Antimicrobial Agents Produced by Marine Aspergillus terreus var. africanus Against Some Virulent Fish Pathogens

Screening of fungal isolates collected from different locations of Alexandria coast, Egypt, was carried out to obtain new biologically active metabolites against some virulent fish pathogens (Edwardsiella tarda, Aeromonas hydrophila, Vibrio ordalli and Vibrio angularuim). Among 26 fungal isolates, Aspergillus terreus var. africanus was identified as the most potent isolate. Production of the bioactive material was optimized using response surface methodology including fermentation media, incubation period, temperature, pH, and thermo-stability. Spectral properties of the gas chromatography/mass spectrum of the ethyl acetate crude extract were determined. Partially purified components of the crude extract were chromatographically separated and bioassayed. Out of ten separated compounds, five were with considerable antibacterial agent. The bio-toxicity of crude showed a slight toxicity against the brine shrimp Artemia salina (LC₅₀ = 1,500 μg/l). Antibacterial activity of the crude was compared with some known standard antibiotics and found to be superior over many where its MIC against some pathogen reached 1 μg/ml.     

Multivariate Homogeneity Testing Using an Extended Concept of Nearest Neighbors

Given independent multivariate random samples {X_ij: j = 1, …, n_i} from F_i, for i = 1,2, a test is desired for H₀: F₁ = F₂ against general alternatives. Consider the k · (n₁ + n₂) possible ways of choosing one observation from the combined samples and then one of its k nearest neighbors, and let S_k be the proportion of these choices in which the point and neighbor are in the same sample. Schilling (1986) proposed S_k as a test statistic, but did not indicate how to determine k. We suggest as test statistic W = N Σ kS_k, which we show is equivalent to a sum of N Wilcoxon rank sums, and also to a sum of two two-sample U-statistics of degrees (1, 2) and (2, 1). Simulation with multivariate normal data suggests that our test is generally more powerful than Schilling's test using k = 1, 2, or 3. We illustrate its use with Fisher's iris data.     

Assessment of shallow groundwater quality and its suitability for drinking purpose near the Béni-Mellal wastewater treatment lagoon (Morocco)

Abstract

The present study aimed to evaluate the suitability for drinking purpose of shallow groundwater near the Béni-Mellal wastewater treatment lagoon based on various physicochemical, heavy metals, and bacteriological parameter analyses. The physicochemical results revealed that some of the samples do not comply with the Moroccan and/or WHO standards for drinking water. Parameters including turbidity, TH, Na⁺, Li⁺, Ba²⁺, Ca²⁺ (～47.1% of samples), Cd (～52.9% of samples), Fe (～82.4% of samples), Pb (～58.8% of samples), T. coliforms, and E. coli exceeded the drinking limits. The statistical analyses revealed that the shallow groundwater chemistry is mainly controlled by geogenic and anthropogenic sources. For quality assessment, using the Moroccan groundwater assessment grid, the values of EC and Cl^–, NO₃^–, NH₄⁺, oxidability, and E. coli, fixed as pollution indicators, showed that most of the wells showed medium-to-poor quality, 14% of them have a very poor water quality, and 20% of them belong to the bad water quality. According to geometric and arithmetic DWQI values, the groundwater quality was frequently fair to good, needing treatment or at least disinfection before public consumption. A sensitivity analysis results indicated that Fe, Cd, Cr, Pb, and E. coli have an important impact on the DWQI computing.