Algal Pigments Research Articles

Use of sedimentary algal pigment analyses to infer past lake-water total phosphorus concentrations

We tested the feasibility of using sedimentary algal pigment analyses by spectral deconvolution to infer past lake-water total phosphorus concentrations. We established equations that link lake-water nutrient concentrations and sediment pigment concentrations, using a combination of calibration in both space and time, with a training set of 31 Swedish lakes. The calibration dataset yielded a significant positive relationship between total carotenoid concentrations and lake-water total phosphorus concentrations. We also compared sediment-pigment-based nutrient inferences with time series of water column monitoring data to evaluate whether temporal changes in total phosphorus concentrations are well captured by analysis of sedimentary pigments. We found that changes in pigment preservation through time can alter the relationship between concentrations of lake-water nutrients and sedimentary pigments, thus limiting the reliability of historical ecological conditions inferred from pigments in the sediment. Our data suggested that ratios of Chlorophyll derivatives to total carotenoids (CD/TC ratio) and Chlorophyll a to Chlorophyll derivatives (CPI) can be used as proxies for pigment preservation. Using our approach, inferred temporal changes in water-column total phosphorus concentrations in lakes are promising, but require further development, specifically with respect to the influence of pigment degradation in both the water column and sediments, as well as the factors that control such degradation.

Heavy metal stress response of microalgal strains Arthronema africanum and Coelastrella sp. BGV

The present study compared the stress response of two microalgal strains – Arthronema africanum (Cyanoprokaryota) and Coelastrella sp. BGV (Chlorophyta), after heavy metals’ treatment. Changes of algal growth, pigment and protein content were analyzed after adding Cu, Cd and Pb (50 µM and 100 µM) to the nutrition medium. It was found that Cd and Pb significantly inhibited growth and protein biosynthesis of microalgae, but the effect of Cu remained less pronounced. In both strains, a decrease of chlorophyll content was observed, while carotenoid content markedly increased, especially in Coelastrella sp. BGV biomass. The addition of 100 µM Cd and 100 µM Pb to the medium caused a strong enhancement of malondialdehyde in both microalgal strains, which corresponded to the significant increase of superoxide dismutase and catalase activity. The antioxidant enzymes appeared to be differently altered by heavy metals’ exposure. The activity of SOD in the Arthronema africanum cells was most strongly affected by Cd, in contrast to Coelastrella sp. BGV that was highly increased by 100 µM Pb. The application of 100 µM Cd and 100 µM Pb increased in a similar manner catalase activity in both microalgae. The strains that were studied showed a high absorption capacity for metal ions, especially for Pb, which was absorbed largely than Cd and Cu. For that reason, we assumed that both microalga and, in particular, Coelastrella sp. BGV, could be successfully used for treatment of contaminated water bodies.

Growth characteristics, biohydrogen production and photochemical activity of photosystems in green microalgae Parachlorella kessleri exposed to nitrogen deprivation

The biohydrogen (H2) generation in green microalgae is associated with electron transfer during photosynthesis. In this study, the ability of Parachlorella kessleri RA-002 isolated in Armenia to generate biohydrogen (H2) in TAP and Tamiya media with and without nitrogen deprivation have been determined. Nitrogen deprivation led to a suppression of the growth rate and a decrease in the content of photosynthetic pigments in algae, as well as to increase of H2 yield. The highest H2 yield was found during the growth of algae in TAP and Tamiya media under nitrogen-deprived conditions, which was 4–5 times more compared to control cells grown without nitrogen deprivation. Diuron inhibited this process, indicating that H2 generation was due to PS II activities. The analysis of the effect of nitrogen-deprived conditions on the activity of photosystem I and II has been carried out. Nitrogen deprivation suppressed of photosynthetic activity of PS II (up to 20% compared to control) that facilitated the formation of anaerobic conditions increasing the total yield of H2.

A Study on Algae Bloom Pigment in the Eutrophic Lake Using Bio-Optical Modelling: Hyperspectral Remote Sensing Approach.

