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1.
A 15-day feeding trial was conducted to investigate the effect of dietary Lactobacillus plantarum on growth performance, digestive enzyme activities and gut morphology of juvenile Pacific white shrimp, Litopenaeus vannamei (initial body weight = 7.96 ± 0.59 g). Four microbound diets were formulated to contain fermentation supernatant (FS), live bacteria (LB), dead bacteria (DB), and cell-free extract (CE) of L. plantarum. Results indicated that final weight was significantly higher in FS, DB, and CE group in comparison to the control group (P < 0.05). The maximum weight gain rate (WGR) and specific growth rate (SGR) of the CE diet group were significantly higher than that of other groups (P < 0.05). The FCR of CE diet group was lower than that of the control, LB, DB, and FS diets groups (P < 0.05). The highest digestive enzyme activities (amylase, lipase, and pepsin activity) in the hepatopancreas and gut of shrimp were observed in the CE diet group. Histological study revealed that dietary CE diet could significantly increase the enterocytes height of shrimp. The administration of cell-free extract of L. plantarum could effectively improve the growth performance of L. vannamei via the improvement of digestive enzyme activities and the enterocytes height of shrimp. The results of this study will be essential to promote application of probiotics in shrimp aquaculture.  相似文献   

2.
The grass shrimp Palaemonetes pugio, a species common to Spartina alterniflora-dominated marshes, may be sensitive to the invasion of the common reed Phragmites australis in northeastern US salt marshes. We examined two questions: (1) Do grass shrimp have a preference for the native plant over the non-native plant? (2) Are grass shrimp more effective foragers on P. australis? We tested the first hypothesis by comparing the amount of time shrimp spend in physical contact with the plant types over a 1-h period. Shrimp were observed under different arrangements of vegetation to control for differences in conspicuous structural features. Additionally, the amount of time shrimp spent foraging on S. alterniflora and P. australis shoots was compared to determine if shrimp graze more often on S. alterniflora. Shrimp spent significantly more time in contact with S. alterniflora only when plant types were grouped at opposite ends of aquaria, but did not exhibit a foraging preference for this plant type. To address our second question, we investigated the effects of shrimp foraging on stem epifauna, an assemblage of semi-aquatic invertebrates associated with macrophyte shoots. Previous research showed that P. australis supports a lower density of stem-dwelling epifauna relative to S. alterniflora. We hypothesized that the primary grazer of this community, P. pugio, can forage on P. australis stems more effectively due to structural differences between the two plants, causing the lower abundance of epifauna through top-down effects. We exposed individual shoots inhabited by epifauna to shrimp and compared faunal densities on exposed shoots to densities on control shoots after 18 h. The reduction of epifauna by predation was proportional on the two plant types. Therefore, top-down effects can be ruled out as an explanation for the patchy distribution of epifauna observed in P. australis–S. alterniflora marshes.  相似文献   

3.
Iron homeostasis was studied in two tropical indica rice cultivars viz. Sharbati (high Fe) and Lalat (low Fe) having contrasting grain Fe concentration. Plants were hydroponically grown with 5 concentrations of Fe (0.05, 2, 5, 15, 50 mg L?1) till maturity. The effect of incremental Fe treatment on the plant was followed by analyzing accumulation of ferritin protein, activities of aconitase enzyme, enzymes of anti-oxidative defense and accumulation of hydrogen peroxide and ascorbic acid. Plant growth was adversely affected beyond 15 mg L?1 of Fe supplementation and effects of Fe stress (both deficiency and excess) were more apparent on the high Fe containing cultivar Sharbati than the low Fe containing Lalat. Level of ferritin protein and aconitase activity increased up to 5 mg L?1 of Fe concentration. Lalat continued to synthesize ferritin protein at much higher Fe level than Sharbati and the cultivar also had higher activities of peroxidase, superoxide dismutase and glutathione reductase. It was concluded that the tolerance of Lalat to Fe stress was because of its higher intrinsic ability to scavenge free radicals of oxidative stress for possessing higher activity of antioxidative enzymes. This, together with its capacity to sequester the excess Fe in ferritin protein over a wider range of Fe concentrations made it more tolerant to Fe stress.  相似文献   

