Characterization of individual spores of two biological insecticides, Bacillus thuringiensis and Lysinibacillus sphaericus, in response to glutaraldehyde using single-cell optical approaches

Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) are the most widely used microbial insecticides. Both encounter unfavorable environmental factors and pesticides in the field. Here, the responses of Bt and Ls spores to glutaraldehyde were characterized using Raman spectroscopy and differential interference contrast imaging at the single-cell level. Bt spores were more sensitive to glutaraldehyde than Ls spores under prolonged exposure: <1.0% of Bt spores were viable after 10 min of 0.5% (v/v) glutaraldehyde treatment, compared to ~ 20% of Ls spores. The Raman spectra of glutaraldehyde-treated Bt and Ls spores were almost identical to those of untreated spores; however, the germination process of individual spores was significantly altered. The time to onset of germination, the period of rapid Ca2+-2,6-pyridinedicarboxylic acid (CaDPA) release, and the period of cortex hydrolysis of treated Bt spores were significantly longer than those of untreated spores, with dodecylamine germination being particularly affected. Similarly, the germination of treated Ls spores was significantly prolonged, although the prolongation was less than that of Bt spores. Although the interiors of Bt and Ls spores were undamaged and CaDPA did not leak, proteins and structures involved in spore germination could be severely damaged, resulting in slower and significantly prolonged germination. This study provides insights into the impact of glutaraldehyde on bacterial spores at the single cell level and the variability in spore response to glutaraldehyde across species and populations.

Parageobacillus thermoglucosidasius Strain Engineering Using a Theophylline Responsive RiboCas for Controlled Gene Expression

The relentless increase in atmospheric greenhouse gas concentrations as a consequence of the exploitation of fossil resources compels the adoption of sustainable routes to chemical and fuel manufacture based on biological fermentation processes. The use of thermophilic chassis in such processes is an attractive proposition; however, their effective exploitation will require improved genome editing tools. In the case of the industrially relevant chassis Parageobacillus thermoglucosidasius, CRISPR/Cas9-based gene editing has been demonstrated. The constitutive promoter used, however, accentuates the deleterious nature of Cas9, causing decreased transformation and low editing efficiencies, together with an increased likelihood of off-target effects or alternative mutations. Here, we rectify this issue by controlling the expression of Cas9 through the use of a synthetic riboswitch that is dependent on the nonmetabolized, nontoxic, and cheap inducer, theophylline. We demonstrate that the riboswitches are dose-dependent, allowing for controlled expression of the target gene. Through their use, we were then able to address the deleterious nature of Cas9 and produce an inducible system, RiboCas93. The benefits of RiboCas93 were demonstrated by increased transformation efficiency of the editing vectors, improved efficiency in mutant generation (100%), and a reduction of Cas9 toxicity, as indicated by a reduction in the number of single nucleotide polymorphisms (SNPs) observed. This new system provides a quick and efficient way to produce mutants in P. thermoglucosidasius.

Bacterial diversity and composition on the rinds of specific melon cultivars and hybrids from across different growing regions in the United States

The goal of this study was to characterize the bacterial diversity on different melon varieties grown in different regions of the US, and determine the influence that region, rind netting, and variety of melon has on the composition of the melon microbiome. Assessing the bacterial diversity of the microbiome on the melon rind can identify antagonistic and protagonistic bacteria for foodborne pathogens and spoilage organisms to improve melon safety, prolong shelf-life, and/or improve overall plant health. Bacterial community composition of melons (n = 603) grown in seven locations over a four-year period were used for 16S rRNA gene amplicon sequencing and analysis to identify bacterial diversity and constituents. Statistically significant differences in alpha diversity based on the rind netting and growing region (p < 0.01) were found among the melon samples. Principal Coordinate Analysis based on the Bray-Curtis dissimilarity distance matrix found that the melon bacterial communities clustered more by region rather than melon variety (R2 value: 0.09 & R2 value: 0.02 respectively). Taxonomic profiling among the growing regions found Enterobacteriaceae, Bacillaceae, Microbacteriaceae, and Pseudomonadaceae present on the different melon rinds at an abundance of ≥ 0.1%, but no specific core microbiome was found for netted melons. However, a core of Pseudomonadaceae, Bacillaceae, and Exiguobacteraceae were found for non-netted melons. The results of this study indicate that bacterial diversity is driven more by the region that the melons were grown in compared to rind netting or melon type. Establishing the foundation for regional differences could improve melon safety, shelf-life, and quality as well as the consumers' health.

The unique biodegradation pathway of benzo[a]pyrene in moderately halophilic Pontibacillus chungwhensis HN14

Benzo[a]pyrene (BaP), as the typical representative of polycyclic aromatic hydrocarbons (PAHs), is a serious hazard to human health and natural environments. Though the study of microbial degradation of PAHs has persisted for decades, the degradation pathway of BaP is still unclear. Previously, Pontibacillus chungwhensis HN14 was isolated from high salinity environment exhibiting a high BaP degradation ability. Here, based on the intermediates identified, BaP was found to be transformed to 4,5-epoxide-BaP, BaP-trans-4,5-dihydrodiol, 1,2-dihydroxy-phenanthrene, 2-carboxy-1-naphthol, and 4,5-dimethoxybenzo[a]pyrene by the strain HN14. Furthermore, functional genes involved in degradation of BaP were identified using genome and transcriptome data. Heterogeneous co-expression of monooxygenase CYP102(HN14) and epoxide hydrolase EH(HN14) suggested that CYP102(HN14) could transform BaP to 4,5-epoxide-BaP, which was further transformed to BaP-trans-4,5-dihydrodiol by EH(HN14). Moreover, gene cyp102(HN14) knockout was performed using CRISPR/Cas9 gene-editing system which confirmed that CYP102(HN14) play a key role in the initial conversion of BaP. Finally, a novel BaP degradation pathway was constructed in bacteria, which showed BaP could be converted into chrysene, phenanthrene, naphthalene pathways for the first time. These findings enhanced our understanding of microbial degradation process for BaP and suggested the potential of using P. chungwhensis HN14 for bioremediation in PAH-contaminated environments.

Efficient bio-remediation of multiple aromatic hydrocarbons using different types of thermotolerant, ring-cleaving dioxygenases derived from Aeribacillus pallidus HB-1

As toxic contaminants, aromatic compounds are widespread in most environmental matrices, and bioenzymatic catalysis plays a critical role in the degradation of xenobiotics. Here, a thermophillic aromatic hydrocarbon degrader Aeribacillus pallidus HB-1 was found. Bioinformatic analysis of the HB-1 genome revealed two ring-cleaving extradiol dioxygenases (EDOs), among which, EDO-0418 was assigned to a new subfamily of type I.1 EDOs and exhibited a broad substrate specificity, particularly towards biarylic substrate. Both EDOs exhibited optimal activities at elevated temperatures (55 and 65 °C, respectively) and showed remarkable thermostability, pH stability, metal ion resistance and tolerance to chemical reagents. Most importantly, simulated wastewater bioreactor experiments demonstrated efficient and uniform degradation performance of mixed aromatic substrates under harsh environments by the two enzymes combined for potential industrial applications. The unveiling of two thermostable dioxygenases with broad substrate specificities and stress tolerance provides a novel approach for highly efficient environmental bioremediation using composite enzyme systems.

Microbial-based metabolites associated with degradation of imidacloprid and its impact on stress-responsive proteins

Imidacloprid (IMD), a neonicotinoid insecticide, is intensively used in agricultural fields for effective protection against aphids, cane beetles, thrips, stink bugs, locusts, etc., is causing serious environmental concerns. In recent years, seed treatment with Imidacloprid is being practiced mainly to prevent sucking insect pests. In India, due to the increase in application of this insecticide residue has been proven to have an impact on the quality of soil and water. In view of this, the current investigation is focussed on sustainable approach to minimize the residual effect of IMD in agricultural fields. The present study reveals a most promising imidacloprid resistant bacterium Lysinibacillus fusiformis IMD-Bio5 strain isolated from insecticide-contaminated soil. The isolated bacterial strain upon tested for its biodegradation potential on mineral salt medium (MSM) showed a significant survival growth at 150 g/L of IMD achieved after 3 days, whereas immobilized cells on MSM amended with 200 g/L of IMD as the sole carbon source provided degradation of 188 and 180 g/L of IMD in silica beads and sponge matrices, respectively. The liquid chromatography mass spectrometry was performed to test the metabolite responsive for IMD biodegradation potential of L. fusiformis IMD-Bio5 which showed the induced activity of the metabolite 6-Chloronicotinic acid. Furthermore, as compared to the untreated control, the Lysinibacillus fusiformis IMD-Bio5 protein profile revealed a range of patterns showing the expression of stress enzymes. Thus, results provided a most effective bacterium enabling the removal of IMD-like hazardous contaminants from the environment, which contributes to better agricultural production and soil quality, while long-term environmental advantages are restored.

