1. Mining bacterial genomes for laccases
University of Ljubljana, Biotechnical Faculty
Dept. of Food Science and Technology, Chair of Microbiology
Mining bacterial genomes for laccases
Luka Ausec, Marko Verce, Miha Črnigoj, Vesna Jerman,
Ines Mandić-Mulec
The 2nd International Symposium “VERA JOHANIDES”, Zagreb, May

2. Why care about laccases
What do they do?
How do they do it?

3. Why care about laccases
What do they do?
How do they do it?
Environmentally friendly

4. Fungal vs. Bacterial Laccases
Ease of pruduction
Substrate range
pH and temperature optimum
Salt tolerance

5. Sources of novel bacterial laccases
DNA potential
Activty
related cultured strains
unknown
known
metagenomics
bioinformatics

6. From genomes to pool of potentials
75% of genes encode
signal peptides
2,200 draft and
completed genomes
1,240 putative laccase genes
6.5 %
on plasmids
Ausec, Zakrzewski et al., PLoS ONE 2011

7. Mining the pool, #1: extremophile
Laccase from
Thioalkalivibrio sp.
substrates
substrate
optimal pH
ABTS 5
K4Fe(CN)6
pyrocatechol 8
pyrogallol 7
2,6-DMP
9.5
syringaldehyde
syringic acid
N.A.
syringaldazine
guaiacol
Vanillic acid
ferulic acid
tyrosine
pH optima pH

8. Mining the pool, #2: anaerobe
Laccase from
Geobacter
metallireducens
pH optimum
temperature
optimum

9. Conclusions Bacterial laccases are diverse
Bioinformatic (HMM-based) approaches successful
Bacterial laccases have promissing traits for biotechnological applications

10. Thank you.

11. Bioinformatic analysis of bacterial laccase-like genes
>2200 completed and draft bacterial genomes
METHODS:
profile Hidden Markov Models (pHMM)
5 models constructed

12. 2-domain laccases
3-domain laccases

13. Figure 3 - List of species encoding laccase genes and possessing plasmids in their genomes. The bars represent the number of laccase genes in the genome (black) and the number of laccase genes on plasmids (gray). The length of the bar shows the total number of genes for each organism.
76 genes on plasmids of 46 organisms