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Molecular beacon-based real-time PCR method for detection of porcine DNA in gelatin and gelatin capsules

Mohamad NA, Mustafa S, Khairil Mokhtar NF, El Sheikha AF

J Sci Food Agric, 2018 Sep;98(12):4570-4577.
PMID: 29505123 DOI: 10.1002/jsfa.8985

BACKGROUND: The pharmaceutical industry has boosted gelatin consumption worldwide. This is supported by the availability of cost-effective gelatin production from porcine by-products. However, cross-contamination of gelatin materials, where porcine gelatin was unintentionally included in the other animal sources of gelatin, has caused significant concerns about halal authenticity. The real-time polymerase chain reaction (PCR) has enabled a highly specific and sensitive animal species detection method in various food products. Hence, such a technique was employed in the present study to detect and quantify porcine DNA in gelatin using a molecular beacon probe, with differences in performance between mitochondrial (cytochrome b gene) and chromosomal DNA-(MPRE42 repetitive element) based porcine-specific PCR assays being compared.
RESULTS: A higher sensitivity was observed in chromosomal DNA (MPRE-PCR assay), where this assay allows the detection of gelatin DNA at amounts as as low as 1 pg, whereas mitochondrial DNA (CBH-PCR assay) can only detect at levels down to 10 pg of gelatin DNA. When an analysis with commercial gelatin and gelatin capsule samples was conducted, the same result was observed, with a significantly more sensitive detection being provided by the repetitive element of chromosomal DNA.
CONCLUSION: The present study has established highly sensitive DNA-based porcine detection systems derived from chromosomal DNA that are feasible for highly processed products such as gelatin and gelatin capsules containing a minute amount of DNA. This sensitive detection method can also be implemented to assist the halal authentication process of various food products available on the market. © 2018 Society of Chemical Industry.
Seasonal variability of anthropogenic indices of PAHs in sediment from the Kuala Selangor River, west coast Peninsular Malaysia

Masood N, Halimoon N, Aris AZ, Zakaria MP, Vaezzadeh V, Magam SM, et al.

Environ Geochem Health, 2018 Dec;40(6):2551-2572.
PMID: 29802607 DOI: 10.1007/s10653-018-0122-z

Rapid increase in industrialization and urbanization in the west coast of Peninsular Malaysia has led to the intense release of petroleum and products of petroleum into the environment. Surface sediment samples were collected from the Selangor River in the west coast of Peninsular Malaysia during four climatic seasons and analyzed for PAHs and biomarkers (hopanes). Sediments were soxhlet extracted and further purified and fractionated through first and second step column chromatography. A gas chromatography-mass spectrometry (GC-MS) was used for analysis of PAHs and hopanes fractions. The average concentrations of total PAHs ranged from 219.7 to 672.3 ng g-1 dw. The highest concentrations of PAHs were detected at 964.7 ng g-1 dw in station S5 in the mouth of the Selangor River during the wet inter-monsoonal season. Both pyrogenic and petrogenic PAHs were detected in the sediments with a predominance of the former. The composition of hopanes was homogeneous showing that petroleum hydrocarbons share an identical source in the study area. Diagnostic ratios of hopanes indicated that some of the sediment samples carry the crankcase oil signature.
Fulltext Stability of Bacteriocin-Like Inhibitory Substance (BLIS) Produced by Pediococcus acidilactici kp10 at Different Extreme Conditions

Md Sidek NL, Halim M, Tan JS, Abbasiliasi S, Mustafa S, Ariff AB

Biomed Res Int, 2018;2018:5973484.
PMID: 30363649 DOI: 10.1155/2018/5973484

Nowadays, bacteriocin industry has substantially grown replacing the role of chemical preservatives in enhancing shelf-life and safety of food. The progress in bacteriocin study has been supported by the emerging of consumer demand on the applications of natural food preservatives. Since food is a complex ecosystem, the characteristics of bacteriocin determine the effectiveness of their incorporation into the food products. Among four commercial media (M17 broth, MRS broth, tryptic soy broth, and nutrient broth) tested, the highest growth of Pediococcus acidilactici kp10 and bacteriocin-like-inhibitory substance (BLIS) production were obtained in the cultivation with M17. BLIS production was found to be a growth associated process where the production was increased concomitantly with the growth of producing strain, P. acidilactici kp10. The antimicrobial property of BLIS against three indicator microorganisms (Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus) remained stable upon heating at 100°C but not detectable at 121°C. The BLIS activity was also observed to be stable and active at a wide pH range (pH 2 to pH 7). The BLIS activity remained constant at -20°C and -80°C for 1 month of storage. However, the activity dropped after 3 and 6 months of storage at 4°C, -20°C, and -80°C with more than 80% reduction. The ability of bacteriocin from P. acidilactici kp10 to inhibit food-borne pathogens while remaining stable and active at extreme pH and temperature is of potential interest for future applications in food preservatives.
Risk assessment of pharmaceutically active compounds (PhACs) in the Klang River estuary, Malaysia