Dynamics of microbial functional guilds involved in the humification process during aerobic composting of chicken manure on an industrial scale

Proper composting treatment of poultry manure waste is recommended before its use as a fertilizer. This involves many bioprocesses driven by microorganisms. Therefore, it is important to understand microbial mechanisms behind these bioprocesses in manure composting systems. Many efforts have been made to study the microbial community structure and diversity in these systems using high-throughput sequencing techniques. However, the dynamics of microbial interaction and functionality, especially for key microbial functional guilds, are not yet fully understood. To address these knowledge gaps, we collected samples from a 150-day industrial chicken manure composting system and performed the microbial network analysis based on the sequencing data. We found that the family Bacillaceae and genus Bacillus might play important roles in organic matter biodegradation at the mesophilic/thermophilic phases. Genera Virgibacillus, Gracilibacillus, Nocardiopsis, Novibacillus, and Bacillaceae_BM62 were identified as the key ones for humic acid synthesis at the mature phases. These findings improve our understanding about the fundamental mechanisms behind manure composting and can aid the development of microbial agents to promote manure composting performance.

Uranium removal in groundwater by Priestia sp. isolated from uranium-contaminated mining soil

Priestia sp. WW1 was isolated from a uranium-contaminated mining soil and identified. The uranium removal characteristics and mechanism of Priestia sp. WW1 were investigated. The results showed that the removal efficiency of uranium decreased with the increase of initial uranium concentration. When the uranium initial concentration was 5 mg/L, the uranium removal efficiency achieved 92.1%. The increase of temperature could promote the uranium removal. Carbon source could affect the removal rate of uranium, which was the fastest when the methanol was used as carbon source. The solution pH had significant effect on the uranium removal efficiency, which reached the maximum under solution pH 5.0. The experimental results and FTIR as well as XPS demonstrated that Priestia sp. WW1 could remove uranium via both adsorption and reduction. The common chloride ions, sulfate ions, Mn(II) and Cu(II) enhanced the uranium removal, while Fe(III) depressed the uranium removal. The Priestia sp. WW1 could effectively remove the uranium in the actual mining groundwater, and the increase of initial biomass could improve the removal efficiency of uranium in the actual mining groundwater. This study provided a promising bacterium for uranium remediation in the groundwater.

Production and characterization of polyhydroxybutyrate bioplastic precursor from Parageobacillus toebii using low-cost substrates and its potential antiviral activity

There is an increasing desire for bioplastics produced from renewable resources as an alternative to their petrochemical counterparts. These biopolymers have long-unnoticed antiviral properties. This study aimed to produce and characterize bioplastics by Parageobacillus toebii using low-cost substrates and determine their antiviral activity against coxsackievirus B4. Seven low-cost substrates (bagasse, water hyacinth, rice straw, rice water, sesame husks, molasses, and corn syrup) were compared with glucose for bioplastic precursor production. The highest bioplastic produced was from water hyacinth and glucose, followed by molasses, rice straw, rice water, sesame husks, and bagasse. Water hyacinth and glucose media were further optimized to increase the bioplastic precursor yield. The optimization of the media leads to increases in bioplastic precursor yields of 1.8-fold (3.456 g/L) and 1.496-fold (2.768 g/L), respectively. These bioplastics were further characterized by thermogravimetric analysis (TGA), Fourier-transformed infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR), and gas chromatography-mass spectrometry (GC-MS). They are thermostable, and their characterizations confirm the presence of polyhydroxybutyrate. The antiviral assay showed reasonable antiviral effects for bioplastics from water hyacinth (80.33 %) and glucose (55.47 %) media at 250 μg/mL maximum non-toxic concentrations (MNTC). The present investigation demonstrates a low-cost model for producing polyhydroxybutyrate bioplastic precursor for antiviral applications.

Molecular Cloning, Characterization, and Application of Organic Solvent-Stable and Detergent-Compatible Thermostable Alkaline Protease from Geobacillus thermoglucosidasius SKF4

Several thermostable proteases have been identified, yet only a handful have undergone the processes of cloning, comprehensive characterization, and full exploitation in various industrial applications. Our primary aim in this study was to clone a thermostable alkaline protease from a thermophilic bacterium and assess its potential for use in various industries. The research involved the amplification of the SpSKF4 protease gene, a thermostable alkaline serine protease obtained from the Geobacillus thermoglucosidasius SKF4 bacterium through polymerase chain reaction (PCR). The purified recombinant SpSKF4 protease was characterized, followed by evaluation of its possible industrial applications. The analysis of the gene sequence revealed an open reading frame (ORF) consisting of 1,206 bp, coding for a protein containing 401 amino acids. The cloned gene was expressed in Escherichia coli. The molecular weight of the enzyme was measured at 28 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The partially purified enzyme has its highest activity at a pH of 10 and a temperature of 80°C. In addition, the enzyme showed a half-life of 15 h at 80°C, and there was a 60% increase in its activity at 10 mM Ca2+ concentration. The activity of the protease was completely inhibited (100%) by phenylmethylsulfonyl fluoride (PMSF); however, the addition of sodium dodecyl sulfate (SDS) resulted in a 20% increase in activity. The enzyme was also stable in various organic solvents and in certain commercial detergents. Furthermore, the enzyme exhibited strong potential for industrial use, particularly as a detergent additive and for facilitating the recovery of silver from X-ray film.

Airborne microorganisms and key environmental factors shaping their community patterns in the core production area of the Maotai-flavor Baijiu

Airborne microorganisms are important parts of the Moutai-flavor Baijiu brewing microbial community, which directly affects the quality of Baijiu. However, environmental factors usually shape airborne microbiomes in different distilleries, even in the different production areas of the same distillery. Unfortunately, current understanding of environmental factors shaping airborne microbiomes in distilleries is very limited. To bridge this gap, we compared airborne microbiomes in the Moutai-flavor Baijiu core production areas of different distilleries in the Chishui River Basin and systematically investigated the key environmental factors that shape the airborne microbiomes. The top abundant bacterial communities are mainly affiliated to the phyla Actinobacteriota, Firmicutes, and Proteobacteri, whereas Ascomycota and Basidiomycota are the predominant fungal communities. The Random Forest analysis indicated that the biomarkers in three distilleries are Saccharomonospora and Bacillus, Thermoactinomyces, Oceanobacillus, and Methylobacterium, which are the core functional flora contributing to the production of Daqu. The correlation and network analyses showed that the distillery age and environmental temperature have a strong regulatory effect on airborne microbiomes, suggesting that the fermentation environment has a domesticating effect on air microbiomes. Our findings will greatly help us understand the relationship between airborne microbiomes and environmental factors in distilleries and support the production of the high-quality Moutai-flavor Baijiu.

Exploration of culturable bacterial associates of aphids and their interactions with entomopathogens

Aphids shelter several bacteria that benefit them in various ways. The associates having an obligatory relationship are non-culturable, while a few of facultative associates are culturable in insect cell lines, axenic media or standard microbiology media. In the present investigation, isolation, and characterization of the culturable bacterial associates of various aphid species, viz., Rhopalosiphum maidis, Rhopalosiphum padi, Sitobion avenae, Schizaphis graminum, and Lipaphis erysimi pseudobrassicae were carried out. A total of 42 isolates were isolated using different growth media, followed by their morphological, biochemical, and molecular characterization. The isolated culturable bacterial associates were found to belong to the genera Acinetobacter, Bacillus, Brevundimonas, Cytobacillus, Fictibacillus, Planococcus, Priestia, Pseudomonas, Staphylococcus, Sutcliffiella, and Tumebacillus which were grouped under seven families of four different orders of phyla Bacillota (Firmicutes) and Pseudomonata (Proteobacteria). Symbiont-entomopathogen interaction study was also conducted, in which the quantification of colony forming units of culturable bacterial associates of entomopathogenic fungal-treated aphids led us to the assumption that the bacterial load in aphid body can be altered by the application of entomopathogens. Whereas, the mycelial growth of entomopathogens Akanthomyces lecanii and Metarhizium anisopliae was found uninhibited by the bacterial associates obtained from Sitobion avenae and Rhopalosiphum padi. Analyzing persistent aphid microflora and their interactions with entomopathogens enhances our understanding of aphid resistance. It also fosters the development of innovative solutions for agricultural pest management, highlighting the intricate dynamics of symbiotic relationships in pest management strategies.

