Effects of sudden shock load on simultaneous biohythane production in two-stage anerobic digestion of high-strength organic wastewater.

The two-stage anaerobic digestion (AD) for biohythane production is a sustainable solution, but it is sensitive to organic shock load that disrupts reactors and inhibits biohythane production. This study investigated biohythane production, reactor performance, and the possibility of post-failure restoration in a two-stage AD system designed for treating high-strength organic wastewater. Sudden shock load was applied by increasing the OLR threefold higher after reaching steady state phase. During shock load phase, hydrogen content, hydrogen yield and methane production rate (MPR) reached its peak values of 62.61 %, 1.641 mol H2/mol glucose, and 1.003 L CH4/L⋅d respectively before declining significantly. Interestingly, during the restorative phase, hydrogen production sharply declined to nearly zero, while methane production exhibited a resilience and reached its peak methane content of 52.2 %. The study successfully demonstrated the system's resilience to sudden shock load, ensuring stable methane production, while hydrogen production did not exhibit the same capability.

Fourteen new records of Crambidae (Lepidoptera) from South Korea.

This article reports 14 species of Crambidae for the first time in South Korea: Paracymoriza distinctalis (Leech, 1889) (Acentropinae), Pseudocatharylla duplicellus (Hampson, 1896) (Crambinae), Psammotis orientalis Munroe Mutuura, 1968, Anania albeoverbascalis Yamanaka, 1966, Anania stachydalis (Germar, 1821), and Ecpyrrhorrhoe rubiginalis (Hbner, 1796)(Pyraustinae), Scoparia iwasakii Sasaki, 1991 (Scoparinae), and Haritalodes basipunctalis (Bremer, 1864), Nagiella inferior (Hampson, 1899), Notarcha aurolinealis (Walker, 1859), Herpetogramma okamotoi Yamanaka, 1976, Glyphodes formosanus Shibuya, 1928, Mecyna fusei (Inoue, 1982), and Udea tritalis (Christoph, 1881)(Spilomelinae). Additionally, the diagnosis, distribution, pictures, and DNA barcode information of adults and male and female genitalia of these 14 crambid moth species are provided.

The relationship between resource abundance and insect herbivory on islands.

We examined the relationship between resource abundance and the feeding activity of phytophagous insects on three common island plants. The aim was to investigate the correlation between phytophagous insects' abundance and availability of food and island geography. We collected 30,835 leaves from three tree species groups (Mallotus japonicus, Prunus species, and Quercus species) on 18 islands in southwest Korea. The number of plant resources for herbivores varied: the number of leaves per shoot was the highest in Mallotus, leaf weight and the water content per leaf was significantly lower in Quercus species. External feeding was higher for Prunus and Quercus species, whereas the internal feeding type was significantly higher for Quercus species. Geography (area and distance), elevation and food resource (elevation, number of plant species, and the forest cover rate) had a variable effect on phytophagous insects feeding activities: distance and the number of plant species were more explainable to the external feeding guild. In contrast, area and forest cover were more to the internal feeding guild.

A novel decoy strategy for polymyxin resistance in Acinetobacter baumannii.

Modification of the outer membrane charge by a polymyxin B (PMB)-induced PmrAB two-component system appears to be a dominant phenomenon in PMB-resistant Acinetobacter baumannii. PMB-resistant variants and many clinical isolates also appeared to produce outer membrane vesicles (OMVs). Genomic, transcriptomic, and proteomic analyses revealed that upregulation of the pmr operon and decreased membrane-linkage proteins (OmpA, OmpW, and BamE) are linked to overproduction of OMVs, which also promoted enhanced biofilm formation. The addition of OMVs from PMB-resistant variants into the cultures of PMB-susceptible A. baumannii and the clinical isolates protected these susceptible bacteria from PMB. Taxonomic profiling of in vitro human gut microbiomes under anaerobic conditions demonstrated that OMVs completely protected the microbial community against PMB treatment. A Galleria mellonella-infection model with PMB treatment showed that OMVs increased the mortality rate of larvae by protecting A. baumannii from PMB. Taken together, OMVs released from A. baumannii functioned as decoys against PMB.

