KKKB 5933: ADVANCED BIOREACTOR ENGINEERING

BERNARD CHUNG KEN VUIA98753KB/4

Controlling malaria vector with Anabaena sp. strain PCC 7120:

A study by Ketseoglou & Bouwer

INTRODUCTION: PHOTOBIOREACTOR

Photobioreactor: specialized bioreactor that uses phototropic

microorganisms to generate bioproducts by using light as the main

energy source (Kunjapur & Eldridge 2010)

Either in an open cultivation system (pond) or in the closed cultivation

system (Ketseoglou & Bouwer 2013)

Closed systems include:

A) Flat plateB) Bubble column C) TubularSource: Posten

2009

Potential bioproducts from phototropic microorganisms: Astaxanthin,

β-carotene, phycobiliproteins, biodiesel, jet fuel, and biofertilizer

INTRODUCTION: PHOTOBIOREACTOR

Arthrospira production plant in Calipatria, CaliforniaSource: Mostafa 2012

INTRODUCTION: MALARIA

Malaria: An insect-transmitted disease that remains one of the greatest global health challenges of the modern era (Oliva et al. 2013).

Caused by Plasmodium falciparum (parasite) and is transmitted by a bite from an infected female Anopheles mosquito (Janneck et al. 2011).

The new technology to develop a better insecticide has bring the attention of using genetically engineered cyanobacteria as biopesticides for the control of mosquitoes (Ketseoglou & Bouwer 2013).

INTRODUCTION: Bti TOXIN

Biopesticide uses the highly toxic crystalline inclusions

produced by Bacillus thuringiensis subspecies israelensis (Bti)

Endotoxin protein produced by Bti is commonly known as the

crystal protein (Cry) through Cry gene

Disadvantages (Ketseoglou & Bouwer 2013):

Possess low persistence in the field (inactivation by

ultraviolet)

Problem due to ingestion by other aquatic organisms

Settling from the mosquito larval feeding zone

INTRODUCTION: Bti TOXIN

Mode of action for Bt toxin crystalSource: Jurat-Fuentes

CASE STUDY: OBJECTIVE

Optimization of photobioreactor growth conditions for acyanobacterium expressing mosquitocidal Bacillus thuringiensisCry proteinsBy: Irene Ketseoglou, Gustav BouwerLink: http://www.sciencedirect.com/science/article/pii/S0168165613002381

Cyanobacterium Anabaena sp. strain PCC 7120 has been genetically engineered to express important Cry genes such as cry4Aa, cry11Aa and p20

Objective: To determine the optimal growth conditions for PCC 7120#11 in an indoor, flat-plate photobioreactor using RSM

Cultivation of PCC 7120#11 till it reaches mid-exponential growth Introduced into the photobioreactor at initial cell concentration of

1.6 x 106 cells mL-1

Experimental Designs: Flat-plate, inclined modular photobioreactor with two

toughened glass plates (6 mm thick, 702 mm length and 516 mm height)

Medium used: 3.7 L BG-11 for algae Temperature: 30 °C pH: 7.2 Continuous illumination: 58 μmol m-2 s-1 with a panel of 8 Grolux

lamp Constant agitation: 140 rpm carbon dioxide-enriched air-bubble

mixing system

Factors such as airflow, photosynthetic photon flux density (PPFD), and CO2 affect the growth and development of cyanobacteria

Response is on the volumetric productivity of PCC

CASE STUDY: METHOD

CASE STUDY: FINDINGS

Effect of input CO2 concentration and airflow rate at low PPFD (53.0 μmol m-2 s-1) on the volumetric productivity

CASE STUDY: FINDINGS

Effect of airflow rate and PPFD on PCC 7120#11 volumetric productivity at a input CO2 concentration of 3.75% (v/v)

CASE STUDY: FINDINGS

1. Prediction equation:

2. Numerical optimization reveals that the highest volumetric productivity of 0.47 g L−1 d−1 were predicted to be a PPFD of 154 μmol m−2 s−1, an airflow rate of 1.02 vvm and an input CO2 concentration of 3.18 % (v/v).

3. For commercialization where cost of production is the main objective, numerical optimization reveals that optimal volumetric productivity of 0.44 g L−1 d−1 were obtained at a PPFD of 139.66 μmol m−2 s−1, an airflow rate of 1.00 vvm and an input CO2 concentration of 1.50 % (v/v)

4. Larvicidal activity: Mean of LC50 as reported for the runs was 9.24 x 105 cells mL-1

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CASE STUDY: CONCLUSIONS

Source Ketseoglou & Bouwer 2013

Yoon et al. 2008 Fontes et al. 1987

Yu et al. 2011

Type of photobioreactor

Flat-plate Bubble (Annular)

Airlift Airlift

Parameters studied

PPFD, CO2 input,

Airflow rate

Superficial gas velocity, pH,

Initial phosphate

concentration, Light intensity

Airflow rate, Light density

Mixotrophic culture

Productivity 0.47 g L−1 d−1 (maximum)0.44 g L−1 d−1 (optimum)

0.67 g L−1 d−1 (optimum)

13 g m−2 d−1 (optimum)

0.43 g L−1 d−1 (optimum)

Comparisons of different findings on the characterization and design studies

THE FUTURE

1. Future PCC 7120#11 studies may want to determine if volumetric

productivity has an impact on the ratio of the LC50 of late-

exponential phase cells to the LC50 of mid-exponential phase cells.

2. A comparison of the different studies suggests that PCC 7120 may

have a lower volumetric productivity maximum than other

cyanobacteria

3. Provide a foundation for future continuous culture optimization

experiments, in which key process parameters are monitored and

controlled on a continual basis

4. Extensive scale-up studies are necessary to evaluate the feasibility

of commercial-scale production of PCC 7120#11