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The detection and quantification of Indole -3 Acetic Acid (IAA) produced by Plant growth promoting rhizobacteria (PGPR) rely on a standard well-documented assay, which remains time-consuming, laborious, and costly. These drawbacks led to sway interest to economic and reliable assays. The aim of this work is to validate and standardize a fast, reliable, and cost-effective microassay to quantify IAA produced by bacteria with an easy microplate method. In order to validate the accuracy of the IAA microplate assay, bacterial samples from different genera were assayed using two methods: the conventional IAA estimation assay and the IAA micro- assay. The microassay shows a prominent reduction in used bacterial supernatant volume as well as Salkowski reagent volume of about 92.5%. It is considerably cheaper than the conventional one of around 56%. The newly performed microplate assay is 23 times faster. The result of IAA quantitative analysis for 13 bacterial strains showed that Bacillus muralis and Bacillus toyonensis produced the highest IAA concentration (23.64±0.003μg/ml and 23.35±0.006μg/ml, respectively). The obtained data from both methods were highly correlated with an R-value of 0.979. The microassay offers the ability to read the optical density of all samples simultaneously since used volumes of bacterial supernatants and Salkowski reagent were minimized to place the mixture in 96-well microplates, which reduces greatly required labor. Furthermore, the application of the IAA micro-plate assay reduces drastically the reagent waste and toxicity hazard of Salkowski reagent in the environment, thus, we can classify it as eco-friendly respecting the Green Chemistry concept according to Environmental Protection Agency (EPA). The IAA microassay is a, reliable, rapid and cost-effective and eco-friendly method to screen plant growth promoting potential of more than 23 bacterial strains by microplate. It could be an alternative for the conventional IAA assay as a routine research tool. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is among the most deleterious contaminant in the aquatic environment and presents a serious risk to humans and ecosystems. This study evaluated the effects of Hg on oxidative stress biomarkers, DNA integrity and histological structure of the respiratory tree of Holothuria forskali exposed to different concentrations of mercury chloride HgCl2 (0.04, 0.08 and 0.16 mg L−1) for 96 h. Exposure of H. forskali to Hg led to oxidative stress with an increase in Malondialdehyde (MDA), hydrogen peroxide (H2O2), advanced oxidation protein product (AOPP) and protein carbonyls (PCO) levels in the treated groups. Alteration of the antioxidant system was also confirmed by the significant increase in glutathione (GSH), nonprotein thiol (NPSH) and vitamin C contents. Moreover, the enzymatic activity of superoxide dismutase (SOD), Glutathione peroxidase (GPX) and Catalase (CAT) increased significantly. Our research revealed that total Metallothionein (MTs) content enhanced in a dose-dependent manner. Interestingly, the exposure to this metal provoked a decrease in Acetylcholinesterase (AChE) activity. Hg genotoxicity was further evidenced by a random DNA degradation that was observed in the treated groups. The histopathological findings confirmed the biochemical results. Overall, our results indicated that mercury-induced genotoxicity, oxidative damage and histopathological injuries in the respiratory tree of H. forskali. [ABSTRACT FROM AUTHOR]