Inland lake is one of the important sources of freshwater ecosystem and serves as a sentinel to the changing aquatic biodiversity. Chlorophyll-a (Chl-a) is a major biological indicator and essential measure of the eutrophic status of lake water because it is strongly related to algae biomass. In the present research, bio-optical algorithms were developed based on the semi-empirical approach using the spectral wavelengths of 400 to 800nm from hyperspectral remote sensing measurement and compared with Sentinel-2MSI image for estimation of Chl-a concentration in the lake water. The results show that the bio-optical algorithm can estimate and predict the algae pigment (Chl-a) concentration in the eutrophic lake with good accuracy of R2 of 0.8958, root mean squared error of 13.028, and mean absolute percentage error of 8.44%. The developed algorithm will be suitable and potential for monitoring algae spatial dynamics and assessment in an inland lake.

Extraction & Analysis of Algal Pigments by Thin Layer Chromotography & Spectrophotometric Analysis

The study focuses to extract and analyse the algal pigments present in the lithophilic algae collected from various sites in the concrete walls of Department of Biotechnology, University of Madras. The samples collected were stored in sterile plastic ware and cultured in a growth medium in the laboratory for further analysis. Significant algal growth was observed in media enriched with CaCo3.Microscopic observations reveals filamentous algae of the family Cyanobacteria. The cultured algal biomass was treated with solvent and the pigments were extracted. The pigment extracts were analysed using two-dimension thin layer chromatography (TLC) and confirmed using UV-Vis Spectrophotometer. The filamentous algae have significant amount of Chlorophyll a &b and Carotenoids.

Extraction & Analysis of Algal Pigments by Thin Layer Chromotography & Spectrophotometric Analysis

Extraction & Analysis of Algal Pigments by Thin Layer Chromotography & Spectrophotometric Analysis

On the phenology and seeding potential of sea-ice microalgal species

Sea ice is an important habitat for a wide variety of microalgal species. Depending on the species composition, sea ice can be a seeding source for pelagic phytoplankton blooms after ice melt in spring. Sea-ice algal communities were studied over 2 full winter seasons in 2014 and 2016 at Rothera Research Station, situated at the Western Antarctic Peninsula (WAP). Algal pigment patterns and microscopic observations were combined with photophysiological studies based on fluorescence analyses to monitor and explain the phenology of ice-algal species. Clear patterns in species succession were identified. Young sea ice contained a mixture of algal species including dinoflagellates, cryptophytes and diatoms like Chaetoceros spp. and Fragillariopsis spp. In winter, severe environmental conditions resulted in a decline in species diversity and selection towards heterotrophy. Pennate diatoms like Amphiprora kufferathii and Berkeleya adeliensis were the first to dominate the nutrient-enriched bottom-ice layers in early spring. The bottom communities exhibited a remarkably stable value for the photoadaptation parameter, Ek, of circa 25 µmol photons m–2 s–1. Whereas pennate diatoms were most abundant in spring ice, the initial seeding event linked to ice melt was associated with flagellate species. Haptophyte species like Phaeocystis antarctica and prymnesiophytes like Pyramimonas spp. best sustained the transition from sea ice to seawater. Comparison with previous studies shows that the seeding patterns observed in Ryder Bay were characteristic over the wider sea-ice domain, Arctic and Antarctic. Over the course of this century, the WAP is predicted to experience continuing thinning and decline in sea-ice cover. For the near future, we expect that especially microalgal communities of haptophytes and chlorophytes will benefit from the changes, with yet unknown implications for carbon fluxes and higher trophic levels.

Estimation of cyanobacteria pigments in the main rivers of South Korea using spatial attention convolutional neural network with hyperspectral imagery