Metabolic engineering of Geobacillus thermoglucosidasius for polymer-grade lactic acid production at high temperature

The production and application of biodegradable polylactic acid are still severely hindered by the cost of its polymer-grade lactic acid monomers. High-temperature biomanufacturing has emerged as an increasingly attractive approach to enable low-cost and high-efficiency bulk chemical production. In this study, thermophilic Geobacillus thermoglucosidasius was reprogrammed to obtain optically pure l-lactic acid- and d-lactic acid-producing strains, G. thermoglucosidasius GTD17 and GTD7, by using rational metabolic engineering strategies including pathway construction, by-product elimination, and production enhancing. Moreover, semi-rational adaptive evolution was carried out to further improve their lactic acid synthesis performance. The final strains GTD17-55 and GTD7-144 produce 151.1 g/L of l-lactic acid and 153.1 g/L of d-lactic acid at 60 °C, respectively. In consideration of the high temperature, productive performance of these strains is superior compared to the state-of-the-art industrial strains. This study lays the foundation for the low-cost and efficient production of biodegradable plastic polylactic acid.

Composting of post-consumption food waste enhanced by bioaugmentation with microbial consortium

There is escalating interest in composting of post-consumption food waste (PCFW) to recycle nutrients and mitigate pollution by inappropriate disposal. The present study aimed to evaluate the performance of bioaugmentation to composting of PCFW, which is in difficulties caused by high sugar, protein and gross lipid content. Inoculation of the microbial consortium effectively induced rapid temperature and pH rising, which led to OM reduction rate at 25.11 % and maturity at 150 % in terms of Germination Index value. EEMs-FRI showed that humification was accelerated in the thermophilic stage and further improved in the mature stage. Bacterial community analysis revealed that microbial inoculant ameliorated acidification, and expedited temperature and pH rising in the initial stage, which in turn accelerated bacteria community succession. The abundance of Actinobacteria was much higher in the thermophilic and mature stage in T2 treatment than in T1, which might explain rapid organic degradation. High temperature enriched thermophilic genera (Thermobifida, Compostibacillus, Neobacillus), and Pseudonocardia and Actinoplanes were enriched in the mature stage, which correlated to effective degradation of organic matter, humification and maturity. Temperature and pH mainly motivated bacterial succession. The results suggest that bioaugmentation is a favorable approach for efficient composting of PCFW.

Characterization of a Thermostable Endolysin of the Aeribacillus Phage AeriP45 as a Potential Staphylococcus Biofilm-Removing Agent

Multidrug-resistant Gram-positive bacteria, including bacteria from the genus Staphylococcus, are currently a challenge for medicine. Therefore, the development of new antimicrobials is required. Promising candidates for new antistaphylococcal drugs are phage endolysins, including endolysins from thermophilic phages against other Gram-positive bacteria. In this study, the recombinant endolysin LysAP45 from the thermophilic Aeribacillus phage AP45 was obtained and characterized. The recombinant endolysin LysAP45 was produced in Escherichia coli M15 cells. It was shown that LysAP45 is able to hydrolyze staphylococcal peptidoglycans from five species and eleven strains. Thermostability tests showed that LysAP45 retained its hydrolytic activity after incubation at 80 °C for at least 30 min. The enzymatically active domain of the recombinant endolysin LysAP45 completely disrupted biofilms formed by multidrug-resistant S. aureus, S. haemolyticus, and S. epidermidis. The results suggested that LysAP45 is a novel thermostable antimicrobial agent capable of destroying biofilms formed by various species of multidrug-resistant Staphylococcus. An unusual putative cell-binding domain was found at the C-terminus of LysAP45. No domains with similar sequences were found among the described endolysins.

Culex quinquefasciatus Resistant to the Binary Toxin from Lysinibacillus sphaericus Displays a Consistent Downregulation of Pantetheinase Transcripts

Culex quinquefasciatus resistance to the binary (Bin) toxin, the major larvicidal component from Lysinibacillus sphaericus, is associated with mutations in the cqm1 gene, encoding the Bin-toxin receptor. Downregulation of the cqm1 transcript was found in the transcriptome of larvae resistant to the L. sphaericus IAB59 strain, which produces both the Bin toxin and a second binary toxin, Cry48Aa/Cry49Aa. Here, we investigated the transcription profiles of two other mosquito colonies having Bin resistance only. These confirmed the cqm1 downregulation and identified transcripts encoding the enzyme pantetheinase as the most downregulated mRNAs in both resistant colonies. Further quantification of these transcripts reinforced their strong downregulation in Bin-resistant larvae. Multiple genes were found encoding this enzyme in Cx. quinquefasciatus and a recombinant pantetheinase was then expressed in Escherichia coli and Sf9 cells, with its presence assessed in the midgut brush border membrane of susceptible larvae. The pantetheinase was expressed as a ~70 kDa protein, potentially membrane-bound, which does not seem to be significantly targeted by glycosylation. This is the first pantetheinase characterization in mosquitoes, and its remarkable downregulation might reflect features impacted by co-selection with the Bin-resistant phenotype or potential roles in the Bin-toxin mode of action that deserve to be investigated.

Endophytic Alkalotolerant Plant Growth-Promoting Bacteria Render Maize (Zea mays L.) Growth Under Alkaline Stress

This study investigates the role of bacterial endophytes from extreme alkaline environments in alleviating alkaline stress and plant development. Stressful environmental factors, such as soil acidity and alkalinity/sodicity, frequently affect plant development. In the present study, alkaline-tolerant endophytic strains were isolated from three plant species Saccharum munja, Calotropis procera, and Chenopodium album, and 15 out of the total of 48 isolates were selected for further examination of their abiotic stress tolerance. Molecular analysis based on 16S rRNA gene sequencing revealed strains from Enterobacter, Acinetobacter, Stenotrophomonas, Bacillus, Lysinibacillus, and Mammaliicoccus genera. Out of 15 isolates based on their quantitative PGP traits and abiotic stress tolerance, 6 were finally selected for greenhouse experiments. Under alkaline conditions, results demonstrated that the strains from the genera Enterobacter, Bacillus, Stenotrophomonas, and Lysinibacillus had beneficial effects on maize growth. These findings suggest that using a combination of bacteria with multiple plant growth-promoting attributes could be a sustainable approach to enhance agricultural yield, even in a challenging alkaline environment. The study concludes that the application of bacterial endophytes from plants growing in extremely alkaline environments might provide other plants with similar stress-tolerance abilities. The outcome of the study provides a basis for future exploration of the mechanisms underlying endophyte-induced stress tolerance.

Ancient Roman bacterium against current issues: strain Aquil_B6, Paenisporosarcina quisquiliarum, or Psychrobacillus psychrodurans?

IMPORTANCE

Since 1988, through the United States government's founding, the National Center for Biotechnology Information (NCBI) has provided an invaluable service to scientific advancement. The universality and total freedom of use if on the one hand allow the use of this database on a global level by all researchers for their valuable work, on the other hand, it has the disadvantage of making it difficult to check the correctness of all the materials present. It is, therefore, of fundamental importance for the correctness and ethics of research to improve the databases at our disposal, identifying and amending the critical issues. This work aims to provide the scientific community with a new sequence for the type strain Paenisporosarcina quisquiliarum SK 55 and broaden the knowledge of the Psychrobacillus psychrodurans species, in particular, considering the ancient strain Aquil_B6 found in an ancient Roman amphora.

Aquibacillus rhizosphaerae sp. nov., an Indole Acetic Acid (IAA)-producing Halotolerant Bacterium Isolated from the Rhizosphere Soil of Kalidium cuspidatum

A bacterium (named strain LR5S19T) was isolated from the rhizosphere soil of the halophyte Kalidium cuspidatum in Baotou, Inner Mongolia, China. Strain LR5S19T was Gram-stain-positive, motile with a polar flagellum, rod shaped, and spore forming at the terminal position in swollen sporangia, and it grew at 10-40 ℃ (optimum 30 ℃), pH 6.0-9.0 (optimum pH 7.0), and in the presence of 1.0-15.0% (w/v) NaCl (optimum 2.0%). The phylogenetic analysis of the 16S rRNA gene showed that strain LR5S19T shared the highest similarity (96.7%) with A. koreensis JCM 12387T, followed by A. kalidii HU2P27T (96.2%), A. sediminis BH258T (96.1%), and 'A. salsiterrae' 3ASR75-54T (96.0%). The ANIb, AAI and dDDH values between strain LR5S19T and its closely related type strains were 69.3-73.8%, 65.4-72.4% and 19.2-20.3%, respectively. The major polar lipids in strain LR5S19T consisted of diphosphatidylglycerol, phosphatidylglycerol, and three unidentified phospholipids, while MK-7 was the major respiratory quinone. The major fatty acids of the strain were anteiso-C15:0 and iso-C15:0. Based on phylogenomic and phenotypic results, strain LR5S19T should be classified as a novel species within the genus Aquibacillus, for which Aquibacillus rhizosphaerae sp. nov. is proposed. The type strain is LR5S19T (= CGMCC 1.62028T = KCTC 43434T). The comparative genomic analysis revealed that all eight members of Aquibacillus could utilize D-glucose via the glycolysis-gluconeogenesis pathway or the pentose phosphate pathway and use the tricarboxylic acid cycle as the metabolic center. The potassium ion transport proteins and compatible solute synthesis pathways in all the members likely also help them cope with hypersaline environments.

