Microalgal Dynamics in Batch Reactors for Municipal Wastewater Treatment Containing Dairy Sewage Water

This study investigates the microalgal community dynamics associated with changes in municipal wastewater quality and discharges from the dairy industry in central Veracruz, Mexico, using an experimental stabilization-reactors system. Thirty one species of microalgae were recorded and 15 physicochemical variables were measured daily over 25 days in pretreated water. The biomass of microalgal groups displayed significant negative correlations with biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspend solids (TSS). Conversely, a significant positive correlation was found with dissolved oxygen, pH and nitrates. Using the Canonical Correspondence Analysis we identified an initial anaerobic phase (Phase I), characterized by high BOD, TSS and COD, ammonium and faecal coliforms. This was followed by a transition phase (Phase II), an initial aerobic phase (Phase III), when water quality improved considerably, and finally an aerobic phase (IV) with a high percent reduction in these parameters and almost complete organic load removal. The most abundant species associated with these phases were Arthrospira jenneri (Cyanophyceae) and Coccomonas sp. (Chlorophyceae) in Phase I; Polytomella sp. (Chlorophyceae) in Phase II; Polytoma tetraolare, Chlamydomonas caeca (Chlorophyceae) and some Cyanophyceae including Geitlerinema, Synechocystis, Cyanobium and Glaucospira in Phase III; Carteria sp. (Chlorophyceae), Lepocynclis ovum and Euglena clavata (Euglenophcyeae) in Phase IV. Maximum richness, diversity, and biomass levels occurred during the aerobic phase. Similar to other wastewater treatment systems the high succession rates decreased with reactor stabilization. These findings provide statistical evidence on the suitability of certain microalgae species as indicators of wastewater stabilization reactor status and effluent quality.     

Seaweed Extracts: A Promising Source of Antibiofilm Agents with Distinct Mechanisms of Action against Pseudomonas aeruginosa

The organization of bacteria in biofilms is one of the adaptive resistance mechanisms providing increased protection against conventional treatments. Thus, the search for new antibiofilm agents for medical purposes, especially of natural origin, is currently the object of much attention. The objective of the study presented here was to explore the potential of extracts derived from three seaweeds: the green Ulva lactuca, the brown Stypocaulon scoparium, and the red Pterocladiella capillacea, in terms of their antibiofilm activity against P. aeruginosa. After preparation of extracts by successive maceration in various solvents, their antibiofilm activity was evaluated on biofilm formation and on mature biofilms. Their inhibition and eradication abilities were determined using two complementary methods: crystal violet staining and quantification of adherent bacteria. The effect of active extracts on biofilm morphology was also investigated by epifluorescence microscopy. Results revealed a promising antibiofilm activity of two extracts (cyclohexane and ethyl acetate) derived from the green alga by exhibiting a distinct mechanism of action, which was supported by microscopic analyses. The ethyl acetate extract was further explored for its interaction with tobramycin and colistin. Interestingly, this extract showed a promising synergistic effect with tobramycin. First analyses of the chemical composition of extracts by GC–MS allowed for the identification of several molecules. Their implication in the interesting antibiofilm activity is discussed. These findings suggest the ability of the green alga U. lactuca to offer a promising source of bioactive candidates that could have both a preventive and a curative effect in the treatment of biofilms.     

A typology of fisheries management tools: using experience to catalyse greater success

Fisheries provide nutrition and livelihoods for coastal populations, but many fisheries are fully or over‐exploited and we lack an approach for analysing which factors affect management tool performance. We conducted a literature review of 390 studies to assess how fisheries characteristics affected management tool performance across both small‐scale and large‐scale fisheries. We defined success as increased or maintained abundance or biomass, reductions in fishing mortality or improvements in population status. Because the literature only covered a narrow set of biological factors, we also conducted an expert elicitation to create a typology of broader fishery characteristics, enabling conditions and design considerations that affect performance. The literature suggested that the most commonly used management tool in a region was often the most successful, although the scale of success varied. Management tools were more often deemed successful when used in combination, particularly pairings of tools that controlled fishing mortality or effort with spatial management. Examples of successful combinations were the use of catch limits with quotas and limited entry, and marine protected areas with effort restrictions. The most common factors associated with inadequate biological performance were ‘structural’ issues, including poor design or implementation. The expert‐derived typologies revealed strong local leadership, high community involvement and governance capacity as common factors of success across management tool categories (i.e. input, output and technical measures), but the degree of importance varied. Our results are designed to inform selection of appropriate management tools based on empirical data and experience to increase the likelihood of successful fisheries management.     

Identification and Characterization of a New Type III Polyketide Synthase from a Marine Yeast,Naganishia uzbekistanensis

A putative Type III Polyketide synthase (PKSIII) encoding gene was identified from a marine yeast, Naganishia uzbekistanensis strain Mo29 (UBOCC-A-208024) (formerly named as Cryptococcus sp.) isolated from deep-sea hydrothermal vents. This gene is part of a distinct phylogenetic branch compared to all known terrestrial fungal sequences. This new gene encodes a C-terminus extension of 74 amino acids compared to other known PKSIII proteins like Neurospora crassa. Full-length and reduced versions of this PKSIII were successfully cloned and overexpressed in a bacterial host, Escherichia coli BL21 (DE3). Both proteins showed the same activity, suggesting that additional amino acid residues at the C-terminus are probably not required for biochemical functions. We demonstrated by LC-ESI-MS/MS that these two recombinant PKSIII proteins could only produce tri- and tetraketide pyrones and alkylresorcinols using only long fatty acid chain from C8 to C16 acyl-CoAs as starter units, in presence of malonyl-CoA. In addition, we showed that some of these molecules exhibit cytotoxic activities against several cancer cell lines.     

