Physiological and biochemical parameters: new tools to screen barley root exudate allelopathic potential (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L. subsp. <Emphasis Type="Italic">vulgare</Emphasis>)

Morphological markers/traits are often used in the detection of allelopathic stress, but optical signals including chlorophyll a fluorescence emission could be useful in developing new screening techniques. In this context, the allelopathic effect of barley (Hordeum vulgare subsp. vulgare) root exudates (three modern varieties and three landraces) were assessed on the morphological (root and shoot length, biomass accumulation), physiological (F_v/F_m and F₀), and biochemical (chlorophyll and protein contents) variables of great brome (Bromus diandrus Roth., syn. Bromus rigidus Roth. subsp. gussonii Parl.). All the measured traits were affected when great brome was grown in a soil substrate in which barley plants had previously developed for 30 days before being removed. The response of receiver plants was affected by treatment with activated charcoal, dependent on barley genotype and on the nature of the growing substrate. The inhibitory effect was lower with the addition of the activated charcoal suggesting the release of putative allelochemicals from barley roots into the soil. The barley landraces were more toxic than modern varieties and their effect was more pronounced in sandy substrate than in silty clay sand substrate. In our investigation, the chlorophyll content and F_v/F_m were the most correlated variables with barley allelopathic potential. These two parameters might be considered as effective tools to quantify susceptibility to allelochemical inhibitors in higher plants.     

Improvement of the Antioxidant Activity of Fenugreek Protein Isolates by <Emphasis Type="Italic">Lactococcus lactis</Emphasis> Fermentation

This study investigated the antioxidant capacity of fenugreek protein isolate and its improvement by Lc. lactis fermentation through bioactive peptides production and the effect of molecular weight variation on fenugreek fractions antioxidant activity. Fenugreek protein isolate showed a significant increase of antioxidant and radical scavenging activity after 24 h of fermentation, by about 23.7, 42.9 and 40% for respectively antioxidant activity coefficient AAC, DPPH and ABTS radical scavenging activity. FI fermentation led to a hydrolysis of peptide bands with MW?>?35 kDa and a generation of new bands with a MW?<?25 kDa. A significant reduction in molecular-mass distribution of hydrolysates and a great increase of total free amino acids content, especially an increase on isoleucine, leucine, glutamic acid, serine, histidine, glutamine and lysine was noted. The infrared results showed that different reactions may take place after fermentation, and showed an increase of proteins, amides and aromatic compounds. However, fenugreek fraction (F2) with MW 15–50 kDa presented the highest activity instead of fraction (F1) with lower MW. Lc. lactis had the ability to degrade and convert fenugreek proteins into bioactive peptides that contribute positively in the improvement of antioxidant activity of FI and fractions. FI presents a significant antioxidant activity and thus, can be considered as a potential source of high added value natural antioxidants and may be employed as a functional food ingredient with good potential applications in food products.     

<Emphasis Type="Italic">Planomonospora algeriensis</Emphasis> sp. nov., an actinobacterium isolated from a Saharan soil of Algeria

A filamentous actinobacterium, designated strain PM3^T, was isolated from a Saharan soil sample collected from Béni-Abbès, Béchar (South-West Algeria). A polyphasic taxonomic study was carried out to establish the status of strain PM3^T. The isolate was found to have morphological and chemotaxonomical properties associated with members of the genus Planomonospora. The new isolated microorganism developed cylindrical sporangia arranged in double parallel rows on aerial mycelium, each one containing a motile single sporangiospore. The cell wall of the strain was found to contain meso-diaminopimelic acid. Whole-cell hydrolysates were found to contain madurose, glucose, mannose and ribose. The predominant menaquinone was identified as MK-9(H₂) (69.6%). The polar lipids detected were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylhydroxyethanolamine and glucosamine-containing lipids. The major fatty acids were found to be C_17:1ω9c (38.6%) and C_17:0 (24.2%). Results of 16S rRNA gene sequence comparison revealed that strain PM3^T shared a high degree of 16S rRNA gene sequence similarity with Planomonospora sphaerica DSM 44632^T (99.3%), Planomonospora parontospora subsp. parontospora DSM 43177^T (99.2%) and P. parontospora subsp. antibiotica DSM 43869^T (99.0%). DNA–DNA hybridization values between strain PM3^T and the type strains of the closely related species were between 58.4 and 70.1%. The combination of phylogenetic analysis, DNA–DNA relatedness data, phenotypic characteristics and chemotaxonomic data support the conclusion that strain PM3^T represents a novel species of the genus Planomonospora, for which the name Planomonospora algeriensis sp. nov. is proposed. The type strain is PM3^T (=DSM 46752^T = CECT 9047^T).     

