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Trichoderma asperellum cultured in reduced concentrations of synthetic medium retained dye decolourization efficacy

Marcharchand S, Ting ASY

J Environ Manage, 2017 Dec 01;203(Pt 1):542-549.
PMID: 28693968 DOI: 10.1016/j.jenvman.2017.06.068

Trichoderma asperellum (Ta) was first cultured in synthetic medium (Potato Dextrose Broth, PDB) of various concentrations (100, 75, 50, 25%). The biomass was harvested and inoculated into dye solutions (crystal violet, CV; methyl violet, MV; malachite green, MG; and cotton blue, CB). Reduced concentrations (20, 50, 75%) affected growth rate but their decolourization efficacies remained unaffected. This was attributed to similar numbers and types of functional groups (hydroxyl, amine, ester-lipid, alkane groups) found on the surface of fungal biomass, as revealed by the Fourier transformed infrared spectroscopy (FTIR) analysis. Their production of NADH-reductase for degradation, and their biosorption activities were also unaffected. In general, Ta cultured in reduced concentrations (20, 50, 75%) retained the ability to perform biosorption and biodegradation, similar to cultures from control (100% PDB). This suggested that reduced nutrient levels (as a cost-feasible strategy) could be used to cultivate biomass of Ta for dye removal activities.
Influence of coloured lights on growth and enzyme production of beneficial endophytic fungi

Ting ASY, Gan PT

Int Microbiol, 2024 Jan 26.
PMID: 38277111 DOI: 10.1007/s10123-024-00486-x

The influence of light regulation on fungal growth and enzyme production was tested on endophytic isolates of Fusarium proliferatum (CCH), Colletotrichum boninense (PL1, PL9, OL2), Colletotrichum gloeosporiodes (OL3) and Colletotrichum siamense (PL3). The isolates were treated with blue, red, green, and yellow light, while white fluorescent light (12 h light/12 h dark photoperiod) and 24 h dark conditions were applied as control. Results revealed that coloured light treatments induced formation of circadian rings, while exposure to white light and dark conditions showed less pronounced circadian rings. Growth and sporulation of endophytes were not significantly influenced by light. By contrast, enzyme production was affected by coloured light treatments, notably with red (amylase), blue (cellulase) and yellow (cellulase, xylanase, L-asparaginase) light, resulting in lower enzyme levels for certain isolates. Under control conditions, enzyme production was relatively higher for amylase, cellulase, xylanase (for cultures incubated in the dark), and for L-asparaginase (for cultures incubated in white fluorescent light). Among the endophytic isolates, F. proliferatum (CCH) showed better response to coloured light treatment as higher sporulation and enzyme production was detected, although growth was significantly suppressed. On the contrary, C. gloeosporiodes (OL3) showed better growth but significantly lower enzyme production and sporulation when treated with the various coloured light. This study revealed that coloured light may have the potential to manipulate growth, sporulation and enzyme production in certain fungal species as strategies for fungal control or for harnessing of valuable enzymes.
Bioencapsulation and Colonization Characteristics of Lactococcus lactis subsp. lactis CF4MRS in Artemia franciscana: a Biological Approach for the Control of Edwardsiellosis in Larviculture

Loh JY, Kay GL, Ting ASY

Mar Biotechnol (NY), 2018 Jun;20(3):353-362.
PMID: 29654379 DOI: 10.1007/s10126-018-9813-9

Predominance of beneficial bacteria helps to establish a healthy microbiota in fish gastrointestinal system and thus to reduce emerging pathogen. In this study, the colonization efficacy of Lactococcus lactis subsp. lactis CF4MRS in Artemia franciscana and its potential as a probiotic in suppressing Edwardsiella sp. infection were investigated in vivo. The colonization extent of the bioencapsulated L. lactis was established through visualization of gfp gene-transformed L. lactis in A. franciscana. Here, we demonstrate that when A. franciscana is administrated with L. lactis at 108 CFU mL-1 for 8 h, the highest relative percentage of survival (RPS = 50.0) is observed after inoculation with Edwardsiella sp. The total counts of L. lactis entrapped in Artemia were the highest (ranged from 3.2 to 5.1 × 108 CFU mL-1), when 108-109 CFU mL-1 of L. lactis was used as starting inoculum, with the bioencapsulation performed within 8-24 h. Fluorescent microscopy showed gfp-transformed L. lactis colonized the external trunk surfaces, mid-gut and locomotion antennules of the A. franciscana nauplii. These illustrations elucidate the efficiency of colonization of L. lactis in the gastrointestinal tract and on the body surfaces of Artemia. In conclusion, L. lactis subsp. lactis CF4MRS shows a good efficacy of colonization in Artemia and has the potential for biocontrol/probiotic activity against Edwardsiella sp. infection.
A novel study based on adaptive metal tolerance behavior in fungi and SEM-EDX analysis

