Fungal load in <Emphasis Type="Italic">Bradysia agrestis</Emphasis>, a phytopathogen-transmitting insect vector

Larvae of Bradysia agrestis, a phytopathogen-transmitting insect vector in East Asia, were sampled from geographically (ecologically) segregated regions to identify their intestinal fungal flora. A total of 24 fungal strains were isolated from the insect vectors and selected based on morphological differences. In addition, 38 fungal strains were isolated from the ulcerated parts of invaded host plants by the same method, revealing the impact of vector fungal flora on their host plants. For molecular identification of the fungi, internal transcribed spacer (ITS) regions were amplified and sequenced. Their sequences were compared with sequences of other fungal strains obtained from NCBI GenBank, and their phylogeny was determined. The dominant fungal genera in the insect vector were Penicillium (25%), Aspergillus (21%), and Cladosporium (13%). In plant scar lesions, most fungal isolates belonged to the genera Fusarium (31.6%), Phoma (7.8%), Didymella (7.8%), and Epicoccum (7.8%). Fungal genera in vectors or host plant lesions differed by study site. Furthermore, diversity indices by study site showed clear differences based on Margalef’s richness (2.06, 2.40, 3.04), and Menhinick’s (1.89, 2.12, 2.53), and Simpson’s indices (0.14, 0.07, 0.07). In addition, common fungal strains in insect vectors were found to be closely related to members of the genera Cladosporium, Penicillium, or Aspergillus. Among these strains, those showing the highest homology with Aspergillus terreus, which regarded as beneficial fungal genera could be considered ideal paratransgenesis candidates. Some other fungal strains from vectors or ulcerated plant parts from each study site after B. agrestis invasion may be harmful in terms of plant disease or agrifood safety. This study provides information on the fungal microbiota of B. agrestis, an emerging problem in East Asia, and proposes paratransgenesis candidates to control this insect vector. Furthermore, potential transferable pathogens or commensal fungi were revealed by comparing the fungal biota between the insect gut and the ulcerated parts of the invaded host plants.     

Comparison of phbC genes cloned from Ralstonia eutropha and Alcaligenes latus for utilization in metabolic engineering of polyhydroxyalkanoate biosynthesis

Two cloned phbC genes, encoding polyhydroxybutyrate (PHB) synthase from Ralstonia eutropha and from Alcaligenes latus, were transformed into a PHB-negative mutant of R. eutropha. The expression characteristics of both genes were compared for the biosyntheses of PHB and its copolymers. Each phbC gene had different characteristics not only in the biosyntheses of PHB, poly(3-hydroxybutyrate-3-hydroxy-valerate), and poly(3-hydroxybutyrate-4-hydroxybutyrate) but also in the resulting morphology of PHB granules.     

Self‐Contained Monolithic Carbon Sponges for Solar‐Driven Interfacial Water Evaporation Distillation and Electricity Generation

Solar vaporization has received tremendous attention for its potential in desalination, sterilization, distillation, etc. However, a few major roadblocks toward practical application are the high cost, process intensive, fragility of solar absorber materials, and low efficiency. Herein an inexpensive cellular carbon sponge that has a broadband light absorption and inbuilt structural features to perform solitary heat localization for in situ photothermic vaporization is reported. The defining advantages of elastic cellular porous sponge are that it self‐confines water to the perpetually hot spots and accommodates cyclical dynamic fluid flow‐volume variable stress for practical usage. By isolating from bulk water, the solar‐to‐vapor conversion efficiency is increased by 2.5‐fold, surpassing that of conventional bulk heating. Notably, complementary solar steam generation‐induced electricity can be harvested during the solar vaporization so as to capitalize on waste heat. Such solar distillation and waste heat‐to‐electricity generation functions may provide potential opportunities for on‐site electricity and fresh water production for remote areas/emergency needs.     

Genome Sequence of the Polymyxin-Producing Plant-Probiotic Rhizobacterium Paenibacillus polymyxa E681

