Activity of Ricinus communis (Euphorbiaceae) and ricinine against the leaf-cutting ant Atta sexdens rubropilosa (Hymenoptera : Formicidae) and the symbiotic fungus Leucoagaricus gongylophorus

The focus of this study was the identification of compounds from plant extracts for use in crop protection. This paper reports on the toxic activity of fractions of leaf extracts of Ricinus communis L (Euphorbiaceae) and isolated active compounds in the leaf-cutting ant Atta sexdens rubropilosa Forel and its symbiotic fungus Leucoagaricus gongylophorus (Singer) Moller. The main compounds responsible for activity against the fungus and ant in leaf extracts of R communis were found to be fatty acids for the former and ricinine for the ants. (C) 2004 Society of Chemical Industry.

Synthetic amides toxic to the leaf-cutting ant Atta sexdens rubropilosa L. and its symbiotic fungus

1 Nine synthetic amides similar to natural N-piperidine-3-(4,5-methylenedioxyphenyl)-2-(E)-propenainide and N-pyrrolidine-3-(4,5-methylenedyoxiphenyl)2-(E)-propenamide were synthesized and identified by their spectroscopic data.2 the toxicity of these synthetic amides to the Atta sexdens rubropilosa workers and the antifungal activity against Leticoagaricus gongylophorus, the symbiotic fungus of the leaf-cutting ants, were determined.3 Workers ants that were fed daily on an artificial diet to which these compounds were added had a higher mortality rate than the controls for N-pyrrolidine-3(3',4'-methylenedioxyphenyl)-2-(E)-propenamide and N-benzyl-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide at a concentration of 100 mu g/mL.4 the completely inhibition (100%) of the fungal growth was observed with N-piperldine-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide and N,N-diethyl-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide at concentrations of 50 and 100 mu g/mL and N-pirrolidine-3-(3',4'-methylenedioxyphenyl)-2-(E)-propenamide at a concentration of 100 mu g/mL.5 the possibility of controlling these insects in the future using synthetic piperamides that can simultaneously target both organisms is discussed.

Engineering design of an integrated sustainable process system for cassava biobased materials

Cassava contributes significantly to biobased material development. Conventional approaches for its bio-derivative-production and application cause significant wastes, tailored material development challenges, with negative environmental impact and application limitations. Transforming cassava into sustainable value-added resources requires redesigning new approaches. Harnessing unexplored material source, and downstream process innovations can mitigate challenges. The ultimate goal proposed an integrated sustainable process system for cassava biomaterial development and potential application. An improved simultaneous release recovery cyanogenesis (SRRC) methodology, incorporating intact bitter cassava, was developed and standardized. Films were formulated, characterised, their mass transport behaviour, simulating real-distribution-chain conditions quantified, and optimised for desirable properties. Integrated process design system, for sustainable waste-elimination and biomaterial development, was developed. Films and bioderivatives for desired MAP, fast-delivery nutraceutical excipients and antifungal active coating applications were demonstrated. SRRC-processed intact bitter cassava produced significantly higher yield safe bio-derivatives than peeled, guaranteeing 16% waste-elimination. Process standardization transformed entire root into higher yield and clarified colour bio-derivatives and efficient material balance at optimal global desirability. Solvent mass through temperature-humidity-stressed films induced structural changes, and influenced water vapour and oxygen permeability. Sevenunit integrated-process design led to cost-effectiveness, energy-efficient and green cassava processing and biomaterials with zero-environment footprints. Desirable optimised bio-derivatives and films demonstrated application in desirable in-package O2/CO2, mouldgrowth inhibition, faster tablet excipient nutraceutical dissolutions and releases, and thymolencapsulated smooth antifungal coatings. Novel material resources, non-root peeling, zero-waste-elimination, and desirable standardised methodology present promising process integration tools for sustainable cassava biobased system development. Emerging design outcomes have potential applications to mitigate cyanide challenges and provide bio-derivative development pathways. Process system leads to zero-waste, with potential to reshape current style one-way processes into circular designs modelled on nature's effective approaches. Indigenous cassava components as natural material reinforcements, and SRRC processing approach has initiated a process with potential wider deployment in broad product research development. This research contributes to scientific knowledge in material science and engineering process design.

Harnessing bacterial signals for suppression of biofilm formation in the nosocomial fungal pathogen Aspergillus fumigatus

Faced with the continued emergence of antibiotic resistance to all known classes of antibiotics, a paradigm shift in approaches toward antifungal therapeutics is required. Well characterized in a broad spectrum of bacterial and fungal pathogens, biofilms are a key factor in limiting the effectiveness of conventional antibiotics. Therefore, therapeutics such as small molecules that prevent or disrupt biofilm formation would render pathogens susceptible to clearance by existing drugs. This is the first report describing the effect of the Pseudomonas aeruginosa alkylhydroxyquinolone interkingdom signal molecules 2-heptyl-3-hydroxy-4-quinolone and 2-heptyl-4-quinolone on biofilm formation in the important fungal pathogen Aspergillus fumigatus. Decoration of the anthranilate ring on the quinolone framework resulted in significant changes in the capacity of these chemical messages to suppress biofilm formation. Addition of methoxy or methyl groups at the C5–C7 positions led to retention of anti-biofilm activity, in some cases dependent on the alkyl chain length at position C2. In contrast, halogenation at either the C3 or C6 positions led to loss of activity, with one notable exception. Microscopic staining provided key insights into the structural impact of the parent and modified molecules, identifying lead compounds for further development.