ABSTRACT Although remote sensing techniques have been used to monitor toxic cyanobacteria with hyperspectral data in inland water, it is difficult to optimize conventional bio-optical algorithms for individual water bodies because of the complex optical properties of various water components. Therefore, this study adopted a spatial attention convolutional neural network (spatial attention CNN) to estimate the chlorophyll-a (Chl-a) and phycocyanin (PC) concentrations in the Geum, Nakdong, and Yeongsan rivers in South Korea in order to evaluate cyanobacteria using remote sensing reflectance data. The CNN model utilized a spatial attention module to analyze the importance of the bands in the reflectance data. Then, the spatial attention CNN model was compared with different bio-optical algorithms for each study area. The spatial attention CNN model was generalized to estimate the pigment concentrations in the target rivers, and the model performance was evaluated by correlation coefficient (R) and root mean squared error (RMSE) between the observed and estimated concentrations of the algal pigments. The spatial attention CNN model, which was generalized to estimate the pigment concentrations in the target rivers, had R values above 0.87 and 0.88 for Chl-a and PC, respectively. However, the optimized band ratio algorithms for Chl-a and PC had R values above 0.83 and 0.70, respectively. Hence, it showed better performance than the conventional bio-optical algorithms. The spatial attention module provided attention weights for visualizing important features in the reflectance data. Specifically, the 600 nm, 650 nm, and near-infrared regions had high attention weights for estimating the concentrations of Chl-a and PC. Based on these findings, this study demonstrated that the spatial attention CNN model has a high potential for good application performance in various water bodies.

Coastal degradation impacts on green turtle's (Chelonia mydas) diet in southeastern Brazil: Nutritional richness and health

This study evaluated the influence of environmental degradation on the nutritional value of the main marine macrophytes consumed by green sea turtles (Chelonia mydas) in areas with different degrees of urbanization. Macrophyte assemblages in the highly urbanized area (HUa) showed lower richness compared to the lightly urbanized area (LUa) (Mann-Whitney U test: 10.0 ± 3.6 SD genera and 11.9 ± 4.2 taxa per transect vs. 20.1 ± 7.0 genera and 23.5 ± 9.2 taxa per transect) respectively. Also, diet was poorer with 4.0 ± 1.6 genera per turtle (vs. 8.5 ± 4.0 in HUa) and less diverse with Shannon index of diversity = 0.45 ± 0.29 (vs. 0.64 ± 0.46 in LUa). Body condition was similar in both areas. About half of individuals were classified as having normal body condition, 14–15% as underweight and 23–34% as being emaciated. Fibropapillomatosis prevalence (χ2 = 8.720; n = 222; df = 1; p = 0.003) was higher in the HUa but, in affected animals, severity was marginally non-significant (χ2 = 5.721; n = 82; df = 2; p = 0.057). Significant differences in energy content (kcal) were detected between areas in both summer (S) and winter (W). All ANOVAs on total lipids (F = 22.15 [S] and 30.39 [W]), total water-soluble proteins (F = 327.65 [S] and 64.42 [W]) and total carbohydrates (F = 70.90 [S] and 27.62 [W]) showed high significance (p < 0.001). Carotenoids concentration yielded significant results for Halodule in summer and Hypnea in winter (ANOVAs, F = 39.42 and 13.07, respectively). For both, tests revealed that concentration was higher in LUa than HUa. High levels of phycobiliproteins and proteins in this area probably reflect nitrogen accumulation. Frequency and severity of fibropapillomatosis suggest that urbanization-caused alterations in species diversity and in chemical composition of marine plants affect green turtles' health. Light abstractThe use of coastal areas by humanity is widespread and increasing. The impacts caused to the coastal environment, be it terrestrial, estuarine or marine, are important and affect numerous species. Our study evaluated the influence of environmental degradation on the nutritional value of the main algae eaten by the green turtle, one of the very few marine megaherbivores (those herbivores with body mass above 10 kg). Diet in the highly urbanized area was richer in proteins, lipids and carbohydrates (sugars) and lower in carotenoids (photosynthetic and photoprotectant pigments in algae and plants; precursors of vitamin A involved in oxygen transport in animals—animals do not synthetize such molecules). High levels in phycobiliproteins (photosynthetic pigments present in some algae) and proteins in the highly urbanized area probably result from organic pollution and nitrogen accumulation in coastal waters. Nitrogen compounds dissolved in water are a threat to vertebrates due to its toxicity and negative effects on the immune system. Our results suggest that algae chemical composition and severity of fibropapillomatosis (tumors caused by a herpesvirus in green sea turtles) are directly related through environmental alterations caused by urbanization.

