Current Biotechnology - Volume 7, Issue 6, 2018

Background: Cassava tuber contains antinutritional compounds and native starch of cassava is not suitable for many food and industrial applications. Modifications by physical, chemical, biological and conventional breeding methods have shortcomings and difficulties. Bioengineering by gene technology is a viable approach to improve starch qualities and remove antinutritional compounds. Objectives: This paper examined the achievements of applications of gene technology to understand starch biosynthesis, production of novel starches, cyacogenic glucosides-free and vitamin A-enriched varieties and set future research goals for safe cassava consumption and expansion of cassava starch functional properties. Method: Searches were conducted for peer-reviewed publications on starch biosynthesis in plants, genetic modification for starch and cyacogenic glucosides synthesis. Quality of the publications was established by the standard method. The information obtained from publications was used to construct the starch biosynthesis pathway in plants, evaluate progress made in molecular understanding and modification of the starch gene. Results: Seven key enzymes involved in starch biosynthesis were identified, including glucan water dikinase for starch degradation. The paper constructed pathway of starch biosynthesis that leads to the generation of amylose and amylopectin polymers in plants. In addition, molecular cloning, phylogenetic relationships, expression pattern, copies number and sequences of four key genes involved in starch biosynthesis in cassava were examined. Furthermore, achievements in genetic manipulation of amylose gene and cyacogenic glucosides in cassava using antisense and RNA interference approaches were summarised. Conclusion: The paper suggested production of cyacogenic glucoside-free, vitamin A-enriched cassava varieties and deployment of gene-editing method for obtaining novel starches from cassava.

Background: Plants are a source of a variety of secondary metabolites. Agrobacterium rhizogenes mediated hairy root cultures offer a great advantage for the production of these metabolites in large amounts in comparison to cell suspension cultures as they have the capability of fast growth along with genetic stability. In order to commercialise secondary metabolite production, the mass production of hairy root cultures is of paramount importance. Various conventional bioreactors, broadly classified as liquid phase and gas phase reactors, have been employed for this purpose which includes airlift, bubble column, stirred tank, trickle bed, nutrient mist, spray reactors and others. Objective: This review discussed various aspects of hairy root culture in bioreactors. Method: Peer-reviewed research literature was searched and screened for information about the evolution of designs of bioreactors used for hairy roots culture. Data was gathered after a keen search from research and review articles and is presented in this review paper. Results: The major limitations of the conventional type bioreactor systems were high shear stress and oxygen deficiency, thus the demand for improved designs led to the evolution and designing of various types of bioreactor systems with low shear stress and better oxygen uptake in order to enhance yield productivity. Amidst these modifications in reactors, hybrid reactors, which are a combination of liquid phase and gas phase reactors, offer a very promising approach for commercialisation of secondary metabolite production using hairy root cultures. Conclusion: Although many efforts have been done to obtain a bioreactor configuration for highest biomass possible, there are still chances of improvement to get the most suitable bioreactor that could provide high oxygen mass transfer, better growth characteristics, homogenous culture environment and minimum shear stress.

Background: Biodiesel represents an alternative energy source with economic, social, environmental, and technological advantages over nonrenewable fuels. Objective: This study investigated two oils derived from plants of the Brazilian Amazon, andiroba (Carapa sp.) oil and babassu (Orbignya sp.) oil, as possible triacylglyceride sources for the production of biofuels by lipase B from Candida antarctica (CALB). Methods: The production of biodiesel ethylic by enzymatic catalyst was carried out in 3-mL Erlenmeyer flasks containing 150 mg (154 μL) of either babassu or andiroba oil, 475 μL of ethanol, and 15 mg of CALB. Results: The physical, chemical, and spectroscopic properties of these oils and their resulting biofuels were also reported. CALB exhibited high activity in the alcoholysis of babassu and andiroba oils under mild conditions and produced biodiesel ethyl esters in high yields (90% and 94%, respectively). The oils and biodiesel were characterized using 1H NMR, Chromatography Gas–Mass Spectrometry (CGMS), Fourier Transform Infrared Spectroscopy (FT-IR), and thermogravimetric analysis (TGA) being the main findings of the study. Conclusion: Ethanolysis of babassu and andiroba oils by catalysis enzymatic (CALB), showed to be a successful route in the synthesis of ethylic biodiesel in high yield. The corresponding biodiesels were characterized by 1H NMR spectra, GC-MS, FT-IR, and TGA analyses. Results described here provide relevant information for the further research uses andiroba and babassu oils, the alternatives to other oils in synthesis of biodiesel.

