ORCID Profile
0000-0003-1966-4387
Current Organisation
Universiti Putra Malaysia
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Publisher: Oxford University Press (OUP)
Date: 2023
Abstract: The present work investigated the profile and bio ersity of lactic acid bacteria (LAB) isolated from selected manufactured and homemade fermented foods in Malaysia. A total of 55 LAB were isolated from 20 s les, and identified based on the sequencing of 16S rRNA gene. The LAB isolates were identified as Lacticaseibacillus rhamnosus (34.5%), Lactiplantibacillus plantarum (20%), Limosilactobacillus fermentum (20%), Lacticaseibacillus paracasei (12.7%), Lacticaseibacillus casei (3.6%), Lactobacillus sp. (1.8%), Enterococcus faecalis (3.6%), Enterococcus faecium (1.8%), and Enterococcus durans (1.8%). Majority (94%) of the LAB isolates exhibited broad-spectrum antimicrobial activity against selected foodborne pathogens, and four isolates (L. fermentum SC1001, L. paracasei K2003, and L. rhamnosus KF1002 and MK2003) could produce bacteriocin-like inhibitory substance (BLIS). Lacticaseibacillus paracasei M1001 (homemade mozzarella) exhibited high-temperature tolerance and acid resistance, was homofermentative, and generated good antimicrobial activity, which strongly implied its potential for industrial applications. The present work results would potentially widen our knowledge of LAB ersity in Malaysian fermented foods and provide a potential for their applications in the food industry or other purposes.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Springer Science and Business Media LLC
Date: 06-09-2017
DOI: 10.1007/S00449-017-1830-Y
Abstract: This study investigates the effects of viscosity, friction, and sonication on the morphology and the production of lovastatin, (+)-geodin, and sulochrin by Aspergillus terreus ATCC 20542. Sodium alginate and gelatine were used to protect the fungal pellet from mechanical force by increasing the media viscosity. Sodium alginate stimulated the production of lovastatin by up to 329.0% and sulochrin by 128.7%, with inhibitory effect on (+)-geodin production at all concentrations used. However, the use of gelatine to increase viscosity significantly suppressed lovastatin, (+)-geodin, and sulochrin's production (maximum reduction at day 9 of 42.7, 60.8, and 68.3%, respectively), which indicated that the types of chemical play a major role in metabolite production. Higher viscosity increased both pellet biomass and size in all conditions. Friction significantly increased (+)-geodin's titre by 1527.5%, lovastatin by 511.1%, and sulochrin by 784.4% while reducing pellet biomass and size. Conversely, sonication produced disperse filamentous morphology with significantly lower metabolites. Sodium alginate-induced lovastatin and sulochrin production suggest that these metabolites are not affected by viscosity rather, their production is affected by the specific action of certain chemicals. In contrast, low viscosity adversely affected (+)-geodin's production, while pellet disintegration can cause a significant production of (+)-geodin.
Publisher: Elsevier BV
Date: 12-2023
Publisher: MDPI AG
Date: 21-07-2021
Abstract: Curculigo is a potent plant with a variety of traditional uses, such as anti-oxidant, anti-diabetic, anti-tumor, anti-bacterial, anti-cancer, anti-osteoporosis, and wound-healing. The comprehensive profiling of the Curculigolatifolia metabolome was carried out by generating a molecular network (MN) from Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) data to profile the methanol extract and correlating them with their antioxidant (2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), total phenolic contents (TPC), and β-carotene) and antimicrobial (disk-diffusion agar method, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC)) properties. The antioxidant capacity was observed to be significantly higher in the rhizome crude extract, with 18.10 ± 0.91 µg/mL DPPH activity, and a β-carotene bleaching result of 35.20%. For the antimicrobial activity, the leaf crude extract exhibited a strong Staphylococcus aureus and Salmonella choleraesuis (8–15 ± 3.0 mm) inhibition in the disk-diffusion agar. The leaf extract also exhibited maximum antibacterial activity against S. aureus (MIC = ±0.25 mg/mL, MBC = ±0.25 mg/mL) and S. choleraesuis (MIC = ±0.25 mg/mL, MBC = ±0.25 mg/mL). LC-MS/MS analysis and MN revealed norlignans and phenolic glycosides as major metabolites in the rhizome and leaf extracts of the negative mode (M − H)−. Fourteen known compounds were identified, and three unknown compounds were putatively identified in the rhizome extract, while ten known compounds and six unknown compounds were putatively identified in the leaf extract.
