Species Of Green Algae Research Articles

Time-Dependent Toxicity and Health Effects Mechanism of Cadmium to Three Green Algae.

As algae are extremely sensitive to heavy-metal ions and can be critical biological indicators in the heavy-metal toxicity analyses conducted by environmental health researchers, this paper explores the sensitivity to temporal toxicity of three species of green algae: Scenedesmus obliquus, Chlorella pyrenoidosa, and Selenastrum capricornutum. The method of time-dependent microplate toxicity analysis was used to systematically investigate the changes in the toxicities of the three green-algae species induced by different concentrations of cadmium (Cd). The chlorophyll a content, antioxidant enzyme activity, and malondialdehyde (MDA) content in the algae were analyzed to explore the mechanism of Cd toxicity after 96 h of exposure. The results showed that the toxic effects of Cd on the three algae species were time-dependent. By comparing the toxic effect of Cd, indicated by pEC50 (the negative logarithm of EC50), on the algae species at four durations of exposure (24, 48, 72, and 96 h), this study found that the indicator organisms had different sensitivities to Cd. The order of sensitivity was C. pyrenoidosa > S. obliquus > S. capricornutum. Cd exposure had significant effects on the chlorophyll a and MDA content and on the enzyme activity of superoxide dismutase (SOD) and catalase (CAT) in the algae species. The chlorophyll a content in the cells of the algae decreased with increasing Cd concentration. The enzyme activity of CAT and content of MDA increased with increasing Cd concentration, which indicated that Cd had an oxidative stress effect on the three algae species.

Soil algae as a potential carrier for nanoplastics: Adsorption and internalization of nanoplastics in algal cells.

Although plastics are widely distributed in soil environments, few studies have assessed their effects on different test species. In this study, the responses (adsorption or internalization) of two green algal species (Chlorococcum infusionum and Chlamydomonas reinhardtii) to nanoplastics in soil were evaluated via microscopic analysis for nine weeks; additionally, the effects of polystyrene (PS) nanoplastics on their photosynthetic activity and growth were assessed. The results showed that PS nanoplastics and C. infusionum or C. reinhardtii cells were aggregated with the formation of palmelloid colonies; additionally, internalization of PS nanoplastics to C. reinhardtii cells was verified. However, no significant effects of PS nanoplastics on photosynthetic activity and growth of soil algae were observed. Algae were more likely to be threatened by plastic aggregation in the soil environment than in the aquatic environment due to the formation of a mucilaginous sheath on their cell. Our results highlighted that soil algae are a potential carrier of nanoplastics to other organisms in the food chain due to plastic aggregation through adsorption or internalization. This study will enhance our understanding of nanoplastic distribution in soil algae.

Metabolic and Proteomic Analysis of Chlorella sorokiniana, Chloroidium saccharofilum, and Chlorella vulgaris Cells Cultured in Autotrophic, Photoheterotrophic, and Mixotrophic Cultivation Modes.

Chlorella is one of the most well-known microalgal genera, currently comprising approximately a hundred species of single-celled green algae according to the AlgaeBase. Strains of the genus Chlorella have the ability to metabolize both inorganic and organic carbon sources in various trophic modes and synthesize valuable metabolites that are widely used in many industries. The aim of this work was to investigate the impact of three trophic modes on the growth parameters, productivities of individual cell components, and biochemical composition of Chlorella sorokiniana, Chloroidium saccharofilum, and Chlorella vulgaris cells with special consideration of protein profiles detected by SDS-PAGE gel electrophoresis and two-dimensional gel electrophoresis with MALDI-TOF/TOF MS. Mixotrophic conditions with the use of an agro-industrial by-product stimulated the growth of all Chlorella species, which was confirmed by the highest specific growth rates and the shortest biomass doubling times. The mixotrophic cultivation of all Chlorella species yielded a high amount of protein-rich biomass with reduced contents of chlorophyll a, chlorophyll b, carotenoids, and carbohydrates. Additionally, this work provides the first information about the proteome of Chloroidium saccharofilum, Chlorella sorokiniana, and Chlorella vulgaris cells cultured in molasses supplementation conditions. The proteomic analysis of the three Chlorella species growing photoheterotrophically and mixotrophically showed increased accumulation of proteins involved in the cell energy metabolism and carbon uptake, photosynthesis process, and protein synthesis, as well as proteins involved in intracellular movements and chaperone proteins.

