Overall development of a bioprocess for the outdoor production of Nannochloropsis gaditana for aquaculture

In this paper, a systematic methodology is shown for the scaling‐up of Nannochloropsis gaditana production for aquaculture uses. First, an adequate culture medium was developed, prepared using fertilizers instead of pure chemicals. Subsequently, the performance of N. gaditana was modelled as a function of average irradiance; this model being validated in continuous culture experiments. The model was used to determine the optimal dilution rate as well as the expected biomass concentration and productivity at optimal conditions. Finally, outdoor experiments were performed to confirm the model's validity and to determine optimal conditions at real production step. Biomass productivity values of up to 0.08 g L^?1 day^?1 were obtained at an optimal dilution rate of 0.25 per day in 0.2 m wide flat‐panel reactors using culture medium containing 0.4 g/L NO^?₃ and 0.034 g/L·PO₄^?3. Fish trials with Atlantic Salmon demonstrated that the inclusion of produced biomass into fed increase the final weight up to 5%, thus confirming the adequacy of the biomass produced for aquaculture uses. The growth model and the scaling‐up strategy proposed here are necessary to develop real industrial‐scale processes capable of supplying microalgal biomass to the aquaculture markets, which in turn require a guaranteed supply and quality of the raw materials provided.     

Steroidal Saponin and Flavonol Content and Antioxidant Activity during Sporophyte Development of Maguey (<Emphasis Type="Italic">Agave salmiana</Emphasis>)

Agave salmiana Otto ex Salm-Dyck has traditionally been used for the production of fermented beverage known as “pulque” that has recently gained acceptance as a functional food. However, the plant requires up to 10 years to be used as raw material. The objective of this work was to evaluate the antioxidant and bioactive principles of Agave salmiana during different stages of development. Wild grown plants from Coahuila, Mexico, were identified based on leaf and spine traits to obtain a representative sample from six different stages of development (I-VI) from 1 to 7 years old. Total phenolic content (TPC), antioxidant activity (AOX), as well as composition and content of flavonols and saponins by HPLC-MS-TOF and HPLC-ELSD-PDA were evaluated. Concentrations of TPC were found to be between 5 to 13 mg gallic acid equivalents/g, reaching a maximum at stage II. The AOX presented a negative tendency from stage I to stage VI (from 148 to 50 μmol Trolox equivalents/g respectively). Kaempferol, quercetin and five saponins were identified. Similar to AOX, flavonols presented a negative concentration tendency with a reduction of 65% between the stage I and VI. Plants of stage III and IV presented the highest content of saponins, particularly chlorogenin glycoside, containing 3.19 and 2.90 mg protodioscin equivalents/g, respectively. These data suggest that plants from stages I to IV may be used as a source of antioxidant and bioactive principles, and that the content of these metabolites could be used as a marker to determine the developmental stage of the plant.     

Cold tolerance during juvenile development in sorghum: a comparative analysis by genomewide association and linkage mapping

Improved cold tolerance during the juvenile phase is a major breeding goal to develop new sorghum cultivars suitable as an alternative energy crop in temperate regions. The objectives of this study were to identify marker‐trait associations for cold tolerance in a sorghum diversity panel fingerprinted with 2620 single nucleotide polymorphism (SNP) markers and to detect quantitative trait loci (QTL) in two F_2:3 populations. Traits of interest were dry matter growth rate (DMGR), leaf appearance rate (LAR), chlorophyll content (SPAD) and chlorophyll fluorescence (F_v′/F_m′ and Ф_PSII) in relation to temperature. The association panel comprised 194 genotypes, while the F_2:3 populations consisted of 80 and 92 genotypes. All populations were tested under controlled conditions in a minimum of four temperature regimes ranging from 9.4°C to 20.8°C. QTL were identified for means across environments and regression parameters describing temperature effects. Several marker‐trait associations for mean (m) DMGR, base temperature (T_b) of SPAD and Ф_PSII and temperature effect on LAR were validated by QTL detected in population 1 or 2. Promising QTL regions were found on chromosomes SBI‐01, SBI‐02, SBI‐03, SBI‐04, SBI‐06 and SBI‐09, among them genomic regions where candidate genes involved in the C‐repeat binding pathway or encoding cold‐shock proteins are located.     