Green mitigation strategy for cultural heritage: bacterial potential for biocide production

Several biosurfactants with antagonistic activity are produced by a variety of microorganisms. Lipopeptides (LPPs) produced by some Bacillus strains, including surfactin, fengycin and iturin are synthesized nonribosomally by mega-peptide synthetase (NRPS) units and they are particularly relevant as antifungal agents. Characterisation, identification and evaluation of the potentials of several bacterial isolates were undertaken in order to establish the production of active lipopeptides against biodeteriogenic fungi from heritage assets. Analysis of the iturin operon revealed four open reading frames (ORFs) with the structural organisation of the peptide synthetases. Therefore, this work adopted a molecular procedure to access antifungal potential of LPP production by Bacillus strains in order to exploit the bioactive compounds synthesis as a green natural approach to be applied in biodegraded cultural heritage context. The results reveal that the bacterial strains with higher antifungal potential exhibit the same morphological and biochemical characteristics, belonging to the genera Bacillus. On the other hand, the higher iturinic genetic expression, for Bacillus sp. 3 and Bacillus sp. 4, is in accordance with the culture antifungal spectra. Accordingly, the adopted methodology combining antifungal screening and molecular data is represent a valuable tool for quick identification of iturin-producing strains, constituting an effective approach for confirming the selection of lipopeptides producer strains.

Toxicological assessment of novel green biocides for cultural heritage.

The damaging of buildings and monuments by biological contamination is a cause of serious concern. Biocides based on chemical toxic compounds have been used to mitigate this problem. However, in the past decade many of the most effective biocides have been banned due to their environmental and health hazards. Therefore, proper remediation actions for microbiologically contaminated historic materials based on environmentally safe solution is of vital importance. Bacillus species are emerging as a promising alternative for built heritage treatment. They produce a great diversity of secondary metabolites with biological activity, well known to possess antagonistic activities against many fungal pathogens. In order to evaluate the antifungal activity of the novel biocides produced in our laboratory by cultures of selected bacterial strains, liquid interaction assays using four biodeteriogenic fungi were achieved, revealing a nearly 100% of inhibitory capacity to fungal proliferation. To confirm their effective safe toxicological properties, in vivo tests using two different biological models were performed. The lyophilized supernatant of the Bacillus culture broth showed no lethality against brine shrimp and also no toxicological effects in Swiss mice through administration of acute dose of 5000 mg/kg by oral gavage. In fact, the bioactive compounds were no lethal at the tested dose unlike Preventol® (commercial biocide) that induced acute toxicity with 10 times minor concentration dose administrated in the same conditions. Therefore, the new bioactive compounds that suppress growth of biodeteriogenic fungi on historical artworks, presenting at the same time no toxicity against other living organisms, constituting an efficient and green safe solution for biodegradation/biodeterioration treatment of Cultural Heritage.

Non-specific transient mutualism between the plant parasitic nematode, Bursaphelenchus xylophilus , and the opportunistic bacterium Serratia quinivorans BXF1, a plant-growth promoting pine endophyte with antagonistic effects

The aim of this study is to understand the biological role of Serratia quinivorans BXF1, a bacterium commonly found associated with Bursaphelenchus xylophilus, the plant parasitic nematode responsible for pine wilt disease. Therefore, we studied strain BXF1 effect in pine wilt disease. We found that strain BXF1 promoted in vitro nematode reproduction. Moreover, the presence of bacteria led to the absence of nematode chitinase gene (Bxcht-1) expression, suggesting an effect for bacterial chitinase in nematode reproduction. Nevertheless, strain BXF1 was unable to colonize the nematode interior, bind to its cuticle with high affinity or protect the nematode from xenobiotic stress. Interestingly, strain BXF1 was able to promote tomato and pine plant-growth, as well as to colonize its interior, thus, acting like a plant-growth promoting endophyte. Consequently, strain BXF1 failed to induce wilting symptoms when inoculated in pine shoot artificial incisions. This bacterium also presented strong antagonistic activities against fungi and bacteria isolated from Pinus pinaster. Our results suggest that B. xylophilus does not possess a strict symbiotic community capable of inducing pine wilt disease symptoms as previously hypothesized. We show that bacteria like BXF1, which possess plant-growth promoting and antagonistic effects, may be opportunistically associated with B. xylophilus, possibly acquired from the bacterial endophytic community of the host pine.

Isolation and Identification of the Chitinolytic Bacteria from Rumen Ecosystem

Rumen is an interesting ecosystem for microbial exploration and their products. Isolation of the chitinolytic bacteria from the rumen ecosystem found 109 colonies that produced clear zone, 84 colonies (86%) anaerobic and 17 colonies (14%) aerobic. Clear zone appeared in the third and fourth days incubation. Four potential isolates were chosen for identification purposes. Results showed that the bacteria were sticky, gram-positive, motile, endospore-forming, mesophilic and aerobic. It was supposed to Bacillus spp. the optimal pH and temperature to produce chitinase from isolate 18 are pH 6.0 and temperature of 35-40ºC. Divalent cations Mg, Ca, Zn, and Mn increase chitinase activity, while Cu and Co inhibit enzyme activity. When isolate 18 was grown on shrimp waste meal, it showed aptimal activity on the fifth days incubation. (Animal Production 5(2): 73-78 (2003) Key Words : Isolation, Identification, Chitinolytic Bacteria, Rumen