Marine Benthic Algal Composition after 45 Years in an Urbanized Bay in Cebu, Philippines

Coastal ecosystems have been seriously impacted by anthropogenic activities, which are compounded by recent climatic and environmental changes. To provide some evidence of these changes, a study of marine benthic algal composition was conducted by comparing historical (1969–1970) and contemporary (2013–2014) collections in Silot Bay in Cebu, Philippines. A quantitative survey revealed a total of 30 species of benthic algae (11 red, nine brown, and 10 green) in the historical collections, whereas only 15 species (four each of red and brown plus seven species of green algae) were accounted in the latter years. This decline in the marine benthic algal composition may be attributed to sedimentation, which is indirectly caused by urbanization and human population increase. Altered environmental conditions inside the Bay may also explain the decline and qualitative changes of algal species composition therein. Continued monitoring of the benthic macroalgal composition and environmental parameters may help document anthropogenic impacts on marine ecosystems. Historical herbarium samples represent a valuable yet underappreciated resource for tracking environmental changes through time.

Germling culture and molecular analysis of evasive micro-filamentous green algae growing in the Maltese islands (central Mediterranean)

Abstract Various species of marine micro-filamentous green algae (<5 mm) remain overlooked globally. They are difficult to identify in field collections due to their diminutive size and their cryptic morphology. During this study, algal cultures combined with DNA barcoding helped to overcome these challenges. Both substratum samples and macrophytic fragments of Posidonia oceanica, Dictyopteris sp. and Halopteris sp. were incubated in laboratory culture. Germlings of Ulvella endostraca and Blastophysa rhizopus grew from the incubated substratum. Blastophysa rhizopus is a new record for the Maltese islands, as is U. endostraca that had only been reported previously from New Zealand. In situ, germlings of both species were also observed to grow as epiphytes, on Dictyopteris sp. in the case of U. endostraca, and on P. oceanica in the case of B. rhizopus. This study employed the in vitro culture of algal germlings, as well as morphological and molecular analyses. DNA data and subsequent phylogenetic analyses of tufA and rbcL sequences supported the separation of U. endostraca from other closely related congeners that have been previously reported from the Maltese islands. Moreover, this study includes a comparison of the micro-filamentous algae identified from Malta with those from other areas of the Mediterranean Sea.

Physiological acclimation of Ulva prolifera to seasonal environmental factors drives green tides in the Yellow Sea

To understand how seasonal factors could drive the formation of green tide blooms and their flotation and decay, we cultured the green tide algal species Ulva prolifera at various temperatures (5, 10, 15, 20, 25, 30, and 35 °C) and light intensities (40, 80, 140, 240, and 400 μmol photons m−2 s−1). The results showed that the ratio of floating U. prolifera increased with increasing light and temperature, which was accompanied by morphological changes. The net photosynthetic rate and the proportion of floating U. prolifera thalli showed a nonlinear relationship. Furthermore, an enclosure experiment confirmed that the flotation of U. prolifera was influenced by light intensity via the regulation of photosynthesis of the thalli. These results suggest that seasonal factors control the photosynthesis of U. prolifera, which drives the flotation and decay of green tide algae in the Yellow Sea.

Establishing and validating axenic cultures of the microalga Haematococcus lacustris (Chlorophyceae)

ABSTRACT Although many isolation techniques for algaeaxenic cultures of algae are known, successful isolation approaches are species and contaminant-specific. The commercially important alga Haematococcus lacustris has been intensively studied due to its natural production of the high-value carotenoid astaxanthin, yet there are no reports of axenic H. lacustris cultures. In this article, we describe the successful isolation of axenic H. lacustris, originally isolated in non-axenic form from its natural habitat and adopted to be used daily in vitro, in our laboratory. We verify the absence of bacteria and identify the bacterial communities in the non-axenic algal culture. using PCR amplification with selected universal primers for 16S rRNA gene amplification in the gDNA. Amplification of the 16S rRNA gene of the non-axenic culture showed the presence of bacteria with high identity to Massilia, Blastococcus and Deinococcus species. The bacteria which were identified in our strain further expand our knowledge of bacterial communities on algae, and because we established axenic H. lacustris culture, testing their effect on growth or astaxanthin accumulation in controlled co-cultures is now available. The isolation technique described herein can be applied to other green algal species to eliminate bacteria, and the selected primers can be used to verify the axenic nature of other green algal cultures. The resulting axenic culture is required for molecular genetics research and will be very valuable for establishing heterotrophic growth in laboratory or industrial bioreactors.