A novel marine bacterium Exiguobacterium marinum a-1 isolated from in situ plastisphere for degradation of additive-free polypropylene

As the ecological niche most closely associated with polymers, microorganisms in the 'plastisphere' have great potential for plastics degradation. Microorganisms isolated from the 'plastisphere' could colonize and degrade commercial plastics containing different additives, but the observed weight loss and surface changes were most likely caused by releasing the additives rather than actual degradation of the plastics itself. Unlike commercial plastics that contain additives, whether marine microorganisms in the 'plastisphere' have adapted to additive-free plastics as a surface to colonize and potentially degrade is not yet known. Herein, a novel marine bacterium, Exiguobacterium marinum a-1, was successfully isolated from mature 'plastisphere' that had been deployed in situ for up to 20 months. Strain a-1 could use additive-free polypropylene (PP) films as its primary energy and carbon source. After strain a-1 was incubated with additive-free PP films for 80 days, the weight of films decreased by 9.2%. The ability of strain a-1 to rapidly form biofilms and effectively colonize the surface of additive-free PP films was confirmed by Scanning Electron Microscopy (SEM), as reflected by the increase in roughness and visible craters on the surface of additive-free PP films. Additionally, the functional groups of -CO, -C-H, and -OH were identified on the treated additive-free PP films according to Fourier Transform Infrared (FTIR). Genomic data from strain a-1 revealed a suite of key genes involved in biosurfactant synthesis, flagellar assembly, and cellular chemotaxis, contributing to its rapid biofilm formation on hydrophobic polymer surfaces. In particular, key enzymes that may be responsible for the degradation of additive-free PP films, such as glutathione peroxidase, cytochrome p450 and esterase were also recognized. This study highlights the potential of microorganisms present in the 'plastisphere' to metabolize plastic polymers and points to the intrinsic importance of the new strain a-1 in the mitigation of plastic pollution.

Feedstock optimization with rice husk chicken manure and mature compost during chicken manure composting: Quality and gaseous emissions

This study investigated the impact of mature compost input on compost quality, greenhouse gases (GHGs, i.e. methane and nitrous oxide) and ammonia emissions during chicken manure and rice husk chicken manure co-composting. The experiment used different volumes of mature compost: 10% (T1), 20% (T2), and 30% (T3) to replace rice husk chicken manure. Results showed that mature compost enhanced compost maturity by promoting the activities of Bacillus, Caldicoprobacter, Thermobifida, Pseudogracilibacillus, Brachybacterium, and Sinibacillus. Compared to CK, T1, T2, and T3 reduced NH3 emission by 32.07%, 33.64%, and 56.12%, and mitigated 14.97%, 16.57%, and 26.18% of total nitrogen loss, respectively. Additionally, T2 and T3 reduced CH4 emission by 40.98% and 62.24%, respectively. The N2O emissions were positive correlation with Lactobacillus, Pseudogracilibacillus and ammonium nitrogen (p < 0.05), while T2 reducing total greenhouse effects. Therefore, replacing rice husk chicken manure with 20% mature compost is an efficient and promising approach for composting.

Bacteria intrinsic to Medicago sativa (alfalfa) reduce Salmonella enterica growth in planta

AIMS

The purpose of this study was to determine whether plant-associated bacteria (PAB) can reduce Salmonella enterica colonization and infection of alfalfa sprouts to reduce the risk of foodborne illness.

METHODS

We isolated PAB from alfalfa seeds and sprouts. Monoclonal isolates of the bacteria were obtained and tested for their ability to inhibit Salmonella Typhimurium growth in alfalfa sprouts over 6 days. Genome sequencing and annotation were used to construct draft genomes of the bacteria isolated in this study using Illumina sequencing platform.

RESULTS

We observed that a cocktail of five PAB could reduce Salmonella growth in alfalfa sprouts from ∼108 to ∼105 CFU g-1, demonstrating a protective role. Genome sequencing revealed that these bacteria were members of the Pseudomonas, Pantoea, and Priestia genus, and did not possess genes that were pathogenic to plants or animals.

CONCLUSIONS

This work demonstrates that PAB can be utilized to reduce pathogen levels in fresh produce, which may be synergistic with other technologies to improve the safety of sprouts and other fresh produce.

[Development of highly efficient electrocompetent cells for electroporation of Geobacillus thermoglucosidasius NCIMB 11955]

Geobacillus thermoglucosidasius is a kind of Gram-positive facultative anaerobic bacteria. The fast growth rate under high temperature and less susceptibility to microbial contamination enable G. thermoglucosidasius to be a desirable producer of biofuels and high-value-added chemicals for the next-generation industrial biotechnology. However, compared with the classical model strain Escherichia coli, the applications of G. thermoglucosidasius are hampered by its low transformation efficiency. This study aimed at obtaining competent cells with high transformation efficiency through inactivating restriction enzymes, adding cell membrane inhibitors and cell wall weakening agents. The results showed that the electro-transformation efficiency achieved 1.2×104 CFU/(μg DNA) by knocking out four genes encoding restriction enzymes. Adding a certain amount of tween 80, dl-threonine and glycine further increased the competent efficiency about 22.5, 44, and 334 times, respectively. The electro-transformation efficiency was enhanced to 4.6×106 CFU/(μg DNA) under the optimized conditions, laying a foundation for genetic manipulation and metabolic engineering of G. thermoglucosidasius.

Plant growth-promoting and heavy metal-resistant Priestia and Bacillus strains associated with pioneer plants from mine tailings

Open mine tailings dams are extreme artificial environments containing sizeable potentially toxic elements (PTEs), including heavy metals (HMs), transition metals, and metalloids. Furthermore, these tailings have nutritional deficiencies, including assimilable phosphorus sources, organic carbon, and combined nitrogen, preventing plant colonization. Bacteria, that colonize these environments, have mechanisms to tolerate the selective pressures of PTEs. In this work, several Priestia megaterium (formerly Bacillus megaterium), Bacillus mojavensis, and Bacillus subtilis strains were isolated from bulk tailings, anthills, rhizosphere, and endosphere of pioneer plants from abandoned mine tailings in Zacatecas, Mexico. Bacillus spp. tolerated moderate HMs concentrations, produced siderophores and indole-3-acetic acid (IAA), solubilized phosphates, and reduced acetylene in the presence of HMs. The strains harbored different PIB-type ATPase genes encoding for efflux pumps and Cation Diffusion Facilitator (CDF) genes. Moreover, nifH and nifD nitrogenase genes were detected in P. megaterium and B. mojavensis genomic DNA. They showed similarity with sequences of the beta-Proteobacteria species, which may represent likely horizontal transfer events. These Bacillus species precede the colonization of mine tailings by plants. Their phenotypic and genotypic features could be essential in the natural recovery of the sites by reducing the oxidative stress of HMs, fixing nitrogen, solubilizing phosphate, and accumulating organic carbon. These traits of the strains reflect the adaptations of Bacillus species to the mine tailings environment and could contribute to the success of phytoremediation efforts.

Efficient synthesis of 2'-deoxyguanosine in one-pot cascade by employing an engineered purine nucleoside phosphorylase from Brevibacterium acetylicum

2'-deoxyguanosine is a key medicinal intermediate that could be used to synthesize anti-cancer drug and biomarker in type 2 diabetes. In this study, an enzymatic cascade using thymidine phosphorylase from Escherichia coli (EcTP) and purine nucleoside phosphorylase from Brevibacterium acetylicum (BaPNP) in a one-pot whole cell catalysis was proposed for the efficient synthesis of 2'-deoxyguanosine. BaPNP was semi-rationally designed to improve its activity, yielding the best triple variant BaPNP-Mu3 (E57A/T189S/L243I), with a 5.6-fold higher production of 2'-deoxyguanosine than that of wild-type BaPNP (BaPNP-Mu0). Molecular dynamics simulation revealed that the engineering of BaPNP-Mu3 resulted in a larger and more flexible substrate entrance channel, which might contribute to its catalytic efficiency. Furthermore, by coordinating the expression of BaPNP-Mu3 and EcTP, a robust whole cell catalyst W05 was created, capable of producing 14.8 mM 2'-deoxyguanosine (74.0% conversion rate) with a high time-space yield (1.32 g/L/h) and therefore being very competitive for industrial applications.