4.
The seaweed genus Gracilaria is a potential candidate for the production of bioethanol due to its high carbohydrate content. Gracilaria is abundant throughout the world and can be found in both wild and cultivated forms. Differences in the ecological factors such as temperature, salinity, and light intensity affecting wild and cultivated specimens may influence the biochemical content of seaweeds, including the carbohydrate content. This study aimed to investigate the proximate composition and potential bioethanol production of wild and cultivated G. gigas and G. verrucosa. Bioethanol was produced using separate hydrolysis fermentation (SHF), employing a combination of enzymatic and acid hydrolysis, followed by fermentation with Saccharomyces cerevisiae ATCC 200062. The highest carbohydrate content was found in wild G. gigas. The highest galactose and glucose contents (20.21 ± 0.32 and 9.70 ± 0.49 g L?1, respectively), as well as the highest production of bioethanol (3.56 ± 0.02 g L?1), were also found in wild G. gigas. Thus, we conclude that wild G. gigas is the most promising candidate for bioethanol production. Further research is needed to optimize bioethanol production from wild G. gigas. Domestication of wild G. gigas is a promising challenge for aquaculture to avoid overexploitation of this wild seaweed resource.  相似文献   

5.
Ascophyllum nodosum, a brown macroalga, is the most widely used seaweed in agriculture. We report a rapid method for the detection of cytokinin-like activity in plants treated with a commercial A. nodosum liquid concentrate (Stimplex®) using a transgenic line of Arabidopsis carrying the ARR5 promoter fused to ß-glucuronidase (GUS) reporter gene. Based on GUS activity assay, an increase in cytokinin-like activity was detected in plants grown in vitro treated with 3 mL L?1 Stimplex®, whereas foliar spray treatments showed similar cytokinin-like activity at a concentration of 5 mL L?1. Histochemical staining showed Stimplex®-induced GUS activity in leaf as well as in the root tissues. Taken together, our results suggest that Stimplex® contains compounds that may elicit endogenous cytokinin-like activity. Furthermore, it is shown that this bioassay can be used for rapid screening of extracts that can stimulate cytokinin-like activities using Arabidopsis AAR5::GUS reporter transgenic plants.  相似文献   

6.
The predator Adalia bipunctata (Coleoptera: Coccinellidae) and the entomopathogenic fungus Lecanicillium muscarium, have been considered as potential biological control against aphids. While it can be difficult to achieve a high control level of Aphis fabae Scopoli (Hemiptera: Aphididae) using only a single beneficial agent, the research presented here aimed to determine the interaction between L. muscarium and A. bipunctata potential for control against A. fabae. Lecanicillium muscarium was found to cause about 30% mortality in A. bipunctata and with a reduction in feeding by about 15%. However, co-application of A. bipunctata and L. muscarium can cause an addititive effect in reducing aphid populations, resulting in about 90% reduction in aphid populations compared with control treatment. Thus, these two biocontrol agents have the potential to be complementary. This research study demonstrates that it is possible to combine A. bipunctata with L. muscarium to provide a sustainable method for management of A. fabae on broad bean cropping system and that field studies are required.  相似文献   

7.

Objective

To improve the production of trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) from linoleic acid in recombinant Yarrowia lipolytica.

Results

Cells of the yeast were permeabilized by freeze/thawing. The optimal conditions for t10,c12-CLA production by the permeabilized cells were at 28 °C, pH 7, 200 rpm with 1.5 g sodium acetate l?1, 100 g wet cells l?1, and 25 g LA l?1. Under these conditions, the permeabilized cells produced 15.6 g t10,c12-CLA l?1 after 40 h, with a conversion yield of 62 %. The permeabilized cells could be used repeatedly for three cycles, with the t10,c12-CLA extracellular production remaining above 10 g l?1.

