Enhancement for the synthesis of bio-energy molecules (carbohydrates and lipids) in Desmodesmus subspicatus: experiments and optimization techniques.

Microalgae are regarded as renewable resources of energy, foods and high-valued compounds using a biorefinery approach. In the present study, we explored isolated microalgae (Desmodesmus subspicatus) for the production of bio-energy molecules (carbohydrate and lipid). Optimizations of media (BG-11) components have been made using the Taguchi orthogonal array (TOA) technique to maximize biomass, carbohydrate and lipid production. Optimized results showed that biomass, carbohydrates and lipid productivity increased by 1.3 times at optimal combinations of media components than standard BG-11 media. Further, the influence of various carbon and nitrogen sources as nutritional supplement with optimum media composition under different light intensities was investigated for productivity of carbohydrate and lipid. Results demonstrated that 1.5 times higher productivity of carbohydrate and lipids were achieved in the presence optimum BG-11 under a broad range of light intensities (84-504 µmol m-2 s-1). Among different nitrogen sources, glycine was found to give higher productivity (1.5 times) followed by urea. Use of the cellulose as a carbon source in the media significantly increases biomass (2.4 times), carbohydrates (2.3 times) and lipids (2.3 times) productivity. Investigations revealed that cultivating Desmodesmus subspicatus under optimum culture conditions has the potential for large-scale bio-ethanol and bio-diesel production.

The effects of in vitro culture on the leaf anatomy of Jatropha curcas L. (Euphorbiaceae) / Efeitos da cultura in vitro na anatomia foliar de Jatropha curcas L. (Euphorbiaceae)

Jatropha curcas (Euphorbiaceae) is an evergreen tree traditionally used in popular medicine, and also as a promising source for bio-fuel production. The in vitro propagation of this species has been studied as an alternative to conventional methods such as cutting and seedling. In vitro culture environment consists on closed flasks, with high relative humidity, reduced gas exchanges and artificial temperature and luminosity conditions. These conditions may induce physiological and anatomical alterations in cultivated plants. The occurrence of anatomical alterations on the leaves of J. curcas was examined in plants cultivated both in vitro and ex vitro, under greenhouse conditions. The stomatal index was higher on the leaves from greenhouse plants. Mesophyll thickness did not differ, but the greenhouse leaves presented an additional palisade layer, which reflects the environmental influence on cell division. The cells of the chlorophyllous parenchyma of young plants grown in greenhouse conditions have larger chloroplasts than those of the plants grown in vitro. The chloroplasts of mature leaves are similar in height, but the mitochondria are smaller. Current results indicate that the leaves of J. curcas respond distinctly to both environments. It is necessary to adjust the abiotic conditions in vitro to avoid precocious senescence, diagnosed by chloroplasts and mesophyll degradation.

Jatropha curcas (Euphorbiaceae) é uma espécie arbórea sempre-verde usada tradicionalmente na medicina popular e com potencial para produção de biodiesel. A propagação in vitro desta espécie tem sido avaliada como alternativa aos meios convencionais de estaquia e plantio. O ambiente in vitro consiste em frascos de vidro fechados, com umidade relativa elevada, trocas gasosas reduzidas, e condições artificialmente controladas de temperatura e luminosidade. Tais condições podem induzir anormalidades fisiológicas e anatômicas nas plantas cultivadas. A ocorrência de alterações anatômicas foi avaliada em folhas de J. curcas cultivadas in vitro e em casa de vegetação visando diagnosticar os efeitos do ambiente in vitro sobre o desenvolvimento das plantas. O índice estomático foi maior nas folhas de plantas crescidas em casa de vegetação. A espessura do mesofilo não apresentou alterações, mas as folhas das plantas crescidas em casa de vegetação apresentaram uma camada adicional de parênquima paliçádico. Citologicamente, as células do parênquima clorofiliano de plantas jovens crescidas em casa de vegetação possuem cloroplastos maiores do que aqueles das plantas crescidas in vitro. Nas plantas maduras, os cloroplastos apresentam tamanhos similares. As mitocôndrias possuem tamanhos reduzidos nas plantas maduras ex vitro. Nossos resultados mostram que as folhas de J. curcas respondem distintamente aos dois ambientes. Ajustes nas condições abióticas in vitro são necessários para evitar a senescência precoce, diagnosticada pela desintegração dos cloroplastos e consequentemente do mesofilo. Current results indicate that the leaves of J. curcas respond distinctly to both environments. It is necessary to adjust the abiotic conditions in vitro to avoid precocious senescence, diagnosed by chloroplasts and consequent mesophyll degradation.