Polar Lipids, Fatty Acids, and Isoprenoid Quinones of Alteromonas putrefaciens (Shewanella putrefaciens)

Adaptations of archaeal and bacterial membranes to variations in temperature, pH and pressure

The cytoplasmic membrane of a prokaryotic cell consists of a lipid bilayer or a monolayer that shields the cellular content from the environment. In addition, the membrane contains proteins that are responsible for transport of proteins and metabolites as well as for signalling and energy transduction. Maintenance of the functionality of the membrane during changing environmental conditions relies on the cell's potential to rapidly adjust the lipid composition of its membrane. Despite the fundamental chemical differences between bacterial ester lipids and archaeal ether lipids, both types are functional under a wide range of environmental conditions. We here provide an overview of archaeal and bacterial strategies of changing the lipid compositions of their membranes. Some molecular adjustments are unique for archaea or bacteria, whereas others are shared between the two domains. Strikingly, shared adjustments were predominantly observed near the growth boundaries of bacteria. Here, we demonstrate that the presence of membrane spanning ether-lipids and methyl branches shows a striking relationship with the growth boundaries of archaea and bacteria.

Changes of membrane fatty acids and proteins of Shewanella putrefaciens treated with cinnamon oil and gamma irradiation

BACKGROUND

In order to detect the antimicrobial mechanism of combined treatment of cinnamon oil and gamma irradiation (GI), the membrane fatty acids and proteins characteristics of Shewanella putrefaciens (S. putrefaciens) treated with cinnamon oil and GI, and the distribution of cinnamon oil in S. putrefaciens were observed in this study.

RESULTS

The membrane lipid profile of S. putrefaciens was notably damaged by treatments of cinnamon oil and the combination of cinnamon oil and GI, with significantly fatty acids decrease in C14:0, C16:0, C16:1, C17:1, C18:1 (p < 0.05). The SDS-PAGE result showed that GI did not have obvious effect on membrane proteins (MP), but GI combined with cinnamon oil changed the MP subunits. Cinnamaldehyde, the main component of cinnamon oil, can not transport into S. putrefaciens obviously. It was transformed into cinnamyl alcohol in the nutrient broth with the action of S. putrefaciens. This indicated that the antimicrobial action of cinnamon oil mainly happened on the membrane of S. putrefaciens.

CONCLUSION

Cinnamon oil could act on the membrane of S. putrefaciens with the damage of fatty acids and proteins, and GI would increase the destructive capability of cinnamon oil on the membrane fatty acids and proteins of S. putrefaciens.

Complete genome sequence of Ferrimonas balearica type strain (PAT)

Ferrimonas balearica Rossello-Mora et al. 1996 is the type species of the genus Ferrimonas, which belongs to the family Ferrimonadaceae within the Gammaproteobacteria. The species is a Gram-negative, motile, facultatively anaerobic, non spore-forming bacterium, which is of special interest because it is a chemoorganotroph and has a strictly respiratory metabolism with oxygen, nitrate, Fe(III)-oxyhydroxide, Fe(III)-citrate, MnO(2), selenate, selenite and thiosulfate as electron acceptors. This is the first completed genome sequence of a member of the genus Ferrimonas and also the first sequence from a member of the family Ferrimonadaceae. The 4,279,159 bp long genome with its 3,803 protein-coding and 144 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

Shewanella affinis sp. nov., isolated from marine invertebrates

Four marine bacterial strains, designated KMM 3587T, KMM 3586, KMM 3821 and KMM 3822, were isolated from the sipuncula Phascolosoma japonicum, a common inhabitant of Troitza Bay in the Gulf of Peter the Great (Sea of Japan region), and from an unidentified hydrocoral species collected in Makarov Bay (Iturup Islands), Kuril Islands, North-West Pacific Ocean. The strains were characterized to clarify their taxonomic position. 16S rRNA gene sequences of KMM 3587T and KMM 3586 indicated 99 % similarity to Shewanella colwelliana. Despite such a high level of 16S rRNA gene sequence similarity, DNA–DNA hybridization experiments demonstrated only 45–52 % binding with DNA of S. colwelliana ATCC 39565T. The DNA G+C contents of the novel strains were 45 mol% and the shared level of DNA hybridization was conspecific (81–97 %), indicating that they represent a single genospecies. The novel strains were mesophilic (able to grow at 10–34 °C), neutrophilic and haemolytic, and able to degrade gelatin, casein and Tween 20, 40 and 80, but not starch, agar, elastin, alginate or chitin. The major fatty acids were i13 : 0, i15 : 0, 16 : 0, 16 : 1ω7 and 17 : 1ω8 (68·9 % of total). The major isoprenoid quinones were Q7 (47–62 %) and Q8 (26–47 %). Eicosapentaenoic acid was produced in minor amounts. Based on these data, the strains are assigned to a novel species, Shewanella affinis sp. nov. (type strain KMM 3587T=CIP 107703T=ATCC BAA-642T).

