Algal Biotechnology

The current review explores the potential application of algal biomass for the production of biofuels and biobased
products. The variety of processes and pathways through which bio-valorization of algal biomass can be
performed are described in this review. Various lipid extraction techniques from algal biomass along with
transesterification reactions for biodiesel production are briefly discussed. Processes such as the pretreatment
and saccharification of algal biomass, fermentation, gasification, pyrolysis, hydrothermal liquefaction, and anaerobic
digestion for the production of biohydrogen, bio-oils, biomethane, biochar (BC), and various bio-based products
are reviewed in detail. The biorefinery model and its collaborative approach with various processes are
highlighted for the production of eco-friendly, sustainable, and cost-effective biofuels and value-added products.
The authors also discuss opportunities and challenges related to bio-valorization of algal biomass and use their
own perspective regarding the processes involved in production and the feasibility to make algal research a reality
for the production of biofuels and bio-based products in a sustainable manner.

The global demand for clean products obtained from biobased resources has increased significantly with the rapid growth of the world's population. In this context, microbially-produced compounds are highly attractive for their safety, reliability, being environment friendly and sustainability. Nevertheless, the cost of the carbon sources required for such approaches accounts for greater than 60% of the total expenses, which further limits the scaling up of industries. In recent years, algae have been used in numerous industrial areas because of their rapid growth rate, easy cultivation, ubiquity and survival in harsh conditions. Over the past decade, notable advances have been observed in the extraction of high-value compounds from algae biomass (ABs). However, few studies have investigated ABs as green substrates for microbial conversion into value-added products. This review presents the potential of ABs as the substrates for microbial growth to produce industrially-important products, which sheds light on the importance of the symbiotic relationship between ABs and microbial species. Moreover, the successful algal-bacterial gene transformation paves the way for accommodating green technology advancements. With the escalated need for natural pigments, biosurfactants, natural plastics and biofuels, ABs have been new resources for microbial biosynthesis of these value-added products, resolving the problem of high carbon consumption. In this review, the fermentative routes, process conditions, and accessibility of sugars are discussed, together with the related metabolic pathways and involved genes. To conclude, the full potential of ABs needs to be explored to support microbial green factories, producing novel bioactive compounds to meet global needs.

A mixed trophic state production process for algal lipids for use as feedstock for renewable biofuel production was developed and deployed at subpilot scale using a green microalga, Auxenochlorella (Chlorella) protothecoides. The process is composed of two separate stages: (1) the photoautotrophic stage, focused on biomass production in open ponds, and (2) the heterotrophic stage focused on lipid production and accumulation in aerobic bioreactors using fixed carbon substrates (e.g., sugar). The process achieved biomass and lipid productivities of 0.5 and 0.27 g/L/h that were, respectively, over 250 and 670 times higher than those obtained from the photoautotrophic cultivation stage. The biomass oil content (over 60 % w/DCW) following the two-stage process was predominantly monounsaturated fatty acids (~82 %) and largely free of contaminating pigments that is more suitable for biodiesel production than photosynthetically generated lipid. Similar process performances were obtained using cassava hydrolysate as an alternative feedstock to glucose.

The objective of the current study was to investigate the effect of using glucose as a sole carbon source as well as in combination with glycerol as a complex carbon substrate in BG-11 media, to produce microalgal biomass (gL-1), lipid (dcw%) and biochemical components, such as total soluble carbohydrates (mgmL-1) and proteins (mgmL-1) by Chlorella pyrenoidosa, over a cultivation period of 12 days. The present study revealed that using glucose as sole carbon source at various concentrations ranging from 1 to 20 (gL-1), total lipid, total biomass, total protein and total carbohydrates increased. In comparison to control showed increased biomass gL-1 (0.29±0.021 to 0.53±0.012), while Lipid content (DCW %) enhanced from (4.87± 0.021 to 14.09±0.016). But it has no stimulatory effects found on photosynthetic pigment i.e. total chlorophyll (µgmL-1) In another batch experiment, results showed that Chlorella species can utilize glycerol as a source of sole carbon source, showed less biomass lipid and carbohydrates but its effect are more promising when cultured in mixture of glucose and glycerol over a cultivation period of 15 days. It was found that biomass and total lipid content enhanced with mixed concentration of glycerol and glucose whereas decreased when chlorella used glycerol as sole carbon source. But it has also stimulatory effects on total carbohydrates.

