R-phycoerythrin (R-PE), a pigment complex found in red algae, was extracted and purified from a newly identified red alga, Colaconema formosanum, and its bioactivities were examined. It was revealed that R-PE treatment resulted in high cell viability (>70%) to the mammalian cell lines NIH-3T3, RBL-2H3, RAW264.7, and Hs68, and had no effect on cell morphology in NIH-3T3 cells. Its suppression effect was insignificant on the production of IL-6 and TNF-α in lipopolysaccharides-stimulated RAW264.7 cells. However, calcium ionophore A23187-induced β-hexosaminidase release was effectively inhibited in a dose-dependent manner in RBL-2H3 cells. Additionally, it was revealed to be non-irritating to bionic epidermal tissues. Notably, procollagen production was promoted in Hs68 cells. Overall, the data revealed that R-PE purified from C. formosanum exhibits anti-allergic and anti-aging bioactivities with no observed consequential toxicity on multiple mammalian cell lines as well as epidermal tissues, suggesting that this macromolecule is a novel material for potential cosmetic use.

We investigated whether phycoerythrin (PE), a pigment sourced from marine algae, could act as an immunomodulatory agent in whiteleg shrimp (Litopenaeus vannamei). To this end, PE was extracted and purified from a PE-rich macroalgae, Colaconema sp. Our in vitro analysis demonstrated that PE enhanced prophenoloxidase and phagocytosis activity but inhibited the production of reactive oxygen species in hemocytes. Additionally, the PE signal could be detected using an in vivo imaging system after its injection into the ventral sinus of the cephalothorax of whiteleg shrimp. The expression profiles of fourteen immune-related genes were monitored in hemocytes from whiteleg shrimp injected with 0.30 μg of PE per gram of body weight, and crustin, lysozyme, penaiedin 4, and anti-lipopolysaccharide factor showed up-regulated post-stimulation. The induction of immune genes and enhancement of innate immune parameters by PE may explain the higher survival rates for shrimp that received different doses of PE prior to being challenged with Vibrio parahaemolyticus or white spot syndrome virus compared to controls. Combined, these results show that PE from Colaconema sp. can differentially stimulate the immune response of whiteleg shrimp in vitro and in vivo and could potentially be used as an immunomodulator in shrimp culture.

Bioactive compounds extracted from natural renewable sources have attracted an increased interest from both industry and academia. Recently, algae have been highlighted as promising sources of bioactive compounds, such as polyphenols, polysaccharides, fatty acids, proteins, and pigments, which can be used as functional ingredients in many industrial applications. Therefore, a simple green extraction and purification methodology capable of recovering biocompounds from algal biomass is of extreme importance in commercial production. In this study, we evaluated the application of three valuable algae (Colaconema formosanum, Sarcodia suae, and Nostoc commune) in combination with Pseudoalteromonas haloplanktis (type strain ATCC 14393) for the production of versatile compounds. The results illustrate that after 6 h of first-stage fermentation, the production of phycobiliproteins in C. formosanum was significantly increased by 156.2%, 188.9%, and 254.17% for PE, PC, and APC, respectively. This indicates that the production of phycobiliproteins from algae can be enhanced by P. haloplanktis. Furthermore, we discovered that after S. suae and N. commune were fermented with P. haloplanktis, mannose was produced. In this study, we describe a feasible biorefinery process for the production of phycobiliproteins and mannose by fermenting marine macroalgae with cyanobacteria. We believe it is worth establishing a scale-up technique by applying this fermentation method to the production of phycobiliproteins and mannose in the future.

Among the minority seawater species in the ornamental fish market, clownfish (Amphiprion ocellaris) have a high market value due to their vibrant appearance. Astaxanthin, a promising coloring agent, is applied in diets as a food additive to enhance the physical appearance of clownfish. However, as the retail price of astaxanthin has been inflating, the industry is eager to find more affordable astaxanthin products. The present study evaluated the nutrients and pigmentation performance of the algae-extracted astaxanthin diets of clownfish, followed by a comparative feeding trial evaluating the graded levels of either Haematococcus pluvialis powder or extracted astaxanthin supplements in the experimental diets. The study included three stages: assessing the utilization of H. pluvialis powder as an astaxanthin source, investigating the optimal practical extraction method, and revisiting the effects of crude extracted astaxanthin on clownfish based on the identified preparation processes. In the first stage, H. pluvialis powder was applied as the feed additive for a feeding trial, resulting in a low-utilization rate of astaxanthin in clownfish. This indicated that a suitable extraction method was essential for clownfish. Two chemical-based methods for astaxanthin extraction were investigated to obtain the optimal extraction yields; results showed that the HClacetone method had an astaxanthin yield of 21.990.52mg/g cell, which was significantly higher than the yield from the acetic acid-DMSO method. Finally, the effects of HClacetone-extracted astaxanthin was compared with the effects of synthesized astaxanthin. The pigmentation performance study was performed using a digital image acquisition and processing technique. A significant increase in the red color signal was observed at week six after fed with 400 and 200mg/kg of the extracted astaxanthin, compared to the control 0mg/kg. In conclusion, H. pluvialis-extracted astaxanthin following the HClacetone method can significantly improve the pigmentation performance of A. ocellaris after 42 days of oral administration.

Aquaculture plays a key role in food production globally and provides a valuable source of protein and nutrition, addressing a worldwide growing demand. Oplegnathus punctatus (spotted knifejaw) is an economically important fish species with a high market value and demand. Previous studies on O. punctatus focused mainly on gonadal development, chromosomal microstructure, selective breeding, characterization of immune genes, and viral diseases. There is no published scientific research regarding vibriosis in this fish species. In this study, two potential pathogenic bacteria, Vibrio harveyi and Enterococcus gallinarum, were isolated from moribund cultured O. punctatus. The sequence of the universal 16S rDNA gene was used to identify potential pathogenic bacteria isolated from the moribund O. punctatus, and morphological assessments and API20E tests of the bacterial isolates were conducted to verify the identity and biochemical characteristics of the isolates. Injection of E. gallinarum did not lead to mortality in O. punctatus during the 21 days of observation. In contrast, fish died overnight when challenged with V. harveyi at 1.25 × 10⁵ CFU/g body weight, suggesting that the cause of death of the cultured O. punctatus was V. harveyi infection. Antimicrobial sensitivity analyses revealed that the V. harveyi strain NTOU is sensitive to flumequine, doxycycline, oxolinic acid, and amoxycillin. Importantly, we demonstrated for the first time that intraperitoneal administration of an inactivated V. harveyi whole-cell vaccine resulted in a high level of protection against V. harveyi infection in O. punctatus.