Marine microalgae are potential producers of antimicrobial compounds. Monospecific, vibrio‐free co‐cultures of marine microalgae, Chaetoceros calcitrans, Tetraselmis suecica, Nannochloropsis sp. and ...Thalassiosira weissflogii, at the exponential phase of growth were inoculated with two Vibrio parahaemolyticus (Vp) strains. Vp M0904, a highly virulent strain responsible for acute hepatopancreatic necrosis disease (AHPND), and Vp M0702, a non‐pathogenic strain, both at 1 × 105 CFU ml−1. Microalgae and bacterial growth, total lipids and carbohydrates were obtained at 1, 2 and 3 days post inoculation with bacteria. Ethanolic (EE) and seawater extracts (SE) of C. calcitrans were also obtained to evaluate the inhibitory activity against Vp M0904. Microalgae cellular growth was not affected by any tested bacteria throughout the experiment; in contrast, Vp M0904 was significantly (p < 0.05) inhibited in co‐culture with C. calcitrans and T. suecica. Meanwhile, Vp M0702 was significantly (p < 0.05) inhibited by all microalgae except for Nannochloropsis sp. Minor, non‐significant variations were found in the lipids and carbohydrate metabolism of all microalgae inoculated with both strains. Low CFU ml−1 of Vp M0904 was registered when it was incubated with SE of C. calcitrans at concentrations over 75 µg ml−1, however, EE did not show any antibacterial activity. The bacteriostatic effect was dependent of microalgae type and Vibrio strain. Hydrophilic compounds of C. calcitrans cells possess antibiotic activities on the highly virulent Vp M0904 responsible for AHPND, a devastating disease for farmed shrimp around the world.
Microalgae are the primary source of food for Artemia franciscana. In turn, Artemia serve as live food for various species in culture. The chemical composition of Artemia is of great importance ...because it affects the nutritional quality of the organisms produced in aquaculture systems. For this reason, the present study aimed to characterize the nutritional value, proximal composition, concentration of chlorophyll a and b, and total carotenoid content in the microalgae Thalassiosira weissflogii, Chaetoceros muelleri, Tetraselmis suecica, and Nannochloropsis sp., which were used to feed juvenile A. franciscana for 6 h. Artemia juveniles fed with these microalgae species exhibited higher concentrations of proteins, carbohydrates, lipids, chlorophyll a and b, and total carotenoids than those in the control. The organisms fed with Tetraselmis suecica presented the highest content of chlorophyll b, while those fed with Thalassiosira weissflogii and Chaetoceros muelleri showed the highest values of total carotenoids and chlorophyll a.
El mercurio y su efecto en el material genético Nieves Soto, Mario; Osuna López, Isidro; Roos Muñoz, Sarahí ...
Investigación y ciencia (Aguascalientes, Mexico),
08/2022
86
Journal Article
Odprti dostop
El mercurio es uno de los metales tóxico de mayor preocupación ambiental. En la presente revisión se muestran los principales aportes antropogénicos de mercurio al ambiente y en particular, algunos ...datos del aporte de mercurio a los océanos. Además, se revisaron estudios en donde se evaluó el daño en el material genético (e.g. ácido desoxirribonucleico) por exposición al mercurio en humanos.
•Two groups of commercial probiotics and one control were evaluated in commercial facilities.•The bacterial community in biofloc system were analyzed.•The densities of VHB were similar in treatments ...with probiotics compared with the control.•Nitrogenous compounds and productive parameters of shrimp were similar among treatments.•The addition of probiotics did not improve the productive response of L. vannamei.
