I will summarize article and make other sources come together for understanding and preparing our own paper.
Shihui Yang, Steven D Brown*
*They are doing research in Oak Ridge National Laboratory(http://www.esd.ornl.gov/). They are also studying on zymomonas mobilis. They published brief paper on Nature in last year about new annotation of zymomonas mobilis and they announced genome sequence of AcR (acetate tolerant strain, but in reality it looks like it is tolerant on sodium) on PNAS.
In previous paper on PNAS(http://www.pnas.org/content/107/23/10395.full) they compared genome of AcR with ZM4 and found 1.5kb deletion that truncated ZMO0117 and DNA upstream of ZMO0119 (nhaA ; sodium proton antipoter) in AcR. They thought that the ZMO0117 promoter affected the expression of nhaA through deletion and this caused sodium acetate tolerance.
-background-
1.Demand for engineering of microbe : alternative energy is in need -> using agricultural biofuel, lignocellulosic biomass which is composed of cellulose is one method -> for fermentation by microbe, pretreament of biomass, breaking cellulose down into smaller molecule like 5- or 6-carbon sugar, is needed (http://biotech.about.com/b/2008/06/11/pretreatment-of-cellulosic-biomass.htm) -> this pretreatment produce inhibitor for microbe -> improved strain which is tolerant on these
inhibitors is developing by mutation.
2. Z.mobilis (Zymomonas mobilis) : ethanol tolerance, virtually unique
property among bacteria, 3~5 times higher productivity than S.cerevisiae and ethanol yield reaching 97% of theoretical maximum (http://www.nature.com/nbt/journal/v23/n1/full/nbt0105-40.html).
It use Entner-Doudoroff pathway for fermentation of glucose (6-C sugar, although some improved strain also use 5-C sugar). This pathway yield 1 ATP from conversion of 1 glucose into 2 ethanol, whereas glycolysis yield 2 ATP. Because Low ATP yield means low cell mass, Z.mobilis have higher potential than S.cerevisiae.
-the aim of this study-
Investigation the role of a hfq gene (ZMO0347) on multiple pretreatment inhibitor tolerances. htq is expressed more intensively in anaerobic stationary phase than aerobic condition (This fact was revealed by same author in BMC Genomics, http://www.biomedcentral.com/1471-2164/10/34). This gene is global regulator that acts as an R
NA chaperone and is involved in coordinating regulatory responses to multiple stresses.
There are some others focusing work such as utilization of specific plasmid and role of LSM protein in S.cerevisiae in this paper. But I will omit these things.
-results-
Using by blastP, they find hfq in ZM4 is similar with E.coli global regulator Hfq protein and Sm protein in S.cerevisiae. ---> An interesting thing is there is two Sm-like domain in ZM4's hfq.
They made AcRIM0347 by introduction of hfq insertion muation in AcR (Z.mobilis acetate tolerant strain).This . And they introduced plasmid p42-0347 (expressing hfq) into ZM4, AcR and AcRIM0347. ---> these can be specified as ZM4(p42-0347), AcR(p42-0347), AcRIM0347(p42-0347).
They tested growth of those above in various acetate counter-ions (NaCl, NaAc, NH4OAc, KAc) and in pretreatment inhibitors (vanillin,
furfural, HMF). ---> AcRIM0347
grow slowly than AcR, ZM4(p42-
0347) was able to grow in NaAc like AcR. AcRIM0347(p42-0347) recover growth to a certain degree in acetate counter-ions and inhibitors.
-conclusion-
hfq play an important role in tolerance to multiple biomass pretreatment inhibitors.