Conclusion

Synthesis of t10,c12-CLA was achieved using a novel method, and the production reported in this work is the highest value reported to date.
  相似文献   

8.
Hybridization between alien and native species is biologically very important and could lead to genetic erosion of native taxa. Solidago × niederederi was discovered over a century ago in Austria and described by Khek as a natural hybrid between the alien (nowadays regarded also as invasive) S. canadensis and native S. virgaurea. Although interspecific hybridization in the genus Solidago is considered to be relatively common, hybrid nature of S. × niederederi has not been independently proven using molecular tools, to date. Because proper identification of the parentage for the hybrid Solidago individuals solely based on morphological features can be misleading, in this paper we report an additive polymorphism pattern expressed in the ITS sequences obtained from individuals representing S. × niederederi, and confirm the previous hypothesis that the parental species of this hybrid are S. canadensis and S. virgaurea. Additionally, based on variability at the cpDNA rpl32-trnL locus, we showed that in natural populations hybridization occurs in both directions.  相似文献   

9.
A greenhouse experiment was conducted in which two leguminous species commonly used in the Yellow River Delta for vegetation restoration, Robinia pseudoacacia and Amorpha fruticosa, were subjected to five salt treatments: 0, 50, 100, 150, and 200 mmol L?1. We aimed to determine which of the two species would be better suited for growth in a saline environment, and whether the acclimation capacity to salinity resulted from an inherently higher phenotypic plasticity. The results showed that salinity affected most growth and biomass parameters but had no effects on most leaf traits and physiological parameters of the two species. Height, relative growth rate of crown area, root biomass, and leaf mass ratio of R. pseudoacacia were reduced by higher salinity, while A. fruticosa was not affected. Chlorophyll a-to-chlorophyll b ratio and total antioxidative capacity of A. fruticosa increased with higher salinity, whereas those of R. pseudoacacia remained unchanged. Root mass ratio and vitamin C concentration of both species were not affected by salinity, whereas vitamin C concentration of A. fruticosa was higher than that of R. pseudoacacia. The root-to-shoot ratio of A. fruticosa was higher than that of R. pseudoacacia in most salt treatments. Of all leaf traits, only leaf area differed between treatments. R. pseudoacacia generally exhibited a greater plasticity than A. fruticosa in response to salinity, but A. fruticosa was more resistant to the higher salinities than R. pseudoacacia, and was thus a better candidate for vegetation restoration in saline areas.  相似文献   

10.
Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes. For D. saccharalis and D. flavipennella, 16 and 18 strains showed over 30% larval mortality in the 7th day, respectively. The LC50 values of strains for D. saccharalis varied from 0.08 × 105 (LIIT-0105) to 4104 × 105 (LIIT-2707) spores + crystals mL?1. For D. flavipennella, the LC50 values of strains varied from 0.40 × 105 (LIIT-2707) to 542 × 105 (LIIT-2109) spores + crystals mL?1. For the LIIT-0105 strain, which was the most toxic to D. saccharalis, the genes cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, cry8, and cry9C were detected, whereas for the strain LIIT-2707, which was the most toxic to D. flavipennella, detected genes were cry1Aa, cry1Ab, cry1Ac, cry1B, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, and cry9. The toxicity data and toxin gene content in these strains of Bt suggest a great variability of activity with potential to be used in the development of novel biopesticides or as source of resistance genes that can be expressed in plants to control pests.  相似文献   