Shewanella waksmanii sp. nov., isolated from a sipuncula (Phascolosoma japonicum)

Two marine bacterial strains, KMM 3823(T) and KMM 3836, isolated from a sipuncula (Phascolosoma japonicum), a common inhabitant of Troitsa Bay in the Gulf of Peter the Great (Sea of Japan), were studied. Comparative 16S rRNA gene sequence-based phylogenetic analysis placed these bacteria into a separate branch of the 'Gammaproteobacteria' within members of the genus SHEWANELLA: KMM 3823(T) showed the highest similarity (96.6 %) with Shewanella fidelis. The DNA G+C contents of the two strains studied were 43.0 mol%. The level of DNA homology between these two strains was conspecific (93 %), indicating that they represent a single genospecies. These organisms were greenish-brown, Gram-negative, polarly flagellated, facultatively anaerobic, mesophilic (temperature range 4-30 degrees C), neutrophilic, haemolytic and were able to degrade elastin, gelatin and DNA. They were susceptible to ampicillin, carbenicillin, gentamicin and kanamycin. The predominant fatty acids were characteristic for shewanellas: 13 : 0-i, 15 : 0-i and 16 : 1(n-7); up to 6.7 % of eicosapentaenoic fatty acid, 20 : 5(n-3), was produced during growth at 28 degrees C. Phylogenetic evidence, confirmed by DNA hybridization and phenotypic characteristics revealed that the two bacteria studied constitute a new species, Shewanella waksmanii sp. nov., the type strain of which is KMM 3823(T) (=CIP 107701(T)=ATCC BAA-643(T)).

Occurrence and diversity of mesophilic Shewanella strains isolated from the North-West Pacific Ocean

Although bacteria of the genus Shewanella belong to one of the readily cultivable groups of "Gammaproteobacteria", little is known about the occurrence and abundance of these microorganisms in the marine ecosystem. Studies revealed that of 654 isolates obtained from marine invertebrates (ophiuroid Amphiopholis kochii, sipuncula Phascolosoma japonicum, and holothurian Apostichopus japonicus, Cucumaria japonica), seawater and sediments of the North-West Pacific Ocean (i.e. the Sea of Japan and Iturup Is, Kurile Islands), 10.7% belonged to the genus Shewanella. The proportion of viable Shewanella species varied from 4% to 20% depending on the source of isolation. From the isolation study, representative strains of different phenotypes (from seventy presumptive Shewanella strains) were selected for detailed characterization using phenotypic, chemotaxonomic, and phylogenetic testing. 16S rDNA sequence-based phylogenetic analysis confirmed the results of tentative identification and placed the majority of these strains within only a few species of the genus Shewanella with 98-99% of 16S rDNA sequences identity mainly with S. japonica and S. colwelliana, suggesting that the strains studied might belong to these species. Numerically dominant strains of S. japonica were metabolically active and produced proteinases (gelatinases, caseinases), lipases, amylases, agarases, and alginases. Shewanella strains studied demonstrated weak antimicrobial and antifungal activities that might be an indication of their passive role in the colonization on living and non-living surfaces.

Shewanella fidelis sp. nov., isolated from sediments and sea water

Two marine bacterial strains, KMM 3582T and KMM 3589, isolated respectively from sediments of the South China Sea and sea water of the Sea of Japan, have been characterized. Comparative 16S rDNA sequence-based phylogenetic analysis placed the two strains in a separate branch of the gamma-Proteobacteria within the members of the genus Shewanella. KMM 3582T showed the highest similarity (97.1 and 97.4%, respectively) to Shewanella pealeana and Shewanella gelidimarina. The G + C contents of the DNAs of the two strains studied were 45.0 mol%. The level of DNA-DNA relatedness between the two strains was 82%, indicating that they represent a single genospecies. These organisms were slightly pinkish, Gram-negative, polarly flagellated, facultatively anaerobic, mesophilic (with temperature range from 4 to 30 degrees C), neutrophilic and haemolytic and were able to degrade alginate, gelatin and DNA. The novel organisms were susceptible to gentamicin, lincomycin, oleandomycin, streptomycin and polymyxin. The predominant fatty acids were characteristic for shewanellae: 13 : 0-i, 15 : 0-i, 16 : 0 and 16 : 1omega7. Eicosapentaenoic acid, 20 : 5omega3, was not detected. Phylogenetic evidence, together with phenotypic characteristics, showed that the two bacteria constitute a novel species of the genus Shewanella. The name Shewanella fidelis sp. nov. is proposed, with the type strain KMM 3582T (=LMG 20551T =ATCC BAA-318T).

