In the era dominated by plastic, the widespread use of plastic in our daily lives has led to a growing accumulation of its degraded byproducts, such as microplastics and plastic additives like Bisphenol A (BPA). BPA is recognized as one of the earliest man-made substances that exhibit endocrine-disrupting properties. It is frequently employed in the manufacturing of epoxy resins, polycarbonates, dental fillings, food storage containers, infant bottles, and water containers. BPA is linked to a range of health issues including obesity, diabetes, chronic respiratory illnesses, cardiovascular diseases, and reproductive abnormalities. This study examines the bacterial bioremediation of the BPA, which is found in many sources and is known for its hazardous effects on the environment. The metabolic pathways for the breakdown of BPA in important bacterial strains were hypothesized based on the observed altered intermediate metabolites during the degradation of BPA. This review discusses the enzymes and genes involved in the bacterial degradation of BPA. The utilization of naturally occurring microorganisms is the most efficient and cost-effective method due to their selectivity of strains, ensuring sustainability.
The delineation of the complex biosynthesis of the potent antibiotic mupirocin, which consists of a mixture of pseudomonic acids (PAs) isolated from Pseudomonas fluorescens NCIMB 10586, presents significant challenges, and the timing and mechanisms of several key transformations remain elusive. Particularly intriguing are the steps that process the linear backbone from the initial polyketide assembly phase to generate the first cyclic intermediate PA-B. These include epoxidation as well as incorporation of the tetrahydropyran (THP) ring and fatty acid side chain required for biological activity. Herein, we show that the mini-module MmpE performs a rare online (ACP-substrate) epoxidation and is integrated ('in-cis') into the polyketide synthase via a docking domain. A linear polyketide fragment with six asymmetric centres was synthesised using a convergent approach and used to demonstrate substrate flux via an atypical KS0 and a previously unannotated ACP (MmpE_ACP). MmpE_ACP-bound synthetic substrates were critical in demonstrating successful epoxidation in vitro by the purified MmpE oxidoreductase domain. Alongside feeding studies, these results confirm the timing as well as chain length dependence of this selective epoxidation. These mechanistic studies pinpoint the location and nature of the polyketide substrate prior to the key formation of the THP ring and esterification that generate PA-B.
Nannochloropsis sp. wet biomass was directly transesterified under microwave (MW) irradiation in the presence of methanol and various alkali and acid catalyst. Two different types of direct transesterification (DT) were used; one step and two step transesterification. The biodiesel yield obtained from the MWDT was compared with that obtained using conventional method (lipid extraction followed by transesterification) and water bath heating DT method. Findings revealed that MWDT efficiencies were higher compared to water bath heating DT by at least 14.34% and can achieve a maximum of 43.37% with proper selection of catalysts. The use of combined catalyst (NaOH and H2SO4) increased the yield obtained by 2.3-folds (water bath heating DT) and 2.87-folds (MWDT) compared with the one step single alkaline catalyst respectively. The property of biodiesel produced by MWDT has high lubricating property, good cetane number and short carbon chain FAME's compared with water bath heating DT.
Six weed species (Leptochola chinensis, Echinochloa crus-galli, Echinochloa colona, Jussiaea linifolia, Oryza sativa (weedy rice) and Cyperus iria) were tested for their salt tolerant traits in terms of chlorophyll, proline and mineral nutrients accumulation against different salinity levels (0, 4, 8, 16, 24, 32, and 40 dS m(-1)). Chlorophyll a, b and total chlorophyll content, proline and mineral nutrients accumulation were determined. Salt stress showed prominent effect on all the parameters investigated and there were significant variations between the all weed species. Chlorophyll content, K+, Ca(2+) and Mg(2+) ions in both shoots and roots significantly decreased; while proline and Na+ accumulation significantly increased with increasing salinity up to 40 dS m(-1). In terms of overall performance, Cyperus iria and E. crus-galliwere relatively more tolerant; E. colona and J. linifolia were tolerant; L. chinensis and O. sativa L were salt sensitive, respectively.
The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C). A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a V max for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent K m for NADH was 0.79 mM. At 5 mM NADH, the apparent V max and apparent K m values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (k cat/K m ) of the Mo-reducing enzyme was 5.47 M(-1) s(-1). The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction.