Paenibacillus polymyxa E681, a spore-forming, low-G+C, Gram-positive bacterium isolated from the rhizosphere of winter barley grown in South Korea, has great potential for agricultural applications due to its ability to promote plant growth and suppress plant diseases. Here we present the complete genome sequence of P. polymyxa E681. Its 5.4-Mb genome encodes functions specialized to the plant-associated lifestyle and characteristics that are beneficial to plants, such as the production of a plant growth hormone, antibiotics, and hydrolytic enzymes.Among the plant-associated microbes, some are beneficial to plants, as they antagonize various plant pathogens, induce immunity, or even promote growth (2, 21, 29). These “plant-probiotic” bacteria (15, 16, 19, 22, 23, 28) have been isolated and commercially developed for use in the biological control of plant diseases or biofertilization (7, 10). Spore-forming bacteria, in particular, members of the phylum Firmicutes and streptomycetes, are considered advantageous in product formulation and stable maintenance in soil (9).The genus Paenibacillus (1) has grown to encompass more than 110 species (http://www.bacterio.cict.fr/p/paenibacillus.html), but its genome information is severely underrepresented. Paenibacillus spp. are important members of soil- or plant-associated ecosystems (3, 8, 20), with Paenibacillus polymyxa as one of the most industrially significant bacteria (13, 17, 25, 31). P. polymyxa E681, an endospore former isolated from the rhizosphere of winter barley in South Korea (14, 27), suppresses plant diseases, produces antibiotics and a plant hormone, secretes a variety of hydrolytic enzymes, and has good root-colonizing ability (4, 26).We determined the genome sequence of a rifampin-resistant clone of E681. About 62,000 chromatograms (∼6.7-fold genome coverage) were produced from plasmid/fosmid/bacterial artificial chromosome libraries with an AB 3700/377 DNA analyzer. Base calling, fragment assembly, contig/scaffold editing, and finishing were performed with Phred/Phrap/Consed. Gaps were closed by primer walking. To improve the sequence quality, 2.4 Gb of 76-bp single-ended sequences were obtained from Illumina Genome Analyzer IIx. Errors were identified using Maq/MapView and rectified by confirmatory sequencing. Yacop-predicted coding sequences were translated and subjected to transitive annotation by searches against UniProt, COG, KEGG Genes, and TIGRFAMs.The genome is composed of one circular chromosome of 5,394,884 bp (45.8% G+C). It has as many as 12 rRNA operons. No plasmid was found. Three-quarters of the 4,805 genes were assigned putative functions. Protein-coding genes are distributed preferentially on the leading strand. Apparently to cope with an ever-changing environment in the rhizosphere, the genome hosts at least 13 extracytoplasmic function sigma factors (12). There are 19 complete/disrupted insertion sequence elements but few phage-related genes.Some antibiotic-biosynthetic genes have been characterized. Polymyxin, produced and transported by PmxA to -E (5), is a potent antimicrobial that recently attracted attention for the treatment of multidrug-resistant Gram-negative bacteria (11, 18, 30). Fusaricidin, an antifungal antibiotic consisting of six amino acids, is synthesized by a single-chain nonribosomal peptide synthetase (6). E681 may also synthesize a polyketide, a tridecaptin-like nonribosomal peptide, and a hybrid of polyketide and nonribosomal peptide. A gene cluster is responsible for the production of a novel lantibiotic.Based on sequence investigation and biochemical analysis, auxin biosynthesis via the indole-3-pyruvic acid pathway was proposed as the only possible mechanism (24). The bacterium also produces volatile compounds that may promote growth and induce resistance of plants and one or more N-acyl-l-homoserine lactonases. Genome analysis revealed a rich set of secreted enzymes that degrade various plant-derived polysaccharides. They include xylanases, pectic enzymes, cellulases, and amylases. Genes involved in nitrogen fixation were not identified.     

Assessment of root-associated paenibacillus polymyxa groups on growth promotion and induced systemic resistance in pepper

Twenty-nine P. polymyxa strains isolated from rhizospheres of various crops were clustered into five genotypic groups on the basis of BOX-PCR analysis. The characteristics of several plant growth-promoting factors among the isolates revealed the distinct attributes in each allocated group. Under gnotobiotic conditions, inoculation of pepper roots with P. polymyxa isolates significantly increased the biomass in 17 of total 29 treated plants with untreated plants. Experiments on induced systemic resistance (ISR) against bacterial spot pathogen Xanthomonas axonopodis pv. vesicatoria in pepper by P. polymyxa strains were conducted and only one isolate (KNUC265) was selected. Further studies into ISR mediation by the KNUC265 strain against the soft-rot pathogen Erwinia carotovora subsp. carotovora in tobacco demonstrated that the tobacco seedlings exposed to either bacterial volatiles or diffusible metabolites exhibited a reduction in disease severity. In conclusion, ISR and plant growth promotion triggered by P. polymyxa isolates were systemically investigated on pepper for the first time. The P. polymyxa KNUC265 strain, which elicited both ISR and plant growth promotion, could be potentially used in improving the yield of pepper and possibly of other crops.     

Isolation and Characterization of Transposon-Insertional Mutants from <Emphasis Type="Italic">Paenibacillus </Emphasis><Emphasis Type="Italic">polymyxa</Emphasis> E681 Altering the Biosynthesis of Indole-3-Acetic Acid

We screened a mini-Tn10 insertional mutant library of the spore-forming bacterium Paenibacillus polymyxa E681 with variable indole-3-acetic acid (IAA) productivity. Four mutants, of which two showed a decrease in IAA production and the other two showed an increase in IAA production, were finally selected. Further analyses demonstrated different levels of IAA intermediates from culture supernatant of wild-type strain and mutants. In addition, mutants showed different promotions on the early growth of 10-day-old maize in terms of the increase in shoot and root weights. DNA fragments flanking the transposon insertion in four mutants were cloned and sequenced. The target sites of insertion were gene gpr1, disrupted at two sites, 49 bp downstream of the spo0F gene, and relA/spoT homologue, which codes for GPR1/FUN34/YaaH family protein, stage 0 sporulation protein F, and RelA/SpoT domain protein, respectively. This evidence suggests that there may be a number of genes involved in the regulation of IAA biosynthesis of P. polymyxa.