Wrapped in a thick, protective outer membrane, Acinetobacter baumannii bacteria can sometimes cause serious infections when they find their way into human lungs and urinary tracts. Antibiotics are increasingly ineffective against this threat, which forces physicians to resort to polymyxin B, an old, positively-charged drug that 'sticks' to the negatively-charged proteins and fatty components at the surface of A. baumannii. Scientists have noticed that when bacteria are exposed to lethal drugs, they often react by releasing vesicles, small 'sacs' made of pieces of the outer membranes which can contain DNA or enzymes. How this strategy protects the cells against antibiotics such as polymyxin B remains poorly understood. To investigate this question, Park et al. examined different strains of A. baumannii, showing that bacteria resistant to polymyxin B had lower levels of outer membrane proteins but would release more vesicles. Adding vesicles from resistant strains to non-resistant A. baumannii cultures helped cells to survive the drugs. In fact, this protective effect extended to other species, shielding whole communities of bacteria against polymyxin B. In vivo, the vesicles protected bacteria in moth larvae infected with A. baumannii, leading to a higher death rate in the animals. Experiments showed that the negatively-charged vesicles worked as decoys, trapping the positively-charged polymyxin B away from its target. Taken together, the findings by Park et al. highlight a new strategy that allows certain strains of bacteria to protect themselves from antibiotics, while also benefitting the rest of the microbial community.

Dumulmycin, an Antitubercular Bicyclic Macrolide from a Riverine Sediment-Derived Streptomyces sp.

Dumulmycin (1) was isolated from Streptomyces sp. DM28, a bacterial strain from a riverine sediment sample. The structure of 1 was elucidated as a bicyclic macrolide possessing 19-membered and 5-membered rings by spectroscopic analysis. The stereochemistry of 1 was determined by J-based configuration analysis, ROESY NMR data, DP4 calculations, and the modified Mosher's method. Genetic analysis identified a trans-acyltransferase polyketide biosynthetic gene cluster for 1. Dumulmycin exhibited in vitro antitubercular activity (MIC50 = 27.1 µM).

Comparative genomics of wild-type and laboratory-evolved biofilm-overproducing Deinococcus metallilatus strains.

Deinococcus metallilatus MA1002 was exposed to ultraviolet radiation to generate mutants with enhanced biofilm production. Two strains (nos 5 and 6) were then selected based on their high biofilm formation, as well as their possession of higher concentrations of extracellular matrix components (eDNA, protein and saccharides) than the wild-type (WT). Genomic sequencing revealed the presence of large genome deletions in a secondary chromosome in the mutants. Expression analyses of the WT and mutant strains indicated the upregulation of genes associated with exopolysaccharide synthesis and stress response. The mutant strains showed high mortality in glucose-supplemented (TYG) medium; however, cell death and biofilm formation were not increased in mutant cells grown under acetate- or glyoxylate-added media, suggesting that metabolic toxicity during glucose metabolism induced a high rate of cell death but improved biofilm formation in mutant strains. In damaged cells, eDNAs contributed to the enhanced biofilm formation of D. metallilatus.

Formicolides A and B, Antioxidative and Antiangiogenic 20-Membered Macrolides from a Wood Ant Gut Bacterium.

Two new macrolides, formicolides A (1) and B (2), were isolated from Streptomyces sp. BA01, a gut bacterial strain of the wood ant (Formica yessensis). Their 20-membered macrocyclic lactone structures were established using NMR and mass spectrometric data. The relative configurations of the formicolides were determined by J-based configuration analysis utilizing ROESY, HETLOC, and HECADE NMR spectroscopic data. Genomic and bioinformatics analysis of the bacterial strain enabled us to identify the type-I polyketide synthase pathway employing a trans-acyltransferase system. The absolute configurations of 1 and 2 are proposed based on detailed analysis of the sequences of the ketoreductases in the modular gene cluster and statistical comparative analysis of the experimental NMR chemical shifts and quantum mechanical calculations. Formicolides A and B (1 and 2) induced quinone reductase activity in murine Hepa-1c1c7 cells and antiangiogenic activity by suppression of tube formation in human umbilical vein endothelial cells.

