Enhancing Diatom, Cyclotella meneghiniana Growth Using Growth-Promoting Bacteria Isolated From the Phycosphere of Chlorophytes and Chrysophytes

The relationship between microalgae and bacteria in a microenvironment, the phycosphere, has a significant role in enhancing the quality and quantity of microalgal production, which would in turn affect consumers' growth and nutritional quality, such as the zooplankton, which are important live feeds in aquaculture. Thus, selecting and characterising suitable microalgal growth-promoting bacteria (MGPB) for enhancing microalgal production is an important process since not all bacteria promote high growth. In this study, physcosphere bacteria associated with chlorophytes and chrysophytes were isolated, screened for their microalgae-promoting attributes (phosphorus solubilisation, indole-3-acetic acid (IAA) production, and nitrogen fixation) and re-inoculated into microalgal cultures. A total of seven bacterial isolates were recorded to have multiple growth promoting traits, with three strains (CY-2, CY-4, CY-5) showing the greatest (P < 0.05) link for those traits. These seven potential MGPB were molecularly characterised using 16S rRNA approach. The phylogenetic tree of the isolated bacteria demonstrated the dominant bacteria associated with the chlorophytes were in the class bacteroidetes, while the chrysophytes appeared to be associated with Firmicutes bacteria suggesting that the compositions were strictly species-specific to the microalgae host. Enhanced Cyclotella meneghiniana growth by the seven isolated bacterial strains was highly dependent on the growth-promoting traits; especially those demonstrated by Pseudomonas hibiscicola and Ochrobactrum haematophilum. These two bacteria showed the potential to enhance the quality of microalgae, and they could be bioencapsulated and used to improve the quality of zooplankton as one of the main live feeds in the aquaculture industry

A Review on a Hidden Gem: Phycoerythrin from Blue-Green Algae

Phycoerythrin (PE) is a pink/red-colored pigment found in rhodophytes, cryptophytes, and blue-green algae (cyanobacteria). The interest in PE is emerging from its role in delivering health benefits. Unfortunately, the current cyanobacterial-PE (C-PE) knowledge is still in the infant stage. It is essential to acquire a more comprehensive understanding of C-PE. This study aimed to review the C-PE structure, up and downstream processes of C-PE, application of C-PE, and strategies to enhance its stability and market value. In addition, this study also presented a strengths, weaknesses, opportunities, and threats (SWOT) analysis on C-PE. Cyanobacteria appeared to be the more promising PE producers compared to rhodophytes, cryptophytes, and macroalgae. Green/blue light is preferred to accumulate higher PE content in cyanobacteria. Currently, the prominent C-PE extraction method is repeated freezing–thawing. A combination of precipitation and chromatography approaches is proposed to obtain greater purity of C-PE. C-PE has been widely exploited in various fields, such as nutraceuticals, pharmaceuticals, therapeutics, cosmetics, biotechnology, food, and feed, owing to its bioactivities and fluorescent properties. This review provides insight into the state-of-art nature of C-PE and advances a step further in commercializing this prospective pigment

Characterisation and selection of freshwater cyanobacteria for phycobiliprotein contents

Some cyanobacteria species have a high capacity for accumulating phycobiliprotein contents in their cells. However, there is a lack of information on screening tropical freshwater cyanobacteria, particularly phycobiliproteins. In addition, it is unclear which characteristics of cyanobacteria (morphological and/or growth) could affect phycobiliprotein contents. This study aimed to screen and characterise Malaysian indigenous freshwater cyanobacteria for the growth, biomass, and pigment contents and determine the major characteristic that contributed to the variation of phycobiliproteins. The surface/volume (S/V) ratio, specific growth rate, biomass productivity, and pigment contents of the isolated cyanobacteria were analysed. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to distinguish the factor responsible for phycobiliprotein variations in cyanobacteria. For the phycobiliprotein contents, Arthrospira sp., Pseudanabaena sp., and Synechococcus elongatus showed significantly higher (p < 0.05) amounts of cyanobacterial phycocyanin (C-PC), phycoerythrin (C-PE), and allophycocyanin (C-APC), respectively, than other studied cyanobacteria. This study showed no apparent trend of similarity and difference between the unicellular and filamentous cyanobacteria. In addition, carotenoid contents demonstrated a positive correlation with total phycobiliproteins, C-PC and C-APC. Based on the current findings, Arthrospira sp., Pseudanabaena sp. and Synechococcus elongatus might be the promising candidate to be the C-PC, C-PE and C-APC sources, respectively, for commercial production purposes. The selection of optimal cyanobacterial strain is crucial for efficient phycobiliprotein production. This study underlined the potential of freshwater cyanobacteria in producing respective and total phycobiliproteins. Future studies such as the optimization process should be adopted to improve the phycobiliprotein production of these cyanobacteria significantly