Previous scientific studies have listed chemical compounds from sea cucumber species. The ability to produce bioactive metabolites derives from their response to various ecological stresses and avoidance of predation. In view of this, the present work aimed to evaluate the antibacterial activity and quantitatively assess the active components of different organs of the sea cucumber Holothuria foskali collected from the north-east of Tunisia. The antibacterial activity of ethyl acetate extracts was tested against Bacillus subtilis , Bacillus cereus , Escherichia coli and Pseudomonas aeruginosa. It was revealed that Escherichia coli and Bacillus subtilis were inhibited by the sea cucumber extracts. To identify the composition of these extracts, Gas Chromatography-Mass Spectroscopy (GC-MS) and Liquid Chromatography-Mass Spectroscopy (LC-MS) methods were used. The GC-MS revealed the presence of 25 major components, the most concentrated ones were characterized as C26H27N5O6 Morphinan-4,5-epoxy-3,6-diol, 6 amino;C17H31F3O2 3-trifluoroacetoxypentadecane; C31H50O2 Stigmasta-5,22-dien-3-ol,acetate; C11H14O2 1-Phthalanol,1,3,3-trimethyl 1-phenyl; C30H48O2 Ergosta-5,22-dien-3-ol,acetate and C25H40O2 (9E)-8-Phenyl-9-octadecenoic acid methyl ester; while the LC-MS revealed the presence of eight molecules, identified as phenolic acid, phytosterol and fat-soluble vitamins. Some molecules are interesting and deserve to be explored for their potential uses as ingredients in functional foods or as raw materials for new drug forms. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is a ubiquitous and a major environmental metal pollutant in the aquatic ecosystem. The present study was performed to evaluate the effect of mercury graded doses exposure on oxidative stress, redox status, metallothionein levels and genotoxicity in the intestine of sea cucumber Holothuria forskali. Specimens were exposed for 96 h to three concentrations of Hg (40, 80 and 160 µg/L). Exposure of H. forskali to Hg promoted oxidative stress with an increase in malondialdehyde (MDA), protein carbonyl (PCO) and advanced oxidation protein products (AOPP) levels. An increase of glutathione (GSH), vitamin C (ViteC) and non-protein thiols (NPSH) contents was also observed. Additionally, antioxidant activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) increased especially with the highest doses of Hg indicating a great defense of the antioxidant system. Our investigation revealed an increase in total Metallothionein (MT) content which was more pronounced at the sharpest concentrations of Hg. A significant decline of AChE activity was also observed. In the intestine of Hg-treated H. forskali genotoxicity was confirmed by DNA degradation. [ABSTRACT FROM AUTHOR]

As a social insect living in large groups, the honey bee Apis mellifera is vulnerable to parasites and pathogens, which have become a major threat for apiculture and pollination services worldwide. The co-occurrence of parasites, mainly Varroa destructor, with viral pathogens is suspected to constitute a primary cause in colony mortality and population losses. In our study, we investigated the presence and possible association of five honey bee pathogens occurring in Tunisian apiaries. This included the endoparasitic microsporidia Nosema ceranae and Nosema apis, the ectoparasitic mite V. destructor and two honey bee RNA virus; deformed wing virus (DWV or DWV genotype A) and Varroa destructor virus-1 (VDV-1), otherwise known as DWV genotype B. There was no statistical association between the five biotic stressors. Interestingly, from the most Varroa-infested colony sample (A27.H4, 45%); we detected a co-infection with three pathogens, DWV, N. apis and N. ceranae. Using a haplotype network analysis, we revealed a high diversity of the Tunisian DWV genotypes A and B from Apis mellifera intermissa with twelve haplotypes showing similarities with various European, Asian, and South American genotypes. We detected double infection by DWV genotypes A and B in the Bizerte region. These co-occurring genotypes were suggested that such co-infection gives rise to recombinant virus with potential enhanced virulence. Here, we support the presence of DWV-VDV-1 recombinant in A. m. intermissa. Overall and despite the lack of a clear epidemiological link between honey bee pathogens and colony health, their interactions may lead to disease and colony losses. [ABSTRACT FROM AUTHOR]

Concentrations of cadmium (Cd), copper (Cu), mercury (Hg), and zinc (Zn) were determined by atomic absorption spectrophotometry in the muscle tissues (arms and mantle) of 3 commercial cephalopods (Loligo vulgaris, Octopus vulgaris, and Sepia officinalis) caught in 3 different Tunisian coastal regions. The highest concentrations found correspond to the essential elements Cu and Zn. Octopuses and cuttlefish showed the highest levels of those elements whereas squid presented with significantly higher values of Hg in both muscular tissues. This may be related to different feeding behavior and detoxification processes among benthic and pelagic cephalopods. Variation of element concentrations between seasons was different between species and seemed to be mostly dependent on the sampling site. From a public health standpoint, average concentrations of Cd, Cu, Hg, and Zn measured in edible tissues of cephalopods from this study did not reveal, in general, any risk for consumers. The estimated target hazard quotients for Cd and Hg for consumers of the selected species were below 1 and within the safety range for human health. Moreover, their consumption could provide in an important contribution to the daily dietary intake of Cu for the Tunisian population, especially regarding the consumption of octopus and cuttlefish muscles., (© 2014 Institute of Food Technologists®)