Drone-borne sensing of major and accessory pigments in algae using deep learning modeling

ABSTRACT Intensive algal blooms increasingly degrade the inland water quality. Hence, this study aimed to analyze the algal phenomena quantitatively and qualitatively using synoptic monitoring, algal pigment analysis, and a deep learning model. Water surface reflectance was measured using field monitoring and drone hyperspectral image sensing. The algal experiment conducted on the water samples provided data on major pigments including chlorophyll-a and phycocyanin, accessory pigments including lutein, fucoxanthin, and zeaxanthin, and absorption coefficients. Based on the reflectance and absorption coefficient spectral inputs, a one-dimensional convolutional neural network (1D-CNN) was developed to estimate the concentrations of the major and minor pigments. The 1D-CNN could model periodic trends of chlorophyll-a, phycocyanin, lutein, fucoxanthin, and zeaxanthin compared to the observed ones, with R2 values of 0.87, 0.71, 0.76, 0.78, and 0.74, respectively. In addition, major and secondary pigment maps developed by applying the trained 1D-CNN model to the processed drone hyperspectral image inputs successfully provided spatial information regarding the spots of interest. The model provided explicit algal biomass information using the estimated major pigments and implicit taxonomical information using accessory pigments such as green algae, diatoms, and cyanobacteria. Therefore, we provide strong evidence of the extendibility of deep learning models for analyzing various algal pigments to gain a better understanding of algal blooms.

Synchronic changes of lake organic and inorganic carbon burial in response to catchment development over the past century: A case study of Shilin Karst area

