Utilization of Agricultural By-Products for Alpha-Amylase Production under Solid State Fermentation by Bacillus Subtilis

The production of alpha-amylase by Bacillus subtilis was investigated under different cultivation conditions on two different solid substrates as the support, i.e. oil palm empty fruit bunch (OPEFB) and rice straw fibers using solid state fermentation (SSF) process. Both solid substrates were first pre-treated using NaOH to remove lignin and silica and to break down the hemicellulose structures. The influences of incubation time, incubation temperature and the additional carbon and nitrogen sources on the production of alpha-amylase by B. subtilis were investigated. After 48 h of incubation, the highest enzyme activities were obtained at 39.9 U/g and 23.5 U/g for rice straw and OPEFB fibers, respectively. The optimum temperature for alpha-amylase production was observed at 45°C for the OPEFB fibers and 55°C for the rice straw fibers. Among the defined carbohydrates, the addition of glucose (0.02 g/g dry substrate) has significantly improved the production of alpha-amylase. Similar effect was observed when yeast extract (0.01 g/g dry substrate) was supplemented as the additional nitrogen source. Rice straw fibers appeared to be the best solid substrate in producing alpha-amylase (276 U/g) in SSF under these optimum cultivation conditions

Polycyclic aromatic hydrocarbons (PAHs) levels and toxicity in herbal teas marketed in Malaysia using QuEChERS and GC-FID

In line with the growing health trend in Malaysia, more consumers drink herbal tea for medicinal benefits. However, herbal tea products could be contaminated with polycyclic aromatic hydrocarbons (PAHs) from various production sources. There is a little study focused on the detection of PAHs in herbal tea species distributed in Malaysia. This study was performed to investigate PAHs content and toxicity in selected commercial herbal teas in Malaysia. A total of seven different Malaysian herbal tea samples were extracted using QuEChERS extraction method and the contamination level of PAHs were evaluated using gas chromatography (GC) with a flame ionization detector (FID). The total content of 10 PAHs (Σ10PAHs) in the herbal tea samples ranged from 2.53 to 9.39 μg/kg. Acenaphthene, fluorene, phenanthrene and anthracene were the most abundant compounds with 53% contribution of all PAHs content. All tested herbal teas species showed low toxic equivalency (TEQ) values ranging from 0.0027 to 0.1148. The least contaminated samples were Strobilanthes crispus, Senna alata, Orthosiphon aristatus, Clinacanthus nutans, and Stevia rebaudiana

A model for arabidopsis thaliana cell suspension growth and sugar uptake kinetics

In this study, a kinetic model was developed for batch growth and sugar consumption by the cell suspension cultures of Arabidopsis thaliana (A. thaliana) Columbia (Col) ecotype cultivated in the continuous dark condition. The model included sucrose hydrolysis by the cell-wall invertase enzyme into glucose and fructose and consumption of these hexoses at different rates to support cell growth. Several assumptions were made in order to simplify modelling of a complex system. The whole living cells in the culture were treated as one uniform biomass by assuming that all individual living cells are of the same size, shape, mass, age and physiology. In addition, temperature and all concentrations in the system were considered as uniform. All kinetic model parameters were obtained from a control experiment where Col cells were grown on 30 gL-1 sucrose as well as other independent experiments where Col cells were supplied with different concentrations and combinations of sugars. The model adequately described and predicted the growth and sugars profile of A. thaliana cells

A model for arabidopsis thaliana cell suspension growth and sugar uptake kinetics

Arabidopsis thaliana (A. thaliana) is a small weed which is related to the cabbage and mustard family. This flowering plant has been used widely as a model plant in genetics and molecular biology research since it is the first plant the full sequenced genome. Thus, A. thaliana literature provides plentiful information from genomics and transcriptomics point of view. However, there is still a lack of physiological information regarding its cell suspension cultures which can be powerful research tools in Plant Biotechnology and especially in Plant Systems and Synthetic Biology. In this study, cell growth and sugar uptake of A. thaliana Col ecotype grown in the continuous dark condition were modelled using the modified Monod and Michelis-menten equations. The model included sucrose hydrolysis by the cell-wall invertase enzyme into hexoses (glucose and fructose) and consumption of these hexoses at different rates to support cell growth. All kinetic model parameters were obtained from a control experiment where Col cells were grown on 30 gL-1 sucrose as well as other independent experiments where Col cells were supplied with different concentrations and combinations of sugars. The model adequately described and predicted the growth and sugars profile of A. thaliana cells. This model can also be applied for larger scale of growth with extended expressions for oxygen uptake rate, carbon dioxide production rate etc

Evaluation of polycyclic aromatic hydrocarbons (PAHs) in moringa oleifera leaves and infusion

Moringa oleifera infusion is a popular drink among herbal infusion consumers. Although M. oleifera is claimed to have medicinal value and promoted health benefits, it does not be simply considered safe if no specific study is conducted to determine Polycyclic aromatic hydrocarbons (PAHs) content in commercial M. oleifera herbal drink. Therefore, this study was conducted to investigate 10 PAHs content in M. oleifera dried leaves and in its infusion. The second objective was to assess the effect of mass-volume ratio on PAHs content in M. oleifera infusion. PAHs extraction procedure was performed using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method. PAHs determination and quantification were performed using Gas Chromatography and Flame Ionization Detector (GC-FID). The mean of total 10 PAHs (∑10PAH) in M. oleifera dried leaves and infusion ranged from 1.06 µg/kg to 5.51 µg/kg and 0.62 µg/kg to 4.80 µg/kg, respectively. Four different mass-volume ratios were used in this study to determine PAHs content that could be extracted from M. oleifera dried leaves into an infusion; 2:250, 20:250, 10:100, and 10:50. The ratio of 2:250 showed the lowest PAHs content in comparison with other ratios. The PAHs content in M. oleifera dried leaves and infusion have statistically significantly different (p > 0.01) from each other. The toxic equivalency quotient (TEQ) value of M. oleifera dried leaves and infusion ranged from 0.01 to 0.09 and 0.00 to 0.07, respectively. PAHs content in M. oleifera dried leaves and infusions complied with the maximum limit set by Commission Regulation (EU) No. 2015/1933