Chen SH, Ng SL, Cheow YL, Ting ASY

J Hazard Mater, 2017 Jul 15;334:132-141.
PMID: 28407540 DOI: 10.1016/j.jhazmat.2017.04.004

Four fungal isolates: Simplicillium chinense (iso 9, accession no. KX425621), Penicillium simplicissimum (iso 10, KP713758), Trichoderma asperellum (iso 11, KP792512), and Coriolopsis sp. (1c3, KM403574) were subjected to a series of induced-tolerance training under high metal concentrations to determine if greater tolerance could be achieved from constant exposure to such conditions. Adaptive tolerance assay (Tolerance Index, TI) and Field-Emission Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX) characterized their metal tolerance. "Untrained" S. chinense, P. simplicissimum and T. asperellum showed tolerance towards 4000-4500ppm Al(III) (TI: 0.64-0.71), 1000ppm Cr(III) (0.52-0.83) and Pb(II) (0.32-0.88). With tolerance training, tolerance towards 2000-6000ppm Al(III), 500-3000ppm Pb(II) and 2000-3000ppm Cr(III) were achieved (TI: 0.01-0.82) compared to untrained cultures (0.00-0.59). In contrast, tolerance training for Coriolopsis sp. and P. simplicissimum was less successful, with TI values similar or lower than untrained cultures. SEM-EDX analysis proposed biosorption and bioaccumulation as mechanisms for metal removal. The latter was demonstrated with the removal of Cr(III) and Pb(II) by S. chinense (12.37 and 11.52mgg-1, respectively) and T. asperellum (10.44 and 7.50mgg-1). Induced-tolerance training may render benefit in the long run, but this delicate approach is suggestively species and metal dependent.
Mechanisms for metal removal established via electron microscopy and spectroscopy: a case study on metal tolerant fungi Penicillium simplicissimum

Chen SH, Cheow YL, Ng SL, Ting ASY

J Hazard Mater, 2019 01 15;362:394-402.
PMID: 30248661 DOI: 10.1016/j.jhazmat.2018.08.077

Penicillium simplicissimum (isolate 10), a metal tolerant fungus, tolerated 1000 mg/L Cu and 500 mg/L Zn, but were inhibited by Cd (100 mg/L), evident by the Tolerance Index (TI) of 0.88, 0.83, and 0.08, respectively. Live cells of P. simplicissimum were more effective in removing Cr (88.6%), Pb (73.7%), Cu (63.8%), Cd (33.1%), and Zn (28.3%) than dead cells (5.3-61.7%). Microscopy approach via SEM-EDX and TEM-EDX suggested that metal removal involved biosorption and bioaccumulation, with metal precipitates detected on the cell wall, and in the cytoplasm and vacuoles. FTIR analysis revealed metals interacted with amino, carbonyl, hydroxyl, phosphoryl (except Cd) and nitro groups in the cell wall. Biosorption and bioaccumulation of metals by live cells reduced Cu and Pb toxicity, observed from good root and (4.00-4.28 cm) and shoot (8.07-8.36 cm) growth of Vigna radiata in the phytotoxicity assay.
Fulltext Editorial: Endophytes and Their Biotechnological Applications

Ting ASY, Chaverri P, Edrada-Ebel RA

Front Bioeng Biotechnol, 2021;9:795174.
PMID: 34926434 DOI: 10.3389/fbioe.2021.795174
Optimization of L-asparaginase production from endophytic Fusarium proliferatum using OFAT and RSM and its cytotoxic evaluation