Caldimonas hydrothermale sp. nov., a novel thermophilic bacterium isolated from roman hot bath in south Tunisia

A polyphasic approach was used to characterize a bacterium, HAN-85^T, isolated from thermal water in natural thermal spring at Tozeur, an oasis in southwest Tunisia. The novel isolate was thermophilic, strictly aerobic and amylolytic bacterium, which stained Gram negative. Cells were short rods motile by means of a single polar flagellum. Their optimum temperature and pH required for growth were 55°C and pH 7, respectively. Comparative 16S rRNA gene sequence analyses showed that strain HAN-85^T belonged to the genus Caldimonas, with highest sequence similarity to the type strains Caldimonas manganoxidans and Caldimonas taiwanensis. DNA–DNA hybridization measurements revealed low DNA relatedness (35.2–44.5%) between the novel isolate and its closest relative, C. manganoxidans. The major cellular fatty acid components were 16:0, 17:0 cyclo and summed feature 3. The DNA G+C content was 68.3 mol%. Taken together, the results of DNA–DNA hybridization, fatty acids profile, physiological tests and biochemical analyses have allowed the genotypic and phenotypic differentiation of the isolate from currently recognized Caldimonas species. Therefore, we suggest that this isolate is a novel species within the genus Caldimonas and propose that it should be named Caldimonas hydrothermale sp. nov. The type strain is HAN-85^T (=DSM 18497^T =LMG 23755^T). The Gen Bank/Embl/DDBJ accession number for the 16S rRNA gene sequence of strain DSM 18497^T is AM283038.     

Annual reproductive cycle and condition index of Mactra corallina (Mollusca: Bivalvia) from the north coast of Tunisia

This work aims to examine the reproductive cycle of the bivalve Mactra corallina inhabiting the Gulf of Tunis (Tunisia). Histological analysis indicated that the reproductive cycle is composed of six stages and was synchronous between sexes. Gonadal development began in January. From April to July, an increase in temperature (from 16 to 28°C) and a rise in chlorophyll a (from 3.25 to 6.35 mg/L) marked the period of sexual maturity in both sexes, which was also confirmed by an elevation in condition index (CI). Partial spawning started in April for males and in May for females, peaking in late summer indicating a prolonged reproductive period. The reproductive cycle of M. corallina finished with an inactive stage during autumn. From the total number of animals used in this study, we identified 104 females (52%) and 96 males (48%) corresponding to a sex ratio 1:0.92 that did not differ significantly from a 1:1 ratio.     

Biological monitoring of exposure to pesticide residues among Belgian florists

Abstract

Many pesticides applied in cut flowers can be readily absorbed through the skin of florists during preparing bouquets and handling contaminated flowers. A study was conducted among volunteer Belgian florists in order to assess their total exposure by measuring concentrations of pesticides (parent compounds and metabolites) in their urines. A total of 42 urine samples (24-h urines) were collected from florists during their professional activities, on the three most important commercial periods. The concentrations of pesticide residues and metabolites in urine samples were analyzed with a multiresidue liquid chromatography tandem mass spectrometry method, after an ethyl acetate extraction. The results are compared with those of a control group of 42 subjects not occupationally exposed to pesticides, collected in the same periods. A total of 70 residues (56 pesticides and 14 metabolites) were identified, with an average of about eight pesticide residues and metabolites per florist’s urine sample and an average total concentration per sample of 4.3 µg/g creatinine, ranging from 0.2 to 67 µg/g creatinine. Significantly higher urinary excretion of metabolites (t-test) was found in florists than in control group. These results demonstrate that Belgian florists are exposed daily to pesticide residues with a potential effect on their health.