Microbial community on industrial salty bovine hides: From the slaughterhouse to the salting

The leather-making industry is an age-old industry and desiccation with salt has been one of the most used methodologies for obtaining valuable skins. However, halophiles may proliferate and affect the integrity of the hide-collagen structure, as well as leading to undesirable red colorations or less-frequent purple stains. To understand the basis of these industrial hide contaminations, the microbial community from raw hide samples, salt-cured samples and four different industrial salts, was analyzed by 16S rRNA gene metabarcoding together with standard cultivation methods. Comparison of raw hides and correctly cured hides revealed a core microbiome that was absent from contaminated hides. In addition, archaea were missing from well-cured hides, whereas Psychrobacter and Acinetobacter were highly represented (23 % and 17.4 %, respectively). In damaged hides, only a few operational taxonomic units (OTUs), from among the hundreds detected, were able to proliferate and, remarkably, a single Halomonas OTU represented 57.66 % of the reads. Halobacteria, mainly Halovenus, Halorubrum and Halovivax, increased by up to 36.24-39.5 % in the red- and purple-affected hides. The major contaminants were isolated and hide infections, together with collagenase activity, were evaluated. The results showed that hides enriched with the non-pigmented isolate Halomonas utahensis COIN160 damaged the collagen fibers similarly to Halorubrum, and together they were considered to be one of the major causes. Putative degrading inhibitors were also identified from among the Alkalibacillus isolates. It was concluded that hide contaminations were driven by clonal outbreaks of a few specific microbes, which may have been non-pigmented collagen degraders. Acinetobacter and Alkalibacillus, members of the core microbiome of raw and well-cured salted hides, are suggested as hide contaminant inhibitors that need further analysis.

Anoxybacillus: an overview of a versatile genus with recent biotechnological applications

The Bacillaceae family members are considered to be a good source of microbial factories for biotechnological processes. In contrast to Bacillus and Geobacillus, Anoxybacillus, which would be thermophilic and spore-forming group of bacteria, is a relatively new genus firstly proposed in the year of 2000. The development of thermostable microbial enzymes, waste management and bioremediation processes would be a crucial parameter in the industrial sectors. There has been increasing interest in Anoxybacillus strains for biotechnological applications. Therefore, various Anoxybacillus strains isolated from different habitats have been explored and identified for biotechnological and industrial purposes such as enzyme production, bioremediation and biodegradation of toxic compounds. Certain strains have ability to produce exopolysaccharides possessing biological activities including antimicrobial, antioxidant and anticancer. This current review provides past and recent discoveries regarding Anoxybacillus strains and their potential biotechnological applications in enzyme industry, environmental processes and medicine.

Synergistic Effect of Melatonin and Lysinibacillus fusiformis L. (PLT16) to Mitigate Drought Stress via Regulation of Hormonal, Antioxidants System, and Physio-Molecular Responses in Soybean Plants

Drought is one of the most detrimental factors that causes significant effects on crop development and yield. However, the negative effects of drought stress may be alleviated with the aid of exogenous melatonin (MET) and the use of plant-growth-promoting bacteria (PGPB). The present investigation aimed to validate the effects of co-inoculation of MET and Lysinibacillus fusiformis on hormonal, antioxidant, and physio-molecular regulation in soybean plants to reduce the effects of drought stress. Therefore, ten randomly selected isolates were subjected to various plant-growth-promoting rhizobacteria (PGPR) traits and a polyethylene-glycol (PEG)-resistance test. Among these, PLT16 tested positive for the production of exopolysaccharide (EPS), siderophore, and indole-3-acetic acid (IAA), along with higher PEG tolerance, in vitro IAA, and organic-acid production. Therefore, PLT16 was further used in combination with MET to visualize the role in drought-stress mitigation in soybean plant. Furthermore, drought stress significantly damages photosynthesis, enhances ROS production, and reduces water stats, hormonal signaling and antioxidant enzymes, and plant growth and development. However, the co-application of MET and PLT16 enhanced plant growth and development and improved photosynthesis pigments (chlorophyll a and b and carotenoids) under both normal conditions and drought stress. This may be because hydrogen-peroxide (H2O2), superoxide-anion (O2-), and malondialdehyde (MDA) levels were reduced and antioxidant activities were enhanced to maintain redox homeostasis and reduce the abscisic-acid (ABA) level and its biosynthesis gene NCED3 while improving the synthesis of jasmonic acid (JA) and salicylic acid (SA) to mitigate drought stress and balance the stomata activity to maintain the relative water states. This may be possible due to a significant increase in endo-melatonin content, regulation of organic acids, and enhancement of nutrient uptake (calcium, potassium, and magnesium) by co-inoculated PLT16 and MET under normal conditions and drought stress. In addition, co-inoculated PLT16 and MET modulated the relative expression of DREB2 and TFs bZIP while enhancing the expression level of ERD1 under drought stress. In conclusion, the current study found that the combined application of melatonin and Lysinibacillus fusiformis inoculation increased plant growth and could be used to regulate plant function during drought stress as an eco-friendly and low-cost approach.

Use of modified ichip for the cultivation of thermo-tolerant microorganisms from the hot spring

BACKGROUND

Thermostable microorganisms are extremophiles. They have a special genetic background and metabolic pathway and can produce a variety of enzymes and other active substances with special functions. Most thermo-tolerant microorganisms from environmental samples have resisted cultivation on artificial growth media. Therefore, it is of great significance to isolate more thermo-tolerant microorganisms and study their characteristics to explore the origin of life and exploit more thermo-tolerant enzymes. Tengchong hot spring in Yunnan contains a lot of thermo-tolerant microbial resources because of its perennial high temperature. The ichip method was developed by D. Nichols in 2010 and can be used to isolate so-called "uncultivable" microorganisms from different environments. Here, we describe the first application of modified ichip to isolate thermo-tolerant bacteria from hot springs.

RESULTS

In this study, 133 strains of bacteria belonging to 19 genera were obtained. 107 strains of bacteria in 17 genera were isolated by modified ichip, and 26 strains of bacteria in 6 genera were isolated by direct plating methods. 25 strains are previously uncultured, 20 of which can only be cultivated after being domesticated by ichip. Two strains of previously unculturable Lysobacter sp., which can withstand 85 °C, were isolated for the first time. Alkalihalobacillus, Lysobacter and Agromyces genera were first found to have 85 °C tolerance.

CONCLUSION

Our results indicate that the modified ichip approach can be successfully applied in a hot spring environment.

Effects of midgut bacteria in Hyphantria cunea (Lepidoptera: Erebidae) on nuclear polyhedrosis virus and Bacillus thuringiensis (Bacillales: Bacillaceae)

Hyphantria cunea Drury (Lepidoptera: Erebidae) is a quarantine pest in China that can cause damage to hundreds of plants. As biological control agents, Nuclear Polyhedrosis Virus (NPV) and Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt) are commonly used to inhibit the prevalence of H. cunea. To investigate the role of midgut bacteria in the infection of NPV and Bt in H. cunea, we performed a series of tests, including isolating the dominant culturable bacteria in the midgut, eliminating intestinal bacteria, and respectively inoculating the dominant strains with NPV and Bt for bioassay. Two dominant bacteria, Klebsiella oxytoca Lautrop (Enterobacterales: Enterobacteriaceae) and Enterococcus mundtii Collins (Lactobacillales: Enterococcaceae), in the midgut of H. cunea were identified, and a strain of H. cunea larvae without intestinal bacteria was successfully established. In the bioassays of entomopathogen infection, K. oxytoca showed significant synergistic effects with both NPV and Bt on the death of H. cunea. In contrast, E. mundtii played antagonistic effects. This phenomenon may be attributed to the differences in the physico-chemical properties of the two gut bacteria and the alkaline environment required for NPV and Bt to infect the host. It is worth noting that the enhanced insecticidal activity of K. oxytoca on NPV and Bt provides a reference for future biological control of H. cunea by intestinal bacteria.

A thermophilic chemolithoautotrophic bacterial consortium suggests a mutual relationship between bacteria in extreme oligotrophic environments

A thermophilic, chemolithoautotrophic, and aerobic microbial consortium (termed carbonitroflex) growing in a nutrient-poor medium and an atmosphere containing N₂, O₂, CO₂, and CO is investigated as a model to expand our understanding of extreme biological systems. Here we show that the consortium is dominated by Carbonactinospora thermoautotrophica (strain StC), followed by Sphaerobacter thermophilus, Chelatococcus spp., and Geobacillus spp. Metagenomic analysis of the consortium reveals a mutual relationship among bacteria, with C. thermoautotrophica StC exhibiting carboxydotrophy and carbon-dioxide storage capacity. C. thermoautotrophica StC, Chelatococcus spp., and S. thermophilus harbor genes encoding CO dehydrogenase and formate oxidase. No pure cultures were obtained under the original growth conditions, indicating that a tightly regulated interactive metabolism might be required for group survival and growth in this extreme oligotrophic system. The breadwinner hypothesis is proposed to explain the metabolic flux model and highlight the vital role of C. thermoautotrophica StC (the sole keystone species and primary carbon producer) in the survival of all consortium members. Our data may contribute to the investigation of complex interactions in extreme environments, exemplifying the interconnections and dependency within microbial communities.