Yap LS, Lee WL, Ting ASY

J Microbiol Methods, 2021 12;191:106358.
PMID: 34743930 DOI: 10.1016/j.mimet.2021.106358

L-asparaginase from endophytic Fusarium proliferatum (isolate CCH, GenBank accession no. MK685139) isolated from the medicinal plant Cymbopogon citratus (Lemon grass), was optimized for its L-asparaginase production and its subsequent cytotoxicity towards Jurkat E6 cell line. The following factors were optimized; carbon source and concentration, nitrogen source and concentration, incubation period, temperature, pH and agitation rate. Optimization of L-asparaginase production was performed using One-Factor-At-A-Time (OFAT) and Response surface methodology (RSM) model. The cytotoxicity of the crude enzyme from isolate CCH was tested on leukemic Jurkat E6 cell line. The optimization exercise revealed that glucose concentration, nitrogen source, L-asparagine concentration and temperature influenced the L-asparaginase production of CCH. The optimum condition suggested using OFAT and RSM results were consistent. As such, the recommended conditions were 0.20% of glucose, 0.99% of L-asparagine and 5.34 days incubation at 30.50 °C. The L-asparaginase production of CCH increased from 16.75 ± 0.76 IU/mL to 22.42 ± 0.20 IU/mL after optimization. The cytotoxicity of the crude enzyme on leukemic Jurkat cell line recorded IC50 value at 33.89 ± 2.63% v/v. To conclude, the enzyme extract produced from Fusarium proliferatum under optimized conditions is a potential alternative resource for L-asparaginase.
Fulltext Impact of ozone treatment on the physico-chemical properties, bioactive compounds, pectin methylesterase activity and microbiological properties of watermelon juice

Lee BJ, Ting ASY, Thoo YY

J Food Sci Technol, 2022 Mar;59(3):979-989.
PMID: 35185203 DOI: 10.1007/s13197-021-05102-8

The increasing consumer demand for higher quality fruit juices has encouraged the use of non-thermal processing to extend the shelf life of perishable juice, watermelon juice. Ozone with its high oxidizing effect serve as an effective non-thermal processing treatment. The aim of this study was to investigate the impact of ozone treatment on the physico-chemical, bioactive compounds, pectin methylesterase (PME) activity and microbiological properties of unclarified and clarified watermelon juice. The ozone gas was pumped into watermelon juice for up to 25 min in a closed chamber. The microorganism inactivation in unclarified and clarified watermelon juices improved across the increasing processing time. Among these juices, the microorganism inactivation efficiency of ozone was found higher on clarified juice (3.466 log) than unclarified juice (3.150 log). It was found that °Brix value and PME activity were not altered by ozone treatment. The other physico-chemical properties (titratable acidity, pH, total colour difference, non-enzymatic browning, cloudiness) and bioactive compounds reduced across processing time. This study demonstrated that ozone treatment is an effective non-thermal processing technique to reduce the microorganism in watermelon juice. Further study is required to optimise the processing parameters of ozone treatment to maintain the overall quality of the watermelon juice.
Fulltext Characterization and modeling of diffusion kinetics of rosemary oleoresin extract from gellan gum-based film

Teoh RW, Ting ASY, Thoo YY

J Food Sci Technol, 2023 Dec;60(12):2978-2989.
PMID: 37786603 DOI: 10.1007/s13197-023-05826-9

Fresh food products are highly prone to oxidation and microbial attack, rendering them unsuitable for consumption. Thus, active food packaging was developed to protect and prolong food shelf-life. Zein/gellan gum (GG) based active film is developed by incorporating rosemary oleoresin extract (ROE) (0-20%). The films were characterized by their barrier and antioxidant properties. The release behavior of ROE in fatty and hydrophilic food stimulants was investigated via mathematical modeling. The active films incorporated with 20% ROE have significantly higher oxygen barrier and oxygen transfer is reduced by 20% compared to the control. A tortuous path is created with ROE, which impedes oxygen movement across the film. ROE addition improved water resistance performance by reducing the active film swelling ratio by 31%. This improvement is attributed to the hydrophobic nature of ROE. FTIR shows that the interaction between ROE and the active film is primarily hydrogen bonding and electrostatic interactions. Active film exhibits excellent antioxidant activity, with high TPC, DPPH scavenging activity, and FRAP. Mathematical modeling revealed a higher diffusivity (D) of ROE in fatty food stimulants at 24 °C, attributed to high polarity and solubility in fatty food stimulants. Overall, this active film has an excellent antioxidant effect and could potentially be used as food packaging for high-fat food products to prevent oxidation.
Characterization and identification of antimicrobial compounds from endophytic Fusarium incarnatum isolated from Cymbidium orchids