Construction and Validation of a Chloroplast Expression Vector for the Production of Recombinant Proteins in Chlorella vulgaris

Microalgae constitute a diverse group of photosynthetic unicellular microorganisms that have gained immense attention for biotechnological applications. They are promising platforms for the production of high-value metabolites and biopharmaceuticals for commercial and therapeutic applications because of their physiological properties and capability to grow easily in natural and artificial environments. Although the proof-of-concept for some applications have been achieved for model species, such as Chlamydomonas reinhardtii, the genetic engineering methods for microalgae are still in their infancy. Thus, an expansion of this field is required. Chlorella vulgaris is an important algal species with a high protein content and requires focus for the development of an efficient nuclear and chloroplast transformation process. This research aimed to establish a chloroplast transformation method for the freshwater green-algae species C. vulgaris based on a specific expression vector (pCMCC, which was named after Chula Mexico Chlorella chloroplast) constructed with endogenous recombination regions, namely, 16S–trn I (left) and trn A–23S (right), and the Prrn promoter. Human basic fibroblast growth factor (bFGF) was adopted as a target biopharmaceutical to establish the chloroplast expression approach. The plasmid pCMCC:bFGF was transformed into C. vulgaris via electroporation using simple carbohydrate-based buffers, which aided in the transfer of the transgene into the chloroplast genome. Cells transformed with the pCMCC:bFGF vector were selected using kanamycin, and resistant colonies were analyzed by polymerase chain reaction and Western blotting to confirm the presence of the transgene and the recombinant bFGF, respectively. The bFGF that accumulated in the transplastomic C. vulgaris clones ranged from 0.26 to 1.42 ng/g fresh weight of biomass, and it was quantified by enzyme-linked immunosorbent assay. Therefore, the designed expression vector, in combination with an optimized electroporation protocol, constitutes a viable approach to successfully develop transplastomic lines of C. vulgaris for the potential low-cost production of biopharmaceuticals using this algal species. This study paves the way for the establishment of chloroplast biotechnology in microalgae other than the model organism C. reinhardtii.

Development of a Microalgae-Based Continuous Starch-to-Hydrogen Conversion Approach

Eukaryotic algae represent a highly heterogeneous group in terms of organization, lifestyle, and metabolic capabilities. Unicellular green microalgae are capable of biohydrogen production through direct and indirect photolysis as well as dark fermentation. Most algae hydrogen studies focus on axenic algal cultures, although these are difficult and expensive to maintain for continuous operation. Moreover, the complex interplays and metabolic fluxes between algae and bacteria in natural ecosystems provide a number of clear biological and technological benefits to large-scale functional algae-based systems. Two green algae species from the Chlamydomonas and Chlorella genera were used to engineer stable synthetic communities by incorporating a starch-degrading bacterium from the Bacillus genus into the inter-kingdom consortium. Continuous photoheterotrophic biohydrogen production was achieved by elaborating an appropriate algal–bacterial ratio and fine-tuning the culture conditions for the synthetic consortia. Medium with starch as only carbon source served as a simple model of cheap substrate for algal hydrogen generation. The engineered pairwise algal–bacterial associations showed increased biomass and biohydrogen yield compared to the axenic control conditions. Chlorella sp. MACC-360 produced a significantly higher amount of hydrogen when both the bacterium partner and starch were added to the media compared to the axenic algae. Continuous, elevated algal hydrogen production was achieved in media supplemented with 8 g L−1 starch as sole carbon source when carefully selected initial cell number values were used for the Chlorella sp. MACC-360–B. amlyloliquefaciens co-cultures.