Formicins, N-Acetylcysteamine-Bearing Indenone Thioesters from a Wood Ant-Associated Bacterium.

Formicins A-C (1-3) were discovered from Streptomyces sp. associated with wood ants. The structures of 1 and 2 were elucidated as indenone thioesters bearing N-acetylcysteamine based on spectroscopic analysis. The configurations of 1-3 were determined by the analysis of ROESY correlations, the phenylglycine methyl ester method, and chemical derivatization from 3 to 2. Formicin A inhibited the growth of human triple-negative breast cancer cells by regulating the liver kinase B1-mediated AMPK signaling pathway.

Protective Role of Bacterial Alkanesulfonate Monooxygenase under Oxidative Stress.

Bacterial alkane metabolism is associated with a number of cellular stresses, including membrane stress and oxidative stress, and the limited uptake of charged ions such as sulfate. In the present study, the genes ssuD and tauD in Acinetobacter oleivorans DR1 cells, which encode an alkanesulfonate monooxygenase and a taurine dioxygenase, respectively, were found to be responsible for hexadecanesulfonate (C16SO3H) and taurine metabolism, and Cbl was experimentally identified as a potential regulator of ssuD and tauD expression. The expression of ssuD and tauD occurred under sulfate-limited conditions generated during n-hexadecane degradation. Interestingly, expression analysis and knockout experiments suggested that both genes are required to protect cells against oxidative stress, including that generated by n-hexadecane degradation and H2O2 exposure. Measurable levels of intracellular hexadecanesulfonate were also produced during n-hexadecane degradation. Phylogenetic analysis suggested that ssuD and tauD are mainly present in soil-dwelling aerobes within the Betaproteobacteria and Gammaproteobacteria classes, which suggests that they function as controllers of the sulfur cycle and play a protective role against oxidative stress in sulfur-limited conditions.IMPORTANCEssuD and tauD, which play a role in the degradation of organosulfonate, were expressed during n-hexadecane metabolism and oxidative stress conditions in A. oleivorans DR1. Our study confirmed that hexadecanesulfonate was accidentally generated during bacterial n-hexadecane degradation in sulfate-limited conditions. Removal of this by-product by SsuD and TauD must be necessary for bacterial survival under oxidative stress generated during n-hexadecane degradation.

Stress responses linked to antimicrobial resistance in Acinetobacter species.

Since the last 20 years, bacteria of the genus Acinetobacter have been the leading cause of hospital-acquired infections. In addition to the ability of Acinetobacter species to acquire rapid antibiotic resistance, limited knowledge on the mechanisms of multidrug resistance to antibiotics limits the treatment options for such infections. Here, we present a review of cellular processes, including oxidative stress defense, energy metabolism, ppGpp signaling, toxin-antitoxin system, and quorum sensing network in Acinetobacter species and their roles in antimicrobial resistance. Although inhibition of stress responses is an attractive approach to the development of effective antimicrobial therapeutic agents, it is crucial to understand the mechanisms that cause antibiotic resistance in Acinetobacter species, as they are not as well studied as those in other pathogenic bacteria. RelA/SpoT has been shown to be involved in ppGpp synthesis in all 50 genomes of 35 Acinetobacter species. However, toxin-antitoxin (TA) systems are present in less than 30% of the 50 genomes (28/30% of SplT/A; 14/14% of HigB/A; 4/6% of HicA/B), except the RelE/B system (30/78%). These data suggested that ppGpp signaling is conserved in Acinetobacter species, but TA systems are not. This review describes our current knowledge on stress responses with respect to antibiotic resistance or tolerance in pathogenic and non-pathogenic Acinetobacter species.

Bacillus miscanthi sp. nov., a alkaliphilic bacterium from the rhizosphere of Miscanthus sacchariflorus.