Chua RW, Song KP, Ting ASY

Int Microbiol, 2023 Nov 17.
PMID: 37975992 DOI: 10.1007/s10123-023-00442-1

This study characterized and identified the antimicrobial compounds from an endophytic fungus (Fusarium incarnatum (C4)) isolated from the orchid, Cymbidium sp. Chromatographic techniques were employed to separate the bioactive compounds from the crude extracts of F. incarnatum (C4). Following bio-guided fractionation, two fractionated extracts (fractions 1 and 2) of F. incarnatum (C4) exhibited antibacterial and antifungal activities against Bacillus cereus (MIC: 0.156 mg/mL) and Ganoderma boninense (MIC: 0.3125 mg/mL), respectively. The active fractions were discovered to comprise of a variety of bioactive compounds with pharmacological importance (alkaloids, flavonoids, phenolic compounds, terpenoids, peptides and fatty acids). Liquid chromatography mass-spectrometry (LCMS) analysis detected the presence of antibacterial (kanzonol N, rifaximin, linoleic acid (d4), cannabisativine, docosanedioic acid, and stearamide) and antifungal components (3-methyl-quinolin-2-ol, prothiocarb, kanzonol N, peganine, 5Z-tridecene, and tetronasin) in fractions 1 and 2, respectively, which may have contributed to the antimicrobial effects. Findings from this study highlighted the important potential of fungal endophytes from medicinal hosts as producers of antimicrobials and antibiotics.
Influence of light regulation on growth and enzyme production in rare endolichenic fungi

Gan PT, Lim YY, Ting ASY

Folia Microbiol (Praha), 2023 Oct;68(5):741-755.
PMID: 37022636 DOI: 10.1007/s12223-023-01050-2

The influence of light regulation on the growth and enzyme production of three endolichenic fungal isolates, i.e. Pseudopestalotiopsis theae (EF13), Fusarium solani (EF5), and Xylaria venustula (PH22), was determined. The isolates were exposed to blue, red, green, yellow, white fluorescent light (12 h light-12 h dark photoperiod) (test), and 24 h dark (control) conditions. Results revealed that the alternating light-dark conditions resulted in the formation of dark rings in most fungal isolates but was absent in PH22. Red light induced sporulation while yellow light elicited higher biomass in all isolates (0.19 ± 0.01 g, 0.07 ± 0.00 g, and 0.11 ± 0.00 g, for EF13, PH22, and EF5, respectively) as compared to incubation in the dark. Results also showed that blue light induced higher amylase activity in PH22 (15.31 ± 0.45 U/mL) and L-asparaginase activity in all isolates (0.45 ± 0.01 U/mL, 0.55 ± 0.39 U/mL, and 0.38 ± 0.01 U/mL, for EF13, PH22, and EF5, respectively) compared to both control conditions. Green light enhanced the production of xylanase (6.57 ± 0.42 U/mL, 10.64 ± 0.12 U/mL, and 7.55 ± 0.56 U/mL for EF13, PH22, and EF5, respectively) and cellulase (6.49 ± 0.48 U/mL, 9.57 ± 0.25 U/mL, and 7.28 ± 0.63 U/mL, for EF13, PH22, and EF5, respectively). In contrast, red light was the least effective light treatment as production of enzymes was the least, with lower levels of amylase, cellulase, xylanase, and L-asparaginase detected. To conclude, all three endolichenic fungi are light-responsive, with fungal growth regulated with the use of red light and yellow light, and manipulation of enzyme production via blue and green light.
Bioprocessing and purification of extracellular L-asparaginase produced by endophytic Colletotrichum gloeosporioides and its anticancer activity

Yap LS, Lee WL, Ting ASY

Prep Biochem Biotechnol, 2023;53(6):653-671.
PMID: 36137173 DOI: 10.1080/10826068.2022.2122064