In biofloc technology systems (BFT) the bacterial community plays the most important role at recycling the organic matter and metabolizing the toxic nitrogenous compounds. The aim of this study was to evaluate the effect of two groups of commercial probiotics on the abundance of viable heterotrophic bacteria (VHB), ammonia oxidizing bacteria (AOB) and Vibrio-like (VLB), nitrogenous compounds and productive parameters of whiteleg shrimp Litopenaeus vannamei in a commercial farm. The study was developed during nursery phase in zero water exchange. Two groups of probiotics (PB1 and PB2) and one control (PBN; no probiotic) were evaluated in three replics. Shrimp postlarvae (7.3 mg) were stocked in ponds (70 m3) at densities of 500 in./m2. Commercial probiotics (Efinol PT-Lab. Robles and Epicin ponds-Epicin hatcheries) were incubated for 36 h in bioreactors (1 m3) and supplied every 3 d in PB1 and PB2 treatments. Basic variables of water quality, nitrogenous compounds and bacterial groups were monitored. At the beginning of the experiment, the abundance of VHB was lower in the PBN treatment, but as the bioassay progressed, the densities were similar to PB1 and PB2. In general VLB showed similar tendency to VHB, but significant difference were determined among treatments. The AOB abundance was similar in all treatments. Nitrogenous compounds and productive parameters of shrimp did not show significant differences between treatments. In the PBN ponds the zero water exchange could have promoted benefical bacteria of the natural biota. The addition of probiotics did not improve the water quality nor productive response of L. vannamei.
Objetivo. Evaluar el efecto de dietas tradicionales (Thalassiosira weissflogii y nauplios de Artemia) y otras dos alternativas (no tradicionales) a base de microalgas y rotíferos sobre la ...supervivencia, el desarrollo y crecimiento de larvas nauplio V (NV) hasta el día de cambio a postlarvas (PL1) de camarón Penaeus vannamei. Materiales y Métodos. Se realizaron dieciséis réplicas (unidades experimentales) para cada una de las tres dietas utilizadas. Las larvas se colocaron en contenedores de 12 L a 35 ups, 30°C y una densidad de 200 larvas/L. La supervivencia, etapa del desarrollo y el crecimiento se determinaron al inicio, cada 24 h y al final del experimento (PL1: día 8). A los datos obtenidos se les aplicó un ANOVA de una vía. Resultados. La dieta no tuvo influencia (p>0.05) sobre supervivencia y el peso. La supervivencia osciló entre 30.4% (dieta alternativa B) y 28.5% (dieta tradicional A). El desarrollo, longitud y peso más bajo a PL1 fue encontrado con la dieta tradicional (6.71; 3.53 mm; 58.37 µm/organismo) en comparación con las dietas alternativas suministradas B y C (6.86-6.76; 3.79-3.82 mm; 60.7-65.0 µm/organismo). Conclusiones. La alimentación más adecuada para la supervivencia, desarrollo y crecimiento larval se obtuvieron con las dietas alternativas no tradicionales (B y C) compuestas de rotíferos.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The aim of this study was to characterize potential fungal species affecting mangrove species in Mexico. The phytopathogens were identified based on morphological and molecular characteristics using ...internal transcribed spacer (ITS1/ITS4) primers then sequenced and compared with the other related sequences in GenBank (NCBI). Three fungal species were identified as Colletotrichum queenslandicum (Weir and Johnst, 2012) from black mangrove (Avicennia germinans); Colletotrichum ti (Weir and Johnst, 2012) from white mangrove (Laguncularia racemosa) and buttonwood mangrove (Conocarpus erectus); Fusarium equiseti (Corda) from red mangrove (Rhizophora mangle). In addition, C. ti and F. equiseti were identified from mango Mangifera indica L. sampled close by the mangrove area. This study provides first evidence of anthracnose on four mangrove species caused by Colletotrichum and Fusarium species in the “Términos” coastal lagoon in Campeche State southern Mexico. This is the first time that C. queenslandicum and C. ti are reported in Mexico. F. equiseti has not been reported affecting M. indica and R. mangle until the present work. Little is known regarding fungal diseases affecting mangroves in Mexico. These ecosystems are protected by Mexican laws and may be threatened by these pathogenic fungus. This is the first report of the effect of Trichoderma harzianum TRICHO-SIN as an effective biological control against of Colletotrichum and Fusarium species.