Polymorphisms in cyanogenic glucoside and cyano‐amino acid content in natural accessions of common vetch (Vicia sativa L.) and selection for improved agronomic performance

Common vetch (Vicia sativa L.) is an important annual forage legume. It is used as a cover crop, green manure, pasture legume and for silage and hay production. Its seeds can be used as a source of highly digestible protein and minerals in animal diets. However, their utilization as a feedstuff for monogastric animals is hindered by the fact that the seeds contain cyanogenic antinutritional factors that reduce their palatability. An effective utilization of V. sativa seeds as a successful monogastric feed stuff requires selection for higher protein availability and minimization of the cyanogenic antinutritional factors content. In this study, we selected one natural accession named Mjez Ibeb, from a collection of 25 accessions and cultivars, based on its superior agronomic performance and its naturally occurring genetic variation for cyanogenic traits. We investigated the genetic variation that exists for the cyanogenesis trait in more detail and analysed the seeds of 133 lines derived from accession Mjez lbeb. Of these, 40 naturally polymorphic lines that showed deficiencies in cyanogenesis and cyano‐amino acid content, were subsequently selected for detailed chemical analysis. Cyanogenic glucosides and cyano‐amino acid concentrations varied widely in the 40 lines. Multivariate analysis was performed and three lines (L₁₆, L₂₁, L₁₈) with low content of cyanogenic compounds were identified.     

Stop me if you can: quantification of the effect of interfaces between plots on the dispersal of Cosmopolites sordidus

BACKGROUND

Cosmopolites sordidus is one of the most damaging pests of banana worldwide. To date, most studies have addressed the control of this pest at the plot level, without considering the landscape scale, whereas between plots dispersion could be important. The aim of this study was to investigate the ability of C. sordidus to cross contrasted field interfaces. The 10 following interfaces were investigated: forests, hedgerows, field tracks, grassy areas, finely and coarsely tilled soil zones, ditches with and without water, vegetable gardening zones, and pheromone trap lines. Individually marked weevils were released on one side of the interface and recovered daily on the other side, allowing the estimation of the velocity and the crossing success of C. sordidus for each interface.

RESULTS

Highest permeabilities (with a crossing success above 70%) were obtained for vegetable gardening zones, finely tilled soil zones, forests, and coarsely tilled soil zones. Intermediate permeabilities were measured for hedgerows, field tracks, grassy areas, and ditches without water. Only the line of pheromone traps and submerged ditches had a strong barrier effect on C. sordidus, with a crossing success below 12%. Wind strength, percentage of sky, and vegetation height were negatively correlated to the C. sordidus crossing success.

CONCLUSION

Overall, our results showed that only ditches with water and lines of pheromone traps were efficient in stopping the dispersal of C. sordidus. The next step will be to conduct research to incorporate the use of these two interfaces at farm and landscape scale into integrated pest management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Parasitism of canola aphids in France in autumn

In light of a recent increase in the aphid populations on young canola (Brassica napus) in autumn in Northwestern Europe, we carried out a survey of their parasitoid species during this season. The study was done in France from 1998 to 2001 using different sampling methods. Results highlighted the presence of two main species of Aphidiinae, Aphidius matricariae and Diaeretiella rapae (and to a lesser extent Aphidius ervi) on Myzus persicae, and of D. rapae on Brevicoryne brassicae. Nine other Aphidiinae species were found occasionally as well as some Aphelinidae parasitoids and hyperparasitoids. There was no difference in parasitoid species pattern between fields in Northern and Southern France. The principal parasitoid species found in the fields were reared in the laboratory to confirm their ability to develop on the canola aphids. Aphidius matricariae and D. rapae were reared successfully on M. persicae, but a low parasitism rate was obtained for A. ervi on this aphid. This study showed that A. matricariae and D. rapae could develop on aphids on canola and that they are present naturally in canola in autumn. However, the parasitism rate is low in autumn, so the options could be the use of these parasitoids in augmentative release biological control programs or in an IPM project on canola fields during this time of the year.     

Single injection of triptorelin or buserelin acetate in saline solution induces ovulation in mares the same as a single injection of hCG

The aim of this study was to assess the efficacy of different doses of buserelin acetate and another GnRH agonist, triptorelin acetate, in saline solution in a single subcutaneous injection, to induce ovulation of growing pre-ovulatory follicle in mare and compare it with the classical treatment of a single injection of hCG. The study is split into 3 experiments over different breeding seasons in the same stud with a random distribution of treatment. The first one was to compare the injection of 6 mg of buserelin with 1,500 IU of hCG; the second one consisted of comparing different doses of buserelin (6 mg and 3 mg); and the third one compared three different doses of buserelin (3, 2 and 1 mg), 0.1 mg of triptorelin with 1,500 IU of hCG as a control group. The results of all experiments showed the same efficacy between all treatments with mares ovulating between 24 and 48 hr after injection: experiment 1: hCG (78% n = 41) and buserelin 6 mg (90% n = 50); experiment 2: buserelin 6 mg (78,1% n = 192) and buserelin 3 mg (78% n = 341); and experiment 3: hCG (87% n = 106), buserelin 3 mg (84,7% n = 137), buserelin 2 mg (82,7% n = 104), buserelin 1 mg (87% n = 54) and triptorelin 0.1 mg (84,7% n = 72). In conclusion, this study contributes to erasing the dogma that has been established since 1975 that a single injection in solution without any long-acting excipient of a GnRH agonist cannot induce ovulation in the mare. This study also shows that a injection of 0.1 mg of triptorelin in solution is a good alternative for ovulation induction and is comparable to small doses of buserelin acetate in solution (1 mg) and 1,500 IU of the gold standard trigger hCG, mainly in countries where human formulation of buserelin is not available.