Role of the tetraheme cytochrome CymA in anaerobic electron transport in cells of Shewanella putrefaciens MR-1 with normal levels of menaquinone

Shewanella putrefaciens MR-1 possesses a complex electron transport system which facilitates its ability to use a diverse array of compounds as terminal electron acceptors for anaerobic respiration. A previous report described a mutant strain (CMTn-1) deficient in CymA, a tetraheme cytochrome c. However, the interpretation of the electron transport role of CymA was complicated by the fact that CMTn-1 was also markedly deficient in menaquinones. This report demonstrates that the depressed menaquinone levels were the result of the rifampin resistance phenotype of the parent of CMTn-1 and not the interruption of the cymA gene. This is the first report of rifampin resistance leading to decreased menaquinone levels, indicating that rifampin-resistant strains should be used with caution when analyzing electron transport processes. A site-directed gene replacement approach was used to isolate a cymA knockout strain (MR1-CYMA) directly from MR-1. While MR1-CYMA retained menaquinone levels comparable to those of MR-1, it lost the ability to reduce iron(III), manganese(IV), and nitrate and to grow by using fumarate as an electron acceptor. All of these functions were restored to wild-type efficacy, and the presence of the cymA transcript and CymA protein was also restored, by complementation of MR1-CYMA with the cymA gene. The requirement for CymA in anaerobic electron transport to iron(III), fumarate, nitrate, and manganese(IV) is therefore not dependent on the levels of menaquinone in these cells. This represents the first successful use of a suicide vector for directed gene replacement in MR-1.

Iso- and anteiso-fatty acids in bacteria: biosynthesis, function, and taxonomic significance

Branched-chain fatty acids of the iso and anteiso series occur in many bacteria as the major acyl constituents of membrane lipids. In addition, omega-cyclohexyl and omega-cycloheptyl fatty acids are present in several bacterial species. These two types of fatty acids are synthesized by the repeated condensation of malonyl coenzyme A with one of the branched-chain and cyclic primers by the same enzyme system. The pathway of de novo branched-chain fatty acid synthesis differs only in initial steps of synthesis from that of the common straight-chain fatty acid (palmitic acid) present in most organisms. The cell membranes composed largely of iso-, anteiso-, and omega-alicyclic acids support growth of bacteria, which inhabit normal as well as extreme environments. The occurrence of these types of fatty acids as major cellular fatty acids is an important criterion used to aid identification and classification of bacteria.

Polar lipids and fatty acids of Pseudomonas caryophylli, Pseudomonas gladioli and Pseudomonas pickettii

The polar lipids and their fatty acid components in Pseudomonas caryophylli, Pseudomonas gladioli and Pseudomonas pickettii have been identified. In addition to diphosphatidylglycerol and phosphatidylglycerol (a trace only for P. pickettii), all three species contained two forms of phosphatidylethanolamine differing in the presence or absence of α-hydroxy fatty acids. This seems to be a distinctive feature of species in Pseudomonas RNA homology group II. Also, P. caryophylli and P. gladioli (but not P. pickettii) produced two forms of ornithine amide lipid, differing in the nature (hydroxy or non-hydroxy) of the ester-linked fatty acid. In all three species, the major non-hydroxy acids were hexadecanoic acid, a hexadecenoic acid, an octadecenoic acid, and cyclopropane derivatives of the monoenoic acids. The α-hydroxy acids were the derivatives of the same components, while the amide-linked acid of the ornithine amide lipids was mainly or entirely 3-hydroxyhexadecanoic acid. The possible taxonomic implications of the data are discussed.

Polar lipids and fatty acids of Pseudomonas cepacia

The polar lipids and fatty acids produced by the reference strains for seven different O serogroups of Pseudomonas cepacia have been identified. Similar results were obtained for all strains. Contrary to a previous report, the only significant phospholipids in this species are phosphatidylethanolamine and bis(phosphatidyl)glycerol, which contributed 57-83% and 17-43%, respectively, of the total lipid phosphorus. The former lipid was found as two chromatographically distinct fractions. In the less polar fraction and in bis(phosphatidyl)glycerol, the major fatty acids were hexadecanoic acid, cis-9,10-methylenehexadecanoic acid, cis-octadec-11-enoic acid, and cis-11,12-methyleneoctadecanoic acid. In the more polar fraction of phosphatidylethanolamine, the fatty acid in one position is a 2-hydroxy acid, mainly 2-hydroxyhexadecenoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecenoic acid, or 2-hydroxymethyleneoctadecanoic acid. Compared with other phospholipids, this fraction of phosphatidylethanolamine was depleted in cis-9,10-methylenehexadecanoic acid. Each strain also produced two ornithine amide lipids. In the major lipid, 3-hydroxyhexadecanoic acid was amide-bound to the alpha-amino group and was itself probably esterified by a 2-hydroxy acid, mainly 2-hydroxyoctadecenoic acid or the derived cyclopropane acid. In the minor ornithine amide lipid, the ester-bound acids were mainly methyleneoctadecanoic acid and hexadecanoic acid. The unusual lipid profiles of P. cepacia are of chemotaxonomic interest.