Dynamique des populations planctoniques et bactériennes au cours d'une production expérimentale de phytoplancton marin naturel. II. Structure et physiologie des populations et leurs interactions

1980 ◽  
Vol 26 (3) ◽  
pp. 297-307 ◽  
Author(s):  
P. P. Lelong ◽  
M. A. Bianchi ◽  
Y. P. Martin
Keyword(s):  
Chlorophyll A ◽  
Initial Conditions ◽  
Skeletonema Costatum ◽  
Physiological State ◽  
Bacterial Flora ◽  
Algal Species ◽  
Shannon Index ◽  
Index Formula ◽  
Bacterial Populations ◽  
Energetic Charge

During the spring, an experiment was conducted on the production of natural phytoplankton in a continuous flow layout of large capacity, and an analysis was made of the simultaneous evolution of microplanktonic populations (taxonomic composition, diversity, class ranges, and energetic charge) and of bacterial populations (structure, diversity, dominances, and catabolic potentialities).Oligotrophic initial conditions were characterized by a poor (0.22 μg of chlorophyll a/L) and diversified (pigment diversity = 4.5) phytoplankton with nanoplanktonic dominance associated with several benthic type diatoms. Bacterial flora, in which pseudomonads were dominant (54.5%), were also diversified (Shannon index [Formula: see text]). Metabolic potentialities of these bacterial communities were several. Enrichment of the milieu caused the selection and development of a small number of algal species dominated by the diatoms Skeletonema costatum (64 × 106/L)and Chaetoceros (3.2 × 106/L) leading to a paucispecific population with a large biomass, a pigment diversity of 1.97, and a chlorophyll a concentration of 25.08 μg/L. The bacterial community then became diversified [Formula: see text] and, although pseudomonads remained dominant (62%), a larger use of organic micromolecules was noted.The establishment of this phytoplanktonic community was followed by a zooplanktonic development in which larger species succeeded smaller ones (ciliates, tintinnides, rotifers, and copepods) corresponding to the global increase of the phytobiomass. Although this system appeared to be in a phase of relative stability, a decrease in the energetic charge showed a disturbance in the physiological state of the planktonic populations. These phenomena led to the vanishing of the diatom's dominance (Chaetoceros, and then S. costatum) and its replacement by nanoplankton (123 × 106 cells/L) and dinoflagellates (300 00 cells/L). A modification in the organic wealth of the milieu with the addition of a particular complex material that was not or little degraded caused deep disturbances in the bacterial populations. Their diversity reached a very low level ([Formula: see text] to 2.25) with a proliferation of vibrions (up to 74%) well equipped with exoenzymes, but more restricted in their nutritional versatility (marked preference for organic macromolecules).During the final phase of experimentation, despite a change in qualitative composition and a more important biomass, microplanktonic and bacterial populations returned to a diversified state nearing that of the initial conditions (pigment diversity = 3.2; [Formula: see text]). [Journal translation]

Modeling of photosynthesis light curves by linear splines

2019 ◽  
pp. 20-29
Author(s):  
Alexander S. Lelekov ◽  
Rudolf P. Trenkenshu
Keyword(s):  
Experimental Data ◽  
Chlorophyll A ◽  
Skeletonema Costatum ◽  
Light Flux ◽  
Photosynthesis Rate ◽  
Light Curves ◽  
External Irradiation ◽  
Exchange Reactions ◽  
Cell Adaptation ◽  
Linear Splines

The paper presents an example of the linear splines use to describe the photosynthesis light curves for microalgae culture. The main mathematical models of the relationship between photosynthesis rate and light are listed. Based on the previously formulated basic principles of modeling microalgae photobiosynthesis, a mathematical model is proposed that describes the dependence of the assimilation number of chlorophyll a on the value of the light flux by linear splines. The advantage of the proposed approach is a clear definition of the point of change of the limiting factor. It is shown that light-limited photosynthesis rate is determined not only by external irradiation, but also by the concentration of chlorophyll a. The light-saturated rate depends on the amount of a key enzyme complex, which limits the rate of energy exchange reactions in the cell. Verification of the proposed model on the example of the diatom microalgae Skeletonema costatum was carried out. It is shown that the higher the degree of cell adaptation to high irradiation, the better the photosynthesis curve is described by linear splines. If S. costatum cells are adapted to low irradiation, deviations of experimental data from the idealized broken line are observed, which are caused by changes in the pigment composition. When the experimental data are normalized, the cell adaptation factor is reduced, all points are described by a single broken line, which indicates the universality of the proposed approach.