Omar TFT, Aris AZ, Yusoff FM, Mustafa S

Environ Geochem Health, 2019 Feb;41(1):211-223.
PMID: 30051257 DOI: 10.1007/s10653-018-0157-1

The concentration profile, distribution and risk assessment of pharmaceutically active compounds (PhACs) in the coastal surface water from the Klang River estuary were measured. Surface coastal water samples were extracted using offline solid phase, applying polymeric C18 cartridges as extraction sorbent and measuring with liquid chromatography mass spectrometry-mass spectrometry (LC MS-MS) technique. Extraction method was optimized for its recovery, sensitivity and linearity. Excellent recoveries were obtained from the optimized method with percentage of recoveries ranging from 73 to 126%. The optimized analytical method achieved good sensitivity with limit of detection ranging from 0.05 to 0.15 ng L-1, while linearity of targeted compounds in the LC MS-MS system was more than 0.990. The results showed that amoxicillin has the highest concentration (102.31 ng L-1) followed by diclofenac (10.80 ng L-1) and primidone (7.74 ng L-1). The percentage of contribution (% of total concentration) for the targeted PhACs is in the following order; amoxicillin (92.90%) > diclofenac (3.95%) > primidone (1.23%) > dexamethasone (0.75%) > testosterone (0.70%) > sulfamethoxazole (0.33%) > progesterone (0.14%). Environmental risk assessment calculated based on deterministic approach (the RQ method), showed no present risk from the presence of PhACs in the coastal water of Klang River estuary. Nonetheless, this baseline assessment can be used for better understanding on PhACs pollution profile and distribution in the tropical coastal and estuarine ecosystem as well as for future comparative studies.
Optimization of culture conditions of soymilk for equol production by Bifidobacterium breve 15700 and Bifidobacterium longum BB536

Mustafa SE, Mustafa S, Abas F, Manap MYABD, Ismail A, Amid M, et al.

Food Chem, 2019 Apr 25;278:767-772.
PMID: 30583440 DOI: 10.1016/j.foodchem.2018.11.107

This study analyzed the effect of pH (X1), temperature (X2) and inulin amount (X3) on transformation of isoflavones (daidzin and daidzein) to equol in soymilk fermented with Bifidobacterium spp. All responses significantly (p  0.05) difference between the experimental and predicted values, suggested the suitability of established models in explaining the daidzin and daidzein transformation to equol as a function of pH, temperature and inulin.
Occurrence and level of emerging organic contaminant in fish and mollusk from Klang River estuary, Malaysia and assessment on human health risk

Omar TFT, Aris AZ, Yusoff FM, Mustafa S

Environ Pollut, 2019 May;248:763-773.
PMID: 30851586 DOI: 10.1016/j.envpol.2019.02.060

The occurrence, level, and distribution of multiclass emerging organic contaminants (EOCs) in fish and mollusks from the Klang River estuary were examined. The targeted EOCs for this assessment were phenolic endocrine disrupting compounds (bisphenol A, 4-OP, and 4-NP), organophosphorous pesticides (quinalphos, chlorpyrifos, and diazinon), estrogenic hormones (E2, E1, and EE2), and pharmaceutically active chemicals (primidone, sulfamethoxazole, dexamethasone, diclofenac, amoxicillin, progesterone, and testosterone). Results from this study showed that the prevalent contamination of the Klang River estuary by EOCs with diclofenac, bisphenol A, progesterone, and amoxicillin were predominantly detected in fish and mollusks. Among the EOCs, diclofenac and progesterone had the highest concentrations in fish and mollusk samples, respectively. The concentrations of diclofenac and progesterone in fish and mollusk samples range from 1.42 ng/g to 10.76 ng/g and from 0.73 ng/g to 9.57 ng/g, respectively. Bisphenol A should also be highlighted because of its significant presence in both fish and mollusks. The concentration of bisphenol A in both matrices range from 0.92 ng/g to 5.79 ng/g. The calculated hazard quotient (HQ) for diclofenac, bisphenol A, and progesterone without consideration to their degradation byproduct were less than one, thus suggesting that the consumption of fish and mollusks from the Klang River estuary will unlikely pose any health risk to consumers on the basis of the current assessment. Nonetheless, this preliminary result is an important finding for pollution studies in Malaysian tropical coastal ecosystems, particularly for organic micropollutant EOCs, and can serve as a baseline database for future reference.
Analytical Modeling of Well Design in Riverbank Filtration Systems

