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    A newly developed droplet digital PCR for Ehrlichia canis detection: comparisons to conventional PCR and blood smear techniques
    (2022-01-01)
    Wichianchot, Sakulchit
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    Hongsrichan, Nuttanan
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    Pinlaor, Somchai
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    Iamrod, Kantapong
    Canine monocytic ehrlichiosis caused by Ehrlichiacanis infection is a life-threatening vector-borne disease in dogs worldwide. Routine blood smear has very low sensitivity and cannot accurately provide a quantitative result. Conventional PCR (cPCR) and real-time PCR (qPCR) are widely used as molecular methods for E. canis detection. qPCR is quantitative but relies on standard curves of known samples. To overcome this difficulty, this study developed a new E. canis quantitative detection method, using droplet digital polymerase chain reaction (ddPCR). ddPCR was evaluated against cPCR and blood smears. PCR amplicons and genomic DNA (gDNA) from 12 microscopic positive samples were used to identify the limits of detection (LODs) in ddPCR and cPCR. Our ddPCR was assessed in 92 field samples, it was compared with cPCR and blood smears. ddPCR showed LOD=1.6 copies/reaction, or 78 times more sensitive than cPCR (LOD=126 copies/ reaction), using PCR amplicons as a template, whereas both ddPCR and cPCR had equal LODs at 0.02 ng gDNA/reaction. In addition, ddPCR had 100% sensitivity and 75% specificity for E. canis detection compared to cPCR and no cross-reaction with other blood pathogens was observed. ddPCR identified more positive samples than cPCR and blood smear. ddPCR improved the overall performance of E. canis detection, with a better LOD and comparable sensitivity and specificity to cPCR. The technique might be helpful for diagnosis of E. canis in light infection, evaluating the number of E. canis and follow-up after treatment.
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    INVESTIGATION OF ANTIFUNGAL ACTIVITY FROM SCENEDESMUS SP. AND CHLAMYDOMONAS SP. CRUDE EXTRACTS
    Scenedesmus sp. and Chlamydomonas sp. are green microalgae used for various biotechnology applications such as an alternative biofuel, antioxidant, human supplement, aquaculture feed etc. In a decade, finding a new antibiotic resource from a novel organism is significant for pharmaceutical research. Microalgae is a promising candidate since they consist of high-value biocompounds such as β-carotene, astaxanthin, flavonoids, polysaccharide. In this study, we aimed to preliminarily investigate antifungal activities of Scenedesmus and Chlamydomonas crude extracts against to Candida albicans, a fungal pathogen. We prepared both of intracellular and extracellular (culture media) crude extracts by using ethanol and methanol as a solvent and then tested C albicans inhibition performed by agar-well diffusion assay. From the preliminary results, we found that 50 mg/mL of Scenedesmus and Chlamydomonas ethanolic crude extracts from intracellular and extracellular could inhibit C. albicans. This preliminary finding could be a platform for a further study in some bio-based organic compounds that is significant for pharmaceutical application.
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    Ethanol-enhanced biohydrogen production and metabolomic response in the green microalga Micractinium sp. KLSc62
    (2025-02-17)
    Klinsalee, Rachaneekorn
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    Laokua, Natwikar
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    Rittiyan, Nutnicha
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    Kornrawudaphikasama, Yosita
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    Tonawut, Yothawut
    Hydrogen (H<inf>2</inf>) is recognized as a viable clean energy option due to its high energy density and minimal environmental impact. Green microalgae have garnered attention as a potential source of hydrogen production because of their ability to produce photosynthetic hydrogen and their environmental benefits. In a recent study, thirteen species of microalgae were screened for their growth potential and hydrogen production when supplemented with ethanol. Among the species evaluated, Micractinium sp. KLSc62 (initially named as G4) yielded the highest hydrogen production rate of 6090.5 ± 28.6 μmol mg⁻<sup>1</sup> Chl with the supplementation of 30 mM ethanol over a 7-day period. Further analysis revealed that ethanol was utilized during H<inf>2</inf> production process, leading to the formation of acetaldehyde as an intermediate before acetate was produced. Metabolic profiling identified 44 metabolites that were up- or down-regulated, categorized into four distinct groups. These findings highlight the potential of Micractinium sp. KLSc62 as an alternative energy producer and a promising candidate for future metabolite production in various chemical applications, emphasizing its utility as a cellular factory.
