Azmi Nik Mahmood

Bio: Azmi Nik Mahmood is an academic researcher from Universiti Teknologi Malaysia. The author has contributed to research in topics: Algae fuel. The author has an hindex of 1, co-authored 1 publications receiving 129 citations.

Fourth generation biofuel: a review on risks and mitigation strategies

Abstract: Fourth generation biofuel (FGB) uses genetically modified (GM) algae to enhance biofuel production. Although GM algae biofuel is a well-known alternative to fossil fuels, the potential environmental and health-related risks are still of great concern. An evaluation of these concerns and accordingly devising appropriate mitigation strategies to deal with them are important to a successful commercialized production of FGB. While extensive research has been carried out on genetic modification and other technologies that aim to increase the productivity of algae strains, only a handful of them deal with the legislative limitations imposed on exploiting and processing GM algae. This paper examines this legislation and the mitigation strategies to meet potential risks associated with the exploitation and processing of FGB. Open-pond system is an economic solution for large-scale cultivation of microalgae; however, the concern regarding the health and environmental risk of cultivating GM algae and the associated stringent regulations is considered as the main barrier of FGB production. Disposal of the residue is another important issue that should be considered in FGB production. The byproducts obtained from energy extraction step and residual water from the harvesting process may contain plasmid or chromosomal DNA that may cause the risk of lateral gene transfer. Hence an appropriate mitigation practices should be used for replacement of the hazardous water residue and by-products with more environmentally friendly alternatives. The results obtained from several field testing projects for open-environment exploitation of GM algae show that under the various conditions used, there was no apparent proof to support possible horizontal gene transfer in release of GM algae.

Microalgal-bacterial consortia: From interspecies interactions to biotechnological applications

Abstract: Microalgae have emerged as a renewable and sustainable candidate for bioenergy production coupled with pollutant removal from wastewater. However, costly biomass harvesting, insufficient biomass productivity, and energy-intensive extraction methods are major bottlenecks restricting their large-scale development. To break through such limitations, researchers have focused on the technologies towards consolidating microalgal-bacterial consortia, which exhibit numerous advantages related to economy, energy, and environment, due to the cooperative interactions between microalgae and bacteria. This paper recapitulates the most recent work on microalgal-bacterial interaction mechanisms, and describes the diverse biotechnological applications of microalgal-bacterial consortia. Based on this review, the interaction mechanisms cover substrate exchange, cell-to-cell signaling, and horizontal gene transfer. Nutrient availability, growth phase, and cultivation conditions are major factors affecting their interactions. In terms of wastewater treatment, attached microalgal-bacterial consortia are economically feasible and technically superior compared to suspended microalgal-bacterial consortia. Appropriate carrier, bioreactor type, operation mode, operational factor, and further perspectives for engineering attached microalgal-bacterial consortia are critically assessed. Bacteria play an important role in promoting microalgal growth, enhancing bio-flocculation and facilitating cell wall disruption, and thus expanding the application potential of microalgal biofuel production. The current state of other promising biotechnological applications of microalgal-bacterial consortia (particularly mitigation of CO2 emissions, microalgal bloom control, and electricity generation) and the appropriate strategies to enhance their practical applications are discussed. The major challenges to scale up microalgal-bacterial consortia and corresponding recommendations for further research are also addressed.