11.
Candida albicans is the most common human fungal pathogen and can grow as yeast or filaments, depending on the environmental conditions. The filamentous form is of particular interest because it can play a direct role in adherence and pathogenicity. Therefore, the purpose of this study was to evaluate the effects of three clinical strains of Lactobacillus on C. albicans filamentation as well as their probiotic potential in pathogen-host interactions via an experimental candidiasis model study in Galleria mellonella. We used the reference strain Candida albicans ATCC 18804 and three clinical strains of Lactobacillus: L. rhamnosus strain 5.2, L. paracasei strain 20.3, and L. fermentum strain 20.4. First, the capacity of C. albicans to form hyphae was tested in vitro through association with the Lactobacillus strains. After that, we verified the ability of these strains to attenuate experimental candidiasis in a Galleria mellonella model through a survival curve assay. Regarding the filamentation assay, a significant reduction in hyphae formation of up to 57% was observed when C. albicans was incubated in the presence of the Lactobacillus strains, compared to a control group composed of only C. albicans. In addition, when the larvae were pretreated with Lactobacillus spp. prior to C. albicans infection, the survival rate of G. mellonela increased in all experimental groups. We concluded that Lactobacillus influences the growth and expression C. albicans virulence factors, which may interfere with the pathogenicity of these microorganisms.  相似文献   

12.
Copper, a common chemical contaminant in aquatic environment, is known to be toxic to aquatic life at high concentrations. In the present study, we evaluated the apoptotic cell ratio and ROS production in hemocytes of the white shrimp Litopenaeus vannamei exposed to 1 or 5 mg L?1 Cu for 0, 3, 6, 12, 24, and 48 h. The expression changes of antioxidant biomarker genes, i.e., copper-zinc superoxide dismutase (Cu-Zn SOD) and catalase (CAT), apoptosis-related genes, i.e., caspase-3 and inhibitor of apoptosis protein (IAP), and a specific biomarker gene of heavy metal pollution, i.e., metallothionein (MT), were also determined in hemocytes. Significant increases in ROS production were observed in both treatment groups at each time points. The apoptotic cell ratios were significantly increased at 6–48 h among shrimp exposed to 1 mg L?1 Cu and at each time points in 5 mg L?1 Cu group. These results indicated that Cu would induce oxidative stress and apoptosis in the hemocyte of L. vannamei. Quantitative real-time PCR analysis revealed that the relative expression levels of Cu-Zn SOD, CAT, caspase-3, IAP, and MT were upregulated in a dose-dependent and time-dependent manner, suggesting the involvement of these genes in stress response against Cu exposure.  相似文献   

13.
Escherichia coliL-asparaginase, an antileukaemic agent in man1, inhibits in vitro mitogen or antigen-induced blastogenesis in man2,3 and in animals (M. Bennett, E. G. Mayhew and T. Han, unpublished data) and suppresses bone-marrow derived antibody precursor cells in the mouse4. We now report that another L-asparaginase preparation—from Erwinia carotovora—also possesses antileukaemic activity5,6 and has a more pronounced immunosuppressive effect on in vitro blastogenesis than the E. coli enzyme.  相似文献   

14.
Two ornamental plants of Althaea rosea Cav. and Malva crispa L. were exposed to various concentrations of lead (Pb) (0, 50, 100, 200 and 500 mg·kg?1) for 70 days to evaluate the accumulating potential and the tolerance characteristics. The results showed that both plant species grown normally under Pb stress, and A. rosea had a higher tolerance than M. crispa, while M. crispa had a higher ability in Pb accumulation than A. rosea. Besides, lower Pb concentration (50 mg·kg?1) stimulated the shoot biomass in both plant species. Pb accumulation in plants was consistent with the increase of Pb levels, and the main accumulation sites were the roots and the older leaves. In addition, the photosynthetic pigments content and chlorophyll fluorescence parameters were influenced by Pb stress. In such case, both of the plants could improve the activities of antioxidant enzymes of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and the contents of the total soluble sugar and soluble protein, which reached the highest value at Pb 100 mg·kg?1, as well as the accumulation of the total thiols (T-SH) and non-protein thiols (NP-SH) to adapt to Pb stress. Thus, it provides the theoretical basis and possibility for ornamental plants of A. rosea and M. crispa in phytoremediation of Pb contaminated areas.  相似文献   

15.