A novel bacterial strain, designated AK13T (=KACC 21401T=DSM 109981T), was isolated from the rhizosphere of Miscanthus sacchariflorus. Strain AK13T was found to be an aerobic, Gram-stain-positive, endospore-forming and rod-shaped bacterium. It formed yellow circular colonies with smooth convex surfaces. The genomic DNA G+C content of strain AK13T was estimated to be 40 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that this strain was most closely related to Bacillus lehensis MLB2T (99.4 %), Bacillus oshimensis K11T (98.8 %) and Bacillus patagoniensis PAT 05T (96.6 %). The average nucleotide identity values between strain AK13T and B. lehensis MLB2T, B. oshimensis K11T and B. patagoniensis PAT 05T were 90.93, 91.05 and 71.87 %, respectively, with the digital DNA-DNA hybridization values of 42.7, 42.6 and 18.8 %, respectively. Cells grew at 5-40 °C (optimum, 28-35 °C), pH 6.5-13 (optimum, pH 8-9) and in the presence of 0-13.0 % (w/v) NaCl (optimum, 1 %). The cell wall of strain AK13T contained meso-diaminopimelic acid, and the major isoprenoid quinone was MK-7. Results of fatty acid methyl ester analysis revealed that iso-C15 : 0 was the predominant cellular fatty acid. Two-dimensional thin-layer chromatography analysis indicated that the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and glycolipid. The genotypic and phenotypic characteristics suggested that strain AK13T represented a novel species of the genus Bacillus, and thus the name Bacillus miscanthi sp. nov. is proposed.

OxyR-controlled surface polysaccharide production and biofilm formation in Acinetobacter oleivorans DR1.

The genomes of several Acinetobacter species possess three distinct polysaccharide-producing operons [two poly-N-acetyl glucosamine (PNAG) and one K-locus]. Using a microfluidic device, an increased amount of polysaccharides and enhanced biofilm formation were observed following continuous exposure to H2O2 and removal of the H2O2-sensing key regulator, OxyR, in Acinetobacter oleivorans DR1 cells. Gene expression analysis revealed that genes located in PNAG1, but not those in PNAG2, were induced and that genes in the K-locus were expressed in the presence of H2O2. Interestingly, the expression of the K-locus gene was enhanced in the PNAG1 mutant and vice versa. The absence of either OxyR or PNAG1 resulted in enhanced biofilm formation, higher surface hydrophobicity, and increased motility, implying that K-locus-driven polysaccharide production in both the oxyR and PNAG1 deletion mutants may be related to these phenotypes. Both the oxyR and K-locus deletion mutants were more sensitive to H2O2 compared with the wildtype and PNAG1 mutant strains. Purified OxyR binds to the promoter regions of both polysaccharide operons with a higher affinity toward the K-locus promoter. Although oxidized OxyR could bind to both promoter regions, the addition of dithiothreitol further enhanced the binding efficiency of OxyR, suggesting that OxyR might function as a repressor for controlling these polysaccharide operons.

Alternative fate of glyoxylate during acetate and hexadecane metabolism in Acinetobacter oleivorans DR1.

The glyoxylate shunt (GS), involving isocitrate lyase (encoded by aceA) and malate synthase G (encoded by glcB), is known to play important roles under several conditions including oxidative stress, antibiotic defense, or certain carbon source metabolism (acetate and fatty acids). Comparative growth analyses of wild type (WT), aceA, and glcB null-strains revealed that aceA, but not glcB, is essential for cells to grow on either acetate (1%) or hexadecane (1%) in Acinetobacter oleivorans DR1. Interestingly. the aceA knockout strain was able to grow slower in 0.1% acetate than the parent strain. Northern Blot analysis showed that the expression of aceA was dependent on the concentration of acetate or H2O2, while glcB was constitutively expressed. Up-regulation of stress response-related genes and down-regulation of main carbon metabolism-participating genes in a ΔaceA mutant, compared to that in the parent strain, suggested that an ΔaceA mutant is susceptible to acetate toxicity, but grows slowly in 0.1% acetate. However, a ΔglcB mutant showed no growth defect in acetate or hexadecane and no susceptibility to H2O2, suggesting the presence of an alternative pathway to eliminate glyoxylate toxicity. A lactate dehydrogenase (LDH, encoded by a ldh) could possibly mediate the conversion from glyoxylate to oxalate based on our RNA-seq profiles. Oxalate production during hexadecane degradation and impaired growth of a ΔldhΔglcB double mutant in both acetate and hexadecane-supplemented media suggested that LDH is a potential detoxifying enzyme for glyoxylate. Our constructed LDH-overexpressing Escherichia coli strain also showed an important role of LDH under lactate, acetate, and glyoxylate metabolisms. The LDH-overexpressing E. coli strain, but not wild type strain, produced oxalate under glyoxylate condition. In conclusion, the GS is a main player, but alternative glyoxylate pathways exist during acetate and hexadecane metabolism in A. oleivorans DR1.