有机碳和无机碳的流域输出是湖泊碳埋藏的重要驱动因子, 而喀斯特地区无机碳循环具有反应迅速且对人类活动影响敏感的特点. 在流域开发持续增强的背景下, 喀斯特地区湖泊有机碳和无机碳的来源、含量与埋藏通量可能会出现同步变化的协同模式. 本文以云南省石林喀斯特地区流域土地利用类型不同的两个中型湖泊(长湖、月湖)开展对比分析, 通过对沉积物钻孔的土壤侵蚀强度(磁化率)、流域外源输入(C∶N比值)、水动力(粒度)、营养盐(总氮、总磷)、藻类生产力(叶绿素色素)等代用指标的分析, 结合监测数据和历史资料重建了两个湖泊环境变化的近百年历史, 并定量识别了有机碳和无机碳埋藏响应流域开发的变化特征与协同模式. 沉积物磁化率和C∶N比值结果揭示了流域地表侵蚀和外源输入的阶段性特征, 同时总氮和总磷含量记录了长湖和月湖营养水平上升的长期模式. 在流域森林覆被较高(33.43%)的长湖中, 全岩和有机质C∶N比值分别与磁化率信号呈显著正相关(r=0.95和0.89, P＜0.001), 且与无机碳和有机碳含量呈显著负相关(r=-0.94, P＜0.001和r=-0.52, P=0.01), 反映了森林植被退化时流域碳输出的减少对沉积物碳含量的影响. 而在流域耕地覆被为主(60.98%)的月湖中, 全岩和有机质C∶N比值与磁化率信号呈显著负相关(r=-0.54, P＜0.01和r=-0.67, P＜0.001), 且全岩C∶N比值与无机碳含量(P=0.15)无显著关系, 反映了耕作强度的增加可能促进了水体富营养化和内源输入的增强. 在两个湖泊中, 营养水平的上升和内源生产力的增加促进了有机碳含量的快速增加. 进一步分析表明, 近百年来长湖有机碳与无机碳含量变化的同步性明显(r=0.54, P＜0.001)而在月湖中无显著关系(P=0.20, P>0.05). 两个湖泊中沉积通量的变化均与全岩C∶N比值呈显著正相关(r=0.48和0.45, P≤0.001), 且有机碳与无机碳埋藏通量均呈现同步变化的显著特征(r=0.72和0.85, P＜0.001). 其中长湖的无机碳埋藏通量显著高于有机碳埋藏通量, 而月湖的有机碳埋藏通量略高于无机碳埋藏通量, 反映了岩溶地区流域外源输入和水体富营养化的差异性驱动影响. 在流域开发增强的梯度下, 森林退化会降低流域碳输出的负荷, 而农业扩张和水体富营养化会促进藻类生长和内源有机碳的累积. 因此, 流域土地利用和水体营养水平对湖泊无机碳和有机碳埋藏变化的长期轨迹和协同模式产生了重要影响, 对喀斯特地区的碳库评估需要考虑无机碳循环的重要性.;Catchment-scale exports of organic and inorganic carbon plays an important role in affecting the lake sediment carbon burial. Inorganic carbon cycling in Karst landscapes is sensitive to human activities due to the rapid kinetics of carbonate dissolution. As with intensive watershed development, the source, content and burial loading of organic and inorganic carbon in Karst region may show a synchronous change. This study selected two medium-sized lakes (Lake Changhu and Lake Yuehu) with contrasting land uses patterns in the Shilin Karst area of central Yunnan for sediment surveys. With the proxies analyses for soil erosion (i.e. magnetic susceptibility (MS)), catchment allochthonous input (C∶N ratio), lake hydrology (particle size), nutrient levels (total phosphorus and nitrogen) and primary production (i.e. algal pigments), together with monitoring data and historical records, the history of limnological changes and catchment development over the last century for both lakes were reconstructed. Furthermore, long-term variation and synchronic pattern of sediment organic carbon (OC) and inorganic carbon (IC) burial in the context of catchment development were quantified. The sediment MS signal recorded the fluctuation in soil erosion intensity and a general pattern of long-term nutrient enrichment in both lakes. In Lake Changhu, with a higher land cover of forest (33.43%), the bulk and organic C∶N ratios were positively related with the MS signal (r=0.95 and 0.89, P < 0.001) but showed a negative relationship with sediment inorganic and organic carbon content (r=-0.94, P < 0.001 and -0.52, P=0.01), respectively, reflecting a significant impact of catchment carbon input. In Lake Yuehu, with a current land cover dominated by the cropland (60.98%), the bulk and organic C∶N ratios were negatively related with the MS signal (r=-0.54, P < 0.01 and -0.67, P < 0.001) and the bulk C∶N ratio showed no relationship with the sediment inorganic content (P=0.15), reflecting that the cropland expansion may have enhanced lake eutrophication and autochthonous input. In both lakes, nutrient enrichment and algal production enhanced the rapid OC accumulation. Additional analyses showed that there existed a significantly synchronous change between OC and IC content in Lake Changhu (r=0.54, P < 0.001) but not in Lake Yuehu (P=0.20, P>0.05). In both lakes, sediment loading was positively related with bulk C∶N ratio (r=0.48 and 0.45, P≤0.001), and there also existed a significantly synchronous change between OC and IC loadings (r=0.72 and 0.85, P < 0.001). Furthermore, the IC burial rate was significantly higher than that of OC in Lake Changhu, while IC consistently lower than OC in the nutrient-rich Lake Yuehu, reflecting differential forcing of vegetation degradation and lake eutrophication. With the intensive development in watershed, forest degradation can reduce the loading of catchment carbon export, while agricultural expansion and eutrophication would promote the growth of algae and the OC accumulation rate. Therefore, land use and lake nutrient levels can significantly impact the long-term trajectory and synchronic variation of sediment OC and IC burial. Thus, IC cycling should be considered in the regional assessment of carbon stock in karst areas.

Impact of Effluent of a Chlor-Alkali Industry on the Photosynthetic Efficiency of Crop Field Inhabiting Cyanobacteria

The Chlor-alkali industry located at Ganjam, Odisha, India caused aquatic and terrestrial mercury contamination by its effluent and solid waste discharges discharged from the industry containing metallic mercury. The Rushikulya river water and the surrounding area were contaminated, which affected the flora and fauna of the area ultimately affecting live flora and fauna of Bay of Bengal. Toxicity study revealed the acute toxic nature of the effluent. At sub-lethal concentration of the effluent, either no impact or little increment in growth values (dry weight) was noted in case the tested alga available in the contaminated sites. At higher concentrations of the effluent, inhibition of growth was noted in the effluent exposed alga. The pigment contents like chlorophyll, phaeophytin, carotene and c-phycocyanin content significantly decreased as compared to the control algal pigments. It was observed that at sub-lethal concentration of the effluent, growth enhancement was noted but with the increase in effluent concentration growth declined. The pigments initially increased at sub-lethal concentrations and with the increase in effluent concentration the pigments significantly decreased indicating toxic stress. Analysis indicated that with the increase in exposure period the residual accumulation of mercury increased significantly showing a positive correlation (r=0.924; P