Publisher: Frontiers Media SA
Date: 10-03-2021
DOI: 10.3389/FMICB.2021.616548
Abstract: Vibrio parahaemolyticus is a foodborne pathogen that is frequently isolated from a variety of seafood. To control this pathogenic Vibrio spp., the implementation of bacteriophages in aquaculture and food industries have shown a promising alternative to antibiotics. In this study, six bacteriophages isolated from the seafood s les demonstrated a narrow host range specificity that infecting only the V. parahaemolyticus strains. Morphological analysis revealed that bacteriophages Vp33, Vp22, Vp21, and Vp02 belong to the Podoviridae family, while bacteriophages Vp08 and Vp11 were categorized into the Siphoviridae family. All bacteriophages were composed of DNA genome and showed distinctive restriction fragment length polymorphism. The optimal MOI for bacteriophage propagation was determined to be 0.001 to 1. One-step growth curve revealed that the latent period ranged from 10 to 20 min, and the burst size of bacteriophage was approximately 17 to 51 PFU/cell. The influence of temperature and pH levels on the stability of bacteriophages showed that all bacteriophages were optimally stable over a wide range of temperatures and pH levels. In vitro lytic activity of all bacteriophages demonstrated to have a significant effect against V. parahaemolyticus . Besides, the application of a bacteriophage cocktail instead of a single bacteriophage suspension was observed to have a better efficiency to control the growth of V . parahaemolyticus . Results from this study provided a basic understanding of the physiological and biological properties of the isolated bacteriophages before it can be readily used as a biocontrol agent against the growth of V. parahaemolyticus .
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.MIMET.2019.105672
Abstract: This study aimed to assess the effect of nitrogen, salt and pre-culture conditions on the production of lovastatin in A. terreus ATCC 20542. Different combinations of nitrogen sources, salts and pre-culture combinations were applied in the fermentation media and lovastatin yield was analysed chromatographically. The exclusion of MnSO The findings from these investigations could be used for future cultivation of A. terreus in the production of desired metabolites.
Publisher: Rynnye Lyan Resources
Date: 30-03-2023
DOI: 10.26656/FR.2017.7(2).829
Abstract: The Salmonella outbreak is one of the leading foodborne diseases in the world with increasing cases being reported annually. However, the current methods for Salmonella detection in foods are outdated, laborious and time-consuming. This necessitated developing a technique that is rapid for Salmonella detection in foods. Thus, the current study aimed to develop a multiplex touchdown PCR (m-TdPCR) protocol for rapid and simultaneous detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in foods. A two-phase m-TdPCR protocol was developed and optimized with primer pairs targeting the Salmonella enterica subsp. enterica (ST11/ST15-0.15 µM), serovars Enteritidis (sdfI gene-1.2 µM), Typhimurium (fliC gene-1.5 µM) and an internal lification control (16S rRNA-0.08 µM). It was found that the m-TdPCR protocol is highly sensitive detecting up to 1 ng of Salmonella DNA and its specificity was verified using the in-silico method. Furthermore, the developed m-TdPCR shows no non-specific PCR licons and is able to detect both S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in real-time when tested against the artificially contaminated food s les at up to 10-3 dilutions. Therefore, the validated m-TdPCR protocol in this study can be used as a tool for rapid detection of S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in food s les and this may significantly reduce any related foodborne incidences in future.
Publisher: Cold Spring Harbor Laboratory
Date: 11-09-2020
DOI: 10.1101/2020.09.10.291559
Abstract: Photosynthetic bacteria from the class Chlorobia (formerly phylum Chlorobi ) sustain carbon fixation in anoxic water columns. They harvest light at extremely low intensities and use various inorganic electron donors to fix carbon dioxide into biomass. Until now, most information on their functional ecology and local adaptations came from isolates and merely 26 sequenced genomes that are poor representatives of natural populations. To address these limitations, we analyzed global metagenomes to profile planktonic Chlorobia cells from the oxyclines of 42 freshwater bodies, spanning subarctic to tropical regions and encompassing all four seasons. We assembled and compiled over 500 genomes, including metagenome-assembled genomes (MAGs), single-cell genomes (SAGs), and reference genomes from cultures, clustering them into 71 metagenomic operational taxonomic units (mOTUs) or “species”. Of the 71 mOTUs, 57 were classified as genus Chlorobium and these mOTUs varied in relative abundance up to ~60% of the microbial communities in the s led anoxic waters. Several Chlorobium -associated mOTUs were globally distributed whereas others were endemic to in idual lakes. Although most clades encoded the ability to oxidize hydrogen, many were lacking genes for the oxidation of specific sulfur and iron substrates. Surprisingly, one globally distributed Scandinavian Chlorobium clade encoded the ability to oxidize hydrogen, sulfur, and iron, suggesting that metabolic versatility facilitated such widespread colonization. Overall, these findings provide new insights into the biogeography of the Chlorobia and the metabolic traits that facilitate niche specialization within lake ecosystems. The reconstruction of genomes from metagenomes has enabled unprecedented insights into the ecology and evolution of environmental microbiomes. We applied this powerful approach to 274 metagenomes collected from erse freshwater habitats that spanned oxic and anoxic zones, s ling seasons, and latitudes. We demonstrate widespread and abundant distributions of planktonic Chlorobia -associated bacteria in hypolimnetic waters of stratified freshwater ecosystems and pinpoint nutrients that likely fuel their electron chains. Being photoautotrophs, these Chlorobia organisms also have the potential to serve as carbon sources that support metalimnetic and hypolimnetic food webs.