The nature of global dietary supplements is transitioning from animal derivatives to plant based. Industries around the world are seeking vegan alternatives to animal-derived supplements. The microalgal industry is expected to undergo a market boom in the current decade. Microalgal supplements (power based and extracts) as well as microalgal fuels are expected to show a significant increase in market value. Microalgae are an under-utilized source of high-value products. They are rich reservoirs of multiple compounds capable of enhancing immunity, fortifying nutritional diets and improving cardiovascular health. Microalgae are also high lipid producing organisms, which make them viable candidates in the global search for energy alternatives. However, the inability to translate in vitro results onto the industrial scale is a major drawback of the microalgal research landscape. It is therefore, vital to find a robust microalgal species capable of producing a feasible quantity of high-value compounds. This paper investigates the potential of four microalgae sourced from the coastal town of Mangalore, India as candidates for nutraceutical industries and the clean energy industry. Desmodesmus komareikii (MK990101) was found to be rich in total lipid, while the three Chlorella species were found to be relatively richer in total protein yields. Chlorella thermophila (MN006612) is capable of yielding harvests up to nearly 280 tonnes/ acre/year. Chlorella thermophila (MN006612) yielded the highest amount of both mono and polyunsaturated fatty acids. The fatty acid profiles of Chlorella thermophila (MN006612), Chlorella vulgaris (MN252517-18) and Chlorella sorokiniana (MN011568) can be explored as an alternative edible oil. Desmodesmus komareikii (MK990101) yielded the highest amount of saturated fatty acids, which are used in the production of clean and quality biofuels.

Motor or engine oil is a lubricant for engines containing majorly of base oils; these base oils include petrol-based hydrocarbons. Petroleum hydrocarbon contamination is one of the major environmental problems resulting from its large scale uses in transportation, industrial and other sectors. Accidental release and workshop seepage of petroleum products are the key concern of the environment. Fresh engine oil contains polycyclic aromatic hydrocarbons (PAHs). Used engine oil also leads to further generation of PAHs. As an attempt to clean up such hydrocarbons, bioremediation or biodegradation methods are adapted. Bioremediation is a cost effective and eco-friendly treatment for oil contaminated materials by the use of micro-organisms. The present study is an attempt to isolate and find out hydrocarbon degrading fungi from oil and petroleum contaminated regions. Biodegradation potential of soil mycobiota isolated from automobile mechanic workshop in Virar on engine oil was investigated using standard methods. The most capable oil degrading fungi was identified morphologically by wet mount technique as Fusarium sp. The biodegradation of hydrocarbons and oil was determined by using 2,6 Dichlorophenol-indophenol (DCPIP) assay and gravimetric analysis. The quantitative estimation of engine oil degradation showed rate of degradation as 87% and 89%. This study confirms that isolated Fusarium sp. has the potential exploited in the bio-treatment and removal of hydrocarbons from the polluted soil. Results were recorded in the form of biodegradation percentage of hydrocarbon. The present study and their results can give unique future prospects in the field of bioremediation and biodegradation of petroleum contaminated soil.

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract The fossil fuels accomplish almost 80% of the world energy needs. The ever increasing exploitation of fossil fuels has led to environmental pollution, global climate change and health problems to living beings. Hence to meet the needs of the future energy and to mitigate the environmental pollution, it is critical to look for the alternate fuels. Global energy infrastructure in the future is believed to be accomplished by the energy generated from the low-cost renewable resources. Algae biomass has emerged as a promising biofuel source, as microalgae-based biofuels are biodegradable, renewable, and eco-friendly in comparison to fossil driven fuels. This study aims to examine the importance of microalgae as an alternative renewable energy source and evaluate the key challenges in the production of microalgae biofuel.

Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30 000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (α-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol.

This study reveals the effect of five different culture media on biomass and oil production of five marine microalgae, Tetraselmis sp, Chaetoceros sp, Chlorella sp, Nannochloropsis sp and Dunaliella sp which were harvested by Flocculation method using Aluminium sulphate. The Conway, MN + , and ASN-III medium resulted in a significantly higher growth (P<0.05) when compared to the Guillard and Chu 10 medium. The results suggest that the ASN-III medium is the best growth medium for Chlorella sp, Nannochloropsis sp and Chaetoceros sp than the other species studied. The maximum oil yield was obtained in the Nannochloropsis sp that was grown in Conway medium. The oil yield in relation with species and culture media are significant (P < 0.05).