Background

Starch is one of the most abundant organic polysaccharides available for the production of bio-ethanol as an alternative transport fuel. Cost-effective utilisation of starch requires consolidated bioprocessing (CBP) where a single microorganism can produce the enzymes required for hydrolysis of starch, and also convert the glucose monomers to ethanol.

Results

The Aspergillus tubingensis T8.4 α-amylase (amyA) and glucoamylase (glaA) genes were cloned and expressed in the laboratory strain Saccharomyces cerevisiae Y294 and the semi-industrial strain, S. cerevisiae Mnuα1. The recombinant AmyA and GlaA displayed protein sizes of 110–150 kDa and 90 kDa, respectively, suggesting significant glycosylation in S. cerevisiae. The Mnuα1[AmyA-GlaA] and Y294[AmyA-GlaA] strains were able to utilise 20 g l-1 raw corn starch as sole carbohydrate source, with ethanol titers of 9.03 and 6.67 g l-1 (0.038 and 0.028 g l-1 h-1), respectively, after 10 days. With a substrate load of 200 g l-1 raw corn starch, Mnuα1[AmyA-GlaA] yielded 70.07 g l-1 ethanol (0.58 g l-1 h-1) after 120 h of fermentation, whereas Y294[AmyA-GlaA] was less efficient at 43.33 g l-1 ethanol (0.36 g l-1 h-1).

Conclusions

In a semi-industrial amylolytic S. cerevisiae strain expressing the A. tubingensis α-amylase and glucoamylase genes, 200 g l-1 raw starch was completely hydrolysed (saccharified) in 120 hours with 74% converted to released sugars plus fermentation products and the remainder presumably to biomass. The single-step conversion of raw starch represents significant progress towards the realisation of CBP without the need for any heat pretreatment. Furthermore, the amylases were produced and secreted by the host strain, thus circumventing the need for exogenous amylases.
  相似文献   

16.
Lactobacillus strains have been considered good candidates as biological control agents for prevention or treatment of plant and animal infections. One L. plantarum strain FB003 and three strains (FB011, FB081, and FB110) which closed to L. sakei were isolated from fermented and salted shrimp and their abilities in inhibiting growth of Vibrio parahaemolyticus were characterized. These strains were selected as potential probiotics based on their oro-gastro-intestinal resistance, gut colonization, adhesion to Caco-2 cells, antimicrobial activities, antibiotic resistance, and safety aspects. Results of this study revealed that these isolates possessed high aggregation activities against pathogens in host intestines. Strain FB011 strain showed higher coaggregation and immunomodulatory activity in the gastro-intestinal tract than L. plantarum. These difference effects of Lactobacillus strains provide valuable information about using them to prevent Vibrio infections in the aquaculture industry.  相似文献   

17.
Maturation is one of the most important ontogenetic transitions in an individual’s life. However, the reproductive ecology of the tropical anguillid eel genus Anguilla at the onset of oceanic spawning migration is poorly understood. To understand the reproductive ecology, the fecundity of the tropical eels Anguilla bicolor bicolor, A. bengalensis bengalensis and A. marmorata was examined using advanced migrating silver eels (Stage IV and V). A close linear relationship was found between total length and fecundity in A. bengalensis bengalensis. The fecundities of A. bicolor bicolor (0.55 to 4.96 × 106), A. bengalensis bengalensis (0.33–1.72 × 106) and A. marmorata (0.99 × 106) were within the range of those observed in temperate eels.  相似文献   