Mustafa S, Darwish M, Bahar A, Aziz ZA

Ground Water, 2019 09;57(5):756-763.
PMID: 30740693 DOI: 10.1111/gwat.12868

Analytical studies for well design adjacent to river banks are the most significant practical task in cases involving the efficiency of riverbank filtration systems. In times when high pollution of river water is joined with increasing water demand, it is necessary to design pumping wells near the river that provide acceptable amounts of river water with minimum contaminant concentrations. This will guarantee the quality and safety of drinking water supplies. This article develops an analytical solution based on the Green's function approach to solve an inverse problem: based on the required level of contaminant concentration and planned pumping time period, the shortest distance to the riverbank that has the maximum percentage of river water is determined. This model is developed in a confined and homogenous aquifer that is partially penetrated by the stream due to the existence of clogging layers. Initially, the analytical results obtained at different pumping times, rates and with different values of initial concentration are checked numerically using the MODFLOW software. Generally, the distance results obtained from the proposed model are acceptable. Then, the model is validated by data related to two pumping wells located at the first riverbank filtration pilot project conducted in Malaysia.
Fulltext Lard classification from other animal fats using Dielectric Spectroscopy technique

Amat Sairin, M., Abd Aziz, S., Tan, C.P., Mustafa, S., Abd Gani, S.S., Rokhani, F.Z.

International Food Research Journal, 2019;26(3):773-782.
MyJurnal

Lard adulteration in processed foods is a major public concern as it involves religion and
health. Most lard discriminating works require huge lab-based equipment and complex sample
preparation. The objective of the present work was to assess the feasibility of dielectric
spectroscopy as a method for classification of fats from different animal sources, in particular,
lard. The dielectric spectra of each animal fat were measured in the radio frequency of 100
Hz – 100 kHz at 45°C to 55°C. The fatty acid composition of each fat was studied by using
data from gas chromatography mass spectrometry (GCMS) to explain the dielectric behaviour
of each fat. The principal component analysis (PCA) and artificial neural network (ANN)
were used to classify different animal fats based on their dielectric spectra. It was found that
lard showed the highest dielectric constant spectra among other animal fats, and was mainly
affected by the composition of C16 and C18 fatty acids. PCA classification plot showed clear
performance in classifying different animal fats. Finally, ANN classification showed different
animal fats were classified into their respective groups effectively at high accuracy of 85%.
Dielectric spectroscopy, in combination with quantitative analysis, was concluded to provide
rapid method to discriminate lard from other animal fats.
Fulltext Effect of enzymatic transesterification using Mucor miehei lipase on physicochemical properties of engkabang (Shorea macrophylla) fat - canola oil blends

Roslan, N. I. M., Marikkar, J. M. N., Manaf, Y. N., Mustafa, S., Miskandar, M. S.

International Food Research Journal, 2019;26(5):1427-1435.
MyJurnal

The effect of transesterification of engkabang (Shorea macrophylla) fat - canola oil (EF35/ CaO65) blend by Mucor miehei lipase (1%, w/w oil) in a solvent-free system was investigated at different time intervals of 6 h, 12 h and 24 h. Compositional changes of the samples withdrawn at specified time intervals while the reaction in progress were analysed by chromatography, whereas the polymorphic forms and thermal properties were analysed by using X-ray diffraction and differential scanning calorimetry, respectively. There were increases in the amounts of monounsaturated and triunsaturated triacylglycerol (TAG) molecular groups with concurrent reductions of the proportions of desaturated TAG molecular groups during different time intervals. This changing TAG composition led to changes in crystallisation behaviour and thermal properties of the samples, reducing some enthalpy values. All samples withdrawn at different time intervals displayed both β' and β type crystal polymorphs even though engkabang fat itself was predominantly β‐type. In terms of melting, solidification and polymorphic properties, the sample withdrawn at 6 h time interval was found to display the closest similarity to lard (LD).
Fulltext Effect of three plant-based shortenings and lard on cookie dough properties and cookies quality

Manaf, Y. N., Marikkar, J. M. N., Mustafa, S., Van Bockstaele, Nusantoro, B. P.