Mpp23Aa/Xpp37Aa Insecticidal Proteins from Bacillus thuringiensis (Bacillales: Bacillaceae) Are Highly Toxic to Anthonomus grandis (Coleoptera: Curculionidae) Larvae

The beetle Anthonomus grandis Boheman, 1843, is the main cotton pest, causing enormous losses in cotton. The breeding of genetically modified plants with A. grandis resistance is seen as an important control strategy. However, the identification of molecules with high toxicity to this insect remains a challenge. The susceptibility of A. grandis larvae to proteins (Cry1Ba, Cry7Ab, and Mpp23Aa/Xpp37Aa) from Bacillus thuringiensis Berliner, 1915, with toxicity reported against Coleopteran, has been evaluated. The ingestion of different protein concentrations (which were incorporated into an artificial diet) by the larvae was tested in the laboratory, and mortality was evaluated after one week. All Cry proteins tested exhibited higher toxicity than that the untreated artificial diet. These Cry proteins showed similar results to the control Cry1Ac, with low toxicity to A. grandis, since it killed less than 50% of larvae, even at the highest concentration applied (100 μg·g-1). Mpp/Xpp proteins provided the highest toxicity with a 0.18 μg·g-1 value for the 50% lethal concentration. Importantly, this parameter is the lowest ever reported for this insect species tested with B. thuringiensis proteins. This result highlights the potential of Mpp23Aa/Xpp37Aa for the development of a biotechnological tool aiming at the field control of A. grandis.

Isolation and Degradation Characteristics of PBAT Film Degrading Bacteria

In recent years, PBAT (polybutylene adipate-co-terephthalate) mulch has become one of the most commonly used biodegradable mulching films. In this paper, five potential strains of PBAT film degrading bacteria were screened from the soil sample using PBAT film as the sole carbon source. A highly efficient PBAT degrading strain JZ1 was isolated by comparing the degradation performance of PBAT mulching film identified as Peribacillus frigoritolerans S2313 by 16S rDNA sequence analysis. The capacity of the strain to degrade PBAT film was optimized by adjusting the cultivation conditions such as nitrogen source, pH, and inoculum volume. After 8 weeks of cultivation, the actual degradation rate of the strain to PBAT mulch film reached 12.45%. SEM (scanning electron microscopy) coupled with EDX (energy dispersive spectroscopy) analysis showed that microbial degradation is an oxidation process and is mainly due to the amorphous regions of the PBAT film. The biodegradation of PBAT film by Peribacillus frigoritolerans may provide a promising method for regulating the degradation progress of PBAT film in the farmlands.

Microbiological inoculation with and without biochar reduces the bioavailability of heavy metals by microbial correlation in pig manure composting

Biochar provides a suitable microenvironment for the growth of microorganisms. It may directly or indirectly affect changes in the population of microorganisms, thus affecting heavy metal bioavailability. This study aims to explore the effects of microbiological inoculation with and without biochar on microorganisms and on the bioavailability of heavy metals during pig manure composting. Three composting experiments were conducted under various conditions including no treatment (CK), only microbiological inoculation (TA), and integration with biochar (TB). Compared with raw materials before compost, TA reduced the bioavailability of Cu by 25.1%, Zn by 25.64%, and both Pb and Cr by 1.75%. TB reduced the bioavailability of Cu by 35.38%, Zn by 19.34%, Pb by 0.81%, and Cr by 3.9%. Furthermore, correlation analysis demonstrated that Debaryomyces were the primary fungi, possibly controlling the passivation of Cr. Bacillus, Fusarium, Pseudogracilibacillus, Sinibacillus, and Botryotrichum were the primary bacteria and fungi potentially governing the passivation of Zn, Lastly, Debaryomyces and Penicillium were the primary bacteria and fungi potentially controlling the passivation of Pb and Cu, respectively. Overall, we demonstrated that pig manure added to the microbial inoculum and biochar effectively reduced the bioavailability of heavy metals, thereby offering an applicable technology for reducing heavy metal contamination during pig manure composting.

Lysinibacillus macroides-mediated control of cellulose-producing morphotype of Salmonella

BACKGROUND

Soil-dwelling human pathogens like Salmonella are transmitted by fresh produce such as tomato, spinach, onion and cabbage. With >2600 serovars, it is difficult to classify the good plant colonizers from the non-colonizers. Generally, soil microbiota are classified as autochthonous or zymogenous organisms, based on their ability to survive in soil. However, such information for soil-dwelling human pathogens is not available Thus there is a need to classify these organisms for designing a strategy to prevent their outbreak. Moreover, soil harbours a plethora of microbes, which can be screened for competitive organisms to control such human pathogens.

RESULTS

In this study, we examined whether the morphotype based on the attachment factors (e.g., cellulose and curli fimbri) of Salmonella was important for its colonization of roots. Secondly, we tracked the location of the bacteria in the plant cell. Interestingly, most of the epidermal cells occupied by Salmonella showed propidium iodide-positive nuclei. As an extension of the study, a screening of competitive rhizospheric bacteria was performed. One isolate, identified as Lysinibacillus macroides, was able to inhibit the biofilm of Salmonella and subsequently reduced its colonization on roots.

CONCLUSION

Based on this study, we classified the Rdar (red, dry and rough) morphotypes as good plant colonists. The ability to colonize and subsequent kill the live plant cell throws light on the zymogenous life cycle of soil-dwelling Salmonella. Additionally, Lysinibacillus macroides served as a biocontrol agent by reducing the burden of Salmonella in various vegetables. Such organisms can further be explored to prevent contamination of the food chain. © 2022 Society of Chemical Industry.

Optimization of consolidated bioprocessing by response surface methodology in the conversion of corn stover to bioethanol by thermophilic Geobacillus thermoglucosidasius

The swift depletion of fossil fuels and their associated environment and economic impact has led the world to explore the sustainable alternate fuels. Amidst the available alternatives lignocellulosic bioethanol provides the edge over the exhausting fossil fuels. In this current study, Response surface methodology, a mathematical and statistical tool was used to optimize the fermentation conditions in consolidated bioprocessing of corn stover by Geobacillus thermoglucosidasius. The impact of inoculum concentration, temperature, pH, agitation speed and time in bioethanol fermentation were screened with Plackett-Burman design and it was farther optimized with central composite design. The analysis by PBD confirmed the significant impact of fermentation time, inoculum concentration, and temperature of the fermentation process. Further, it was optimized with CCD. This showed that 15% v/v of Inoculum concentration, 50 °C of temperature and fermentation time of 72 h increased the bioethanol concentration to a maximum of 9.04 g/L with 0.45 g/g significant yield and a conversion efficiency of 88%. Thus, the CCD showed a satisfactory result in consolidated bioprocessing of bioethanol from corn stover. Thus, in the future, this approach of optimization will yield a good base for consistent production of bioethanol.

Lysinibacillus sphaericus mediates stress responses and attenuates arsenic toxicity in Caenorhabditis elegans

Exposure to toxic metals alters host response and that leads to disease development. Studies have revealed the effects of metals on microbial physiology, however, the role of metal resistant bacteria on host response to metals is unclear. The hypothesis that xenobiotic interactions between gut microbes and arsenic influence the host physiology and toxicity was assessed in a Caenorhabditis elegans model. The arsenic-resistant Lysinibacillus sphaericus B1CDA was fed to C. elegans to determine the host responses to arsenic in comparison to Escherichia coli OP50 food. L. sphaericus diet extended C. elegans lifespan compared to E. coli diet, with an increased expression of genes involved in lifespan, stress response and immunity (hif-1, hsp-16.2, mtl-2, abf-2, clec-60), as well as reduced fat accumulation. Arsenic-exposed worms fed L. sphaericus also had a longer lifespan than those fed E. coli and had an increased expression of genes involved in cytoprotection, stress resistance (mtl-1, mtl-2) and oxidative stress response (cyp-35A2, isp-1, ctl-2, sod-1), together with a decreased accumulation of reactive oxygen species (ROS). In comparison with E. coli, L. sphaericus B1CDA diet increased C. elegans fitness while detoxifying arsenic induced ROS and extending lifespan.