Green algae as bioindicators for long-term nutrient pollution along a coastal eutrophication gradient

Eutrophication is a strong driver that modifies coastal areas globally and measures to reduce nutrient input are implemented in many areas. As nutrient concentrations in coastal waters can vary drastically with time and space, quantifying the impacts of the actions taken to reduce eutrophication can be logistically challenging. In this study, we assessed the variation in nutrient concentrations along a coastal eutrophication gradient in the Northern Baltic Sea and estimated whether ephemeral macroalgae can function as bioindicators to reflect long-term water nutrient concentrations. We studied spatial variation in total phosphorus (P) and nitrogen (N) concentrations in two green algal species, Cladophora glomerata and Ulva intestinalis, and temporal variation in nutrient concentrations in C. glomerata. Nutrient concentrations in water and algae showed seasonal and between-year variation along the gradient. Phosphorus and nitrogen concentrations in C. glomerata reflected the preceding (0–4 months) nutrient concentrations in water, while nutrient concentrations in U. intestinalis were less reliable indicators of the current and preceding water nutrient concentrations. While more data is needed to evaluate between-year variation, the results indicate that C. glomerata is a useful tool to assess both the spatial and temporal variation in nutrient run-off from land, especially to complement sparse water nutrient analyses.

Chlorophyta microalgae as dietary protein supplement: a comparative analysis of productivity related to photosynthesis

Microalgae are studied as innovative sources of a wide range of highly valuable products, including proteins for the food/feed sectors. However, protein content varies depending on algal species, culture conditions and harvesting period. The Phylum Chlorophyta includes most of the described species of green algae. Due to their remarkable peculiarities, four Chlorophyta species belonging to two distinct classes were selected for the research: Chlorella vulgaris and Chlorella protothecoides as Trebouxiophyceae, and Neochloris oleoabundans and Scenedesmus acutus as Chlorophyceae. The algae were studied to obtain comparative results about their growth performance, and total protein content and profile under the same culture conditions. Since photosynthetic process directly influences biomass production, photosynthetic pigment, PSII maximum quantum yield and thylakoid protein content and profile were analysed. SDS-PAGE and 2D BN/SDS-PAGE were performed to expand information on the organization and assembly of the resolved thylakoid complexes of samples. Despite the algal species showed similar growth rates and photosynthetic efficiency, S. acutus showed the highest capability to accumulate proteins and photosynthetic pigments. Regarding the thylakoid protein profile, the two Trebouxiophyceae showed very similar pattern, whereas different amounts of LHCII occurred within the two Chlorophyceae. Finally, the separation of thylakoid protein complexes in 2D BN/SDS-PAGE revealed a more complex pattern in S. acutus as compared to the other species. Overall, it is suggested that a higher stability of the photosynthetic membranes can result in higher biomass and protein production. Altogether, results have highlighted the metabolic uniqueness of each strain, resulting in a non-obvious comparison with the other species.

Utilization of glucan phosphatase Starch Excess4 to enhance in‐vitro starch degradation

Starch is one of the most attractive natural polymers because of its biodegradability, abundance, and renewability. However, the inert nature and semicrystalline structure of native starch granules make starch essentially unusable for most industrial applications without further processing. Therefore, starch is additionally modified via physical, chemical, and biotechnological methods to increase processability and function. Starch obtained from corn, rice, wheat, potato, and cassava, serves as the main resource for the majority of starch‐based products. However, much of our understanding of starch metabolism is coming from Arabidopsis thaliana transitory starch metabolism. More systematic studies are needed to understand starch turnover in different species and organs of biotechnologically important species. Reversible starch phosphorylation is essential for efficient starch degradation and SEX4 is a key enzyme in this process. We employed biochemical and functional analyses to study SEX4 from agronomically important crops. Taken together, our findings provide an in depth understanding of SEX4 dephosphorylation of agronomically important plants and green algae species and provide compelling evidence of how SEX4 can be utilized to enhance native starch degradation.

Marine biorefinery: an environmentally sustainable solution to turn marine biomass and processing wastes into value-added products and profits

Marine biorefinery: an environmentally sustainable solution to turn marine biomass and processing wastes into value-added products and profits

Can biogenic n-heptadecane be utilized to represent algae cell density dynamics in water environment? Evidences from field investigation and laboratory validation.