scholarly journals Biogeochemical controls on the bacterial populations in the eastern Atlantic Ocean

2011 ◽  
Vol 8 (12) ◽  
pp. 3747-3759 ◽  
Author(s):  
S. B. Neogi ◽  
B. P. Koch ◽  
P. Schmitt-Kopplin ◽  
C. Pohl ◽  
G. Kattner ◽  
...  
Keyword(s):  
Surface Layer ◽  
Atlantic Ocean ◽  
Chlorophyll A ◽  
Bacterial Abundance ◽  
Aquatic Organisms ◽  
Bacterial Populations ◽  
Organic C ◽  
Cultivable Bacteria ◽  
Eastern Atlantic Ocean ◽  
Vibrio Spp

Abstract. Little is known about bacterial dynamics in the oligotrophic ocean, particularly about cultivable bacteria. We examined the abundance of total and cultivable bacteria in relation to changes in biogeochemical conditions in the eastern Atlantic Ocean with special regard to Vibrio spp., a group of bacteria that can cause diseases in human and aquatic organisms. Surface, deep water and plankton (<20 μm, 20–55 μm and >55 μm) samples were collected between 50° N and 24° S. Chlorophyll-a was very low (<0.3 μg l−1) in most areas of the nutrient-poor Atlantic, except at a few locations near upwelling regions. In surface water, dissolved organic carbon (DOC) and nitrogen (DON) concentrations were 64–95 μM C and 2–10 μM N accounting for ≥90 % and ≥76 % of total organic C and N, respectively. DOC and DON gradually decreased to ~45 μM C and <5 μM N in the bottom water. In the surface layer, culture independent total bacteria and other prokaryotes represented by 4´-6-diamidino-2-phenylindole (DAPI) counts, ranged mostly between 107 and 108 cells l−1, while cultivable bacterial counts (CBC) and Vibrio spp. were found at concentrations of 104–107 and 102–105 colony forming units (CFU) l−1, respectively. Most bacteria (>99 %) were found in the nanoplankton fraction (<20 μm), however, bacterial abundance did not correlate with suspended particulates (chlorophyll-a, particulate organic C [POC] and N [PON]). Instead, we found a highly significant correlation between bacterial abundance and temperature (p < 0.001) and a significant correlation with DOC and DON (p < 0.005 and <0.01, respectively). In comparison to CBC and DAPI-stained prokaryotes, cultivable Vibrio showed a stronger and highly significant correlation with DOC and DON (p < 0.0005 and p < 0.005, respectively). In cold waters of the mesopelagic and abyssal zones, CBC was 50 to 100-times lower than in the surface layer; however, cultivable Vibrio spp. could be isolated from the bathypelagic zone and even near the seafloor (average ~10 CFU l−1). The depth-wise decrease in CBC and Vibrio coincided with the decrease in both DOC and POC. Our study indicates that Vibrio and other bacteria may largely depend on dissolved organic matter to survive in nutrient-poor oceanic habitats.

scholarly journals Field Spectroscopy as a Tool for Enhancing Water Quality Monitoring in the ACE Basin, SC

2017 ◽  
pp. 41-55 ◽  
Author(s):  
Caitlyn C. Mayer ◽  
Khalid A. Ali
Keyword(s):  
Water Quality ◽  
South Carolina ◽  
Chlorophyll A ◽  
Algal Species ◽  
Water Quality Monitoring ◽  
Water Systems ◽  
Quality Monitoring ◽  
Least Squares Regression ◽  
Monitoring Methods