Camporidines A and B: Antimetastatic and Anti-inflammatory Polyketide Alkaloids from a Gut Bacterium of Camponotus kiusiuensis.

Chemical studies of gut bacteria of the carpenter ant Camponotus kiusiuensis led to the discovery of two new alkaloids, camporidines A and B (1 and 2), from Streptomyces sp. STA1. The structures of 1 and 2 were established as new polyketide alkaloids bearing a piperidine-cyclopentene-epoxide 6/5/3 tricyclic system based on NMR spectroscopic and mass spectrometric analysis. The relative configurations of the camporidines were determined by their 1H-1H NOESY/ROESY and 1D NOE NMR correlations. The experimental ECD spectra of 1 and 2 were compared with their calculated ECD spectra to assign their absolute configurations. Camporidine A (1) displayed antimetastatic activity by suppression of cell invasion against the metastatic breast cancer cell line MDA-MB-231 and showed an anti-inflammatory effect by suppressing nitric oxide production induced by lipopolysaccharide. In addition, the putative biosynthetic gene cluster of the camporidines was identified, and the biosynthetic pathway of the camporidines was proposed based on bioinformatic analysis of the full genome of Streptomyces sp. STA1. Camporidines A and B (1 and 2) could be biosynthesized by a modular type I PKS containing an acyl transferase domain that accepts an unusual extender unit, which becomes the (C1'-C6') hexyl side chain. The post-PKS modification enzymes were predicted to perform an amination and an oxidation along with spontaneous Schiff base formation and generate the unique piperidine-cyclopentene-epoxide 6/5/3 tricyclic framework.

Culture-independent and culture-dependent analyses of the bacterial community in the phycosphere of cyanobloom-forming Microcystis aeruginosa.

Confocal and scanning electron microscopic observations have previously shown the strong bacterial association of Microcystis aeruginosa cells on their surfaces. DNA-based analyses of the associated bacterial communities were carried out using two M. aeruginosa strains grown in the laboratory and eight newly collected cyanobacterial bloom samples. M. aeruginosa was the most predominant species (66-100%) within the phylum Cyanobacteria. Rhizobium, Hydrogenophaga and Brevundimonas species were commonly found, and Flavobacterium species were present in all the cyanobacterial bloom samples. In total, 396 colonies from various samples were screened, revealing that most culturable bacteria belonged to the class Alphaproteobacteria (19%) including Rhizobium, Brevundimonas, and Porphyrobacter species. The genetic variation among the M. aeruginosa strains and different habitat conditions may have led to the presence of distinct bacterial populations among the tested samples. Among all the tested seven culturable isolates, Rhizobium sp. MK23 showed the best growth-promotion effect on the axenic M. aeruginosa strains. H2O2 was observed to be produced during the growth of M. aeruginosa PCC7806 under light conditions, this strain was more resistant to H2O2 when associated with Rhizobium sp. MK23. Our data suggested that Rhizobium species along with other associated bacteria might help the growth of M. aeruginosa by decomposing H2O2 under the aerobic growing conditions.