Auxenochlorella protothecoides SC3'ten Ekstre Edilen Pigmentlerin Pseudomonas aeruginosa'ya karşı Antimikrobiyal Aktivitesinin Değerlendirilmesi

Nowadays, natural microbial pigments are emerging as potential candidate therapeutic agents that can be used in antibiotic resistance. In this paper, we report the antimicrobial activity of green algae pigments. Green algae SC3 isolate was isolated from soil in Erzurum. Pigments extracted by methanol: dimethyl sulfoxide solvents were partially characterized by Thin Layer Chromatography (TLC), UV-Absorbance, and Fourier-transform infrared spectroscopy (FTIR). The antimicrobial activity of pigments was determined with agar well diffusion and microbroth assays against Pseudomonas aeruginosa (ATCC 27853 and clinic isolate), Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922). To identify green algae, total DNA was isolated and both 18S rRNA and 16S rRNA for the chloroplast genome were amplified using universal primers. Thus, this alga was identified as Auxenochlorella protothecoides and submitted to Genbank (Accession number: MW139225 and MW063613). According to our results, the best antimicrobial activity was recorded against P. aeruginosa. Our results show for the first time the antimicrobial activity of the total pigments from A. protothecoides green algae.

Retrieval of Phytoplankton Pigment Composition from Their In Vivo Absorption Spectra

Algal pigment composition is an indicator of phytoplankton community structure that can be estimated from optical observations. Assessing the potential capability to retrieve different types of pigments from phytoplankton absorption is critical for further applications. This study investigated the performance of three models and the utility of hyperspectral in vivo phytoplankton absorption spectra for retrieving pigment composition using a large database (n = 1392). Models based on chlorophyll-a (Chl-a model), Gaussian decomposition (Gaussian model), and partial least squares (PLS) regression (PLS model) were compared. Both the Gaussian model and the PLS model were applied to hyperspectral phytoplankton absorption data. Statistical analysis revealed the advantages and limitations of each model. The Chl-a model performed well for chlorophyll-c (Chl-c), diadinoxanthin, fucoxanthin, photosynthetic carotenoids (PSC), and photoprotective carotenoids (PPC), with a median absolute percent difference for cross-validation (MAPDCV) &lt; 58%. The Gaussian model yielded good results for predicting Chl-a, Chl-c, PSC, and PPC (MAPDCV &lt; 43%). The performance of the PLS model was comparable to that of the Chl-a model, and it exhibited improved retrievals of chlorophyll-b, alloxanthin, peridinin, and zeaxanthin. Additional work undertaken with the PLS model revealed the prospects of hyperspectral-resolution data and spectral derivative analyses for retrieving marker pigment concentrations. This study demonstrated the applicability of in situ hyperspectral phytoplankton absorption data for retrieving pigment composition and provided useful insights regarding the development of bio-optical algorithms from hyperspectral and satellite-based ocean-colour observations.

Phycoremediation of contaminated water by cadmium (Cd) using two cyanobacterial strains (Trichormus variabilis and Nostoc muscorum)

BackgroundWater pollution with heavy metals is a severe dilemma that concerns the whole world related to its risk to natural ecosystems and human health. The main objective was to evaluate the removal efficiency of Cd of various concentrations from contaminated aqueous solution by use of two cyanobacterial strains (Nostoc muscorum and Trichormus variabilis). For this purpose, a specially designed laboratory pilot-scale experiment was conducted using these two cyanobacterial strains on four different initial concentrations of Cd (0, 0.5, 1.0 and 2.0 mg L−1) for 21 days.ResultsN. muscorum was more efficient than T. variabilis for removing Cd (II), with the optimum value of residual Cd of 0.033 mg L−1 achieved by N. muscorum after 21 days with initial concentration of 0.5 mg L−1, translating to removal efficiency of 93.4%, while the residual Cd (II) achieved by T. variabilis under the same conditions was 0.054 mg L−1 (89.13% removal efficiency). Algal growth parameters and photosynthetic pigments were estimated for both cyanobacterial strains throughout the incubation period.ConclusionsHigh Cd concentration had a more toxic impact on algal growth. The outcomes of this study will help to produce treated water that could be reused in agrarian activities.