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    Freshwater green alga Chlorella sp. KLSc59 produced all forms of omega-3 oil: ALA, EPA, and DHA
    (2024-06-01)
    Preechaphonkul, Nathanan
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    Sirikwanpong, Sukrit
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    Omega-3 fats are known to be the essential nutrient for human health, obtainable only through food sources. Algae and phytoplankton are primary sources that can synthesize various useful metabolites, such as carotenoids, antioxidants, and omega-3 oil. As the trend toward healthy alternative food options grows, this study aimed to screen eight strains of freshwater microalgae that might be promising sources of omega-3 oil. The results showed that three algal strains-BNG2, Chlorella sp. KLSc59, and Chlorella sp. KLSc61-had the ability to produce all forms of omega-3 oil, including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Among these strains, Chlorella sp. KLSc59 exhibited the most consistent omega-3 fatty acids-production when detected with gas chromatography equipped with flame ionization detector. Under optimal conditions (30 % flask volume, 10 mM CaCl<inf>2</inf>, pH of 6.0, and light incubation at 162 μmol photons m<sup>−2</sup> s<sup>−1</sup>) for 5 days, Chlorella sp. KLSc59 produced the highest amount of omega-3 fat, yielding 21.74 ± 0.63 % of the total peak area (equivalent to 18.43 ± 0.6 μg/mg DCW), including 21.53 ± 0.66 % (equivalent to 18.26 ± 0.7 μg/mg DCW) ALA, 0.03 ± 0.2 % (equivalent to 0.02 ± 0.0 μg/mg DCW) EPA, and 0.18 ± 0.01 % (equivalent to 0.15 ± 0.0 μg/mg DCW) DHA, with an omega-6 to omega-3 ratio of 2.28. This study highlights the potential use of Chlorella sp. KLSc59 for omega-3 oil production and its role as an alternative source of omega-3 oil for the next generation.
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    Bioprospecting of cyanobacteria from Thai karstic caves as potential producers of phenolic compounds with antioxidant capacity
    (2026-04-01)
    Suphan, Sutthawan
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    Kula, Kasinee
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    Lomthong, Thanasak
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    Sujarit, Kanaporn
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    Cyanobacteria are highly adaptable microorganisms that can survive in extreme environments. Survival of cyanobacteria in assorted habitats has positively impelled them to produce a range of bioactive compounds, which show a variety of beneficial biological activities. The karstic caves are harsh environments with low light and nutrient input and serve as a unique habitat for exploring cyanobacterial biodiversity as producers of natural products of economic and ecological importance. A total of 86 cyanobacterial strains isolated from 23 karstic caves in four regions of Thailand showed photosynthetic pigments correlated with growth performance and exhibited potential for producing phenolic compounds with significant antioxidant capacity. Based on DPPH scavenging efficiency per unit concentration of crude extract, Leptolyngbya sp. LKK14, Nostoc sp. SW02, and Leptolyngbya sp. LP01 exhibited the superior antioxidant potency. The highest contents of total phenolics (42.10 mgGAE/gCE) and flavonoids (395.90 mgQE/gCE) were found in Leptolyngbya sp. LP01 extract. The presence of phenolic compounds correlated with antioxidant activity; Leptolyngbya sp. LP01 showed the highest antioxidant activity, as measured by DPPH, ABTS, and FRAP assays, with respective values of 15.79, 20.87, and 42.69 mgAAE/gCE. Nine phenolic compounds were tentatively identified based on MS/MS fragmentation patterns compared with library data by LC-ESI-QTOF-MS/MS approach, suggesting that the extract of Leptolyngbya sp. LP01 contains valuable biological antioxidants. This study contributes to our current understanding of cyanobacterial biodiversity in poorly studied habitats, particularly in terms of their biotechnological potential as producers of secondary metabolites suitable for application in the food, pharmaceutical, and cosmetic industries.
