and broad spectrum of antimicrobial activity. Bacterial exopolysaccharides (EPS) have recently emerged as a promising biological substrate for the green synthesis of AgNPs. EPS possess polyanionic functional groups (hydroxyl, carboxylic, sulfate, and phosphate) that effectively reduce and stabilize AgNPs. EPS-mediated AgNPs exhibit a wide range of antimicrobial activity against various pathogenic microbes, including Gram-positive and Gram-negative bacteria, as well as fungi. The extraction and purification of bacterial EPS play a vital role in obtaining high-quality and -quantity EPS for industrial applications. This study focuses on the comprehensive methodology of EPS extraction and purification, encompassing screening, fermentation optimization, pretreatment, protein elimination, precipitation, and purification. The review specifically highlights the utilization of bacterial EPS-mediated AgNPs, covering EPS extraction, the synthesis mechanism of green EPS-mediated AgNPs, their characterization, and their potential applications as antimicrobial agents against pathogens. These EPS-mediated AgNPs offer numerous advantages, including biocompatibility, biodegradability, non-toxicity, and eco-friendliness, making them a promising alternative to traditional antimicrobials and opening new avenues in nanotechnology-based approaches to combat microbial infections.

The shift of soil microbial community induced by cropping sequence affect soil properties and crop yield.

Rational cropping maintains high soil fertility and a healthy ecosystem. Soil microorganism is the controller of soil fertility. Meanwhile, soil microbial communities also respond to different cropping patterns. The mechanisms by which biotic and abiotic factors were affected by different cropping sequences remain unclear in the major grain-producing regions of northeastern China. To evaluate the effects of different cropping sequences under conventional fertilization practices on soil properties, microbial communities, and crop yield, six types of plant cropping systems were performed, including soybean monoculture, wheat-soybean rotation, wheat-maize-soybean rotation, soybean-maize-maize rotation, maize-soybean-soybean rotation and maize monoculture. Our results showed that compared with the single cropping system, soybean and maize crop rotation in different combinations or sequences can increase soil total organic carbon and nutrients, and promote soybean and maize yield, especially using soybean-maize-maize and maize-soybean-soybean planting system. The 16S rRNA and internal transcribed spacer (ITS) amplicon sequencing showed that different cropping systems had different effects on bacterial and fungal communities. The bacterial and fungal communities of soybean monoculture were less diverse when compared to the other crop rotation planting system. Among the different cropping sequences, the number of observed bacterial species was greater in soybean-maize-maize planting setup and fungal species in maize-soybean-soybean planting setup. Some dominant and functional bacterial and fungal taxa in the rotation soils were observed. Network-based analysis suggests that bacterial phyla Acidobacteria and Actinobacteria while fungal phylum Ascomycota showed a positive correlation with other microbial communities. The phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) result showed the presence of various metabolic pathways. Besides, the soybean-maize-maize significantly increased the proportion of some beneficial microorganisms in the soil and reduced the soil-borne animal and plant pathogens. These results warrant further investigation into the mechanisms driving responses of beneficial microbial communities and their capacity on improving soil fertility during legume cropping. The present study extends our understanding of how different crop rotations effect soil parameters, microbial diversity, and metabolic functions, and reveals the importance of crop rotation sequences. These findings could be used to guide decision-making from the microbial perspective for annual crop planting and soil management approaches.

Stress Dependent Biofilm Formation and Bioactive Melanin Pigment Production by a Thermophilic Bacillus Species from Chilean Hot Spring.

Thermophilic bacteria able to survive extreme temperature stress are of great biotechnological interest due to their extracellular production of bioactive molecules as a part of a survival strategy, or by intracellular modifications. In the present study, thermophilic Bacillus haynesii CamB6, isolated from a Chilean hot spring, was studied for the formation of different stress response molecules. The polymeric pigment produced by the bacterial strain was characterized by different physicochemical techniques. On exposure to ranges of temperature (50-60 °C), pH (5.0-7.0), and sources of nitrogen and carbon (1-5 g·L-1), the bacteria responded with a biofilm network formation in a hydrophobic polystyrene surface. Biofilm formation under fed-batch conditions was also statistically validated. The bacteria showed a planktonic pellicle network formation in the presence of induced hypoxia and salinity stress (19.45 g·L-1) under static conditions. Salinity stress also resulted in the intracellular response of brown pigment production. The pigment was structurally and functionally characterized by UV-Vis absorbance and the presence of different characteristic peaks via FTIR analysis (bacterial pyomelanin fingerprints) were assessed. A high thermal stability and TGA profile indicated the brown pigment was a probable pyomelanin candidate. Micropyrolysis (Py-GC/MS) showed that isoprene, pyrrole, benzene, pyridine, and their derivatives were the major components detected. In addition, acetic acid, indole, phenol, and its derivatives were observed. The absence of sulfocompounds in the pyrolyzed products agreed with those reported in the literature for pyomelanin. The pigment surface morphology was analyzed via SEM, and the elemental composition via EDS also demonstrated the similarity of the brown pigment to that of the melanin family. The pyomelanin pigment was observed to be bioactive with promising antioxidant capacity (H2O2, Fe2+) compared to the standard antioxidant molecules. In conclusion, B. haynesii CamB6 demonstrated the formation of several biomolecules as a stress response mechanism that is bioactive, showing its probable biotechnological applications in future.