Streptoglycerides A-D with a Rare 6/5/5 Tricyclic Ring Skeleton from a Marine Actinomycete Streptomyces species.

Four novel secondary metabolites possessing a unique 6/5/5 tricyclic ring system, streptoglycerides A-D (1-4), were isolated from a marine actinomycete Streptomyces sp. derived from a mangrove sample collected on Kosrae Island. Their structures and absolute configurations were elucidated by spectroscopic data and electronic circular dichroism data. Streptoglyceride C (3) showed a weak inhibitory effect on the production of nitric oxide in BV-2 microglia cells.

Zoonotic Diseases and Phytochemical Medicines for Microbial Infections in Veterinary Science: Current State and Future Perspective.

Diseases caused by bacterial infections in small-scale and industrial livestock are becoming serious global health concern in veterinary science. Zoonotic bacteria, including Staphylococcus, Campylobacter, and Bartonella species, that infect animals and humans cause various illnesses, such as fever, diarrhea, and related complications. Bacterial diseases in animals can be treated with various classes of antibiotics, including fluoroquinolones, beta-lactams, aminoglycosides, and macrolides. However, the overuse and misuse of antibiotics have led to drug resistance in infectious agents, e.g., methicillin-resistant Staphylococcus; this hampers the treatment of infections in livestock, and such problems are increasing worldwide. Dietary phytochemicals and herbal medicines are useful and viable alternatives to pharmaceuticals because they are economical, effective, non-resistance-forming, renewable, and environmentally friendly. They are small molecules with high structural diversity that cause selective stress to or stimulation of resident microbiota, consequently causing an abundance of such microorganisms; thus, they can be used in preventing various diseases, ranging from metabolic and inflammatory diseases to cancer. In addition, the antioxidant effects of phytochemicals prevent substantial losses in the livestock industry by increasing animal fertility and preventing diseases. Potentially effective plant extracts could be used in combination with antibiotics to decrease the required dose of antibiotics and increase their effectiveness. This strategy can help avoid the side effects of chemical antimicrobials and allow the effective use of phytochemicals for treating diseases. Furthermore, phytochemicals are considered as potential alternatives to antibiotics because of their economical, non-resistance-forming and environmentally friendly properties. Flavonoids such as resveratrol, epigallocatechin gallate, and phenols such as galangin, puerarin, and ursolic acid are proven to be effective as antimicrobial agents. This review provides invaluable information about the types of microbial infections in animals and the current knowledge on phytotherapeutic agents classified by their mode of actions. It also provides insights into potential strategies for effectively treating animal infections using phytochemicals.

Lack of glyoxylate shunt dysregulates iron homeostasis in Pseudomonas aeruginosa.

The aceA and glcB genes, encoding isocitrate lyase (ICL) and malate synthase, respectively, are not in an operon in many bacteria, including Pseudomonas aeruginosa, unlike in Escherichia coli. Here, we show that expression of aceA in P. aeruginosa is specifically upregulated under H2O2-induced oxidative stress and under iron-limiting conditions. In contrast, the addition of exogenous redox active compounds or antibiotics increases the expression of glcB. The transcriptional start sites of aceA under iron-limiting conditions and in the presence of iron were found to be identical by 5' RACE. Interestingly, the enzymatic activities of ICL and isocitrate dehydrogenase had opposite responses under different iron conditions, suggesting that the glyoxylate shunt (GS) might be important under iron-limiting conditions. Remarkably, the intracellular iron concentration was lower while the iron demand was higher in the GS-activated cells growing on acetate compared to cells growing on glucose. Absence of GS dysregulated iron homeostasis led to changes in the cellular iron pool, with higher intracellular chelatable iron levels. In addition, GS mutants were found to have higher cytochrome c oxidase activity on iron-supplemented agar plates of minimal media, which promoted the growth of the GS mutants. However, deletion of the GS genes resulted in higher sensitivity to a high concentration of H2O2, presumably due to iron-mediated killing. In conclusion, the GS system appears to be tightly linked to iron homeostasis in the promotion of P. aeruginosa survival under oxidative stress.