Ramakrishnan Nagasundara Ramanan

Utilization of plant-based natural coagulants as future alternatives towards sustainable water clarification.

Rapid industrial developments coupled with surging population growth have complicated issues dealing with water scarcity as the quest for clean and sanitized water intensifies globally. Existing fresh water supplies could be contaminated with organic, inorganic and biological matters that have potential harm to the society. Turbidity in general is a measure of water cloudiness induced by such colloidal and suspended matters and is also one of the major criteria in raw water monitoring to meet the stipulated water quality guidelines. Turbidity reduction is often accomplished using chemical coagulants such as alum. The use of alum is widely associated with potential development of health issues and generation of voluminous sludge. Natural coagulants that are available in abundance can certainly be considered in addressing the drawbacks associated with the use of chemical coagulants. Twenty one types of plant-based natural coagulants categorized as fruit waste and others are identified and presented collectively with their research summary in this review. The barriers and prospects of commercialization of natural coagulants in near future are also discussed.

Isolation of Pediococcus acidilactici Kp10 with ability to secrete bacteriocin-like inhibitory substance from milk products for applications in food industry

BackgroundLactic acid bacteria (LAB) can be isolated from traditional milk products. LAB that secrete substances that inhibit pathogenic bacteria and are resistant to acid, bile, and pepsin but not vancomycin may have potential in food applications.ResultsLAB isolated from a range of traditional fermented products were screened for the production of bacteriocin-like inhibitory substances. A total of 222 LAB strains were isolated from fermented milk products in the form of fresh curds, dried curds, and ghara (a traditional flavor enhancer prepared from whey), and fermented cocoa bean. Eleven LAB isolates that produced antimicrobial substances were identified as Lactococcus lactis, Lactobacillus plantarum, and Pediococcus acidilactici strains by biochemical methods and 16S rDNA gene sequencing. Of these, the cell-free supernatant of Kp10 (P. acidilactici) most strongly inhibited Listeria monocytogenes. Further analysis identified the antimicrobial substance produced by Kp10 as proteinaceous in nature and active over a wide pH range. Kp10 (P. acidilactici) was found to be catalase-negative, able to produce β-galactosidase, resistant to bile salts (0.3%) and acidic conditions (pH 3), and susceptible to most antibiotics.ConclusionTraditionally prepared fermented milk products are good sources of LAB with characteristics suitable for industrial applications. The isolate Kp10 (P. acidilactici) shows potential for the production of probiotic and functional foods.

A review on common vegetables and legumes as promising plant-based natural coagulants in water clarification

Abstract Coagulation and flocculation provide a rather straightforward method towards water clarification. However, ongoing debates over worrying health issues linked to chemical coagulants have paved the way to develop plant-based natural coagulants. Natural coagulants are not only water clarifying agents, but they also have antimicrobial and heavy metal removal properties in some instances. These are highly attractive in the transformation of raw surface water into potable drinking water. A total of 14 plant-based natural coagulants categorized as common vegetables and legumes are identified and presented collectively in this comprehensive review. The two main coagulation mechanisms leading to the observed coagulation activities are postulated to be charge neutralization and bridging. Turbidity removal efficiencies were proven to be greatly affected by pH variations and the dosage of natural coagulants used. The existing research gaps are acknowledged in this work to provide a platform towards the necessity of further research in the water treatment processes.

Recovery of Human Interferon Alpha-2b from Recombinant Escherichia coli by Aqueous Two-Phase System

Recovery of periplasmic human recombinant interferon alpha-2b (IFN-α2b) from Escherichia coli rosetta-gami2 (DE3) using a single-step polyethylene glycol (PEG)-potassium phosphate aqueous two-phase system (ATPS) was investigated in this study. The influences of system parameters including PEG molecular weight, tie-line length, volume ratio, crude stock loading, system pH, and sodium chloride (NaCl) concentration (%, w/w) were studied. The results showed that the optimum condition to obtain the high purification factor of IFN-α2b in a single step was achieved by ATPS composed of 4% (w/w) PEG 8000, 13% (w/w) potassium phosphate, 0.5% (w/w) NaCl, 10% (w/w) crude stock, and a system pH of 6.5. A purification factor of 26.3 and recovery yield of 40.7% were obtained from optimized ATPS.

Improved mannan-degrading enzymes’ production by Aspergillus niger through medium optimization

The effect of different carbon and nitrogen sources on the production of mannan-degrading enzymes, focussing on β-mannanase, by Aspergillus niger was investigated using shake flask culture. The β-mannanase activity obtained during growth of A. niger on guar gum (GG, 1495 nkat mL(-1)) was much higher than those observed on other carbon substrates, locust bean gum (1148 nkat mL(-1)), α-cellulose (10.7 nkat mL(-1)), glucose (8.8 nkat mL(-1)) and carboxymethylcellulose (4.6 nkat mL(-1)). For fermentation using GG as a carbon source, bacteriological peptone gave the highest β-mannanase activity (1744 nkat mL(-1)) followed by peptone from meat (1168 nkat mL(-1)), yeast extract (817 nkat mL(-1)), ammonium sulphate (241 nkat mL(-1)), ammonium nitrate (113 nkat mL(-1)) and ammonium chloride (99 nkat mL(-1)) when used as a nitrogen source. The composition of bacteriological peptone and initial pH of the medium were further optimized using response surface methodology (RSM). Medium consisted of 21.3 g L(-1) GG and 57 g L(-1) peptone with initial culture pH of 5.5 was optimum for β-mannanase production (2063 nkat mL(-1)) by A. niger. The β-mannanase production obtained in this study using A. niger was significantly higher than those reported in the literature.

