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Bacterial production of fatty acid and biodiesel: opportunity and challenges 41

2.5 Future prospects: opportunity and challenges

Nowadays, the petroleum industries are facing a growing demand for clean, eco-
friendly energy supply. This is mainly dependent on the contemporary development
of green chemistry associated with the climate shift, increasing atmospheric concen-
tration of greenhouse gases, energy utilization during production processes, and
inadequate accessibility of fuel-based resources. Considering the increasing
demands and international regulations, tremendous efforts have been made to
deduce a new biochemical route for the production of fatty acids and biodiesel.
Encouraging bio-based feedstocks and waste materials are the emerging, feasible,
and environment friendly raw materials for the production of such bio-based fuels
and other value-added products.
Production of biofuels and biomaterials from biomass and municipal waste has
attracted worldwide attention due to their biodegradability and low environmental
impacts. The main stumbling block in the path of achieving the goal of sustainable
development and resource management is the extensive usage of fossil fuels such
as oil, coal, and natural gas (Venkata Mohan et al., 2016). In such a scenario,
biorefineries come out as an emerging concept involving the simultaneous
production of biofuels and bio-based products along with curtailing the environ-
mental damage by managing and utilizing the waste. Biodiesel is composed of
monoalkyl esters of higher chain of fatty acids, produced though the transesterifi-
cation reaction by alcohol in the presence of a catalyst (Kumar et al., 2016c). In
general, oils or fats extracted from various sources, such as cyanobacteria, algae,
jatropha, palm trees, and soybeans, have been used as precursor for the production
of biodiesel (Schenk et al., 2008). The production of biodiesel from waste oil is
very limited due to the limited supply of waste oil, while it is effective for the
small scale-independent producers. Large-scale commercial producers regularly
use oil extracted from seeds such as soybean, rapeseed, palm, and corn.
Unfortunately, the biodiesel produced from seed oil is a debatable food versus
feed topic concluding biodiesel as a commercially more expensive resource. The
higher yield of bacterial biomass using waste materials as carbon source, which
can be subsequently converted to fatty acid, could be a possible alternative to
reduce the raw material cost of biodiesel production. Diverse groups of fatty acids
and their derivatives were produced efficiently using substrates such as alkanoic
acids and alkanes. Nevertheless, their high toxicity and lower miscibility along
with their shooting market prices present new challenges (Ro ¨ttig and Steinbu ¨chel,
2016). The major challenge that appears in the production of lipids-derived
fuels from microbes is the involved carbon source as it contributes up to 85%
of the overall production cost, making the production process expensive.
Therefore the employment of nonexpensive carbon or nitrogen sources from
municipal, agricultural, or industrial waste and excess available materials, such as
hydrolyzed plant biomass, molasses, crude glycerol from biodiesel industry, whey
from cheese industry, and sludge from waste water treatment plant would reduce
the involved cost.