Biochemical composition was assessed in green (Ulva expansa, Caulerpa sertularioides, Rhizoclonium riparium, Codium isabelae), red (Spyridia filamentosa, Gracilaria vermiculophylla), and brown ...(Padina durvillaei) seaweeds collected from different tropical lagoons on the Pacific coast of Sinaloa, Mexico. Protein content was higher in C. sertularioides, S. filamentosa, and G. vermiculophylla (10–12%), followed by R. riparium, P. durvillaei, and U. expansa (8%, 6%, and 4%, respectively). Lipid content was in the range of 0.3–1.5%, with the highest value found in R. riparium. The highest content of nitrogen-free extract (i.e., carbohydrates) (69%) and the lowest ash value (25%) were assessed in P. durvillaei. Polyunsaturated fatty acid content was in the range of 5–45%, with higher values in R. riparium (45%), C. sertularioides (39%), and P. durvillaei (23%). Red seaweeds showed the highest value of cholesterol+dehydrocholesterol (>90%), while green seaweeds showed the highest contents of β-sitosterol (71–77%), except for U. expansa, for which fucosterol+isofucosterol (79%) was highest. Pigment composition was different among seaweeds but coincided with previous reports. The biochemical components used as biomarkers were assessed by principal component analysis to discriminate among assessed variables and to cluster seaweed species according to the common variability of their biochemical composition. Results showed that composition was similar within seaweed divisions but particularly different in U. expansa and P. durvillaei. Biochemical compounds that contributed to total variability were β-sitosterol, 20:4n-6, 20:5n-3, chlorophyll a and b, and β-carotene, and to a lesser extent fucosterol+isofocusterol and 22:6n-3. Results showed that the analyzed seaweed species may be useful for animal nutrition and appropriate for human consumption.
The antioxidant activity of meals, growth performance, dry matter, crude protein and amino acid apparent digestibility coefficients (ADC) were determined for three macroalgae in Pacific white shrimp ...juveniles: Gracilaria vermiculophylla, Dictyota dichotoma and Ulva lactuca. For the digestibility determination, test diets included 15% of the test ingredients and 85% of a control diet supplemented with 1% chromic oxide. The amino acid content in the ingredients, diets and feces were analyzed using HPLC. In general, nutrient digestibility values were far higher in the diets with macroalgae meals than in the control diet. In conclusion, diets with the macroalgae U. lactuca and G. vermiculophylla in particular showed high antioxidant activity, high amino acid digestibility and improved Litopenaeus vannamei growth.
The combined effect of salinity (25, 30, 35, and 40psu) and temperature (25, 30, and 35°C) was evaluated on survival and development of nauplii V (NV) larvae until postlarvae (PL1) of Litopenaeus ...vannamei. Four replicates were applied to each combination of salinity and temperature. The larvae were placed in 12 L beakers a density of 100larvae/L. Salinity was increased dissolving commercial salt without iodine, into marine water, whereas fresh filtered tap water was used to decrease the salinity from seawater. The NV were adapted at 35psu and 30°C during 30 minutes. Thereafter, larvae were transferred at each experimental combination of salinity and temperature. Every 24 h, samples of larvae were obtained to determine in vivo their stage of development and survival. All data were analyzed using a two-way ANOVA. Survival and larval development were significantly affected by salinity, temperature and interaction of both factors. Maximum ultimate survival to PL1 was obtained at 30°C and 30psu (82.2%) followed by 30 and 35°C at 25psu (71.5 y 71.6%). The highest development at PL1 was found at 30°C and 30psu (6.76). Larval development during experiment was lower at 25°C as compared to 30 and 35°C, regardless of the salinity levels. The most adequate conditions for survival and larval development were obtained between 30-35°C and 25-30psu.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