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    Effect of pH on Biohydrogen Production in Green Alga Tetraspora sp. CU2551
    The green alga Tetraspora sp. CU2551 has previously been identified as a hydrogen producing organism. With the promising potential in a high H<inf>2</inf> production yield, we further studied the enhancement of the H<inf>2</inf> production capacity by a substrate-level control to the key enzyme, Hydrogenase. This enzyme catalyzes the formation of biohydrogen gas from protons and electrons. Here, we investigated the effect of pH on the production rate which directly affected the flow of proton flux to the hydrogenase enzyme. The result revealed that pH of culture TAP medium was simply controlled by the use of HCl/NaOH solution over the pH range of 6.5 - 9.0 without any effect on the growth of algal cells. The H<inf>2</inf> production was observed in all ranges of our focusing pH with comparable to the control condition (pH 7.0 of TAP medium). In our best condition, an increase of the H<inf>2</inf> yield about 24% was found in cells cultivated in TAP medium adjusted the pH to 6.5 compared to the control condition. Our finding confirms the successful biohydrogen production enhancement by a substrate-level control for the key hydrogenase enzyme.
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    Upregulation of Hox-hydrogenase gene expression by nutrient adjustment in the filamentous non-heterocystous cyanobacterium Arthrospira sp. PCC 8005
    (2020-12-01)
    Raksajit, Wuttinun
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    Mäenpää, Pirkko
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    Lehto, Kirsi
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    Incharoensakdi, Aran
    Arthrospira sp. PCC 8005 is potentially able to produce hydrogen catalysed by hox gene–encoded bidirectional hydrogenase with the aid of hyp gene–encoded accessory proteins. In the present study, we investigated the physiological factors affecting the hoxE, hoxY, hoxH, and hypF transcription in Arthrospira sp. PCC 8005. About a 4-fold increase of biomass and chlorophyll-a content was observed in cells grown for 7 days in Zarrouk’s medium supplemented with Fe<sup>2+</sup>. Cells grown in N-deprived medium with added Ni<sup>2+</sup> had increased H<inf>2</inf> production and hydrogenase activity with a maximal value of 7.24 ± 0.25 μmol H<inf>2</inf> mg<sup>−1</sup> Chla h<sup>−1</sup> and 0.61 ± 0.03 μmol H<inf>2</inf> mg<sup>−1</sup> Chla h<sup>−1</sup>, respectively. RT-PCR analysis revealed that cells grown in the N-deprived medium supplemented with Fe<sup>2+</sup> or Ni<sup>2+</sup> increased hoxE, hoxY, and hoxH transcripts. However, the highest increase of the hoxE, hoxY, hoxH, and hypF transcripts was observed in cells grown in the S-deprived medium supplemented with a combination of Fe<sup>2+</sup> and β-mercaptoethanol. These results indicated that the increased expression of hox genes in Arthrospira sp. PCC 8005 can be achieved by proper adjustment of the nutrients in the growth medium. Phylogenetic analysis revealed that the small hydrogenase subunit, HoxY sequence, from Arthrospira sp. PCC 8005 was clustered together along with other cyanobacterial HoxY which is highly related to Arthrospira platensis NIES46.
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    Discovery and characterization of bioactive compounds from Limnophila aromatica: nevadensin and related flavonoids as potent antimicrobial agents
    (2025-08-01)
    Maswanna, Thanaporn
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    Limnophila aromatica, a traditional medicinal plant, has been previously reported to possess notable antimicrobial properties. However, the specific bioactive constituents responsible for this activity remain largely unidentified. This study aimed to isolate, identify, and evaluate the antibacterial potential of compounds from a 100% ethanolic extract of L. aromatica. The crude ethanolic extract exhibited the highest antibacterial activity against Methicillin-resistant Staphylococcus aureus (MRSA) and was subsequently subjected to Diaion HP-20 column chromatography, followed by preparative HPLC. Seven major peaks were identified using UV-Vis spectra, LC-QTOF-MS, and NMR analyses. The antibacterial efficacy of these isolated compounds was assessed using disc diffusion and broth microdilution assays against Bacillus subtilis, S. aureus, MRSA, Escherichia coli, and Pseudomonas aeruginosa. The isolated compounds were identified as norethindrone acetate, isothymusin, nevadensin, gardenin B, 5,3’-dihydroxy-7,8,2’-trimethoxyisoflavone, jasmolin II, and oleanolic acid. Nevadensin, the predominant compound (79.55%), demonstrated potent bactericidal activity against B. subtilis, S. aureus, and MRSA. Jasmolin II and gardenin B also exhibited promising antibacterial effects. Although the disc diffusion assay was limited by compound diffusion, the broth microdilution method confirmed significant MIC values, ranging from 0.59 to 2.86 mg/ml while the MBC values ranged from 0.59 to 12.72 mg/ml. This study highlights nevadensin and other flavonoids from L. aromatica as potential candidates for the development of alternative antibacterial therapies, particularly against drug-resistant Gram-positive bacteria.