Bioinformatics approaches for improved recombinant protein production in Escherichia coli: protein solubility prediction

The solubility of recombinant protein expressed in Escherichia coli often represents the production yield. However, up-to-date, instances of successful production of soluble recombinant proteins in E. coli expression system with high yield remain scarce. This is mainly due to the difficulties in improving the overall production capacity, as most of the well-established strategies usually involve a series of trial and error steps with unguaranteed success. One way to concurrently improve the production yield and minimize the production cost would be incorporating the potency of bioinformatics tools to conduct in silico studies, which forecasts the outcome before actual experimental work. In this article, we review and compare seven prediction tools available, which predict the solubility of protein expressed in E. coli, using the following criteria: prediction performance, usability, utility, prediction tool development and validation methodologies. This comprehensive review will be a valuable resource for researchers with limited prior experience in bioinformatics tools. As such, this will facilitate their choice of appropriate tools for studies related to enhancement of intracellular recombinant protein production in E. coli.

Review of Microbial Lipase Purification Using Aqueous Two-phase Systems

Microbial lipase has been recognized as one of the important biocatalysts due to its widely diversified enzymatic properties and substrate specificities. With the increased awareness of environmental protection and cost issue, lipase-catalyzed reactions have been viewed as the sustainable replacement for the chemical-driven reactions used in manufacture of biochemical products, biopharmaceuticals, nutraceuticals, foods and agrochemicals. However, production of lipases derived from microbial origin would normally require an effort-intensive purification step owing to the complexity of culture broth and the necessity of retaining lipase’s bioactive state. A great variety of lipases from bacterial and fungal sources have been purified to homogeneity by using general purification strategies such as precipitation and chromatographic separation. As a whole, these traditional purification techniques are usually multi-steps, laborious, non-specific, operated at small scale and potentially unsatisfactory in term of purity level. Alternative purification methods are therefore being explored in order to improve the overall yield and reduce the processing time. Advances in the purification methods have greatly expanded the choices of selection in designing the highly specialized purification scheme for various microbial lipases. This review focuses on the application of aqueous two-phase system (ATPS) as an alternative bioseparation method used in the purification of lipase from microbial sources. Moreover, the integration of ATPS in bioprocessing units such as fermentation as well as other purification technique was also reviewed.

Determination and Optimization of Flavonoid and Extract Yield from Brown Mango using Response Surface Methodology

The optimum extraction conditions to obtain the highest flavonoid content and extract yield from Mangifera pajang pericarp (MPP) were analyzed using response surface methodology (RSM). A full factorial central composite design was used to investigate the effects of ethanol concentration (20–80%), temperature (30–65°C) and liquid to solid ratio (20–50 mL/g) on the recovery of extract yield and flavonoids. A second order polynomial model produced a satisfactory fitting of the experimental data with regard to extract yield (R 2 = 0.9890, p < 0.0001) and flavonoids (R 2 = 0.9652, p < 0.0001). The optimum conditions to obtain higher extract yield, were 54%, 50°C, and 42.4 mL/g, while for flavonoids were 68%, 57°C, and 20.2 mL/g, respectively. The experimental values agreed with those predicted with 99% and 96% confidence interval for extract yield and flavonoids respectively. This indicates the suitability of RSM in optimizing the extraction of flavonoids and extract yield from MPP.

Selection of Experimental Domain using Two-Level Factorial Design to Determine Extract Yield, Antioxidant Capacity, Phenolics, and Flavonoids from Mangifera pajang Kosterm

Mangifera pajang Kosterm. is an important underutilized fruit of Malaysia. Two level factorial design was used for initial screening of the following independent factors, namely pH (2-6), ethanol concentration (20–80%), extraction temperature (30–65°C), time (30–240 min) and liquid to solid ratio (20–50 mL/g) to determine the extract yield, the antioxidant capacity, and the phenolic and flavonoid contents from Mangifera pajang pericarp. Among all the factors, ethanol concentration and liquid to solid ratio was very significant (p < 0.0001) in obtaining higher extract yield, antioxidant capacity, and phenolic content, whereas the pH, the extraction time, and temperature did not contribute significantly. From these results, we conclude that by altering ethanol concentration and liquid to solid ratio, significant differences can be noticed in obtaining high or lower concentrations on the recovery of extract yield, antioxidant capacity, and phenolic content.

Comparison of expression systems for the production of human interferon-α2b

The production of human interferon alpha2b (IFN-α2b) in two expression systems, tobacco (Nicotiana tabaccum) and Escherichia coli, was compared in various aspects such as safety, yield, quality of product and productivity. In the E. coli system, IFN-α2b was expressed under a pelB signal sequence and a T7lac promoter in a pET 26b(+) vector. The same gene was also cloned in expression plant vector (pCAMBIA1304) between cauliflower mosaic virus promoter (CaMV35S) and poly A termination region (Nos) and expressed in transgenic tobacco plants. The expression of protein in both systems was confirmed by western immunoblotting and the quantity of the protein was determined by immunoassay. The amount of periplasmic expression in E. coli was 60 µg/L of culture, while the amount of nuclear expression in the plant was 4.46 µg/kg of fresh leaves. The result of this study demonstrated that IFN-α2b was successfully expressed in periplasm of bacterial and plant systems. The limitations on the production of IFN-α2b by both systems are addressed and discussed to form the basis for the selection of the appropriate expression platform.