The Ashepoo, Combahee, Edisto (ACE) Basin in South Carolina is one of the largest undeveloped estuaries in the Southeastern United States. This system is monitored and protected by several government agencies to ensure its health and preservation. However, as populations in surrounding cities rapidly expand and land is urbanized, the surrounding water systems may decline from an influx of contaminants, leading to hypoxia, fish kills, and eutrophication. Conventional in situ water quality monitoring methods are timely and costly. Satellite remote sensing methods are used globally to monitor water systems and can produce an instantaneous synopsis of color-producing agents (CPAs), including chlorophyll-a, suspended matter (TSM), and colored-dissolved organic matter by applying bio-optical models. In this study, field, laboratory, and historical land use land cover (LULC) data were collected during the summers of 2002, 2011, 2015, and 2016. The results indicated higher levels of chlorophyll, ranging from 2.94 to 12.19 μg/L, and TSM values were from 60.4 to 155.2 mg/L between field seasons, with values increasing with time. A model was developed using multivariate, partial least squares regression (PLSR) to identify wavelengths that are more sensitive to chlorophyll-a (R2 = 0.49; RMSE = 1.8 μg/L) and TSM (R2 = 0.40; RMSE = 12.9 mg/L). The imbrication of absorption and reflectance features characterizing sediments and algal species in ACE Basin waters make it difficult for remote sensors to distinguish variations among in situ concentrations. The results from this study provide a strong foundation for the future of water quality monitoring and for the protection of biodiversity in the ACE basin.

Exploration of the antioxidant system and photosynthetic system of a marine algicidal Bacillus and its effect on four harmful algal bloom species

2016 ◽  
Vol 62 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Shaoling Hou ◽  
Wanjiao Shu ◽  
Shuo Tan ◽  
Ling Zhao ◽  
Pinghe Yin
Keyword(s):  
Antioxidant System ◽  
Algal Bloom ◽  
Harmful Algal Bloom ◽  
Skeletonema Costatum ◽  
Algal Species ◽  
Photosynthetic System ◽  
Genes Expression ◽  
Total Antioxidant ◽  
Bacterium Strain ◽  
Harmful Algal Bloom Species

A novel marine bacterium, strain B1, initially showed 96.4% algicidal activity against Phaeocystis globosa. Under this situation, 3 other harmful algal species (Skeletonema costatum, Heterosigma akashiwo, and Prorocentrum donghaiense) were chosen to study the algicidal effects of strain B1, and the algicidal activities were 91.4%, 90.7%, and 90.6%, respectively. To explore the algicidal mechanism of strain B1 on these 4 harmful algal species, the characteristics of the antioxidant system and photosynthetic system were studied. Sensitivity to strain B1 supernatant, enzyme activity, and gene expression varied with algal species, while the algicidal patterns were similar. Strain B1 supernatant increased malondialdehyde contents; decreased chlorophyll a contents; changed total antioxidant and superoxide dismutase activity; and restrained psbA, psbD, and rbcL genes expression, which eventually resulted in the algal cells death. The algicidal procedure was observed using field emission scanning electron microscopy, which indicated that algal cells were lysed and cellular substances were released. These findings suggested that the antioxidant and photosynthetic system of these 4 algal species was destroyed under strain B1 supernatant stress. This is the first report to explore and compare the mechanism of a marine Bacillus against harmful algal bloom species of covered 4 phyla.

scholarly journals Algal Oxylipins Mediate the Resistance of Diatoms against Algicidal Bacteria

Marine Drugs ◽  
2018 ◽  
Vol 16 (12) ◽  
pp. 486 ◽  
Author(s):  
Nils Meyer ◽  
Johanna Rettner ◽  
Markus Werner ◽  
Oliver Werz ◽  
Georg Pohnert
Keyword(s):  
Fatty Acid ◽  
Bacterial Infection ◽  
Skeletonema Costatum ◽  
Algal Species ◽  
Lipid Mediators ◽  
Algicidal Bacteria ◽  
Mechanisms Of Resistance ◽  
Algicidal Bacterium ◽  
Diatom Skeletonema Costatum ◽  
Plankton Communities

Algicidal bacteria can lyse microalgal blooms and trigger shifts within plankton communities. Resistant algal species can escape lysis, and have the opportunity to dominate the phytoplankton after a bacterial infection. Despite their important function in ecosystem regulation, little is known about mechanisms of resistance. Here, we show that the diatom Chaetoceros didymus releases eicosanoid oxylipins into the medium, and that the lytic algicidal bacterium, Kordia algicida, induces the production of several wound-activated oxylipins in this resistant diatom. Neither releases nor an induction occurs in the susceptible diatom Skeletonema costatum that is lysed by the bacterium within a few days. Among the upregulated oxylipins, hydroxylated eicosapentaenoic acids (HEPEs) dominate. However, also, resolvins, known lipid mediators in mammals, increase upon exposure of the algae to the algicidal bacteria. The prevailing hydroxylated fatty acid, 15-HEPE, significantly inhibits growth of K. algicida at a concentration of approximately 1 µM. The oxylipin production may represent an independent line of defense of the resistant alga, acting in addition to the previously reported upregulation of proteases.