L-asparaginase is an enzyme commonly used to treat acute lymphoblastic leukemia. Commercialized bacterial L-asparaginase has been reported to cause several life-threatening complications during treatment, hence the need to seek alternative sources of L-asparaginase. In this study, the novelty of upstream and downstream bioprocessing of L-asparaginase from a fungal endophyte, Colletotrichum gloeosporioides, and the cytotoxicity evaluation was demonstrated. Six variables (carbon source and concentration, nitrogen source and concentration, incubation period, temperature, pH and agitation rate) known to influence L-asparaginase production were studied using One-Factor-At-A-Time (OFAT) approach, with four significant variables further optimized using Response Surface Methodology (RSM). The crude extract produced using optimized condition was purified, characterized and examined for its anticancer effect. Purification of fungal L-asparaginase was performed via ultrafiltration and size exclusion chromatography, which are less common techniques. The protein profile and monomeric weight of L-asparaginase were determined using SDS-PAGE and Western blot. Cytotoxicity of purified L-asparaginase on leukemic Jurkat E6 and oral carcinoma cells were studied using MTS assay for 24 h and 48 h. OFAT results from optimization showed that glucose and L-asparagine concentrations, incubation period and temperature, were significant factors affecting L-asparaginase production by C. gloeosporioides. RSM analysis further evidence the significant interaction between glucose and L-asparagine concentrations in inducing L-asparaginase production. Purified L-asparaginase was profiled with specific activity of 255.02 IU/mg protein, purification fold of 6.12, and 34.63% of enzyme recovery. SDS and Western blot revealed that the purified L-asparaginase might be a tetramer with monomeric units of 25 kDa. Purified L-asparaginase was discovered to be more efficient against Jurkat leukemic cells than against H103 oral carcinoma cells, as lower IC50 value was observed for Jurkat cell lines (46 .36 ± 1.52 µg/mL for Jurkat and 125.56 ± 7.28 µg/mL for H103). In short, purified L-asparaginase derived from endophytic C. gloeosporioides showed high purity and significant anticancer effect toward cancer cells. This study therefore demonstrated the potential of fungal L-asparaginase as alternative chemotherapy drug in the future.
Fulltext Volatile organic compounds and sensory profile of dark chocolates made with cocoa beans fermented with Pichia kudriavzevii and Hanseniaspora thailandica

Ooi TS, Ting ASY, Siow LF

J Food Sci Technol, 2022 Jul;59(7):2714-2723.
PMID: 35734109 DOI: 10.1007/s13197-021-05292-1

Volatile organic compounds (VOCs) are important to determine the aroma and sensory perception of cocoa. Starter cultures can modulate the volatile profile of cocoa beans during fermentation. This study aimed to determine the VOCs and sensory of chocolates produced using cocoa beans fermented with yeast starters (Pichia kudriavzevii (MH979681), Hanseniaspora thailandica (MH979675) and the mixture of the two yeasts (Mix)). The VOCs of chocolates were determined by Head-Space Solid Phase Microextraction followed by Gas Chromatography-Mass Spectrophotometry. Sensory analysis was determined by using trained panels. VOCs profiles of chocolates produced using beans fermented with HT, PK or Mix were noticeably different from Ghana and control chocolates (no starter). The addition of yeast starters during cocoa fermentation produced chocolates that were preferred by trained panels. Bitterness and astringency were the more intense flavour attributes in chocolates produced using cocoa beans added with yeast starters. The chocolate produced using cocoa beans fermented with PK was the most acidic; whereas chocolate produced using beans fermented with Mix had the sweetest taste. The addition of PK or HT is helpful in producing chocolate with a distinct flavour.
Inducing antioxidant and antimicrobial activities in endophytic and endolichenic fungi by the use of light spectra treatments

Gan PT, Lim YY, Ting ASY

Arch Microbiol, 2023 Aug 11;205(9):304.
PMID: 37566125 DOI: 10.1007/s00203-023-03649-y

