Nature of resistance of Lyamungu coffee hybrids to coffee berry disease (CBD) caused by Colletotrichum kahawae were evaluated using conidia germination on cuticular wax extracted from the hybrids, stimulatory effects on the infection of the pathogen, and evidence of genetic resistance on studies using hypocotyls and green berries in the field. Significant differences (P £ 0.05) were found between the levels of conidia germination on the extracted wax of the coffee genotypes. Nine coffee genotypes showed no conidia germination and five showed conidia germination percentage of below 20%. Conidial germination percentage levels of up to 90% were found on CBD susceptible variety N39. Light micrographs showed that hyphal growth of C. kahawae strains were restricted in epidermal cells and cortex of CBD resistant genotypes 20498 and 20509. Callose and thick walls were observed in cortex cells of resistant genotypes 20498 and 20509. Field evaluation also revealed same genotypes which exhibit highest levels of CBD resistance. In order to understand resistance of Lyamungu coffee hybrids, pathogenicity of 26 C. kahawae strains from different eco-agricultural zone in Tanzania was studied under laboratory conditions. Pathogenicity tests both on detached green coffee berries and hypocotyls drew a distinction between highly and less pathogenic strains. The C. kahawae strain 2006/14 was found to be the most pathogenic because it showed high sporulation capacity and also induces CBD symptoms 3 days after infection both on green coffee berries and hypocotyls.

In contaminated soils, the efficiency of natural attenuation or engineered bioremediation largely depends on the biodegradation capacities of the total microflorae. In the present study, the biodegradation capacities of various bacteria towards petroleum-hydrocarbons were determined under laboratory conditions. The purpose of the study was to isolate and characterize petroleum-degrading bacteria from contaminated soil obtained from a refinery in Arzew, Algeria. A collection of 15 bacterial isolates were obtained by enrichment cultivation from oil-contaminated soil and an indigenous microbial consortium was developed by assembling four species of bacteria which could degrade different fractions of the petroleum hydrocarbons. 16S rRNA gene analysis was used to identify members of the consortium and oil biodegradability was analyzed by Thin Layer Chromatography (TLC) with Flame Ionization Detection (FID) that performs quantitative compositional analysis of oil samples. The Iatroscan TLC/FID system measured the relative percentages of the four major fractions of petroleum i.e. saturates aromatics, resins and asphaltenes. Results indicated that the constructed consortium which comprised the genera Pseudomona, Shewanella, Enterobacter and Serratia used the hydrocarbons as sole sources of carbon where biodegradation was defined by an initial rapid decrease in the saturate and aromatic fractions from 56.44% and 34.72% to 51.77% and 27.77% respectively, coinciding with an increase in the asphaltene fraction. The resin content remained relatively constant throughout the project. Alkane hydroxylase genes (alkB) were positively amplified in the Pseudomonas isolate by the polymerase chain reaction (PCR) method using degenerate primers. This functional gene was used as a marker to assess the catabolic potential of the bacteria for alkane pollutant biodegradation. The selected bacterial consortium looks promising for its application in bioremediation technologies.

This is the first report to use electrospun nanofibers which could be of considerable interest to the development of new antibacterial compounds against certain species of bacteria affect plants in different ways as bacterial leaf spot (bacterial midrib rot), Pseudomonas cichorii and bacterial blight Dickeya dadantii (Erwinia chrysanthemi). Electrospun nylon-6/chitosan (nylon-6/Ch) nanofibers were obtained from formic acid as a single solvent. Surface modification of electrospun nylon-6/chitosan nanofibers was observed by soaking the mat in aqueous solution of glycidyltrimethylammonium chloride (GTMAC) at room temperature overnight to give nylon-6/N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (nylon-6/HTCC). The morphological, structural and thermal properties of the nylon-6/chitosan nanofibers were studied by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). Biological screening demonstrated that Nylon-6/HTCC mat exhibited high potential antibacterial activity against Pseudomonas cichorii and Dickeya dadantii (Erwinia chrysanthemi) on protein profile. Pseudomonas cichorii and Dickeya dadantii (Erwinia chrysanthemi) examined using SEM were totally deformed and exhibited severe destruction.