Note. Effect of trisodium phosphate on mesophilic and psychrotrophic bacterial flora attached to the skin of chicken carcasses during refrigerated storage Nota. Efecto del fosfato trisódico en los microorganismos mesófilos y psicrotrofos presentes en la piel de canales de pollo durante su almacenamiento en refrigeración

2000 ◽  
Vol 6 (4) ◽  
pp. 345-350 ◽  
Author(s):  
R. Capita ◽  
C. Alonso-Calleja ◽  
M.T. García Arias ◽  
B. Moreno ◽  
M.C. García-Fernández
Keyword(s):  
Tap Water ◽  
Bacterial Flora ◽  
Trisodium Phosphate ◽  
Refrigerated Storage ◽  
Water Control ◽  
Bacterial Populations ◽  
Ph Values ◽  
Popula Tions ◽  
Chicken Skin ◽  
Plate Counts

The potential for using trisodium phosphate (TSP) to reduce mesophilic and psychrotrophic popula tions on the skin of chicken carcasses was explored. Skin samples were immersed in sterile tap water (control) or an 8%, 10% or 12% solution of TSP at 20 °C for 15 min. Surface pH values and mesophilic and psychrotrophic plate counts were determined after 0, 1, 3 and 5 days of storage at 2° C. After washing, bacterial populations were significantly smaller in the samples treated with TSP than in the controls. The concentration of the TSP solution was a significant factor in reducing the populations of the bacteria on chicken skin. Before storage, the reduction in the presence of bacteria achieved in treated samples with respect to controls ranged between 0.95 log10 cycles and 1.78 log10 cycles in the case of mesophilic microorganisms, and 0.92 log10 cycles and 1.94 log10 cycles in the case of psychrotrophic strains. These differences between the concentrations of bacteria in samples immersed in water and those treated with TSP increased over time, ranging from 2.35 log 10 cycles to 3.08 log10 cycles (mesophilic microorganisms), and from 2.79 log10 cycles to 4.09 log10 cycles (psychrotrophic microorganisms) on day 5 of storage. The pH of the skin remained more or less constant throughout the study period, ranging between 8 and 9 in skin treated with TSP, depending on the concentration, while it was two units lower in the control samples.

ENDOPHYTIC BACTERIAL FLORA IN SOLANUM TUBEROSUM AND ITS SIGNIFICANCE IN BACTERIAL RING ROT DIAGNOSIS

1974 ◽  
Vol 54 (1) ◽  
pp. 115-122 ◽  
Author(s):  
S. H. DE BOER ◽  
R. J. COPEMAN
Keyword(s):  
Solanum Tuberosum ◽  
Bacterial Population ◽  
Bacterial Flora ◽  
Stem Tissue ◽  
Bacterial Ring Rot ◽  
Bacterial Populations ◽  
Corynebacterium Sepedonicum ◽  
Potato Plants ◽  
Ring Rot ◽  
Significant Difference

The aerobic endophytic bacterial population in "healthy" potato plants was found to vary from fewer than 1 × 103 to 4.2 × 107 cells/cm3 of stem tissue and from 0 to 1.6 × 104 cells/cm3 in tubers. No significant correlation was found between the bacterial population in stems and tubers of the same plant, nor was there a significant difference in the bacterial populations of virus-free plants when compared with PVX-infected plants. Strains of Micrococcus, Pseudomonas, Bacillus, Flavobacterium, Xanthomonas, Agrobacterium, and coryneforms were isolated in addition to several isolates that could not be identified. All isolates were nonpathogenic, including the coryneforms, some of which were morphologically indistinguishable from Corynebacterium sepedonicum but which were biochemically different.