International Food Research Journal, 2019;26(6):1795-1802.
MyJurnal

Tropical fats such as palm oil (PO) from Elaeis guineensis (oil palm), cocoa (Theobroma cacao
L.) butter (CB), avocado (Persea americana) oil (Avo), palm stearin (PS), and Mee (Madhuca
longifolia) fat (MF) are useful raw materials for the formulation of bakery shortenings. Blending
these fats at differing ratios such as binary [MF:PS (99:1)], ternary [Avo:PS:CB (84:7:9)], and
quaternary [PO:PS:SBO:CB (38:5:52:5)] would lead to fat mixtures as replacement for lard
(LD). In the present work, the influence of these three fat blends and LD on cookie dough
textural properties and cookie quality was investigated. The results showed that the hardness of
cookies was correlated to the hardness of dough, which was influenced by the solid fat content
(SFC). The degree of unsaturation of triacylglycerol molecules also seemed to influence these
parameters. Nevertheless, the cookies of all different types of shortenings did not show any
significant differences with regard to their width and thickness. This could be probably due
to the fact that cookies made from formulated plant-based shortenings and LD expanded
uniformly during baking.
Fulltext Spray-dried immobilized lipase from Geobacillus sp. strain ARM in sago

Mohtar NS, Abdul Rahman MB, Mustafa S, Mohamad Ali MS, Raja Abd Rahman RNZ

PeerJ, 2019;7:e6880.
PMID: 31183251 DOI: 10.7717/peerj.6880

Sago starch is traditionally used as food especially in Southeast Asia. Generally, sago is safe for consumption, biodegradable, easily available and inexpensive. Therefore, this research was done to expand the potential of sago by using it as a support for enzyme immobilization. In this study, ARM lipase, which was isolated from Geobacillus sp. strain ARM, was overexpressed in Escherichia coli system and then purified using affinity chromatography. The specific activity of the pure enzyme was 650 U/mg, increased 7 folds from the cell lysate. The purified enzyme was immobilized in gelatinized sago and spray-dried by entrapment technique in order to enhance the enzyme operational stability for handling at high temperature and also for storage. The morphology of the gelatinized sago and immobilized enzyme was studied by scanning electron microscopy. The results showed that the spray-dried gelatinized sago was shrunken and became irregular in structure as compared to untreated sago powder. The surface areas and porosities of spray-dried gelatinized sago with and without the enzyme were analyzed using BET and BJH method and have shown an increase in surface area and decrease in pore size. The immobilized ARM lipase showed good performance at 60-80 °C, with a half-life of 4 h and in a pH range 6-9. The immobilized enzyme could be stored at 10 °C with the half-life for 9 months. Collectively, the spray-dried immobilized lipase shows promising capability for industrial uses, especially in food processing.
Fulltext Loop mediated isothermal amplification; a review on its application and strategy in animal species authentication of meat based food products

Tasrip, N.A., Khairil Mokhtar, N. F., Hanapi, U.K., Abdul Manaf, Y. N., Ali, M.E., Cheah, Y.K., et al.

International Food Research Journal, 2019;26(1):1-10.
MyJurnal

Isothermal amplification is a technique that can amplify target DNA sequences at a single incubation temperature. Loop-mediated isothermal amplification (LAMP) is an extension of the isothermal DNA amplification technique that combines rapidity, simplicity, high specificity and sensitivity. Due to its overwhelming characteristics, LAMP has been explored for its feasibility in detecting various subjects, and recently in meat-based food products for DNA-based meat species authentication. It has been developed to target various meat species such as porcine, chicken, horse, and ostrich with sensitivity as low as 0.1 pg/μL. Further improvement with the use of magnetic beads, electrochemiluminescence and special dye such as calcein and crystal violet had increased the sensitivity of the LAMP assay. Other important characteristics were specific target gene primers as well as a shorter incubation time, warranting a good prospect for rapid testing authentication.
Fulltext Encapsulation of Bifidobacterium pseudocatenulatum Strain G4 within Bovine Gelatin-Genipin-Sodium Alginate Combinations: Optimisation Approach Using Face Central Composition Design-Response Surface Methodology (FCCD-RSM)

Khalil KA, Mustafa S, Mohammad R, Ariff AB, Ahmad SA, Dahalan FA, et al.

