Nature article about Lithium Bioextraction by J. Sedlakova-Kadukova, R. Marcincakova, A. Luptakova, M. Vojtko, M. Fujda and P. Pristas explained in a simple manner.

1. Authors: J. Sedlakova-Kadukova, R. Marcincakova, A.
Luptakova, M. Vojtko, M. Fujda and P. Pristas
Published as Scientific Research article in Nature
Presented By
Suby Mon Benny
MSc Microbiology
[20LS601032]
Comparison of three different
Bioleaching systems for Li
recovery from lepidolite

2. Abstract
A consortium of autotrophic bacteria Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans,
heterotrophic fungus Aspergillus niger and heterotrophic yeast Rhodotorula mucilaginosa.
11mg l-1 Li extracted in the absence of nutrients within 336 days.
Bioaccumulation is the main process.
XRD analysis used to differentiate bacterial leaching and bioleaching by fungus or yeast.

3. Introduction

4. Materials and Methods
• Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2) (University of Birmingham, UK). Ore
mined from Beauvoir(France).
Sample-
• A. niger strain An-S (Dept of Soil Science, Faculty of Natural Sciences in
Bratislava),
• A. ferrooxidans strain SmolnikLC and A. thiooxidans strain (Institute of
Geotechnics, Slovak Academy of Sciences in Kosice) and
• R. mucilaginosa(rubra) CCY 20-1-36 (Collection of Yeast Cultures from Chemical
Institute of Slovak Academy of Sciences in Bratislava)
Microorganisms-

5. • Bioleaching by A. niger
• Media composition- Glucose 5 g l-1 &
(NH4)2SO4 -0.5 g l-1, pH- 5.1(10M
H2SO4).
• Add 2g crushed mineral and 5ml 8-
day old conidia.
• Collect sample at pre-determined
intervals.
• Filter through 0.45μm pore size
membrane filter.
• Air dry the biomass for 24h and
mineralize in oven for 4h at 500℃.
• Digest the biomass in 2M HCl.

6. • Bioleaching by A. ferroxidans and
A. thiooxidans
• Media composition (Rich)- KH2PO4-
0.1 g, (NH4)2SO4- 2 g, KCl- 0.1 g,
MgSO4.7H2O- 4 g, FeSO4.&H2O- 44.2
g and elemental sulphur 4 g, pH- 3.
• Poor medium- H2SO4 & elemental
sulphur, pH 3
• Add bacterial consortium.
• After pH drops to 1.5 add crushed
lepidolite.
• Collect sample at regular intervals.
• Filter using 0.2μm pore size
membrane filter.

7. • Bioleaching by R. mucilaginosa
• Two media was used- Rich & Poor.
• Rich media composition- Glucose 5 g l-
1, (NH4)2SO4 -0.5 g l-1, KH2PO4- 0.1 g,
MgSO4- 0.34 g and yeast extract- 7 g.
• Poor media composition- Glucose 5 g l-
1, (NH4)2SO4 -0.5 g l-1
• pH adjusted to 5.1.
• Air dry the biomass for 24h and
mineralize in oven for 4h at 500℃.
• Digest the biomass in 2M HCl.

8. Analytical and characterization methods
pH measured using GRYF
208L pH meter.
Li conc measured by AAS
(Perkin Elmer 3,100) at 670
nm.
Microbial association with
ore observed using JEOL-
SEM (JEOL JSM-35CE).
Mineral composition estimated by
diffractometer Bruker D2 Phaser (Bruker
AXS, GmbH, Germany) in Bragg-
Brentano geometry (configuration Theta-
2Theta), Cuκα radiation.

9. Results and
discussion
• Bioleaching kinetics-
• R. mucilaginosa was
the fastest, Li
detected at 6th day.
• Li conc in solution
decreased by 13th day.
• A. niger was the
slowest, Li detected at
26th day.
• Media composition
determined bacterial
bioleaching efficiency.

10. • Changes in pH
• For A. niger pH
decreased 5.1- 3 within
first 12 days then to 2.5.
• For bacterial culture pH
decreased drastically to
1.2 during first 7 days
and then to 0.9.

11. XRD analysis & Li distribution
• Bioaccumulation was
observed only in A. niger and
R. mucilaginosa.
• No bioaccumulation was
observed in the bacterial
consortium.
• Composition of medium had
very strong effect on
bioleaching by R. mucilaginosa

12. Conclusions
• Li extraction was highest using
bacteria but requires long time.
• Yeast and fungi has strong ability to
accumulate Li.
• Efficiency of bioleaching was more
when using poor medium.
• Bioaccumulation requires rich medium
for producing good amount of biomass

13. Thank you