Diel Periodicity of Chlorophyll a Concentration in Oregon Coastal Waters

1972 ◽  
Vol 29 (9) ◽  
pp. 1253-1259 ◽  
Author(s):  
Walter A. Glooschenko ◽  
Herbert Curl Jr. ◽  
Lawrence F. Small
Keyword(s):  
Light Intensity ◽  
Chlorophyll A ◽  
Coastal Waters ◽  
Dark Period ◽  
Skeletonema Costatum ◽  
Time Of Day ◽  
Light Period ◽  
Diel Periodicity ◽  
Low Light ◽  
Chlorophyll Precursor

Concentrations of chlorophyll a in phytoplankton exhibited a diel periodicity in Oregon coastal waters. Maximum surface concentrations often occurred around midnight and highest 25-m concentrations early in the evening (or even in late afternoon). Concentrations at intermediate depths fell in between and in a predictable progression with depth and time of day. Minimum chlorophyll a values occurred in the afternoon. No definite periodicity was established at 50 m.Laboratory studies with Skeletonema costatum demonstrated that the diel cycle of chlorophyll a per cell was related to the light intensity and duration to which cells were exposed. Highest concentrations of this pigment occurred early in the dark period and lowest concentrations in the light period when cells were grown under photoperiods of 9, 12, and 15 hr at a light intensity of approximately 1200 ft-c. Pigment bleaching probably was responsible for the low concentrations during the light period. The decline of chlorophyll a from the maximum early in the dark period began after the cells possibly became deficient in some chlorophyll precursor or energy-yielding substrate. Addition of an external carbon source during the dark period prolonged the high chlorophyll a concentrations in the dark before the decline began. Under low light (400 ft-c) chlorophyll a synthesis occurred only in the light. This phenomenon was most likely due to an insufficient amount of energy-yielding substrate or precursor synthesized during the low-light period, and the lack of bleaching in the light period at this lower intensity. The laboratory results were consistent with interpretations of the field data. A correction for diel pigment periodicity is recommended for models estimating photosynthesis from chlorophyll and light data and for oceanographic surveys during which sampling of chlorophyll a is carried out throughout the 24-hr day.

scholarly journals Role of Tryptophan-Metabolizing Microbiota On Diarrhea Mice Caused by Folium sennae Extracts

2020 ◽  
Author(s):  
Chenyang Zhang ◽  
Haoqing Shao ◽  
Dandan Li ◽  
Nenqun Xiao ◽  
Zhoujin Tan
Keyword(s):  
Cytochrome P450 ◽  
Intestinal Microbiota ◽  
Bacterial Flora ◽  
Shannon Index ◽  
Tryptophan Metabolism ◽  
Control Group ◽  
Cytochrome P450 Enzymes ◽  
Significant Difference ◽  
Tryptophan Derivatives

Abstract Background: Although reports have provided evidence that diarrhea caused by Folium sennae can result in intestinal microbiota diversity disorder, the intestinal bacterial characteristic and specific mechanism are still unknown. The objective of our study was to investigate the mechanism of diarrhea caused by Folium sennae, which was associated with intestinal bacterial characteristic reshaping and metabolic abnormality. Results: For the intervention of Folium sennae extracts, Chao1 index and Shannon index were statistical decreased. The Beta diversity clusters of mice interfered by Folium sennae extracts were distinctly separated from control group. Combining PPI network analysis, cytochrome P450 enzymes metabolism was the main signaling pathway of diarrhea caused by Folium sennae. Moreover, 10 bacterial flora communities had statistical significant difference with Folium sennae intervention: the abundance of Paraprevotella, Streptococcus, Epulopiscium, Sutterella and Mycoplasma increased significantly; and the abundance of Adlercreutzia, Lactobacillus, Dehalobacterium, Dorea and Oscillospira reduced significantly. 7 of the 10 intestinal microbiota communities were related to the synthesis of tryptophan derivatives, which affected the transformation of aminotryptophan into L-tryptophan, leading to abnormal tryptophan metabolism in the host. Conclusions: Folium sennae targeted cytochrome P450 3A4 to alter intestinal bacterial characteristic and intervene the tryptophan metabolism of intestinal microbiota, such as Streptococcus, Sutterella and Dorea, which could be the intestinal microecological mechanism of diarrhea caused by Folium sennae extracts.

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