Metabolic responses of avocado plants to stress induced by Rosellinia necatrix analysed by fluorescence and thermal imaging

European Journal of Plant Pathology - One of the most important soilborne diseases affecting avocado (Persea americana Mill.) crops is white root rot, caused by the fungus Rosellinia necatrix. In...     

RNA/DNA ratio is an early responding,accurate performance parameter in growth experiments of noble crayfish Astacus astacus (L.)

Recent intensification efforts of astacid culture considerably depend on the appropriate assessment of the animal's physiological condition both for research and application. We conducted a 4 weeks feeding experiment to assess temporal resolution and accuracy of different response parameters (RNA/DNA ratio, RNA per wet weight, carapace length, wet weight, specific growth rate). Juvenile noble crayfish were exposed to five feeding regimes that differed in feeding frequency and food availability. Continuous growth was detected in all feeding regimes with individual increase up to 90% (wet weight) and 17% (carapace length), respectively. Morphometric parameters allowed separation of three weight‐groups or two length‐groups. During the experimental period RNA/DNA ratios showed both decrease (?17%) and increase (+35%), with superior accuracy than morphometric parameters, separating four groups. Based on RNA/DNA ratios, different feeding regimes were detected earlier, with two groups separated already after 3 weeks. RNA/DNA ratio was clearly superior to RNA per unit wet weight, as the latter failed to detect any differences between groups. In conclusion, RNA/DNA ratio is a valuable tool in nutritional studies with freshwater crayfish if overall growth is the key variable of interest.     

Postharvest efficacy of resistance inducers for the control of green mold on important Sicilian citrus varieties

Journal of Plant Diseases and Protection - The disease reducing activity of acibenzolar-S-methyl (ASM), chitosan and β-aminobutyric acid (BABA) against postharvest green mold (GM) of citrus...     

Effect of rearing and slaughter conditions on behaviour, physiology and meat quality of Large White and Duroc-sired pigs

The present study investigated the effect of outdoor rearing and genetic background on behaviour and meat quality traits in heavyweight pigs. Large White and Duroc-sired pigs were reared in groups of 3 castrated males and 3 females, conventionally or in fields, from April to October, in a study with two replicates. Compared to indoor pigs, outdoor pigs were more active and showed a larger range of behaviour suggesting improved welfare from a behavioural point of view. During 5 h of isolation, outdoor pigs were less active and had lower heart rates, and in another test, they reacted less to a non-familiar object (traffic cone). Pigs were slaughtered at 150 kg live weight, half of each treatment group after mixing, short transport, and overnight lairage and half immediately following short transport. Outdoor pigs were less aggressive during pre-slaughter mixing. Ante- and post-mortem glycogen content of the Longissimus lumborum (LL), Semimembranonus (SM) and Semispinalis capitis (SC) muscles depended on slaughter conditions, sire breed, rearing conditions, gender and year of experimentation, sometimes influencing ultimate pH. Effects of rearing on muscle glycogen content and post-mortem pH were stronger during the second year of rearing. Effect of slaughter conditions on glycogen content and ultimate pH depended on fighting levels during pre-slaughter mixing. Outdoor rearing increased muscle redness. Drip and cooking loss were higher in Large White than Duroc-sired pigs. Drip and cooking loss were correlated with early post-mortem and ultimate pH. Thawing loss was correlated with early post-mortem temperature and ultimate pH. Finally, reactivity to isolation had a predictive value as pigs more active during isolation had less skin damage due to fighting during pre-slaughter mixing. In conclusion, despite large effects of year of experimentation, outdoor rearing, sire breed, and slaughter conditions influenced behaviour and muscle characteristics.