Publisher: Hindawi Limited
Date: 04-2019
DOI: 10.1155/2019/2504540
Abstract: Crude glycerol (CG) can be used as a substrate for microbial bioconversion. However, due to presence of many impurities, many microorganisms are unable to utilise this substrate efficiently. The present study is trying to improve CG using as the feedstock of Aspergillus terreus for the production of lovastatin, (+)-geodin, and sulochrin. The CG was pretreated chemically (solvents) and physically (activated carbon (AC) and water softener (WS)) to separate most of the impurities from the CG. For solvent pretreatments, petroleum ether (PE) produced the largest increase of lovastatin (92.8%) when compared to positive control and pure glycerol (PG) and up to 820% when compared to negative control (CG). In contrast, diethyl ether (DE) produced the largest increase in (+)-geodin at 80.81% (versus CG) and 176.23% (versus PG). The largest increase in toluene (Tol) was observed in sulochrin production, at 67.22% (versus CG) and 183.85% (versus PG). For physical pretreatments, the pattern of metabolite production in AC (lovastatin: 20.65 mg/L, (+)-geodin: 7.42 mg/L, sulochrin: 11.74 mg/L) resembled PG (lovastatin: 21.8 mg/L, (+)-geodin: 8.60 mg/L, sulochrin: 8.18 mg/L), while WS (lovastatin: 11.25 mg/L, (+)-geodin: 15.38 mg/L, sulochrin: 16.85 mg/L) resembled CG (lovastatin: 7.1 mg/L, (+)-geodin: 17.10 mg/L, sulochrin: 14.78 mg/L) at day 6 of fermentation. These results indicate that solvent pretreatments on CG are excellent for metabolites production in A. terreus , depending on the solvents used. In contrast, physical pretreatments are only feasible for (+)-geodin and sulochrin production. Therefore, different strategies can be employed to manipulate the A. terreus bioconversion using improved CG by using a few simple pretreatment strategies.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Hindawi Limited
Date: 13-11-2019
DOI: 10.1111/JFPP.14322
Publisher: Springer Science and Business Media LLC
Date: 21-09-2021
DOI: 10.1007/S12033-021-00393-W
Abstract: Lovastatin is an anti-cholesterol medicine that is commonly prescribed to manage cholesterol levels, and minimise the risk of suffering from heart-related diseases. Aspergillus terreus (ATCC 20542) supplied with carbohydrates or sugar alcohols can produce lovastatin. The present work explored the application of metabolic engineering in A. terreus to re-route the precursor flow towards the lovastatin biosynthetic pathway by simultaneously overexpressing the gene for acetyl-CoA carboxylase (acc) to increase the precursor flux, and eliminate ( +)-geodin biosynthesis (a competing secondary metabolite) by removing the gene for emodin anthrone polyketide synthase (gedC). Alterations to metabolic flux in the double mutant (gedCΔ*acc
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.NBT.2019.04.003
Abstract: Lovastatin is widely prescribed to reduce elevated levels of cholesterol and prevent heart-related diseases. Cultivation of Aspergillus terreus (ATCC 20542) with carbohydrates or low-value feedstocks such as glycerol produces lovastatin as a secondary metabolite and (+)-geodin as a by-product. An A. terreus mutant strain was developed (gedCΔ) with a disrupted (+)-geodin biosynthesis pathway. The gedCΔ mutant was created by inserting the antibiotic marker hygromycin B (hyg) within the gedC gene that encodes emodin anthrone polyketide synthase (PKS), a primary gene responsible for initiating (+)-geodin biosynthesis. The effects of emodin anthrone PKS gene disruption on (+)-geodin and lovastatin biosynthesis and the production of the precursors acetyl-CoA and malonyl-CoA were investigated with cultures based on glycerol alone and in combination with lactose. The gedCΔ strain showed improved lovastatin production, particularly when cultivated on the glycerol-lactose mixture, increasing lovastatin production by 80% (113 mg/L) while simultaneously inhibiting (+)-geodin biosynthesis compared to the wild-type strain. This study thus shows that suppression of the (+)-geodin pathway increases lovastatin yield and demonstrates a practical approach of manipulating carbon flux by modulating enzyme activity.