The Stability of Phycocyanin, Phycoerythrin, and Astaxanthin from Algae Towards Temperature, pH, Light, and Oxygen as a Commercial Natural Food Colorant

Nowadays, food industries are exploring more about naturally-derived colorants. Algae is proposed to be an excellent alternative source for natural colorants as it needs lesser biomass. Phycocyanin, phycoerythrin, and astaxanthin are commercially used blue-green, red, and red-orange algae-sourced pigments due to their high protein yield, health benefits, and ease of extractions methods. A literature survey conducted using Google Scholar and ScienceDirect database with inclusion and exclusion criteria gained 44 papers used as primary references to assess those algae pigments' stability towards temperature, pH, light, and oxygen for food applications. Low pH levels and addition of preservatives (sugar, citric acid) or polyhydric alcohols enhance phycocyanin range of stability (pH of 5–6 and &gt;40oC with pH &gt;5 or &lt;3). Phycoerythrin’s stability at -20 to 4°C and neutral pH is improved by adding additives (citric acid, benzoic acid) or nanofibers, cross-linking method, complex formation, and microencapsulation. Phycocyanin and phycoerythrin’s light stability depend on the light’s composition, quality, and quantity; hence, utilization of dark-colored packaging to prevent light exposure is done. Astaxanthin’s instability towards light exposure (causing photoexcitation), temperature of &gt;30°C, and pH of &gt;4 can be solved through chitosan solution coating and microencapsulation using various wall materials and complex formation. Phycocyanin is unaffected against oxygen (unlike phycoerythrin and astaxanthin), yet all of them exert antioxidant properties. Therefore, the inconsistency of these colorants’ stability depending on food processing conditions demand further development through research to widen their commercial food applications.

Climate cascades affect coastal Antarctic seafloor ecosystem functioning.

Polar seafloor ecosystems are changing rapidly and dramatically, challenging previously held paradigms of extreme dynamical stability. Warming-related declines in polar sea ice are expected to alter fluxes of phytoplankton and under-ice algae to the seafloor. Yet, how changes in food flux cascade through to seafloor communities and functions remains unclear. We leveraged natural spatial and temporal gradients in summertime sea ice extent to better understand the trajectories and implications of climate-related change in McMurdo Sound, Antarctica. McMurdo Sound was expected to be one of the last coastal marine environments on Earth to be affected by planetary warming, but the situation may be changing. Comparing satellite observations of selected coastal sites in McMurdo Sound between 2010-2017 and 2002-2009 revealed more ice-free days per year, and shorter distances to open water during the warmest months each year, in the more recent period. Interdecadal Pacific Oscillation (IPO), Oceanic Niño Index (ONI) and Antarctic Oscillation (AAO) climate indices peaked concurrently between 2014 and 2017 when sea ice breakouts in McMurdo Sound were most spatially and temporally extensive. Increases in sediment chlorophyll a and phaeophytin content (indicating increased deposition of detrital algal food material) were recorded during 2014-2017 at three coastal study sites in McMurdo Sound following the major sea ice breakouts. Soft-sediment seafloor ecosystem metabolism (measured in benthic incubation chambers as dissolved oxygen and inorganic nutrient fluxes) was correlated with sediment algal pigment concentration. Epifaunal invertebrate density, particularly opportunistic sessile suspension feeders, and infaunal community composition also shifted with increased food supply. The ecological characteristics and functions measured at the food-poor sites shifted towards those observed at richer sites at a surprisingly fast pace. These results indicate the sensitivity of the benthos and shed light on Antarctic marine trophic cascades and trajectories of response of iconic high-latitude seafloor habitats to a warming climate.