Oceanobacillus alkalisoli sp. nov., an alkaliphilic bacterium isolated from saline-alkaline soil

Two alkaliphilic strains, designated APA_J-2 (6-2)T and APA_J-5 (13-2), were isolated from saline-alkali soil sampled in Jilin Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains APA_J-2 (6-2)T and APA_J-5(13–2) were closely related to members of the genus Oceanobacillus , and had the highest sequence similarity to Oceanobacillus indicireducens JCM 17251T (96.8 and 96.9 %, respectively). The 16S rRNA gene sequence similarity between the two novel isolates was 99.6 %, indicating that they were similar species. Cells were Gram-stain-positive, aerobic, motile and rod-shaped. The strains grew at 15–45 °C (optimum, 37 °C), pH 8.0–11.0. (optimum, pH 9) and with 0–10 % (w/v) NaCl (optimum, 5 %). The strains contained menaquinone-7 as the respiratory quinone and anteiso-C15 : 0 as the predominant cellular fatty acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The genomic DNA G+C content was 40.0 mol%. The average nucleotide identity (ANI), amino acid identity (AAI) and digital DNA–DNA hybridization (dDDH) values of strain APA_J-2 (6-2)T with O. indicireducens JCM 17251T were 85.5, 87.9 and 30.7 %, respectively. The ANI, AAI and dDDH values of strain APA_J-5 (13-2) with O. indicireducens JCM 17251T were 85.7, 87.7 and 30.8 %, respectively. Based on the phylogenetic, phenotypic, biochemical, chemotaxonomic and genome data, strains APA_J-2 (6-2)T and APA_J-5 (13-2) represent a novel species of the genus Oceanobacillus , for which the name Oceanobacillus alkalisoli sp. nov. is proposed. The type strain is APA_J-2 (6-2)T (=KCTC 43253T=GDMCC 1.2242T).

Control for chlorine resistant spore forming bacteria by the coupling of pre-oxidation and coagulation sedimentation, and UV-AOPs enhanced inactivation in drinking water treatment

Spore forming bacteria (SFB) are strongly chlorine resistant. Their presence in drinking water may cause diseases and pose threat to public health. Three SFB strains, i.e. Bacillus alvei, Bacillus cereus, and Lysinibacillus fusiformis, were isolated and identified from the finished water of a drinking water treatment plant where bacteria colonies occasionally reached the limit value. Due to their chlorine resistance, a SFB control strategy coupling pre-oxidation, coagulation sedimentation, and UV-AOPs inactivation in water treatment process was studied in lab scale. Five minutes pre-oxidation treatment by applying Cl₂ and ClO₂ induced remarkable spore transformation. Longer pre-oxidation exposure time didn't have apparent improvement. Cl₂ and ClO₂ dosages of 0.9 mg/L and 0.5 mg/L were suggested, respectively. The formed spores can be efficiently removed by the following coagulation sedimentation treatment. At a suggested dosage combination of 20 mg/L PAC and 0.08 mg/L PAM, spore removal efficiency reached about 3.15-lg. Comparing to applying sole UV irradiation, enhanced UV inactivation by adding 0.1 mM H₂O₂, or Cl₂, or peroxymonosulfate (PMS) substantially improved the inactivation of the most chlorine resistant SFB strain, Lysinibacillus fusiformis. UV-AOPs stably achieved 2-lg inactivation rate at UV dosage of 40 mJ/cm². UV/H₂O₂, UV/Cl₂ and UV/PMS inactivation kinetically enhanced 1.20 times, 1.36 times and 1.91 times over sole UV irradiation. Intracellular DNA and ATP leakages were detected, and remarkable damages of Lysinibacillus fusiformis cells' surface and ultrastructure were observed. These findings evidenced cell wall and cell membrane destructions, guaranteeing substantial SFB cells inactivation. This study was carried out based on three SFB strains isolated from a finished water, and common engineering practical operations. By providing engineeringly relevant references, the outcomes obtained would be helpful for dealing with SFB outbreak risk in drinking water treatment.

One-Pot Purification and Immobilization of Phenylalanine Dehydrogenase from Bacillus nanhaiensi by Functional Reduced Graphene Oxide

The one-pot immobilization of halophilic phenylalanine dehydrogenase from marine microorganism with metal ions modified reduced graphene oxide (CRGO) material was studied. Phenylalanine dehydrogenase was from Bacillus nanhaiensi and expressed with a C-terminal His-tag. Investigation of CRGO, CRGO-PEI, CRCO-Mn, and CRGO-PEI-Mn for one-pot purification and immobilization of phenylalanine dehydrogenase from crude enzyme solution was carried out. Enzyme activity yield rate achieved 80.0% by immobilization with CRCO-Mn, and the loading capacity was 6.7 mg/mg. Manganese ion coordination greatly improved the selectivity of the CRGO for the target His-tagged enzyme. Furthermore, the effect of NaCl concentration on the immobilization was investigated, which the loading capacity of CRGO-PEI and CRGO-Mn-PEI was increased by 10.7% and 30.6% with 1 M NaCl, respectively. The adsorption curves of crude enzyme one-pot immobilized by CRGO-Mn and purified enzyme immobilized by CRGO-Mn were similar. Therefore, one-pot immobilization strategy is promising for industrial application with advantages such as high efficiency and low cost, which shorten the pipelines for enzyme discovery towards industrial applications through the establishing of marine enzyme collections.

Evaluation of Bacillus thuringiensis Subsp. Israelensis and Bacillus sphaericus Combination Against Culex pipiens in Highly Vegetated Ditches

Among the few mosquito larvicides available in the market, Bacillus thuringiensis subsp. israelensis (Bti) and B. sphaericus (Bs) represent the most environmentally safe alternatives. The combination of the 2 products is known to overcome their specific limitations by producing a synergistic effect. The aim of the study was to assess the effect and persistence of a single treatment with a granular Bti + Bs formulation on highly vegetated ditches in northeastern Italy that represents the primary rural larval sites for Culex pipiens, the primary vector of the West Nile virus in Europe. The analysis takes into account the nonlinear temporal effects on the population dynamics of larvae and pupae. The results showed a dramatic reduction in mosquito larval abundance 24 h posttreatment (93%) and was effective against larvae up to 22 days (100%). The residual effect after 28 days was 99.5%, and a limited residual effect was observed after 39 days (31.2%). A reduction in pupal density was observed after 4 days (70%) and was >98% from days 14 to 28 posttreatment, persisting for up to 39 days (84% after 39 days). The results demonstrate the effective use of the Bti + Bs formulation against Cx. pipiens in vegetated ditches in rural areas. Our modeling framework provides a flexible statistical approach to predict the residual effect of the product over time, in order to plan a seasonal intervention scheme.

Enzyme-mediated biocalcification by a novel alkaliphilic Bacillus psychrodurans LC40 and its eco-friendly application as a biosealant for crack healing

Biocalcification is a natural biochemical process, which has been regarded as a promising method for sequestering heavy metals or carbon dioxide in the environment, healing cracks in concrete structures, and stabilizing soil. One of the key factors in this process is calcium carbonate-producing bacteria. The purpose of this study was to maximize the production of calcium carbonate by alkaliphilic Bacillus psychrodurans LC40 isolated from a limestone cave, by manipulating the medium composition for fast and non-detrimental crack healing, and to investigate the mechanism of its production. Strain LC40 could grow well in the strongly alkaline region (pH 9.5-11), indicating its alkaliphilic nature. The optimal medium for calcium carbonate production contained 2% tryptone, 1.5% urea, 0.15% NaHCO₃, and 150 mM calcium formate (pH 6). Using this medium, the yield of calcium carbonate at 72 h was approximately 8.6-fold higher than that obtained through Urea-CaCl₂ medium. In this culture, the urease and carbonic anhydrase activities were observed simultaneously, and the pH of the medium was found to have increased to 9.4, leading to maximum calcium carbonate production. This suggests that this pH value is achieved by the synergistic action of the two enzymes, resulting in a high calcium carbonate yield. The crystals were characterized by FESEM, EDS and XRD, which confirmed the production of rhombohedral and spherical calcium carbonate crystals containing vaterite and calcite. Strain LC40 completely healed a 0.75 mm wide crack in a very short time of 3 days using the optimized medium as a cementation solution. Our findings indicate that B. psychrodurans LC40 could be a promising candidate for the development of eco-friendly biosealant applicable to environmentally stressed concrete structures.