Publisher: Wiley
Date: 14-02-2015
Publisher: Elsevier BV
Date: 04-0003
Publisher: Elsevier BV
Date: 05-2023
Publisher: Hindawi Limited
Date: 06-12-2022
DOI: 10.1111/JFPP.16172
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.NBT.2018.04.008
Abstract: The present work describes the application of homologous recombination techniques in a wild-type Aspergillus terreus (ATCC 20542) strain to increase the flow of precursors towards the lovastatin biosynthesis pathway. A new strain was generated to overexpress acetyl-CoA carboxylase (ACCase) by replacing the native ACCase promoter with a strong constitutive PadhA promoter from Aspergillus nidulans. Glycerol and a mixture of lactose and glycerol were used independently as the carbon feedstock to determine the degree of response by the A. terreus strains towards the production of acetyl-CoA, and malonyl-CoA. The new strain increased the levels of malonyl-CoA and acetyl-CoA by 240% and 14%, respectively, compared to the wild-type strain. As a result, lovastatin production was increased by 40% and (+)-geodin was decreased by 31% using the new strain. This study shows for the first time that the metabolism of Aspergillus terreus can be manipulated to attain higher levels of precursors and valuable secondary metabolites.
Publisher: Springer Science and Business Media LLC
Date: 23-10-2022
DOI: 10.1007/S12033-022-00584-Z
Abstract: There is an increasing demand for natural food preservatives due to consumers' concern on the negative effects of chemical preservatives in food products. Nisin (bacteriocin) is an effective food biopreservative that has been approved globally. However, its low yield proves to be a limiting factor and must be addressed to meet the increasingly high demand from the food industry. The present work thus investigated the effects of in idual and combined fermentation factors on Lactococcus lactis ATCC 11454 growth and nisin activity using the one-factor-at-a-time (OFAT) method. The level of each factor that gave the highest nisin production was then selected and combined to further improve its activity. The best combined conditions for highest cell growth and nisin activity were 30 °C, pH 6.0, and mild agitation with the addition of 1.0% w/v glucose, 1.0% w/v skim milk, and 0.5% v/v Tween 20. This increased nisin production by 22.7% as compared to control (basic condition). The present work provided critical information on the relationship between fermentation conditions, growth, and nisin activity of L. lactis ATCC 11454 that could be explored to understand the potential and limitation of the strain. This fermentation strategy can also serve as a benchmark to further enhance the production of bacteriocin or other biopreservative compounds.
Publisher: Rynnye Lyan Resources
Date: 13-03-2022
DOI: 10.26656/FR.2017.6(2).149
Abstract: Over the last two decades, only a handful of research have been conducted pertaining to food safety in the aviation industry. The gap of knowledge in in-flight food safety literature has long been silenced. Therefore, it was the objective of this study to conduct preliminary screenings to evaluate the environmental quality of the service equipment (GE), safety equipment (SE) and common facilities (CF) within the confinement of commercial aeroplanes in Malaysia. A total of 112 swab s les (n = 112) were analyzed to detect the prevalence of Escherichia coli, Vibrio, Salmonella and coliforms using conventional microbiological methods. The qualitative aerobic mesophilic plate count revealed that 99 (88.39%) and 13 (11.61%) were reported as positive and negative s les, respectively. It was reported that all 17 s les taken from the long-haul flight were positive, with 8 (9.14%), 4 (3.57%) and 5 (4.46%) s les belonging to the GE, SE, and CF, respectively. Forty-five positive swab s les taken from medium-haul flight sectors showed that 30 (26.79%), 8 (9.14%), 7 (6.25%) s les were that of the GE, SE, and CF, respectively. Meanwhile, 19 (16.96%), 8 (9.14%), and 10 (8.93%) of the shorthaul flights s les were that of the GE, SE, and CF, respectively. It was therefore concluded that GE, SE and CF were reported at 57 (50.89%), 20 (17.86%) and 22 (19.64%), respectively. In view of the large numbers and high percentages of positive s le results, it is our opinion that the cleaning, sanitizing and disinfecting procedures of the galley equipment, safety equipment and common facilities are revisited. The assurance in conformance to the hazard analysis and critical control points (HACCP) management system may enhance the safety and reliability of all stakeholders especially the flight attendants who are the final custodians of the environmental hygiene and that of themselves.
No related grants have been discovered for Hanan Hasan.