Int J Microbiol, 2019;2019:4208986.
PMID: 31093290 DOI: 10.1155/2019/4208986

Bovine gelatin is a biopolymer which has good potential to be used in encapsulating matrices for probiotic candidate Bifidobacterium pseudocatenulatum strain G4 (G4) because of its amphoteric nature characteristic. Beads were prepared by the extrusion method using genipin and sodium alginate as a cross-linking agent. The optimisation of bovine gelatin-genipin-sodium alginate combinations was carried out using face central composition design (FCCD) to investigate G4 beads' strength, before and after exposed to simulated gastric (SGF), intestinal fluids (SIF), and encapsulation yield. A result of ANOVA and the polynomial regression model revealed the combinations of all three factors have a significant effect (p < 0.05) on the bead strength. Meanwhile, for G4 encapsulation yield, only genipin showed less significant effect on the response. However, the use of this matrix remained due to the intermolecular cross-linking ability with bovine gelatin. Optimum compositions of bovine gelatin-genipin-sodium alginate were obtained at 11.21% (w/v), 1.96 mM, and 2.60% (w/v), respectively. A model was validated for accurate prediction of the response and showed no significant difference (p > 0.05) with experimental values.
Immunohistochemical, histological and ultrastructural evaluation of protection provided by cholera vaccine against V. cholerae O139

Murugaiah C, Nik Mohd Noor NZ, Al-Talib H, Mustafa S, Manickam R, Pattabhiraman L

Microb Pathog, 2020 Mar;140:103964.
PMID: 31904450 DOI: 10.1016/j.micpath.2020.103964

In our previous study, complete protection was observed in rabbit immunized with 1 × 1010 CFU of live attenuated VCUSM21P vaccine against challenge with 1 × 109 CFU Vibrio cholerae O139. In the present study, we investigated whether the vaccines can effectively protect immunized animals from any pathologic changes using histological, immunohistochemical and ultrastructural techniques. Severe pathology is evident in wild type injected ileum in non-immunized, showing extensive villous destruction, edema, necrosis and inflammation with infiltration of large numbers of inflammatory cells, extensive damage to the villi and microvilli with pore formation. Histology of ileum injected with wild type in immunized rabbit shows no significant pathological changes except for a few inflammatory cells in lamina propria with mild edema in mucosa and submucosa. immunohistochemical staining revealed O139 antigens of wild type are seen in the lamina propria of edematous villi, muscularis mucosa and submucosa with weak presence in the muscle coat in non-immunized rabbit after challenged with wild type in non-immunized rabbits, but in immunized rabbit localisation of the O139 LPS antigen is seen at the tips of the intact villi, within lamina propria and muscularis mucosa only. These observations suggest that the vaccine can effectively protect animals from any pathologic changes and eliminate V. cholerae O139 from the immunized animals.
Potential authentication of various meat-based products using simple and efficient DNA extraction method

Khairil Mokhtar NF, El Sheikha AF, Azmi NI, Mustafa S

J Sci Food Agric, 2020 Mar 15;100(4):1687-1693.
PMID: 31803942 DOI: 10.1002/jsfa.10183

BACKGROUND: The growth of halal food consumption worldwide has resulted in an increase in the request for halal authentication. DNA-based detection using powerful real-time polymerase chain reaction (PCR) technique has been shown to be highly specific and sensitive authentication tool. The efficient DNA extraction method in terms of quality and quantity is a backbone step to obtain successful real-time PCR assays. In this study, different DNA extraction methods using three lysis buffers were evaluated and developed to recommend a much more efficient method as well as achieve a successful detection using real-time PCR.
RESULTS: The lysis buffer 2 (LB2) has been shown to be the best lysis buffer for DNA extraction from both raw and processed meat samples comparing to other lysis buffers tested. Hence, the LB2 has been found to be ideal to detect meat and porcine DNAs by real-time PCR using pairs of porcine specific primers and universal primers which amplified at 119 bp fragment and 93 bp fragment, respectively. This assay allows detection as low as 0.0001 ng of DNA. Higher efficiency and sensitivity of real-time PCR via a simplified DNA extraction method using LB2 have been observed, as well as a reproducible and high correlation coefficient (R2 = 0.9979) based on the regression analysis of the standard curve have been obtained.
CONCLUSION: This study has established a fast, simple, inexpensive and efficient DNA extraction method that is feasible for raw and processed meat products. This extraction technique allows an accurate DNA detection by real-time PCR and can also be implemented to assist the halal authentication of various meat-based products available in the market. © 2019 Society of Chemical Industry.
A survey on smartphone dependence and psychological effects among undergraduate students in a Malaysian University

