Biotechnological Applications of Jatropha curcas for Bioenergy

Biotechnological Applications of Jatropha curcas for Bioenergy and Bioactive Compound Production

Currently, the energy and other value-added commodities around the globe come from fossil fuel–based refineries.

However, the consumption of fossil fuels for energy and other materials has resulted in the creation of various undesirable and complicated problems, for example:

• The emission of greenhouse gases (global warming)
• Steady increase in the prices of fossil fuel products
• Reduction in fossil fuel reserves

The Need for Renewable Energy Alternatives

Therefore, it has become critical to seek alternative sustainable, environmentally friendly, cost-effective, and, more importantly, renewable energy resources for biofuels production and valuable bio-based commodities.

Biomass is one of the ideal alternatives that can be used in a biorefinery context to fulfill global demands and replace fossil fuel refineries.

Biomass can be further categorized into edible and non-edible feedstocks.

• Edible feedstocks face challenges such as fuel vs. food competition, ultimately increasing food prices.
• Non-edible feedstocks, such as Jatropha curcas, are ideal, renewable, and sustainable options for biorefinery concepts, with no fuel-versus-feed competition.

Study Objectives and Feedstock

In the current study, J. curcas seed was used as a feedstock for a biorefinery to produce:

• Sustainable energy carriers: biogas and biodiesel
• Bioactive commodities through jointly applied conversion technologies

Biodiesel and Biogas Production from Jatropha curcas

Biodiesel production from J. curcas seed oil was found to be the most feasible option.

Biogas production from pressed cake after methanolic extraction was identified as the best method for biogas generation.

The methanolic extract of pressed cake also showed:

• Good antimicrobial and antioxidant activities
• Enhanced biogas production
• Reduced negative effects on the microbial profile in the reactor

Extraction and Bioconversion Approaches

Biodiesel production from oil extracted from J. curcas seed was evaluated via:

• Chemical approach (two-step process)
• Biological approach (lipase-based)

The pressed cake, obtained after oil extraction, was also used for biogas production.

Though the cake contains antimicrobial phytochemicals that inhibit microbial communities during anaerobic digestion (AD), the methanolic extract:

• Enhanced biogas production
• Improved microbial evenness, richness, and abundance in the reactor

Phytochemical and Antimicrobial Analysis

Phytochemical analysis of J. curcas de-oiled pressed cake extracts was carried out using GC-MS and FTIR.

Extracts were tested individually and in combination with commercial antibiotics against:

• Clinical bacterial pathogens
• Multidrug-resistant (MDR) bacterial strains

The de-oiled pressed cake extracts and seed oil were also tested for:

• Antioxidant
• Cytotoxic
• Enzyme inhibition
• Antifungal activities against phytopathogenic fungi

Microbial Community and Biogas Yield Evaluation

Microbial communities and biogas yields were evaluated in continuous reactors fed with:

• Whole seed
• Seed oil
• Pressed cake
• Methanolic residues

High-throughput Illumina MiSeq sequencing was used to study antimicrobial effects on microbial communities during AD.

Co-Digestion and Biomethane Yields

The carbon-to-nitrogen (C/N) ratio was optimized for co-digestion of J. curcas de-oiled seed kernel and mango peels.

Key findings:

• Highest biomethane yield (61%) occurred at a 1:4 mango peel:seed kernel volatile solids ratio
• The 1:1 and 2:1 ratios yielded 52%, 39%, and 32% of theoretical maximums, respectively

Lipase-Mediated Biodiesel Production

Indigenous lipase-producing bacterial strains were isolated for bacterial-based biodiesel production.

Optimization was performed using:

• Plackett-Burman design
• Central Composite Design

The highest biodiesel yields (~97–98%) were achieved using strains:

• Brevibacterium SB11 MH715025
• Pseudomonas SB15 MH715026

Quality and Standards of Biodiesel

The fuel properties of biodiesel produced through both chemical and bacterial processes complied with international standards:

• ASTM D6751
• EU-14103

Synergistic Antibacterial and Antifungal Potential

• Methanolic extracts showed higher antibacterial activity than seed oil, n-hexane, and aqueous extracts.
• Synergism with rifampicin was the highest among all combinations tested.
  • Synergistic activity: Methanolic (45%), n-hexane (33%), aqueous (9%), and seed oil (26%)
• Methanolic extract also had the strongest antifungal and antioxidant effects

Reactor Optimization and Microbial Abundance

• Methanolic extract inhibited hydrolysis phase of AD and decreased biogas yield by 35.5%
• Fermentative bacteria were more abundant in reactors with methanolic residues
• Jatropha oil and whole seed did not inhibit methanogens

Operational parameters, like Organic Loading Rate (OLR) and Hydraulic Retention Time (HRT), affected microbial profiles:

• Higher methanogenic abundance at HRT of 20 days vs. 15 and 10 days

Conclusion

The study concludes that Jatropha curcas seed is a multipurpose substrate, viable for:

• Antimicrobials
• Antioxidants
• Cytotoxic agents
• Bioenergy carriers (biogas and biodiesel)

Using J. curcas in a biorefinery context instead of for biofuel alone can greatly increase its economic value, particularly for biofuel and pharmaceutical sectors.

Additionally, removing antimicrobials from the seeds before digestion reduces toxicity and enhances fuel conversion efficiency.

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Biotechnological Applications of Jatropha curcas Seeds for Bioenergy Carriers and Bioactive Compounds

Full PDF Copy of the Thesis

Focus Keyword: Jatropha curcas biorefinery

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Sources & Thesis Details

Thesis Title: Biotechnological Applications of Jatropha curcas Seeds for Bioenergy Carriers and Bioactive Compounds
Researcher: Abdul Haq
Supervisor/Guide: Not listed in abstract
Institution: Quaid-i-Azam University, Islamabad
Department: Biological & Medical Sciences, Microbiology
Degree Year: 2020
Publisher: Quaid-i-Azam University, Islamabad
Gov’t Doc No.: 20252

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