The monitoring and prediction of algae cell density are the fundamental supports for eutrophication management. As the molecular marker of algae, n-heptadecane has been successfully utilized to reflect algae biomass in sedimentary studies. However, whether biogenic n-heptadecane (bio C17) can be utilized to represent algae cell density dynamics in water environment still remains an issue. Current study aims to provide novel evidences from both field investigation and laboratory validation for it. Firstly, we found a strinkingly positive correlation between algae cell density dynamics and bio C17 variations (p = 4.34 × 10–10) via meta-analysis using field dataset in Lake Chaohu. Then, we selected Microcystis aeruginosa, Chlorella vulgaris and Melosira sp. as model species of cyanobacteria, green algae and diatom, respectively, for laboratory validation. Our results illustrated that n-heptadecane was synchronized with the growth for cyanobacteria and green algae but not for diatom. The association between bio C17 and algae cell density was species-dependent, and the relationship between bio C17 and cell density was linear within 107 cells∙mL–1. Therefore, we established and optimized a generalized additive model to fit observed algae cell density in Lake Chaohu. In the optimal model, bio C17, Pielou evenness index J and Shannon-Wiener index H’ were included, totally explaining 66% of the variance of algae cell density. Model comparisons revealed that considering algae community could indeed improve the interpretation of algae cell density in natural environment. In conclusion, our study provided novel evidences that bio C17 can be utilized to represent the cell density dynamics of cyanobacteria and green algae in the environment.

SEAFEEDTM: INOVASI PAKAN FUNGSIONAL UNTUK TERNAK RUMINANSIA BERBASIS SELADA LAUT LOKAL SUMBAWA Ulva lactuca (Linnaeus) YANG DIFORTIFIKASI DENGAN PROBIOTIK, PREBIOTIK DAN POSTBIOTIK

Sumbawa Island is included in the Thousand Cow Village program because it has a high potential of cattle reaching more than 738,000 heads in 2020. However, the limited number of quality cattle feed producers in Sumbawa causes local farmers to rely heavily on expensive commercial feed. Alternative uses of forage and fresh grass are also commonly used, but they have the potential to pose a serious threat to the health of the digestive tract of cattle and become the largest contributor to methane gas in the atmosphere. The “SeafeedTM” innovation, is a functional feed product for ruminant livestock made from local Sumbawa sea lettuce from the Ulva lactuca species, a species of green algae with high nutrition which is very abundant in the northern waters of Sumbawa Island and its potential has not been utilized optimally. The protein content which reaches 14% and soluble fiber >45% in Ulva lactuca sea lettuce makes this species a very prospective candidate to be used as a high-quality feed source. The ingredients used are sea celery (Ulva lactuca), bran, premix-porbiotic & prebotik, and molasses. A simple method of manufacture with a mixed composition, namely 10% sea cress, premix-probiotics & prebiotics, 30% molasses and 60% bran. Seafeed is an innovative ruminant feed made from local seaweed from Sumbawa which has complete nutritional content to support the growth of livestock. The content of probiotics, prebiotics, and postbiotics makes this product into the category of functional feed that functions to increase immunity in livestock. It is hoped that this product can be developed commercially to support the ability of farmers on Sumbawa Island to utilize local biological natural resources as feed ingredients so that dependence on commercial feed supplies can be reduced.

Spatial Distribution of Unique Biological Communities and Their Control Over Surface Reflectivity of the Stanley Glacier, Uganda

Diverse microbes have been revealed to live in glaciers worldwide, but only a few biological studies were dedicated to glaciers in tropical Africa. These glaciers are shrinking rapidly and are expected to disappear shortly. In this study, we carried out biological and glaciological field observations on Stanley Glacier, the largest remaining glacier in the Rwenzori Mountains, Uganda, Africa. Microbial aggregates ranging from micrometer to centimeter in size were found on the glacier surface and contained moss and various types of Chlorophyta, among which a new endemic species of green alga. Concentrations of total impurities on the glacier surface, including microbial aggregates, varied spatially and decreased as altitude increased. The large microbial aggregates (larger than 4 cm in diameter) were found only at the glacier surface near the terminus and side margins, where the surface was less frequently covered with snow. It is also shown that the total organic matter on the glacier surface is determined by the timing of snow cover, which affects the quantity of solar radiation reaching the glacier ice surface. Furthermore, the total impurity content was negatively correlated with surface reflectivity, revealing their potential role in albedo reduction at the glacier surface through positive feedback between enhanced meltwater and increased biological growth.

