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  1. Antifungal Mechanism of Rhodotorula mucilaginosa and Aureobasidium sp. nov. Isolated from Cerbera manghas L. against the Growth of Destructive Molds in Post Harvested Apples
    Sukmawati D, Shabrina A, Indrayanti R, Kurniati TH, Nurjayadi M, Hidayat I, et al.
    Recent Pat Food Nutr Agric, 2020;11(3):219-228.
    PMID: 32324527 DOI: 10.2174/2212798411666200423101159
    BACKGROUND: Apples often experience postharvest damage due to being attacked by mold organisms. Several groups of molds such as Aspergillus sp., Penicilium expansum, Botrytis cinerea, and Venturia sp. can cause a serious postharvest disease exhibited as watery regions where areas of blue-green tufts of spores develop. Current methods using fungicides to control pathogenic fungi can cause resistance if applied in the long term. An alternative procedure using yeast as a biological agent has been found.

    OBJECTIVE: The aim of this study is to screen potential yeast, which has the ability to inhibit the growth of Aspergillus brasielensis (isolate A1) and Aspergillus flavus section flavi (isolate A17) isolated from apple fruits.

    METHODS: Antagonism test using YMA dual culture medium using in vitro assays and ITS rDNA identification were performed.

    RESULTS: The result showed that 3 out of 19 yeast isolated from Cerbera manghas L, T1, T3 and T4, demonstrated the potential ability as a biocontrol agent. ITS rDNA identification demonstrated that T1 has a similarity to Rhodotorula mucilaginosa while T3 and T4 were identified as Aureobasidium sp. nov. The 3 isolates exhibited the ability to reduce the growth of A. brasiliensis sensu lato better than dithane 0.3% with a Disease Incidence (DI) of 100% and a Disease Severity (DS) value of 45%. Only isolate T1 and T3 were able to reduce decay symptoms in apples inoculated with A. flavus sensu lato (with DO and DS were 100% and 25%, respectively) compared to dithane pesticides 0.3%.

    CONCLUSION: This study indicated that competition between nutrients occurs between pathogenic molds and under-yeast in vitro and in vivo conditions. However, further studies in the future might be able to elucidate the 'killer' activity and interaction with the pathogen cells and the bio-product production using Rhodotorula mucilaginosa and Aureoubasidium namibiae strains to control postharvest diseases.

    Matched MeSH terms: Aspergillus flavus/genetics
  2. Fulltext Heterologous, Expression, and Characterization of Thermostable Glucoamylase Derived from Aspergillus flavus NSH9 in Pichia pastoris
    Karim KM, Husaini A, Hossain MA, Sing NN, Mohd Sinang F, Hussain MH, et al.
    Biomed Res Int, 2016;2016:5962028.
    PMID: 27504454 DOI: 10.1155/2016/5962028
    A novel thermostable glucoamylase cDNA without starch binding domain (SBD) of Aspergillus flavus NSH9 was successfully identified, isolated, and overexpressed in Pichia pastoris GS115. The complete open reading frame of glucoamylase from Aspergillus flavus NSH9 was identified by employing PCR that encodes 493 amino acids lacking in the SBD. The first 17 amino acids were presumed to be a signal peptide. The cDNA was cloned into Pichia pastoris and the highest expression of recombinant glucoamylase (rGA) was observed after 8 days of incubation period with 1% methanol. The molecular weight of the purified rGA was about 78 kDa and exhibited optimum catalytic activity at pH 5.0 and temperature of 70°C. The enzyme was stable at higher temperature with 50% of residual activity observed after 20 min at 90°C and 100°C. Low concentration of metal (Mg(++), Fe(++), Zn(++), Cu(++), and Pb(++)) had positive effect on rGA activity. This rGA has the potential for use and application in the saccharification steps, due to its thermostability, in the starch processing industries.
    Matched MeSH terms: Aspergillus flavus/genetics
  3. Characterization and expression in Pichia pastoris of a raw starch degrading glucoamylase (GA2) derived from Aspergillus flavus NSH9
    Karim KMR, Husaini A, Sing NN, Tasnim T, Mohd Sinang F, Hussain H, et al.
    Protein Expr Purif, 2019 12;164:105462.
    PMID: 31351992 DOI: 10.1016/j.pep.2019.105462
    The Aspergillus flavus NSH9 gene, encoding a pH and thermostable glucoamylase with a starch binding domain (SBD), was expressed in Pichia pastoris to produce recombinant glucoamylase (rGA2). The full-length glucoamylase gene (2039 bp), and cDNA (1839 bp) encode a 612 amino acid protein most similar to glucoamylase from Aspergillus oryzae RIB40; the first 19 amino acids are presumed to be a signal peptide for secretion, and the SBD is at the C-terminal. The cDNA was successfully secreted by Pichia at 8.23 U mL-1, and the rGA2 was found to be: a 80 kDa monomer, stable from pH 3.0-9.0, with optimum catalytic activity at pH 5.0, active at temperatures up to 80°C (rGA2 retained 58% of its activity after 60 min of incubation at 70°C), and metal ions such as Na+, K+, Ca++ and Mg++ enhanced rGA2 enzyme activity. The starch degrading ability of rGA2 was also observed on raw sago starch and where prolonged incubation generated larger, deeper, holes on the starch granules, indicating rGA2 is an excellent candidate for industrial starch processing applications.
    Matched MeSH terms: Aspergillus flavus/genetics
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