Draft genome sequence and functional analysis of Lysinibacillus xylanilyticus t26, a plant growth-promoting bacterium isolated from Capsicum chinense rhizosphere

Capsicum chinense is the chilli species containing the highest amount of capsaicin, and is an important traditional spice crop of Northeast India. Capsaicinoids derived from C. chinense are used in anticancer and anti-obesity treatments, as temperature regulators, in pain therapy, and as antioxidants. The current production and yield are very low due to the lack of organized cultivation and scientific inputs, and various plant diseases. Synthetic pesticides are frequently applied to boost yields, which creates potential risks to the environment, crops, and humans. The use of plant growth-promoting rhizobacteria is an alternative strategy in crop disease management to reduce the dependency on agrochemicals, which have detrimental effects on the environment. Lysinibacillus xylanilyticus t26 isolated from the C. chinense rhizosphere has shown good prospects in plant growth promotion and biocontrol. It showed strong antagonistic activity against Pythium ultimum ITCC 1650, Rhizoctonia solani ITCC 6491, and Fusarium oxysporum ITCC 6246. The draft genome sequencing of L. xylanilyticus t26 yielded a total of 5.69 Mbp with a G+C content of 36.80%. Genome analysis revealed that L. xylanilyticus t26 is very similar to L. xylanilyticus MH683160.1, and is phylogenetically related to L. xylanilyticus IBBPo7. Bioinformatics analysis predicted that it harbored type III polyketides, non-ribosomal peptides, terpenes, and lantibiotics including cerecidin, bacteriocins, siderophores, and thiopeptides, which are important traits of rhizobacteria for the utilization of minerals and to compete with other microbes for food. The strain t26 is a potential biocontrol agent for soil-borne fungal diseases. In this study, we derived the possible siderophore production pathways through the analysis of L. xylanilyticus t26 draft genome and plant growth response bioassays. The availability of genome data provides information that this draft genome harbored a siderophore BGC, which is 33% similar to petrobactin.

Lysinibacillus fusiformis bacteremia: Case report and literature review

A 93-year-old woman was diagnosed with Lysinibacillus fusiformis bacteremia complicated with coma blisters. Initial gram staining for L. fusiformis indicated the presence of gram-negative rods; however, subsequent staining of colonies from Mueller-Hinton agar revealed the presence of gram-positive and gram-negative rods with spherical endospores, and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (VITEK ® MS and microflex® LT/SH) definitively identified the organism as L. fusiformis. The two-week administration of piperacillin/tazobactam and ampicillin resulted in an improvement of the patient's general condition, and the skin lesions gradually improved.

Bacillus subtilis (Bacillales, Bacillaceae) Spores Affect Survival and Population Growth in the Grain Aphid Sitobion avenae (Hemiptera, Aphididae) in Relation to the Presence of the Facultative Bacterial Endosymbiont Regiella insecticola (Enterobacteriales, Enterobacteriaceae)

The grain aphid Sitobion avenae (Fabricius) is one of the most important cereal pests, damaging crops through sap sucking and virus transmission. Sitobion avenae harbors the secondary endosymbiont Regiella insecticola, which is highly prevalent in populations in south-central Chile and other regions of the world. In order to develop ecological alternatives for biological control, we studied the effect of applying the spores of a strain of the bacterium Bacillus subtilis on the survival and fecundity of the most prevalent genotype of S. avenae in central Chile. The strain selected was one that in previous studies had shown the ability to outcompete other bacteria. Using clones of this aphid genotype infected and uninfected with R. insecticola, we found that applying B. subtilis spores through artificial diets and spraying on leaves decreased both adult survival and nymph production. The detection of spores within the aphid body was negatively correlated with nymph production and was lower in the presence of R. insecticola when applied in diets. B. subtilis spores applied on leaves reduced the number of aphids, an effect that was stronger on aphids harboring R. insecticola. A possible interaction between endosymbiotic bacteria and bacterial antagonists within the aphid body is discussed.

Nanoparticle-associated single step hydrogen fermentation for the conversion of starch potato waste biomass by thermophilic Parageobacillus thermoglucosidasius

In the present study, starch-based potato peel waste biomass (PWB) was utilized as a potential substrate for hydrogen production via dark fermentation by the thermophillic amylase producing strain Parageobacillus thermoglucosidasius KCTC 33548. Supplementation of Fe₃O₄ nanoparticles (300 mg/L) led to a 4.15-fold increase in hydrogen production as compared to the control. The addition of optimized concentrations of both Fe₃O₄ nanoparticles (300 mg/L) and L-cysteine (250 mg/L) during hydrogen fermentation using pure starch and PWB generated maximum cumulative hydrogen yields of 167 and 71.9 mL with maximum production rates of 2.81 and 1.26 mL/h, respectively. Further, the correlation between Fe₃O₄ and the expression of hydrogenase isoforms and the related hydrogenase activity was explored. The possible mechanisms of the action of Fe₃O₄ on enhanced hydrogenase activity and hydrogen production was elucidated. To our knowledge, there are no such studies reported on enhanced hydrogen production from PWB in a single step.

Combined application of two Bacillus species enhance phytoremediation potential of Brassica napus in an industrial metal-contaminated soil

This study aimed to assess the impact of individual as well as combined application of Lysinibacillus macroides and Bacillus safensis in phytoremediation potential of Brassica napus grown in soil contaminated by industrial effluents. In response to five metals; copper, chromium, nickel, lead, and cadmium, results revealed that germination percentage, fresh and dry weights, and photosynthetic pigments of B. napus decreased under contaminated soil. On the other hand, electrolyte leakage due to cellular injury, metabolites (proline and glycine betaine), antioxidant enzymes (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase), accumulation of hydrogen peroxide and metals in plant's roots, shoots and leaves increased. Inoculation significantly reduced these effects as proved by the enhancement of germination percentage, fresh and dry biomass, and photosynthetic pigments. Simultaneously, the antioxidant enzymes, metabolites contents (proline and glycine betaine) and metal concentrations in plant's roots, shoots and leaves decreased. Combined application of both Bacilli strains was found more effective as compared to individual inoculation. It was concluded that metal resistant Bacillus species in combination had growth effects on B. napus and enhanced its phytoremediation efficiency in contaminated soil.Novelty statementBrassica napus; a hyper-accumulator of metals, loses phytoremediation potential with the passage of growth. Two Bacillus species (Lysinibacillus macroides and Bacillus safensis) having known bioremediation abilities were employed individually as well as in combination under metals contaminated soil to increase phytoremediation efficiency of B. napus. The metals containing soil used is a unique aspect in this study because selected soil, contaminated by industrial effluents, has not been evaluated or reported earlier. Combined application of Bacilli improved phytoremediation potential of B. napus more as compared to application of individual Bacillus strain which is yet another unique aspect of this investigation.

Proteomic insights into Lysinibacillus sp.-mediated biosolubilization of manganese

There has been alarming depletion of manganese (Mn) reserves owing to the ongoing extensive mining operations for catering the massive industrial demand of this element. Moreover, the mining operations have been leading to the generation of Mn-rich waste, thereby contaminating both terrestrial and aquatic bodies. The current scenario necessitates the development of alternative processes for bioremediation as well as economic recovery of Mn from mining wastes. The present investigation aims to report the bioleaching of Mn by Lysinibacillus sp. from mining waste residues in the context of mine waste remediation. Results confirmed that the native isolate had a high Mn biosolubilization potential with a solubilizing efficiency of 84% at the end of a 21-day study under optimized conditions of pulp density 2% (< 150-μm particle size), pH 6.5, and temperature 30 °C. Fourier transform infrared spectroscopy (FTIR) studies followed by liquid chromatography mass spectrometry (LC-MS) analysis were used to ascertain the change in microbial protein conformation, configuration, and protein identification. The results revealed the expression of heat shock proteins (HSP) from the family HSP which is predominantly expressed in bacteria during stress conditions. This study represents the application of native bacterial strain in Mn biosolubilization. We foresee the utility of proteomics-based studies to provide a methodological framework to the underlying mechanism of metal solubilization, thereby facilitating the two-tier benefit of recovery of Mn from alternative sources as well as bioremediation of waste having high manganese content.

Evaluation in the performance of the biodegradation of herbicide diuron to high concentrations by Lysinibacillus fusiformis acclimatized by sequential batch culture

We evaluated and characterized the biodegradation of the herbicide diuron in its commercial form above its saturation concentration by Lysinibacillus fusiformis acclimatized by sequential batch culturing. Acclimatization was carried out in eight cycles in liquid culture, improving the capacity of L. fusiformis to remove diuron from 55.13 ± 1.3% in the first batch to 87.2 ± 0.11% in the eighth batch. Diuron biosorption was characterized with Langmuir and Freundlich isotherms, obtaining a maximum biosorption (q_max) of 0.00885 mg mg^-1. In diuron biodegradation assays, a consumption substrate biomass yield (Y_SD/X) of 6.266 mg mg^-1 was obtained, showing that biodegradation was the main mechanism in diuron removal. Diuron biodegradation by L. fusiformis was characterized by the Monod model, with a maximum specific growth rate (μ_max) of 0.0245 h^-1 and an affinity constant (K_SD) of 344.09 mg L^-1. A low accumulation of 3,4-dichloroaniline with the production of chloride ions indicated dechlorination when diuron was present at high concentrations. A phytotoxic assay conducted with Lactuca sativa showed that the toxicity of an effluent with diuron at 250 mg L^-1 decreased when it was pretreated with acclimatized L. fusiformis. Acclimatization by sequential batch culturing improved the ability of L. fusiformis to biodegrade diuron at high concentrations, showing potential in the bioremediation of diuron-contaminated sites.