On the Retrieval of the Water Quality Parameters from Sentinel-3/2 and Landsat-8 OLI in the Nile Delta’s Coastal and Inland Waters

Reduced water quality due to the eutrophication process causes large economic losses worldwide. Multi-source remotely-sensed water quality monitoring can help provide effective water resource management. The research evaluates the retrieval of the water quality parameters: chlorophyll-a (Chl-a), total suspended matter (TSM), and chromophoric dissolved organic matter (CDOM), over optically different water types. Cross-sensor performance analysis of three satellite data sources: Sentinel-3 Ocean Land Color Imager (OLCI), Sentinel-2A Multi-Spectral Instrument (MSI), and Landsat-8 Operational Land Imager (OLI), acquired during a 45 min overpass on the Nile Delta coast on 22 March 2020 was performed. Atmospheric correction using the case 2 Regional Coast Color (C2RCC) was applied using local water temperature and salinity averages. Owing to the lack of ground-truth measurements in the coastal water, results were inter-compared with standard simultaneous color products of the Copernicus Marine Environment Monitoring Service (CMEMS), OLCI water full resolution (WFR), and the MODIS Aqua, in order to highlight the sensor data relative performance in the Nile Delta’s coastal and inland waters. Validation of estimates was carried out for the only cloud-free MSI data available in the 18–20 September 2020 period for the Burullus Lake nearly contemporaneous with in situ measurements in the 22–25 September 2020. Inter-comparison of the retrieved parameters showed good congruence and correlation among all data in the coastal water, while this comparison returned low positive or negative correlation in the inland lake waters. In the coastal water, all investigated sensors and reference data showed Chl-a content average of 3.14 mg m−3 with a range level of 0.39–4.81 mg m−3. TSM averaged 7.66 g m−3 in the range of 6.32–10.18 g m−3. CDOM clarified mean of 0.18 m−1 in the range level of 0.13–0.30 m−1. Analysis of the Mean Absolute Error (MAE) and the Root Mean Squared Error (RMSE) clarified that the MSI sensor was ranked first achieving the smallest MAE and RMSE for the Chl-a contents, while the EFR proved superior for TSM and CDOM estimates. Validation of results in Burullus Lake indicated a clear underestimation on average of 35.35% for the Chl-a induced by the land adjacency effect, shallow bottom depths, and the optical dominance of the TSM and the CDOM absorption intermixed in turbid water loaded with abundant green algae species and counts. The underestimation error increased at larger estimates of the algal composition/abundance (total counts, Chlorophyacea, Euglenophycaea, and Bacillariophycaea) and the biological contents (carbohydrates, lipids, and proteins), arranged in decreasing order. The largest normalized RMSE estimates marked the downstream areas where the inflow of polluted water persistently brings nutrient loads of nitrogen and phosphorous compounds as well as substantial amounts of detrital particles and sediments discharged from the agricultural and industrial drains and the land use changes related to agricultural practices, resulting in the increase of water turbidity giving rise to inaccurate Chl-a estimates.

Isolation, identification, and optimization of growth conditions for the marine microalgae isolated from the Gulf of Mannar, South-east coast of India