Preserved human amniotic membrane either air dried or glycerol preserved has been used effectively to treat superficial and partial thickness wounds without leaving any obvious hypertrophic scar. The preserved amnion, sterilised by ionising radiation, is known as an effective barrier for heat, fluid and protein loss while adheres nicely on wound. Air drying slightly reduced the oxygen transmission rate (OTR) of the amnion and the value significantly dropped after 15 kGy (p < 0.05). Glycerol preservation significantly reduced (p < 0.05) the OTR indicating less oxygen transmitted through the well structured cells of the amnion. Increase in the OTR with the increasing radiation doses up to 35 kGy possibly due to direct effects of radiation that resulted in large intercellular gaps. Both preservation methods significantly increased (p < 0.05) the water vapour transmission rate (WVTR). However, the low WVTR in the air dried amnion at 15 and 25 kGy was postulated due to cross-linking of collagen. Changes in the biophysical properties can be linked to direct and indirect effects of radiation on collagen bundles. The radiation dose of 25 kGy caused no adverse effect on biophysical properties hence it is still acceptable to sterilize both the air dried and the glycerol preserved amnions.
Astaxanthin, a carotenoid pigment found in several aquatic organisms, is responsible for the red colour of salmon, trout and crustaceans. In this study, astaxanthin production from freshwater microalga Chlorella sorokiniana and marine microalga Tetraselmis sp. was investigated. Cell growth and astaxanthin production were determined spectrophotometrically at 620 and 480 nm, respectively. Astaxanthin was extracted using acetone and measured subsequent to biomass removal. Aerated conditions favoured astaxanthin production in C. sorokiniana, whereas Tetraselmis sp. was best cultured under unaerated conditions. C. sorokiniana produced more astaxanthin with the highest yield reached at 7.83 mg/l in 6.0 mM in nitrate containing medium compared to Tetraselmis sp. which recorded the highest yield of only 1.96 mg/l in 1.5 mM nitrate containing medium. Production in C. sorokiniana started at the early exponential phase, indicating that astaxanthin may be a growth-associated product in this microalga. Further optimization of astaxanthin production was performed using C. sorokiniana through a 2(3) full factorial experimental design, and a yield of 8.39 mg/l was achieved. Overall, the study has shown that both microalgae are capable of producing astaxanthin. Additionally, this research has highlighted C. sorokiniana as a potential astaxanthin producer that could serve as a natural astaxanthin source in the current market.
An extractive bioconversion with Bacillus cereus cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) in aqueous two-phase system (ATPS) was investigated for the synthesis and recovery of cyclodextrins (CDs). Optimum condition for the extractive bioconversion of CDs was achieved in ATPS consisted of 7.7% (w/w) polyethylene glycol (PEG) 20,000 and 10.3% (w/w) dextran T500 with volume ratio (VR) of 4.0. Enzymatic conversion of starch occurred mainly in dextran-rich bottom phase whereas the product, CDs was transferred to top phase and a higher partition coefficient of CDs was achieved. Repetitive batch of CDs synthesis was employed by replenishment of the top phase components and addition of starch every 8h. An average total CDs concentration of 13.7 mg/mL, (4.77 mg/mLα-CD, 5.02 mg/mLβ-CD and 3.91 mg/mLγ-CD) was recovered in the top phase of PEG 20,000/dextran T500 ATPS. This study showed the effectiveness of ATPS application in extractive bioconversion of CDs synthesis with B. cereus CGTase.
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has been extensively studied for its preferential ability to induce apoptosis of cancer cells. Beyond the cytotoxic capacity of TRAIL, new physiological and pathological roles for TRAIL have been identified, and there is now growing evidence supporting its involvement in the development of obesity and diabetes. This review summarizes the most recent findings associating TRAIL with obesity and diabetes in both humans and experimental settings. We also present and discuss some of the reported controversies behind TRAIL signaling and function. Understanding TRAIL mechanism(s) in vivo and its involvement in disease may lead to novel strategies to combat the growing pandemic of obesity and diabetes worldwide.
Salmonella enterica serovar Typhi (S. Typhi) is strictly a human intracellular pathogen. It causes acute systemic (typhoid fever) and chronic infections that result in long-term asymptomatic human carriage. S. Typhi displays diverse disease manifestations in human infection and exhibits high clonality. The principal factors underlying the unique lifestyle of S. Typhi in its human host during acute and chronic infections remain largely unknown and are therefore the main objective of this study.
Armillaria sp. F022, a white-rot fungus isolated from decayed wood in tropical rain forest was used to biodegrade anthracene in cultured medium. The percentage of anthracene removal by Armillaria sp. F022 reached 13 % after 7 days and at the end of the experiment, anthracene removal level was at 87 %. The anthracene removal through sorption and transformation was investigated. 69 % of eliminated anthracene was transformed by Armillaria sp. F022 to form other organic structure, while only 18 % was absorbed in the mycelia. In the kinetic experiment, anthracene dissipation will not stop even though the biomass had stopped growing. Anthracene removal by Armillaria sp. F022 was correlated with protein concentration (whole biomass) in the culture. The production of enzyme was affected by biomass production. Anthracene was transformed to two stable metabolic products. The metabolites were extracted in ethyl-acetate, isolated by column chromatography, and then identified using gas chromatography-mass spectrometry (GC-MS).