The influence of light exposure on antioxidant and antimicrobial activities of nine fungal isolates [Pseudopestalotiopsis theae (EF13), Fusarium solani (EF5), Xylaria venustula (PH22), Fusarium proliferatum (CCH), Colletotrichum boninese (PL9), Colletotrichum boninese (PL1), Colletotrichum boninese (OL2), Colletotrichum gloeosporioides (OL3) and Colletotrichum siamense (PL3)] were determined. The isolates were incubated in blue, red, green, yellow and white fluorescent light (12 h photoperiod of alternating light/dark). It was observed that green light induced higher total phenolic content (TPC) (2.96 ± 0.16 mg-30.71 ± 1.03 mg GAE/g) and ferric reducing antioxidant power (FRAP) in most isolates (4.82 ± 0.04-53.55 ± 4.33 mg GAE/g), whereas red light induced higher total flavonoid content (TFC) levels (1.14 ± 0.08-18.40 ± 1.12 mg QE/g). The crude extracts from most fungal cultures exposed to green and red lights were also notably more potent against the tested pathogens, as larger zones of inhibition (ZOI) (9.00 ± 1.00-38.30 ± 2.90 mm) and lower minimum inhibitory concentration (MIC) (0.0196-1.25 mg/mL) were achieved for antimicrobial effect. This study showed that light treatments are effective strategies in enhancing production of more potent antimicrobial compounds and valuable antioxidants from fungal isolates.
Comparative analysis of antimicrobial compounds from endophytic Buergenerula spartinae from orchid

Chua RW, Song KP, Ting ASY

Antonie Van Leeuwenhoek, 2023 Oct;116(10):1057-1072.
PMID: 37597137 DOI: 10.1007/s10482-023-01870-9

A rare fungal endophyte, identified as Buergenerula spartinae (C28), was isolated from the roots of Cymbidium orchids and was characterised and evaluated for its antimicrobial activities. Bio-guided fractionation revealed 4 fractions from B. spartinae (C28) having antibacterial activities against at least one bacterial pathogen tested (Bacillus cereus and Staphylococcus aureus). However, inhibitory activities were absent against pathogenic fungi (Ganoderma boninense, Pythium ultimum and Fusarium solani). Fraction 2 and fraction 4 of B. spartinae (C28) exhibited potent antibacterial activities against S. aureus (MIC: 0.078 mg/mL) and B. cereus (MIC: 0.313 mg/mL), respectively. LCMS analysis revealed the presence of antibacterial agents and antibiotics in fraction 2 (benoxinate, pyropheophorbide A, (-)-ormosanine and N-undecylbenzenesulfonic acid) and fraction 4 (kaempferol 3-p-coumarate, 6-methoxy naphthalene acetic acid, levofuraltadone, hinokitiol glucoside, 3-α(S)-strictosidine, pyropheophorbide A, 5'-hydroxystreptomycin, kanzonol N and 3-butylidene-7-hydroxyphthalide), which may be responsible for the antibacterial activities observed. Most of the bioactive compounds profiled from the antibacterial fractions were discovered for the first time from endophytic isolates (i.e. from B. spartinae (C28)). Buergenerula spartinae (C28) from Cymbidium sp. is therefore, an untapped resource of bioactive compounds for potential applications in healthcare and commercial industries.
Antioxidant properties and L-asparaginase activities of endophytic fungi from Cymbidium orchids

Chua RW, Song KP, Ting ASY

Folia Microbiol (Praha), 2023 Nov 23.
PMID: 37995083 DOI: 10.1007/s12223-023-01112-5

This study profiled the various endophytic fungi isolated from the orchid Cymbidium sp. and their L-asparaginase production and antioxidant potential. The L-asparaginase production was first screened through qualitative plate screening then quantified by the Nesslerization method. The antioxidant potential was quantified via the 2,2-diphenyl-1-picrylhydrazyl assay. A total of 30 endophytic fungi were isolated and all fungal isolates exhibited various degrees of radical scavenging activities (45.28% to 76.4%). Isolate Lasiodiplodia theobromae (C11) had the highest antioxidant capacity, represented by the lowest IC50 value (5.75 mg/mL) and highest ascorbic acid equivalent antioxidant capacity value (12.17 mg/g). Additionally, 16 isolates produced L-asparaginase (53.33%), which includes primarily species of Fusarium proliferatum, Fusarium fujikuroi, Fusarium incarnatum, and Fusarium oxysporum. A new isolate has also been discovered from Cymbidium orchid, Buergenerula spartinae (C28), which showed the highest L-asparaginase activity (1.736 unit/mL). These findings supported the postulation that medicinal species of Orchidaceae such as Cymbidium sp. harbor endophytes that are producers of L-asparaginase and antioxidants with various potential applications.
Antioxidant and L-asparaginase activities of culturable endophytic fungi from ornamental Dendrobium orchids

