Ramkhamhaeng International Journal of Science and Technology

The Potential of Single-Cell Oils Derived from Marine Fungus (Aspergillus pseudofelis MMERU 25) as Alternative Feedstock Sources for Biodiesel Production

2023-10-23T11:47:02+07:00

The potential of single-cell oils derived from marine fungi can serve as a feedstock for biodiesel production. However, different marine fungal species exhibit distinct capabilities for high lipid production under varying conditions, resulting in variations in biodiesel characteristics. Therefore, the objective of this study is to investigate culture media conditions, the optimal duration for lipid production, and the biodiesel characteristics of Aspergillus pseudofelis MMERU 25. Cultivation was conducted using 70% MEB for 20 days and molasses (2.5, 5.0, 10.0, and 10.5 ml) mixed with 70% MEB for 15 days. Biodiesel characteristics, including chemical profiles, viscosity, acidity, methyl esters and linolenic acid content, H.H.V, and iodine value were also analyzed. The results indicate that A. pseudofelis MMERU 25 achieves the highest lipid production within 10 days in 70% MEB and reaches the maximum lipid yield at a 2.5 ml concentration of molasses in 70% MEB within 15 days. When A. pseudofelis MMERU 25 is cultured in 70% MEB for 10 days, the biodiesel quantity reaches 360 ml/kg of dry biomass. The biodiesel characteristics are consistent with previous research and the standards of biodiesel qualities by the DOEB, except for acidity, methyl esters content, and H.H.V. These parameters can be controlled to eliminate residual acids in biodiesel and adjust reaction conditions to enhance its suitability for use as a biodiesel feedstock. Therefore, biodiesel produced from marine fungi has the potential to be an alternative energy source for Thailand in the future.

Inhibitory effect of Ficus racemosa leaf extract on Staphylococcus aureus

2023-11-28T14:49:59+07:00

Current antimicrobial research does not only focus on the identification of new chemical antibiotics but also on the identification of natural compounds present in plant-based traditional medicines. In Thailand, Ficus racemosa is an excellent representative of medicinal plants that provides health benefits in several diseases. Preliminary evaluation of the antibacterial activity of Ficus racemosa leaf extract against Staphylococcus aureus. Fresh leaves of F. racemosa were collected and extracted in methanol. The methanolic extract of F. racemosa was diluted in sterile distilled water and analyzed for contained phytochemical agents. Antibacterial activity against D-test negative and D-test positive S. aureus was evaluated by agar disk diffusion and broth dilution methods to determine inhibition zone, minimum inhibitory titer, and minimum bactericidal titer, respectively. Stability of active agents against S. aureus was tested on the day of extract preparation and 15 days later. Chemical analysis suggested the presence of flavonoids and tannins in the methanolic extract of F. racemosa. Inhibition of bacteria was dose dependent and not different between the two tested S. aureus strains at day 1 and day 15. Higher concentrated F. racemosa extract showed higher antibacterial activity than lower concentrated extract in all measurements. Agar disk diffusion seemed not to be suitable to evaluate antibacterial activity of the F. racemosa methanolic extract as it showed only a very narrow inhibition zone. However, the broth dilution assay allowed to determine an inhibitory titer. Our data indicates that methanolic F. racemosa leaf extract contains potent antimicrobial compounds. The ability to inhibit the growth of two different drug-susceptible strains of S. aureus suggests that these plant-derived compounds are alternative antimicrobial drugs.

Seasonal changes of meiofauna assemblage at Hin Ploeng underwater pinnacle, Rayong Province, the Eastern Gulf of Thailand

2023-12-15T07:42:00+07:00

Meiofauna in sediments are important components of the seafloor, coral reefs, and associated ecosystems, playing vital roles in the marine benthic food web and biogeochemical cycles. Understanding the dynamics of meiofauna in marine ecosystems in Thailand is still limited, particularly in underwater pinnacle ecosystems. This study aims to examine the seasonal changes of meiofauna at Hin Ploeng, an underwater pinnacle located in Rayong Province, the Eastern Gulf of Thailand. The meiofauna samples were taken in both summer and rainy seasons using a PVC core of 3.5 cm diameter. Eighteen groups of meiofauna were found with the dominant groups of Foraminifera, Nematoda, Harpacticoida, Ostracoda, and Bivalvia. The abundance of most meiofauna (forams, nematodes, and gastropods) varied seasonally (p<0.05). The diversity of meiofauna in the rainy season (H′ = 0.43) was significantly higher than that in the summer season (H′ = 0.08) (p<0.05). This study provides crucial information on the meiofaunal assemblage from the underwater pinnacle sediments, suggesting that underwater pinnacles with diverse meiofauna have important ecological functions and processes in marine and coastal ecosystems.

Growth and survival of coral micro-fragment in Chonburi Province, the Upper Gulf of Thailand

2023-12-10T06:48:51+07:00

Coral reefs are an important ecosystem with their unique characteristics and high biodiversity. They provide great benefits to the coastal communities and national economy. However, coral reefs and their ecosystem services have significantly declined. The advancement of coral restoration is necessary to develop improved techniques and methods, aiming to ensure the success of large-scale coral restoration projects. This study aims to compare the growth and survival rates of coral micro-fragments among four species, i.e, Diploastrea heliopora, Pavona desussata, Pavona varians and Lithophyllon undulatum in coral nursery plots at Ko Larn, Chonburi Province, the upper Gulf of Thailand. The results showed that the highest growth rate was observed in the coral micro-fragments with an initial size of 1 cm. D. heliopora had the highest growth rate (59.70%) and P. varians had the lowest micro-fragment growth rate (50.04%). The survival rate of every micro-fragment with initial sizes between 1 and 3 cm was higher than 95.67%. Among the initial sizes, there were significant differences in the survival rates of coral micro-fragments (One-way ANOVA, p < 0.05). The survival rates of D. heliopora and L. undulatum micro-fragments were higher than those of P. varians and P. decussata (Tukey's HSD, p < 0.05). This study highlights the critical importance of active coral reef restorations through the use of newly developed technologies of coral micro-fragmentation and colony fusion techniques, to enhance ecotourism, community-based tourism, and carbon-neutral tourism, as well as the efficacy and efficiency of efforts to restore coral reefs.