We attempted to synthesize a polyhydroxyalkanoate (PHA) containing newly reported 3-hydroxy-4-methylvalerate (3H4MV) monomer by using wild type Burkholderia sp. USM (JCM15050) and its transformed strain harboring the PHA synthase gene of Aeromonas caviae (phaCAc). The introduction of 3H4MV as a second monomer will improve the material properties of 3HB-based polymers. To promote the accumulation of PHA containing 3H4MV monomer, isocaproic acid was provided as co-carbon source. Approximately 1mol% of 3H4MV was detected in wild type Burkholderia sp. cultures when they were fed glucose or fructose together with isocaproic acid. Thus, the wild type strain can synthesize the 3H4MV monomer. High 3H4MV fractions, of about 40mol%, were obtained when the transformed strain was cultivated on glucose or fructose together with isocaproic acid. In addition, the ability of the transformed strain to mobilize accumulated PHA containing 3H4MV monomer was demonstrated in this study. This is the first report on mobilization of the 3H4MV monomer.
Agricultural waste, such as sago waste (SW), is one of the sources of pollution to streams and rivers in Sarawak, particularly those situated near sago processing plants. In addition, unbalanced and excessive use of chemical fertilizers can cause soil and water pollution. Humic substances can be used as organic fertilizers, which reduce pollution. The objectives of this study were to produce K- and ammonium-based organic fertilizer from composted SW and to determine the efficiency of the organic-based fertilizer produced. Humic substances were isolated using standard procedures. Liquid fertilizers were formulated except for T2 (NPK fertilizer), which was in solid form. There were six treatments with three replications. Organic fertilizers were applied to soil in pots on the 10th day after sowing (DAS), but on the 28th DAS, only plants of T2 were fertilized. The plant samples were harvested on the 57th DAS during the tassel stage. The dry matter of plant parts (leaves, stems, and roots) were determined and analyzed for N, P, and K using standard procedures. Soil of every treatment was also analyzed for exchangeable K, Ca, Mg, and Na, organic matter, organic carbon, available P, pH, total N, P, nitrate and ammonium contents using standard procedures. Treatments with humin (T5 and T6) showed remarkable results on dry matter production; N, P, and K contents; their uptake; as well as their use efficiency by maize. The inclusion of humin might have loosened the soil and increased the soil porosity, hence the better growth of the plants. Humin plus inorganic fertilizer provided additional nutrients for the plants. The addition of inorganic fertilizer into compost is a combination of quick and slow release sources, which supplies N throughout the crop growth period. Common fertilization by surface application of T2 without any additives (acidic and high CEC materials) causes N and K to be easily lost. High Ca in the soil may have reacted with phosphate from fertilizer to form Ca phosphate, an insoluble compound of phosphate that is generally not available to plants, especially roots. Mixing soil with humin produced from composted SW before application of fertilizers (T5 and T6) significantly increased maize dry matter production and nutrient use efficiency. Additionally, this practice does not only improve N, P, and K use efficiency, but it also helps to reduce the use of N-, P-, and K-based fertilizers by 50%.
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) [P(3HB-co-3HV-co-4HB)] terpolymer was produced using Cupriavidus sp. USMAA2-4 via one-step cultivation process through combination of various carbon sources such as 1,4-butanediol or γ-butyrolactone with either 1-pentanol, valeric acid, or 1-propanol. Oleic acid was added to increase the biomass production. The composition of 3HV and 4HB monomers were greatly affected by the concentration of 1,4-butanediol and 1-pentanol. Terpolymers with 3HV and 4HB molar fractions ranging from 2 to 41 mol.% and 5 to 31 mol.%, respectively, were produced by varying the concentration of carbon precursors. The thermal and mechanical properties of the terpolymers containing different proportions of the constituent monomers were characterized using gel permeation chromatography (GPC), DSC, and tensile machine. GPC analysis showed that the molecular weights (M (w)) of the terpolymer produced were within the range of 346 to 1,710 kDa. The monomer compositions of 3HV and 4HB were also found to have great influences on the thermal and mechanical properties of the terpolymer P(3HB-co-3HV-co-4HB) produced.
Poly(3-hydroxybutyrate-co-38 mol%-3-hydroxyvalerate) [P(3HB-co-38mol%-3HV)] was produced by Cupriavidus sp. USMAA2-4 in the presence of oleic acid and 1-pentanol. Due to enormous production of empty fruit bunch (EFB) in the oil palm plantation and high production cost of P(3HB-co-3HV), oil palm EFB fibers were used for biocomposites preparation. In this study, maleic anhydride (MA) and benzoyl peroxide (DBPO) were used to improve the miscibility between P(3HB-co-3HV) and EFB fibers. Introduction of MA into P(3HB-co-3HV) backbone reduced the molecular weight and improved the thermal stability of P(3HB-co-3HV). Thermal stability of P(3HB-co-3HV)/EFB composites was shown to be comparable to that of commercial packaging product. Composites with 35% EFB fibers content have the highest tensile strength compared to 30% and 40%. P(3HB-co-3HV)/EFB blends showed less chemicals leached compared to commercial packaging.