Chua RW, Song KP, Ting ASY

Lett Appl Microbiol, 2024 Mar 01;77(3).
PMID: 37563083 DOI: 10.1093/lambio/ovad096

This study reports the antioxidant potential and L-asparaginase production of culturable fungal endophytes from Dendrobium orchids in Malaysia. Twenty-nine isolates were screened using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay to determine their free radical scavenging activities and antioxidant capacity (IC50 and AEAC). L-asparaginase production of fungal endophytes was detected by the qualitative plate assay, and the enzyme activities estimated via the Nesslerization method. All 29 endophytic isolates exhibited various degrees of radical scavenging activities (35.37%-77.23%), with Fusarium fujikuroi (D1) identified as having the highest antioxidant capacity (IC50 6.097 mg/mL) and the highest AEAC value (11.55 mg/g). For L-asparaginase production, the majority of the isolates (89.66%) showed positive results, especially among the culturable species of Fusarium, Trichoderma, and Daldinia. Most Fusarium spp. were able to produce L-asparaginase (80.77%), but the highest L-asparaginase activity was detected in Daldinia eschscholtzii (D14) with 2.128 units/mL. Results from this study highlighted the potential of endophytic fungi from medicinal orchids (Dendrobium sp.) as natural sources of bioactive compounds to be developed into novel antioxidants and anticancer drugs.
Investigating metal removal potential by Effective Microorganisms (EM) in alginate-immobilized and free-cell forms

Ting ASY, Rahman NHA, Isa MIHM, Tan WS

Bioresour Technol, 2013 Nov;147:636-639.
PMID: 24001691 DOI: 10.1016/j.biortech.2013.08.064

Metal removal potential of both alginate-immobilized and free-cells of Effective Microorganisms (EM-1™ Inoculant) was investigated in this study. Results revealed that removal of Cr(III), Cu(II) and Pb(II) followed a similar trend where alginate-immobilized EM were more efficient compared to free-cells of EM. For these metals, 0.940, 2.695 and 4.011 mg g(-1) of Cr(III), Cu(II) and Pb(II) were removed compared to only 0.160, 0.859 and 0.755 mg ml(-1) removed by free-cells, respectively. The higher efficiency of alginate-immobilized EM was primarily attributed to the alginate matrix. This was evident when both alginate-immobilized EM and plain alginate beads (without EM), were not significantly different in their removal efficacies. Presence of alginate also enhanced the use of the biosorbents as maximum metal sorption was achieved after 120 min as opposed to only 60 min for free-cells. EM per se in immobilized or free-cell forms did not enhance metal removal efficacy.
Fulltext Persistent mosquito fogging can be detrimental to non-target invertebrates in an urban tropical forest