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    INVESTIGATION OF ANTIMICROBIAL CAPACITY AND ANTIOXIDANT EFFICIENCY FROM CHLORELLA SPP. CRUDE EXTRACTS
    Functional food, nutraceutical and pharmaceutical products are currently shared as an important part of the consumer market. Microalga plays a significant role in producing a source of good antioxidants including nutrient supplements such as chlorophyll, beta-carotene, astaxanthin etc. A Eukaryotic green microalga, Chlorella, is a unicellular microalga that itself is rich in a source of chlorophyll, carotenoids, the essential amino acids, bioactive compounds including fatty acids and these bioproducts make Chlorella as a great potential for human food and supplements, animal feed and biofuel feedstock. In this study, we aimed to test antimicrobial activity and antioxidant from four different Chlorella strains (Chlorella sp. KU11, Chlorella sp. V55, Chlorella sp. B2-59 and Chlorella sp. N11/59) for pharmaceutical and nutraceutical application. All four-ethanolic crude extracts of Chlorella were tested against six pathogens such as Streptococcus mutans ATCC25175, Bacillus subtilis ATCC6633, Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, Pseudomonas aeruginosa ATCC27853, and Candida albicans ATCC10231 using agar-well diffusion and the minimum inhibitory concentrating (MIC) assay. The result showed that 50 mg/mL of Chlorella sp. KU and Chlorella sp. V55 crude extracts could inhibit S. mutans, B. subtilis and S. aureus and 100 mg/mL of both crude extracts were able to inhibit E. coli, P. aeruginosa and C. albicans. From the minimum inhibitory concentrating (MIC) assay, we found that Chlorella sp. KU and Chlorella sp. V55 could inhibit S. mutans, B. subtilis, S. aureus E. coli, P. aeruginosa and C. albicans at 25, 50, 50, 100, 100 and 100 mg/mL, respectively and 50, 6.25, 25, 100, 100 and 100 mg/mL, respectively. The antioxidant activity of the four crude extracts were performed by DPPH radical scavenging assay and we found that the Chlorella sp. N11/59 crude extract showed the highest antioxidant efficiency with 63.73% and IC50 value was 2.8293 mg/mL. This finding suggested that microalgae can be a promising platform for pharmaceutical and nutraceutical application.
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    Identification of major carotenoids from green alga Tetraspora sp. CU2551: partial purification and characterization of lutein, canthaxanthin, neochrome, and β-carotene
    (2022-08-01)
    Maswanna, Thanaporn
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    The green algae Tetraspora sp. CU2551 was previously identified as a strain with high potential for biohydrogen production; however, its algal biomass characteristics changed from green to reddish orange within 43 days of biohydrogen production. The crude pigments were extracted, partially purified, and characterized by chemical determination. The present study focused on elucidating the carotenoid composition of the selected green alga Tetraspora sp. CU2551. The pigment extract was partially purified and fractionated using thin layer chromatography, and yielded two major and two minor carotenoid bands. The fractions were confirmed by high-performance liquid chromatography with a diode array detector (HPLC–DAD) before being identified and confirmed using Liquid Chromatograph-Quadrupole Time of Flight-Mass Spectrometry (LC-QTOF-MS). The spectral data of these fractions revealed four sub-fractions of interest that were lutein, canthaxanthin, neochrome, and β-carotene, which had percentages in the crude extracts of 30.57%, 25.47%, 7.89%, and 0.71%, respectively. Lutein and canthaxanthin were found to be the major carotenoid pigments present. Our findings in this present study are the first reporting of Tetraspora sp. CU2551 as a potential alternate source for carotenoid pigment production.