Nasser NS, Loh JL, Rashid AA, Sharifat H, Ahmad U, Ibrahim B, et al.

Med J Malaysia, 2020 07;75(4):356-362.
PMID: 32723994

OBJECTIVE: Problematic smartphone use (PSU) is the development of pathological dependence at the expense of performing activities of daily living, thus having negative health and psychological impact on the users. Previous PSU studies focused on medical students and little is known regarding its effect on students undergoing other courses. The objective of this study is to identify the pattern of smartphone usage and determine the psychological factors affecting PSU among undergraduate students in Malaysia and compare the pattern among students from different fields of study.
METHOD: A prospective cross-sectional study was conducted using the validated Smartphone Addiction Scale-Malay version (SAS-M) questionnaire. One-way ANOVA was used to determine the correlation between the PSU among the students categorised by their ethnicity, hand dominance and by their field of study. MLR analysis was applied to predict PSU based on socio-demographic data, usage patterns, psychological factors and fields of study.
RESULTS: A total of 1060 students completed the questionnaire. Most students had some degree of problematic usage of the smartphone. Students used smartphones predominantly to access SNAs, namely Instagram. Longer duration on the smartphone per day, younger age at first using a smartphone and underlying depression carried higher risk of developing PSU, whereas the field of study (science vs. humanities based) did not contribute to an increased risk of developing PSU.
CONCLUSION: Findings from this study can help better inform university administrators about at- risk groups of undergraduate students who may benefit from targeted intervention designed to reduce their addictive behaviour patterns.
Fulltext An integrated linkage map of interspecific backcross 2 (BC2) populations reveals QTLs associated with fatty acid composition and vegetative parameters influencing compactness in oil palm

Yaakub Z, Kamaruddin K, Singh R, Mustafa S, Marjuni M, Ting NC, et al.

BMC Plant Biol, 2020 Jul 29;20(1):356.
PMID: 32727448 DOI: 10.1186/s12870-020-02563-5

BACKGROUND: Molecular breeding has opened new avenues for crop improvement with the potential for faster progress. As oil palm is the major producer of vegetable oil in the world, its improvement, such as developing compact planting materials and altering its oils' fatty acid composition for wider application, is important.
RESULTS: This study sought to identify the QTLs associated with fatty acid composition and vegetative traits for compactness in the crop. It integrated two interspecific backcross two (BC2) mapping populations to improve the genetic resolution and evaluate the consistency of the QTLs identified. A total 1963 markers (1814 SNPs and 149 SSRs) spanning a total map length of 1793 cM were integrated into a consensus map. For the first time, some QTLs associated with vegetative parameters and carotene content were identified in interspecific hybrids, apart from those associated with fatty acid composition. The analysis identified 8, 3 and 8 genomic loci significantly associated with fatty acids, carotene content and compactness, respectively.
CONCLUSIONS: Major genomic region influencing the traits for compactness and fatty acid composition was identified in the same chromosomal region in the two populations using two methods for QTL detection. Several significant loci influencing compactness, carotene content and FAC were common to both populations, while others were specific to particular genetic backgrounds. It is hoped that the QTLs identified will be useful tools for marker-assisted selection and accelerate the identification of desirable genotypes for breeding.
Solute transport modelling to manage groundwater pollution from surface water resources

Mustafa S, Bahar A, Aziz ZA, Darwish M

J Contam Hydrol, 2020 Aug;233:103662.
PMID: 32569923 DOI: 10.1016/j.jconhyd.2020.103662