Lee NSM, Clements GR, Ting ASY, Wong ZH, Yek SH

PeerJ, 2020;8:e10033.
PMID: 33062440 DOI: 10.7717/peerj.10033

Background: Human population growth has led to biodiversity declines in tropical cities. While habitat loss and fragmentation have been the main drivers of urban biodiversity loss, man-made interventions to reduce health risks have also emerged as an unintentional threat. For instance, insecticide fogging to control mosquito populations has become the most common method of preventing the expansion of mosquito-borne diseases such as Dengue. However, the effectiveness of fogging in killing mosquitoes has been called into question. One concern is the unintended effect of insecticide fogging on non-target invertebrates that are crucial for the maintenance of urban ecosystems. Here, we investigate the impacts of fogging on: (1) target invertebrate taxon (Diptera, including mosquitoes); (2) non-target invertebrate taxa; and (3) the foraging behavior of an invertebrate pollinator taxon (Lepidoptera) within an urban tropical forest.
Methods: We carried out fogging with Pyrethroid insecticide (Detral 2.5 EC) at 10 different sites in a forest situated in the state of Selangor, Peninsular Malaysia. Across the sites, we counted the numbers of knocked-down invertebrates and identified them based on morphology to different taxa. We constructed Bayesian hierarchical Poisson regression models to investigate the effects of fogging on: (1) a target invertebrate taxon (Diptera) 3-h post-fogging; (2) selected non-target invertebrate taxa 3-h post-fogging; and (3) an invertebrate pollinator taxon (Lepidoptera) 24-h post-fogging.
Results: A total of 1,874 invertebrates from 19 invertebrate orders were knocked down by the fogging treatment across the 10 sites. Furthermore, 72.7% of the invertebrates counted 3-h post-fogging was considered dead. Our regression models showed that given the data and prior information, the probability that fogging had a negative effect on invertebrate taxa 3-h post-fogging was 100%, with reductions to 11% of the pre-fogging count of live individuals for the target invertebrate taxon (Diptera), and between 5% and 58% of the pre-fogging count of live individuals for non-target invertebrate taxa. For the invertebrate pollinator, the probability that fogging had a negative effect 24-h post-fogging was also 100%, with reductions to 53% of the pre-fogging count of live individuals.
Discussion: Our Bayesian models unequivocally demonstrate that fogging has detrimental effects on one pollinator order and non-target invertebrate orders, especially taxa that have comparatively lower levels of chitinisation. While fogging is effective in killing the target order (Diptera), no mosquitos were found dead in our experiment. In order to maintain urban biodiversity, we recommend that health authorities and the private sector move away from persistent insecticide fogging and to explore alternative measures to control adult mosquito populations.
Fulltext Determining Soil Microbial Communities and Their Influence on Ganoderma Disease Incidences in Oil Palm (Elaeis guineensis) via High-Throughput Sequencing

Goh YK, Zoqratt MZHM, Goh YK, Ayub Q, Ting ASY

Biology (Basel), 2020 Nov 27;9(12).
PMID: 33260913 DOI: 10.3390/biology9120424

Basal stem rot (BSR), caused by Ganoderma boninense, is the most devastating oil palm disease in South East Asia, costing US$500 million annually. Various soil physicochemical parameters have been associated with an increase in BSR incidences. However, very little attention has been directed to understanding the relationship between soil microbiome and BSR incidence in oil palm fields. The prokaryotic and eukaryotic microbial diversities of two coastal soils, Blenheim soil (Typic Quartzipsamment-calcareous shell deposits, light texture) with low disease incidence (1.9%) and Bernam soil (Typic Endoaquept-non-acid sulfate) with high disease incidence (33.1%), were determined using the 16S (V3-V4 region) and 18S (V9 region) rRNA amplicon sequencing. Soil physicochemical properties (pH, electrical conductivity, soil organic matter, nitrogen, phosphorus, cation exchange capacity, exchangeable cations, micronutrients, and soil physical parameters) were also analyzed for the two coastal soils. Results revealed that Blenheim soil comprises higher prokaryotic and eukaryotic diversities, accompanied by higher pH and calcium content. Blenheim soil was observed to have a higher relative abundance of bacterial taxa associated with disease suppression such as Calditrichaeota, Zixibacteria, GAL15, Omnitrophicaeota, Rokubacteria, AKYG587 (Planctomycetes), JdFR-76 (Calditrichaeota), and Rubrobacter (Actinobacteria). In contrast, Bernam soil had a higher proportion of other bacterial taxa, Chloroflexi and Acidothermus (Actinobacteria). Cercomonas (Cercozoa) and Calcarisporiella (Ascomycota) were eukaryotes that are abundant in Blenheim soil, while Uronema (Ciliophora) and mammals were present in higher abundance in Bernam soil. Some of the bacterial taxa have been reported previously in disease-suppressive and -conducive soils as potential disease-suppressive or disease-inducible bacteria. Furthermore, Cercomonas was reported previously as potential bacterivorous flagellates involved in the selection of highly toxic biocontrol bacteria, which might contribute to disease suppression indirectly. The results from this study may provide valuable information related to soil microbial community structures and their association with soil characteristics and soil susceptibility to Ganoderma.

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