Fucoxanthin production of microalgae under different culture factors: a systematic review

Fucoxanthin is one of the light-harvesting pigments in brown microalgae, which is increasingly gaining attention due to its numerous health-promoting properties. Currently, the production of microalgal fucoxanthin is not yet feasible from an economic perspective. However, the cultivation of microalgae at favourable conditions holds great potential to increase the viability of this fucoxanthin source. Hence, this study aimed to review the fucoxanthin production of microalgae under different conditions systematically. A literature search was performed using the Web of Science, Scopus and PubMed databases. A total of 188 articles were downloaded and 28 articles were selected for the current review by two independent authors. Microalgae appeared to be a more reliable fucoxanthin source compared to macroalgae. Overall, a consensus fucoxanthin production condition was obtained and proposed: light intensity ranging from 10 to 100 µmol/m2/s could achieve a higher fucoxanthin content. However, the optimal light condition in producing fucoxanthin is species-specific. The current review serves as an antecedent by offering insights into the fucoxanthin-producing microalgae response to different culture factors via a systematic analysis. With the current findings and recommendations, the feasibility of producing fucoxanthin commercially could be enhanced and possibly achieve practical and sustainable fucoxanthin production

Assessment of Malaysian brown seaweed Padina gymnospora antioxidant properties and antimicrobial activity in different solvent extractions

The combination of a proton nuclear magnetic resonance (1H-NMR)-based metabolomics approach and principal component analysis (PCA) was used to differentiate variations of active metabolites in Padina gymnospora subjected to different extraction solvents. Their proximate composition and phytochemical, antioxidant, and antimicrobial activity were also evaluated. A total of 13 metabolites were identified in the different solvents (polar, semipolar, and nonpolar) via 1H-NMR analysis. The present study demonstrated that P. gymnospora brown seaweed was rich in protein, lipid, and carbohydrates. Phytochemical investigation of the different P. gymnospora extracts revealed various secondary metabolites. The most abundant essential amino acid was leucine [5.79 ± 0.06 mg g−1 dry weight (DW)], and the most abundant nonessential amino acid was glutamic acid (8.62 ± 0.04 mg g−1 DW). The presence of metabolites such as alanine, N-phenylacetylphenylalanine, glutamic acid, 2-hydroxyisobutyric acid, sarcosine, and π-methylhistidine in the seaweed extracts was strongly correlated with their level of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity. P. gymnospora appeared to have antibacterial activity against Staphylococcus aureus (ATCC 43,300). The study also revealed P. gymnospora’s potential for use as a rich source of antioxidant agents, implying that commercial cultivation of this seaweed may be incentivized

Chemical, Nutrient and Physicochemical Properties of Brown Seaweed, Sargassum polycystum C. Agardh (Phaeophyceae) Collected from Port Dickson, Peninsular Malaysia

Recent increased interest in seaweed is motivated by attention generated in their bioactive components that have potential applications in the functional food and nutraceutical industries. In the present study, nutritional composition, metabolite profiles, phytochemical screening and physicochemical properties of freeze-dried brown seaweed, Sargassum polycystum were evaluated. Results showed that the S. polycystum had protein content of 8.65 ± 1.06%, lipid of 3.42 ± 0.01%, carbohydrate of 36.55 ± 1.09% and total dietary fibre content of 2.75 ± 0.58% on dry weight basis. The mineral content of S. polycystum including Na, K, Ca, Mg Fe, Se and Mn were 8876.45 ± 0.47, 1711.05 ± 0.07, 1079.75 ± 0.30, 213.85 ± 0.02, 277.6 ± 0.12, 4.70 ± 0.00 and 4.45 ± 0.00 mg 100/g DW, respectively. Total carotenoid, chlorophyll a and b content in S. polycystum were detected at 45.28 ± 1.77, 141.98 ± 1.18 and 111.29 µg/g respectively. The total amino acid content was 74.90 ± 1.45%. The study revealed various secondary metabolites and major constituents of S. polycystum fibre to include fucose, mannose, galactose, xylose and rhamnose. The metabolites extracted from the seaweeds comprised n-hexadecanoic acid, 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester, benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy- methyl ester, 1-dodecanol, 3,7,11-trimethyl-, which were the most abundant. The physicochemical properties of S. polycystum such as water-holding and swelling capacity were comparable to several commercial fibre-rich products. In conclusion, results of this study indicate that S. polycystum is a potential candidate as functional food sources for human consumption and its cultivation needs to be encouraged