Background: Endophytic bacteria release active metabolites by utilizing nutrients secreted by plants and induce gene expression and enhance plant growth under abiotic stresses. Objective: To understand the dynamics of drought markers (27 genes) in endophyte Acinetobacter sp. associated maize under drought compared to control plants using quantitative real-time PCR (qRTPCR). Method and Result: Four endophytic bacteria Pseudomonas putida FMZR9, Acinetobacter baumannii MZ30V92, Enterobacter asburiae MRC12, and Sinorhizobium meliloti MRC31 screened for stress tolerance showed 1- aminocyclopropane-1-carboxylic acid (ACC)-deaminase activity, exopolysaccharides (EPS), sugars, amino acids and proline under no-stress and stressed conditions [-1.02 matric potential (MPa)]. Endophytes showed protease, pectinase, cellulase and chitinases as well as swimming, swarming (except FMZR9) and twitching motility (except FMZR9 and MRC31). Acinetobacter baumannii MZ30V92 transformed with gfp gene colonized inside epidermal and cortical cells in maize root (603 colony forming units (CFU)/g ±3.11) improving dry biomass with high relative water content (RWC) and leaf water potential (LWP) compared to control. Inoculation with MZ30V92 downregulated drought-responsive genes (27) like dehydrins, antioxidative genes, ethylene (ET) and abscisic acid (ABA) regulators in roots and leaves of Zea mays as compared to uninoculated plants under drought stress. There was no significant difference in the transcription of dehydration responsive genes in inoculated tissues (root and leaves) compared to uninoculated under no-stress. Conclusion: Endophyte MZ30V92 is active inside the plant tissue and primes the plant by downregulating drought stress genes and alleviating drought stress effects. This report shows the potential of endophytic bacteria in alleviating drought stress effects in maize.

Background: Bacterial leaf blight and sheath brown rot caused by Xanthomonas oryzae pv. oryzae (Xoo) and Pseudomonas fuscovaginae, are severe diseases of rice (Oryza sativa L.) causing significant losses in both yield and quality. To evaluate more effective control measures, we evaluated bioformulations formulated from Piper sarmentosum Roxb. (Piperaceae) (pokok Kaduk or wild betel) leaf extracts in promoting rice seedlings growth and disease suppression. Methods: The bio-formulations were developed using crude plant extracts, (surfactant Emereen 1820 alkylpolyglucoside and Emereen 1604 castor oil ethoxylate), and water. The bio-formulations were applied as seed treatments to evaluate their effects on seed germination and seedling vigour and were then tested for their efficacy to control leaf blight and sheath brown rot of rice under glasshouse conditions. Results: Preliminary laboratory experimental results showed that bio-formulations improved seed germination and seedling vigour. It also enhanced seedling height, root length, seedling and root dry weight compared to the control. A significantly lower disease incidence and severity were observed in rice treated with the bio-formulations under glasshouse condition. Conclusion: The results obtained from this study suggested that the P. sarmentosum extract bioformulations can potentially be applied as bio-pesticides for the management of rice diseases. However, further studies are required to re-evaluate the effects of the formulation under similar field conditions in endemic areas and scale-up possibilities for further applications.

Background: Groundnut (Arachis hypogaea L.) is an important cash crop in the tropical and subtropical regions of the world. Salinity is a major threat to agriculture globally and is one of the greatest inhibitions with regard to the expansion of cultivated land. The development of salt-tolerant varieties will be of great help in increasing crop yield by bringing newer areas of land under cultivation which are otherwise considered unfit owing to high salinity. Objective: The present work was undertaken to assess the suitability of tissue culture systems, which provide better control over conditions of growth, for identifying salt tolerant varieties. Methods: Groundnut plants were grown under both in vitro and in vivo conditions under salt stress. Few biochemical parameters were analyzed under both conditions. Results: It was found that there was an increase in the biochemical parameters like phenolic compounds, hydrogen peroxide, peroxidase enzyme and proteins in the salt-treated plants. The trends were similar in both cases except for a set of marginally higher values in the in vitro cultures. Conclusion: The results point towards the potential of plant tissue culture system as effective and reliable for carrying out salt tolerance studies in groundnut. The system is easy to control so that tolerance potential of the plants can be well assessed.