Siti Aminah Mohd Hassan
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Preferred name
Siti Aminah Mohd Hassan
Official Name
Siti Aminah, Mohd Hassan
Alternative Name
Mohd Hassan, S.A.
Mohd Hassan, Siti Aminah
S.A., Mohd Hassan
Main Affiliation
Scopus Author ID
57200985065
Researcher ID
CSU-9112-2022

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Growth Optimisation of Bacillus subtilis in medium supplemented with prebiotic gum Arabic

2020-12-18 , Norhidayah Abd Aziz , Noor Hasyierah Mohd Salleh , Adilah Anuar , Amira Farzana Samat , Lian Ou Li , Siti Aminah Mohd Hassan , Abu Hassan A.F.

Bacillus subtilis is a type of gastrointestinal bacteria that build up a healthy gut microbiota. The bacterial species has been well documented to involve in maintaining a healthy gut homeostasis in which disruption in it's microbial composition or "dysbiosis"has recently been linked to obesity. Probiotic in vivo restoration of dysbiosed microbiota have been proved successful in obese CD-1 mice model. However, prebiotic study using Gum Arabic (GA) assessing to optimise an in vitro lumen system specifically targeting to enhance the growth of B. subtilis are still lacking since this bacteria are depleted in obese individuals. Thus, this study aimed to establish the optimal growth conditions in simulated in vitro lumen system and to the best of our knowledge, this is the first in vitro study attempted to optimize the growth of B. subtilis in medium supplemented with prebiotic GA. Growth screening analysis suggested an optimal dosage of 1.0% and 0.5% glucose and GA, respectively. The highest growth rate was recorded at 0.7995 hours-1 with doubling time of 52.02 minutes with extended period of stationary phase. The optimal GA concentration and fermentation conditions were determined at 0.67%, pH 7.4 and temperature of 37 C. The validated suggested model indicates that the supplementation of GA into an optimal fermentation systems is promising to enhance the growth of gut microflora Bacillus subtilis, for restoration of a dysbiosed gut microbiota in vitro.

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Evaluation of various lignocellulosic biomass and cereal grains as potential spawn materials for wild Schizophyllum commune cultivation

2020-12-18 , Siti Aminah Mohd Hassan , Sam Sung Ting , Nur Zatul 'Iffah Zakaria , Norhidayah Abd Aziz , Zarina Zakaria , Nurfatirah N. , Azhar M.

Rapid mycelium growth in spawn production and on growth substrate could suppress contamination, which is significant in mushroom industry. The aim of the study is to investigate the potential of lignocellulosic biomass waste as new materials alternative to common cereal grains in producing spawn for wild S. commune cultivation on rice husk, paddy straw, and rubber wood sawdust. The fastest mycelium growth among lignocellulosic biomass was found on rice husk spawn (1.27 cm/day) and 1.98 cm/day for wheat grain. The shortest duration for substrate colonization for both lignocellulosic and grain spawn is on paddy straw, followed by rice husk, and rubber wood sawdust.

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Optimization of Sodium Hydroxide pretreatment and enzymatic saccharification of spent rubberwood sawdust for glucose production

2014 , Siti Aminah Mohd Hassan

Large quantities of oyster mushroom spent medium (MSM) were disposed of as agricultural waste to the environment and thereby constituting environmental pollution. Economic reuse of the waste mushroom medium to produce glucose might be a viable solution instead of disposal. Therefore, the study was conducted to improve the added value of mushroom spent medium as an alternative glucose source to the current expensive sugar crops and starchy products. Firstly, the chemical characteristics, surface morphology, and suitability of mushroom spent medium in comparison to rubber sawdust (RSD) and growth medium (GM) were examined in order to investigate its potential as a new glucose feedstock. The composition analysis proved that decreases in lignocellulosic contents occurred after cultivation of Pleurotus sajor caju. The amount of lignin, hemicelluloses, and cellulose in MSM showed lower values than those in RSD and GM which were 22.40, 27.93, and 27.97% respectively. The surface morphology of MSM appeared to be rough and broken and traces of hyphen on the fibre surface were observed as a result from the mushroom cultivation process. RSD and FM had an even and smooth flat surface, indicating a rigid and highly ordered surface structure. Preliminary study on effectiveness and feasibility of the three pretreatment techniques (autoclaving at 121°C, heating in water bath, soaking at room temperature) with different NaOH concentration on RSD, GM, and MSM revealed the best result of 30.13 g glucose/100g dry substrate and 33.50% of hydrolysis weight decrease obtained from MSM, which had been treated in water bath at 90°C for 2 h. The scanning electron microscope (SEM) images of the corresponding MSM hydrolysate showed severe disruptions of biomass structure, irregular cracks, and pores. One factor at a time (OFAT) method was applied to screen the range of parameters in NaOH pretreatment via heating in water bath and enzymatic saccharification. With known parameters’ range, the Response surface methodology (RSM) based on Box-Behnken Design (BBD) was adopted to optimize the conditions of NaOH pretreatment via heating in water bath method and enzymatic saccharification of MSM. The optimum conditions of MSM pretreatment at substrate loading of 5.0% (w/v) were found to be NaOH concentration of 2.63 M, reaction temperature of 92.26°C, and treatment time of 112.92 min with maximum glucose yield of 34.55 g/100g dry substrate after 48 h of enzymatic saccharification at constant enzyme loading of 67 FPU/g dry substrate and substrate loading of 1.0% (w/v). The MSM hydrolysate obtained under optimal NaOH pretreatment conditions were further used to optimize enzymatic saccharification conditions at constant substrate loading of 1.0% (w/v). Under optimized conditions (agitation rate of 150.74 rpm, enzyme loading of 94.92 FPU/g substrate, and hydrolysis time of 56.89 h), a maximum glucose yield of 71.21 g/100 g dry substrate was achieved. The Analysis of Variance (ANOVA) test revealed that the model and all independent parameters were considered statistically significant at 95% for both optimization studies using the second order polynomial equation. The model validation showed a good agreement between experimental results and the predicted responses. Therefore the models could be successfully used to identify the effective combinations of the three different factors in both optimization studies for predicting the glucose yield from MSM.

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