18.
The gene encoding the xlnR xylanolytic activator of the heterologous fungus Aspergillus niger was incorporated into the Penicillium canescens genome. Integration of the xlnR gene resulted in the increase in a number of activities, i.e. endoxylanase, β-xylosidase, α-L-arabinofuranosidase, α-galactosidase, and feruloyl esterase, compared to the host P. canescens PCA 10 strain, while β-galactosidase, β-glucosidase, endoglucanase, and CMCase activities remained constant. Two different expression constructs were developed. The first consisted of the nucleotide sequence containing the mature P. canescens phytase gene under control of the axhA promoter region gene encoding A. niger (1,4)-β-D-arabinoxylan-arabinofuranohydrolase. The second construct combined the P. canescens phytase gene and the bgaS promoter region encoding homologous β-galactosidase. Both expression cassettes were transformed into P. canescens host strain containing xlnR. Phytase synthesis was observed only for strains with the bgaS promoter on arabinose-containing culture media. In conclusion, the bgaS and axhA promoters were regulated by different inducers and activators in the P. canescens strain containing a structural tandem of the axhA promoter and the gene of the xlnR xylanolytic activator.  相似文献   

19.
Brachystelma glabrum Hook.f. is an endemic plant species of Eastern Ghats, India. In this study, efficient protocols for in vitro micropropagation, flowering, and tuberization of this plant were developed. Sterilized shoot tip and nodal explants were cultured on Murashige and Skoog (MS) medium supplemented with different plant growth regulators (PGRs) and additives for shoot induction and multiplication. Both shoot tip and nodal explants showed the best response (90 and 100%, respectively) on MS medium supplemented with thidiazuron (TDZ) at 1.0 mg L?1. The microshoots multiplied best on MS + TDZ (1.0 mg L?1) in combination with α-naphthaleneacetic acid (NAA) at 0.5 mg L?1 and coconut water (CW) at 25%. The highest number of in vitro flowers (4.0 flowers per microshoot) was observed on MS medium supplemented with a combination of N6-benzyladenine (BA) and indole-3-butyric acid (IBA), each at 1.5 mg L?1. In vitro-derived shoots produced aerial tubers on MS + TDZ (2.0 mg L?1) + IBA (0.5 mg L?1) and basal tubers on MS + TDZ at 2.0 mg L?1. In vitro shoots were best rooted on half-strength (½) MS + NAA at 0.5 mg L?1. The rooted plantlets were successfully acclimatized in pots with 70% survival after a hardening period of 1 mo. This protocol provides an effective method for the conservation of this endemic plant species.  相似文献   

20.
Gut bacterium Pantoea sp. is one of the predominant bacterial species in the larval gut of the diamondback moth, Plutella xylostella. The phenotypic characters of Pantoea sp. were investigated with BIOLOG phenotype MicroArray (PM) in this study. Totally 950 different metabolic phenotypes were tested using the PM plates 1–10. Results exhibited that Pantoea sp. was able to metabolize 37.37 % of the tested carbon sources, 91.32 % of nitrogen sources, 100 % of sulfur sources, and 98.31 % of phosphorus sources. Most informative utilization patterns for carbon sources of Pantoea sp. were organic acids and carbohydrates, and for nitrogen were various amino acids. The bacterium had 94 different biosynthetic pathways. It had a wide range of adaptabilities, and could still metabolize in osmolytes with up to 9 % sodium chloride, 6 % potassium chloride, 5 % sodium sulfate, 20 % ethylene glycol, 4 % sodium formate, 4 % urea, 5 % sodium lactate, 200 mmol/L sodium phosphate (pH 7.0), 100 mmol/L ammonium sulfate (pH 8.0), 100 mmol/L sodium nitrate, and 100 mmol/L sodium nitrite, respectively. It also exhibited active metabolism under pH values between 4.5 and 10. Pantoea sp. showed active decarboxylase activities while poor deaminase activities in the presence of various amino acids. The phenotypic characterization of Pantoea sp. increased our knowledge of the bacterium, in particular its interactions with insect hosts and the adaptability in gut environments, and showed us some possible approaches to controlling diamondback moth through decreasing Pantoea sp. density.  相似文献   

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