Marine microalgae were isolated from the selected locations from the coastal waters of Gulf of Mannar during December 2019 to February 2021. A total of 16 microalgal species were collected and identified morphologically using a light microscope with image capture system. Of these, five pure isolates of three pennate diatoms viz., Cylindrotheca fusiformis, Amphora sp., and Navicula clavata, and two species of green algae (Nannochloropsis salina and Chlorella sp.) were identified morphologically by field-emission scanning electron microscopy (FE-SEM) and confirmed by PCR amplification sequence analysis of 18S rRNA. The isolates confirmed by PCR were C. fusiformis, Amphora sp., N. clavata, and N. salina whereas Chlorella sp., was confirmed through FE-SEM. Optimization of culture conditions for the identified microalgae was studied with different culture media (Diatom Artificial Medium (DAM), F/2 medium, and Walne’s medium) by various salinities to assess their best growth for commercial application. At 30 ppt salinity, the maximum cell density of C. fusiformis observed in DAM was 7.63 × 106 cells/mL, whereas Amphora sp. and N. clavata showed maximum cell density of 1.20 × 106 and 1.35 × 106 cells/mL, respectively, in F/2 medium. At 35 ppt salinity, maximum cell density of Chlorella sp. was 12.1 × 106 cells/mL in the F/2 medium. Similarly, the maximum growth of 13.7 × 106 cells/mL was obtained at 35 ppt salinity for N. salina in Walne’s medium. As the microalgal strains were isolated at succession stage, they can tolerate a wide range of environmental conditions and could be mass produced in outdoor conditions for industrial applications

Evolution and Stress Responses of CLO Genes and Potential Function of the GhCLO06 Gene in Salt Resistance of Cotton.

The caleosin (CLO) protein family displays calcium-binding properties and plays an important role in the abiotic stress response. Here, a total of 107 CLO genes were identified in 15 plant species, while no CLO genes were detected in two green algal species. Evolutionary analysis revealed that the CLO gene family may have evolved mainly in terrestrial plants and that biological functional differentiation between species and functional expansion within species have occurred. Of these, 56 CLO genes were identified in four cotton species. Collinearity analysis showed that CLO gene family expansion mainly occurred through segmental duplication and whole-genome duplication in cotton. Sequence alignment and phylogenetic analysis showed that the CLO proteins of the four cotton species were mainly divided into two types: H-caleosins (class I) and L-caleosins (class II). Cis-acting element analysis and quantitative RT–PCR (qRT–PCR) suggested that GhCLOs might be regulated by abscisic acid (ABA) and methyl jasmonate (MeJA). Moreover, transcriptome data and qRT–PCR results revealed that GhCLO genes responded to salt and drought stresses. Under salt stress, gene-silenced plants (TRV: GhCLO06) showed obvious yellowing and wilting, higher malondialdehyde (MDA) content accumulation, and significantly lower activities of superoxide dismutase (SOD) and peroxidase (POD), indicating that GhCLO06 plays a positive regulatory role in cotton salt tolerance. In gene-silenced plants (TRV: GhCLO06), ABA-related genes (GhABF2, GhABI5, and GhNAC4) were significantly upregulated after salt stress, suggesting that the regulation of salt tolerance may be related to the ABA signaling pathway. This research provides an important reference for further understanding and analyzing the molecular regulatory mechanism of CLOs for salt tolerance.

The Marine Benthic Algae Diversity of Gabon: Case of the Rocky Foreshore of Cap Estérias

This study has allowed to classify the marine macroalgae from the intertidal zone on the Atlantic side of Cap Estérias (Gabon). This area has a rich biodiversity but very few studies in the knowledge of benthic macroalgae have been done. The first study on the knowledge of the algae of the Gabonese coast was made in February 1974 by John and Lawson. This article has been revised to transcribe books and our study would aim to update the existing collection. The algae census is spread over a year from August 2020 to August 2021 and is the first detailed study carried out over a year, with regard to this part of the Gabonese coast. This study has allowed to know the specific diversity, to determine the structure of the flora and its spread out over time. The results show a significant algal diversity of thirty five (35) identified species. Three classes of macroalgae were determined and the percentage of species in the class (%EC): Floridaophyceae at 50% EC, Phaeophyceae at 30% EC and Ulvophyceae at 20% EC. The red algae are the most common in the area with sixteen (16) species determined against twelve (12) species of brown algae and seven (7) species of green algae. The Phaeophyceae class presents the Dictyotaceae family which is the most diverse with 7 species found. Some species seen appear in the collection of John et al., but others are new species encountered in Gabon such as Caulerpa sertularioides, Bryopsis plumosa (two Ulvophytes), Padina arborescens which is a Pheophyte and Galaxaura filamentosa, Digenea simplex,Hildenbrandia rubra, Asparagopsis armata and Caulacanthus ustulatus which are Rhodophytes. Some species are permanently present, they are found in all seasons but with significant abundance from July to September.