Terpenes and terpenoids are among the key impact substances in the food and fragrance industries. Equipped with pharmacological properties and applications as ideal precursors for the biotechnological production of natural aroma chemicals, interests in these compounds have been escalating. Hence, the syntheses of new derivatives that can show improved properties are often called for. Stereoselective biotransformation offers several benefits to increase the rate of production, in terms of both the percentage yield and its enantiomeric excesses. Baker's yeast (Saccharomyces cerevisiae) is broadly used as a whole cell stereospecific reduction biocatalyst, due to its capability in reducing carbonyls and carbon-carbon double bonds, which also extends its functionality as a versatile biocatalyst in terpenoid biotransformation. This review provides some insights on the development and prospects in the reductive biotransformation of monoterpenoids and sesquiterpenoids using S. cerevisiae, with an overview of strategies to overcome the common challenges in large-scale implementation.
Plant cell culture technology is potentially useful in producing high-valued secondary metabolites. Eurycoma longifolia root extracts are consumed as a health tonic but more popularly used as an aphrodisiac. Studies on the aphrodisiac properties and the possible compounds involved have been widely studied. There are many potentially useful compounds reported from the root extracts of E. longifolia. However, studies on the in vitro production of useful compounds from this plant have not been reported. This chapter will describe methods of callus induction and extraction of 9-methoxycanthin-6-one from E. longifolia Jack explants with emphasis on the tap and fibrous roots. This compound, known to have anti-tumour activity, is present in intact plant parts and in callus tissues of different explants.
The combination of plant oils and 3-hydroxyvalerate (3HV) precursors were evaluated for the biosynthesis of polyhydroxyalkanoate (PHA) copolymers containing 3HV monomers by Cupriavidus necator H16. Among various mixtures of plant oils and 3HV-precursors, the mixture of palm kernel oil and sodium propionate was suitable for the biosynthesis of high concentration of PHA (6.8gL(-1)) containing 7mol% of 3HV. The 3HV monomer composition can be regulated in the range of 0-23mol% by changing culture parameters such as the initial pH, and the nitrogen source and its concentration. PHA copolymers with high weight-average molecular weights (Mw) ranging from 1,400,000 to 3,100,000Da were successfully produced from mixtures of plant oils and 3HV-precursors. The mixture of plant oils and sodium propionate resulted in PHA copolymers with higher M(w) compared to the mixture of plant oils and sodium valerate. DSC analysis on the PHA containing 3HV monomers showed the presence of two distinct melting temperature (Tm), which indicated that the PHA synthesized might be a blend of P(3HB) and P(3HB-co-3HV). Sodium propionate appears to be the better precursor of 3HV than sodium valerate.
The oil palm sector is one of the major plantation industries in Malaysia. Palm kernel cake is a byproduct of extracted palm kernel oil. Mostly palm kernel cake is wasted or is mixed with other nutrients and used as animal feed, especially for ruminant animals. Recently, palm kernel cake has been identified as an important ingredient for the formulation of animal feed, and it is also exported especially to Europe, South Korea, and Japan. It can barely be consumed by nonruminant (monogastric) animals owing to the high percentages of hemicellulose and cellulose contents. Palm kernel cake must undergo suitable pretreatment in order to decrease the percentage of hemicellulose and cellulose. One of the methods employed in this study is fermentation with microorganisms, particularly fungi, to partially degrade the hemicellulose and cellulose content. This work focused on the production of enzymes by Aspergillus niger and profiling using palm kernel cake as carbon source.
Brain oedema is thought to form and to clear through the use of water-protein channels, aquaporin-4 (AQP4), which are found in the astrocyte endfeet. The model developed here is used to study the function of AQP4 in the formation and elimination of oedema fluid in ischaemia-reperfusion injury. The cerebral space is assumed to be made of four fluid compartments: astrocyte, neuron, ECS and blood microvessels, and a solid matrix for the tissue, and this is modelled using multiple-network poroelastic theory. AQP4 allows the movement of water between astrocyte and the ECS and the microvessels. It is found that the presence of AQP4 may help in reducing vasogenic oedema shown by a decrease in brain tissue extracellular pressure. However, the astrocyte pressure will increase to compensate for this decrease, which may lead to cytotoxic oedema. In addition, the swelling will also depend on the ionic concentrations in the astrocyte and extracellular space, which may change after ischaemic stroke. Understanding the role of AQP4 in oedema may thus help the development of a treatment plan in reducing brain swelling after ischaemia-reperfusion.