This article provides an analytical solute transport model to investigate the potential of groundwater contamination by polluted surface water in a two dimensional domain. The clogging of streambed which makes the aquifer partially penetrated by the stream, is considered in the model. The impacts of pumping process, hydraulic conductivity and clogging layer on the quality of water produced from nearby drinking water wells are evaluated. It is found that results are consistent with numerical simulation conducted by MODFLOW software. Moreover, the model is applied using data of contamination occurrence in Malaysia, where high contaminants concentrations are found close to streams. Results show that the pumping activities (rate and time period) are crucial factors when evaluating the risk of groundwater contamination from surface water. Additionally, this study illustrates that the increase in either hydraulic conductivity or leakance coefficient parameters due to the clogging layer will enlarge the area of contamination. The model is able to determine the suitable pumping rate and location of the well so that the contamination plume never reaches the extraction well, which is useful in constructing riverbank filtration sites.
Diel osmorespiration rhythms of juvenile marble goby (Oxyeleotris marmorata)

Lim LS, Tan SY, Tuzan AD, Kawamura G, Mustafa S, Rahmah S, et al.

Fish Physiol Biochem, 2020 Aug;46(4):1621-1629.
PMID: 32430644 DOI: 10.1007/s10695-020-00817-5

Oxyeleotris marmorata is an ambush predator. It is known for slow growth rate and high market demand. Farming of O. marmorata still remains a challenge. In order to establish a proper feeding practice to stimulate growth, knowledge of its metabolic processes and cost should be examined. Therefore, this study was designed to investigate the diel osmorespiration rhythms of O. marmorata in response to feeding challenge by using an osmorespirometry assay. The results have shown that oxygen consumption rate of the fed fish was approximately 3 times higher than that of the unfed fish in early evening to support specific dynamic action. Digestion and ingestion processes were likely to be completed within 18-20 h in parallel with the ammonia excretion noticeable in early morning. Under resting metabolism, metabolic oxygen consumption was influenced by diel phase, but no effect was noted in ammonia excretion. As a nocturnal species, O. marmorata exhibited standard aerobic metabolic mode under dark phase followed by light phase, with high oxygen consumption rate found in either fed or unfed fish. It can be confirmed that both the diel phase and feeding have a significant interactive impact on oxygen consumption rate, whereas ammonia metabolism is impacted by feeding state. High metabolic rate of O. marmorata supports the nocturnal foraging activity in this fish. This finding suggested that feeding of O. marmorata should be performed during nighttime and water renewal should be conducted during daytime.
Influence of Culture Conditions and Medium Compositions on the Production of Bacteriocin-Like Inhibitory Substances by Lactococcus lactis Gh1

Jawan R, Abbasiliasi S, Tan JS, Mustafa S, Halim M, Ariff AB

Microorganisms, 2020 Sep 23;8(10).
PMID: 32977375 DOI: 10.3390/microorganisms8101454

Antibacterial peptides or bacteriocins produced by many strains of lactic acid bacteria have been used as food preservatives for many years without any known adverse effects. Bacteriocin titres can be modified by altering the physiological and nutritional factors of the producing bacterium to improve the production in terms of yield and productivity. The effects of culture conditions (initial pH, inoculum age and inoculum size) and medium compositions (organic and inorganic nitrogen sources; carbon sources) were assessed for the production of bacteriocin-like inhibitory substances (BLIS) by Lactococcus lactis Gh1 in shake flask cultures. An inoculum of the mid-exponential phase culture at 1% (v/v) was the optimal age and size, while initial pH of culture media at alkaline and acidic state did not show a significant impact on BLIS secretion. Organic nitrogen sources were more favourable for BLIS production compared to inorganic sources. Production of BLIS by L. lactis Gh1 in soytone was 1.28-times higher as compared to that of organic nitrogen sources ((NH4)2SO4). The highest cell concentration (XmX = 0.69 ± 0.026 g·L-1) and specific growth rate (μmax = 0.14 h-1) were also observed in cultivation using soytone. By replacing carbon sources with fructose, BLIS production was increased up to 34.94% compared to BHI medium, which gave the biomass cell concentration and specific growth rate of 0.66 ± 0.002 g·L-1 and 0.11 h-1, respectively. It can be concluded that the fermentation factors have pronounced influences on the growth of L. lactis Gh1 and BLIS production. Results from this study could be used for subsequent application in process design and optimisation for improving BLIS production by L. lactis Gh1 at larger scale.

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