CHLOROPHIL ACTIVITY TEST OF SOME TYPES OF VEGETABLES AS AN ANTIBACTERY FOR Escherichia coli AND Staphylococcus aureus

Background: Chlorophyll is a green color pigment in plants, algae and photosynthetic bacteria. The chlorophyll contained in the leaves has a function as an antioxidant, anti-inflammatory, and antibacterial. This study aims to determine the ability of chlorophyll from several types of vegetables to inhibit Escherichia coli and Staphylococcus aureus and determine the differences in the diameter of the inhibition zone between them. &#x0D; Methods: This study was a laboratory experimental study using a completely randomized design (CRD) divided into 4 treatments, namely aquadest (P0), cassava leaf chlorophyll (P1), kale leaf chlorophyll (P2), and spinach leaf chlorophyll (P3). 6 repetitions each. Microbiological tests were carried out using the well diffusion method.&#x0D; Results: Anova test showed that the chlorophyll extracts of cassava, kale and spinach were very influential (P = 0.000) in inhibiting the growth of Escherichia coli and Staphylococcus aureus. Duncan's further test showed that the largest average inhibition zone diameter for Escherichia coli was formed by cassava leaf chlorophyll (17.66 mm) and was significantly different from kale leaf chlorophyll (7 mm) and spinach leaves (6.16 mm). Similar to Staphylococcus aureus, the largest average inhibition zone diameter was also formed by cassava leaf chlorophyll, which was 18.16 mm and significantly different from kale leaf chlorophyll (6.75 mm) and spinach leaves (6.08 mm). &#x0D; Conclusion: The chlorophyll extract of cassava leaves, kale and spinach can inhibit the growth of Escherichia coli and Staphylococcus aureus with the largest inhibition zone diameter formed by the chlorophyll extract of cassava leaves.

Micro Algal pigments: An introduction to their biosynthesis, applications and genetic engineering

Algae are an enormous biological group, forming 50% of photosynthetic organisms. In addition to having chlorophyll for the absorption of light photons, algae are rich in red, orange, and yellow carotenoids, which mainly protect cells against harmful radiation and free radicals. Moreover, these organisms have phycobiliproteins (red and blue pigments), which are involved in capturing and passing light energy to chlorophylls during photosynthesis and have a wide range of antioxidant properties. Algae also play a key role in substituting artificial colorants with natural colorants due to the adverse side-effects of chemical colorants, especially since natural colors are commonly used by individuals and various industries. Recently, algal pigments have been widely used in medical, nutraceutical, cosmeceutical, and pharmaceutical industries owing to their antioxidant, antidiabetic, anti-obesity, anti-inflammatory, antiaging, antimalarial, and neuroprotective properties. The growing demand for algal bioproducts highlights the importance of evaluating the trends influential factors in their production. The current review study provided an introduction to algal pigment classification, distribution, function, application, and biological production. In addition, we have discussed crucial biochemical pathways, enzymes, and gene/biotechnological modifications, such as transformation and expression regulation, which noticeably affect the metabolism of their sink and source.

Development of a multi-excitation fluorescence (MEF) imaging method to improve the information content of benthic coral reef surveys

Benthic surveys are a key component of monitoring and conservation efforts for coral reefs worldwide. While traditional image-based surveys rely on manual annotation of photographs to characterise benthic composition, automatic image annotation based on computer vision is becoming increasingly common. However, accurate classification of some benthic groups from reflectance images presents a challenge to local ecologists and computers alike. Most coral reef organisms produce one or a combination of fluorescent pigments, such as Green Fluorescent Protein (GFP)-like proteins found in corals, chlorophyll-a found in all photosynthetic organisms, and phycobiliproteins found in red macroalgae, crustose coralline algae (CCA) and cyanobacteria. Building on the potential of these pigments as a target for automatic image annotation, we developed a novel imaging method based on off-the-shelf components to improve classification of coral and other biotic substrates using a multi-excitation fluorescence (MEF) imaging system. We used RGB cameras to image the fluorescence emission of coral and algal pigments stimulated by narrow-waveband blue and green light, and then combined the information into three-channel pseudocolour images. Using a set of a priori rules defined by the relative pixel intensity produced in different channels, the method achieved successful classification of organisms into three categories based on the dominant fluorescent pigment expressed, facilitating discrimination of traditionally problematic groups. This work provides a conceptual foundation for future technological developments that will improve the cost, accuracy and speed of coral reef surveys.