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Veeranagouda, Yaligara,Lee, Kyoung,Cho, Ah Ra,Cho, Kyungyun,Anderson, Erin M,Lam, Joseph S Published by Elsevier/North Holland on behalf of t 2011 FEMS microbiology letters Vol.315 No.1
<P>In the presence of vaporized p-cresol, Pseudomonas alkylphenolia KL28 forms specialized aerial structures (SAS). A transposon mutant of strain KL28 (C23) incapable of forming mature SAS was isolated. Genetic analysis of the C23 mutant revealed the transposon insertion in a gene (ssg) encoding a putative glycosyltransferase, which is homologous to the Pseudomonas aeruginosa PAO1 PA5001 gene. Deletion of ssg in KL28 caused the loss of lipopolysaccharide O antigen and altered the composition of the exopolysaccharide. Wild-type KL28 produced a fucose-, glucose- and mannose-rich exopolysaccharide, while the mutant exopolysaccharide completely lacked fucose and mannose, resulting in an exopolysaccharide with glucose as the major component. The mutant strain showed reduced surface spreading, pellicle and biofilm formation, probably due to the cumulative effect of lipopolysaccharide truncation and altered exopolysaccharide composition. Our results show that the ssg gene of KL28 is involved in both lipopolysaccharide and exopolysaccharide biosynthesis and thus plays an important role in cell surface properties and cell-cell interactions of P. alkylphenolia.</P>
송명민,Yaligara Veeranagouda,Munkhtsatsral Ganzorig,이경 한국미생물학회 2018 The journal of microbiology Vol.56 No.11
The colonization of liquid surfaces as floating biofilms or pellicles is a bacterial adaptation to optimally occupy the airliquid (A-L) niche. In aerobic heterotrophs, pellicle formation is beneficial for the utilization of O2 and nonpolar organic compounds. Pseudomonas alkylphenolica KL28, an alkylphenol degrader, forms flat circular pellicles that are 0.3– 0.5 mm in diameter. In this study, we first monitored the pellicle developmental patterns of multicellular organization from the initial settlement stage. The pellicles developed by clonal growth and mutants for flagella and pilus formation established normal pellicles. In contrast, the mutants of an epm gene cluster for biosynthesis of alginate-like polymer were incompetent in cell alignment for initial two-dimensional (2D) pellicle growth, suggesting the role of the Epm polymer as a structural scaffold for pellicle biofilms. Microscopic observation revealed that the initial 2D growth transited to multilayers by an accumulated self-produced extracellular polymeric substance that may exert a constraint force. Electron microscopy and confocal laser scanning microscopy revealed that the fully matured pellicle structures were densly packed with matrix-encased cells displaying distinct arrangements. The cells on the surface of the pellicle were relatively flat, and those inside were longitudinally cross-packed. The extracellular polysaccharide stained by Congo red was denser on the pellicle rim and a thin film was observed in the open spaces, indicative of its role in pellicle flotation. Our results demonstrate that P. alkylphenolica KL28 coordinately dictates the cell arrangements of pellicle biofilms by the controlled growth of constituent cells that accumulate extracellular polymeric substances.
Ultramicrocells form by reductive division in macroscopic <i>Pseudomonas</i> aerial structures
Lee, Kyoung,Veeranagouda, Yaligara Blackwell Publishing Ltd 2009 Environmental microbiology Vol.11 No.5
<P>Summary</P><P>Bacterial aerial growth with reductive cellular division and morphological development has not been reported from single-cell bacteria. Here we show that within 1 month of incubation in vaporized <I>p</I>-cresol, <I>Pseudomonas</I> sp. KL28 form shiny, highly branched specialized aerial structures of millimetre-scale diameter. The developmental process displayed spatially and temporally distinct stages; an initial sphere stage was followed by ramification, which led to highly branched tip formation. In this morphogenesis process, the extracellular matrix (ECM) played an important role for maintaining the integrity of sectional populations and the boundaries between adjacent sectors. In addition, cellular division, lysis and migration within the aerial structures were also accompanied. During prolonged incubation, clusters of short-rod cells covered by an outer layer of thick ECM underwent reductive transformation and then replicative reductive division to form oval ultramicrocells of < 0.4 &mgr;m in diameter. In addition, the aerial structures protected these rather fragile cells from desiccation and served as a selection pressure for wrinkly, spreading cell variants. The formation of aerial structures is affected positively and negatively by a GacA regulator and RpoS, respectively, and is linked to other phenotypes. Our results demonstrate that <I>Pseudomonas</I> has an ecological adaptation to form mushroom-like aerial structures, which can be a tool for studying cell–cell interactions and bacterial development.</P>
Purification and Physiochemical Characterization of Melanin Pigment from Klebsiella sp. GSK
( Sajjan,Shrishailnath ),( Guruprasad Kulkarni ),( Veeranagouda Yaligara ),( Kyoung Lee ),( T. B. Karegoudar ) 한국미생물 · 생명공학회 2010 Journal of microbiology and biotechnology Vol.20 No.11
A bacterium capable of producing melanin pigment in the presence of L-tyrosine was isolated from a crop field soil sample and identified as Klebsiella sp. GSK based on morphological, biochemical, and 16S rDNA sequencing. The polymerization of this pigment occurs outside the cell wall, which has a granular structure as melanin ghosts. Chemical characterization of the pigment particles showed then to be acid resistant, alkali soluble, and insoluble in most of the organic solvents and water. The pigment got bleached when subjected to the action of oxidants as well as reductants. This pigment was precipitated with FeCl3, ammoniacal silver nitrate, and potassium ferricynide. The pigment showed high absorbance in the UV region and decreased absorbance when shifted towards the visible region. The melanin pigment was further charecterized by FT-IR and EPR spectroscopies. A key enzyme, 4- hydroxyphenylacetic acid hydroxylase, that catalyzes the formation of melanin pigment by hydroxylation of Ltyrosine was detected in this bacterium. Inhibition studies with specific inhibitors, kojic acid and KCN, proved that melanin is synthesized by the DOPA-melanin pathway.
( Ah Ra Cho ),( Eun Jin Lim ),( Yaligara Veeranagouda ),( Kyoung Lee ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.11
In this study, the chromosome-encoded pcuRCAXB genes that are required for p-cresol degradation have been identified by using a newly constructed green fluorescent protein (GFP)-based promoter probe transposon in the long-chain alkylphenol degrader Pseudomonas alkylphenolia. The deduced amino acid sequences of the genes showed the highest identities at the levels of 65-93% compared with those in the databases. The transposon was identified to be inserted in the pcuA gene, with the promoterless gfp gene being under the control of the pcu catabolic gene promoter. The expression of GFP was positively induced by p-cresol and was about 10 times higher by cells grown on agar than those in liquid culture. In addition, phydroxybenzoic acid was detected during p-cresol degradation. These results indicate that P. alkylphenolia additionally possesses a protocatechuate ortho-cleavage route for pcresol degradation that is dominantly expressed in colonies.