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Cyclopropane fatty acid (CFA) synthesis was investigated in Oenococcus oeni. The data obtained demonstrated that acid-grown cells or cells harvested in the stationary growth phase showed changes in fatty acid composition similar to those of ethanol-grown cells. An increase of the CFA content and a decrease of the oleic acid content were observed. The biosynthesis of CFAs from unsaturated fatty acid phospholipids is catalysed by CFA synthases. Quantitative real-time-PCR experiments were performed on the cfa gene of O. oeni, which encodes a putative CFA synthase. The level of cfa transcripts increased when cells were harvested in stationary phase and when cells were grown in the presence of ethanol or at low pH, suggesting transcriptional regulation of the cfa gene under different stress conditions. In contrast to Escherichia coli, only one functional promoter was identified upstream of the cfa gene of O. oeni. The function of the cfa gene was confirmed by complementation of a cfa-deficient E. coli strain. Nevertheless, the complementation remained partial because the conversion percentage of unsaturated fatty acids into CFA of the complemented strain was much lower than that of the wild-type strain. Moreover, a prevalence of cycC19 : 0 was observed in the membrane of the complemented strain. This could be due to a specific affinity of the CFA synthase from O. oeni. In spite of this partial complementation, the complemented strain of E. coli totally recovered its viability after ethanol shock (10%, v/v) whereas its viability was only partly recovered after an acid shock at pH 3.0.

The Pseudomonas fluorescens RIWE8 mutant was analyzed to determine the effects of lacZ genetic modification on the ecological behavior of Pseudomonas fluorescens. Pseudomonas fluorescens R2f and RIWE8 strains grown in field soil microplots indicated the presence of higher reporter gene activity in wheat rhizosphere with RIWE8 strains. However, the genetically modified strains and the parental strain exhibited minor differences in their ecological properties.

A small microcosm system was developed to assess the impact of various ecological factors on the transformation frequency of Acinetobacter calcoaceticus BD413 with chromosomal DNA in soil. Analysis of the natural transformation of Acinetobacter calcoaceticus in sterile and nonsterile soil systems indicated the inhibitory effects of the soil matrix on the availability of DNA. Furthermore, the growth of the gram-negative microbe in freshly released DNA was a prerequisite to in situ transformation which occurred in the maize rhizosphere.

The PYK2 gene of Saccharomyces cervisiae encodes a functional pyruvate kinase isoenzyme which exhibits low activity and high transcript levels during the growth of yeasts in an ethanol medium. The regulation of yeast pyruvate kinase was dependent on fructose-1,6-bisphosphate and other control parameters that influence PYK2 gene activity. Furthermore, overexpression of the unregulated Pyk2p enzyme activity during growth of yeast cells in ethanol did not cause any deleterious effects on the microbial cell wall.

The mechanisms of carbohydrate metabolism In Mycobacterium smegmatis were characterized by suppressor mutations of the phosphoglucose isomerase (pgi) gene. The glucose utilization mutants exhibited defective carbon synthesis and required glucose or galactose as a sole carbon source for growth. However, complementation of the mutants with the cloned copy of pgi restored both intracellular levels of Pgi and the wild-type phenotype.

The mechanisms that initiate chromosome replication and cell division in Bacillus subtilis was analyzed to determine the role of dnaA and oriC genes. Temperature-sensitive growth in Bacillus subtilis was suppressed by the integration of a plasmid containing the minimal replication region of pLS32 into the chromosome. The replication of the pLS32 plasmid was also dependent on DnaB, DnaC helicase and DnaD proteins which were required as host factors.

The genetic mechanisms of Rhizobium meliloti cell division machinery were analyzed to determine capability of the cells to form long filaments when cell division was blocked. Rhizobium meliloti cells that were treated with the DNA replication inhibitor mitomycin C elongated and branched at one pole to form Y-shaped cells compared to nalidixic acid which inhibited growth. Furthermore, the formation of Y-shaped cells was caused by the blockage of the DNA replication-segregation cycle in Rhizobium meliloti cells.

Isogenic sodA and sobB Bordetella pertussis mutants were analyzed to identify and characterize the iron-regulated Mn-containing superoxide dismutase (SodA) of the pathogenic bacteria. Bordetella pertussis sodA mutants exhibited normal growth compared to sodB gene mutants which exhibited impaired cellular viability. Furthermore, sodA mutations did not alter the virulence of Bordetella pertussis compared to sodB mutations which imparted avirulence.

Mutated cell division cycle (cdc) genes isolated from N-methyl-N'-nitrosoguanidine (NTG)-treated Caulobacter crescentus were analyzed to determine the chromosomal organization of the cdc genes. Analysis of isolated cdc genes exhibiting NTG-induced mutations from Caulobacter crescentus indicated the role of cell cycle progression in mediating developmental regulation. Furthermore, the cdc mutants exhibited defective cell growth and cell division.

The expression of the hya and cbd operons in Escherichia coli rpoS+ and rpoS359 strains under different conditions were analyzed to determine the role of the appY gene in the induction of the operons. The expression of cbd and hya operons of Escherichia coli was reduced in the absence of the sigmaS promoter under different growth conditions. Furthermore, initiations with sigmaS RNA polymerase was necessary for the expression of the operons during phosphate starvation or exponential growth.

Batch cultures of Ralstonia solanacearum were monitored for the expression of LacZ reporter fusions in selected PhcA-regulated genes to determine expression of PhcA-regulated virulence factors during exponential growth. Monitoring of beta-galactosidase synthesis in batch cultures of Ralstonia solanacearum indicated the differential expression of three PhcA-regulated genes with lacZ genomic fusions during the exponential growth phase. Furthermore, the addition of 3-hydroxypalmitic acid methyl ester in the batch cultures produced slight effects in PhcA-regulated gene expression and motility.

The uncharacterized open reading frame (omicron251) of Escherichia coli ubiE gene which encodes for three methyl transferase motifs was analyzed to determine its role in the biosynthesis of menaquinone and ubiquinone. The disruption of the omicron251 region of the ubiE gene in wild-type Escherichia coli cell impaired cellular growth on succinate. Mutations in the UbiE-encoding open reading frame also impaired the synthesis of menaquinone and ubiquinone. Furthermore, the ubiE gene mediated normal spore germination and vegetative growth.

Single-copy gnt::lacZ fusion and Northern hybridization analysis were utilized to characterize the expression of the Escherichia coli gntT gene and determine the biochemical function of its protein product. Northern hybridization analysis of the Escherichia coli gntT gene indicated the presence of properties that were characteristic of integral membrane transport proteins. Furthermore, gntT gene expression was enhanced during the logarithmic phase indicating the role of GntT in promoting microbial growth.

The Pseudomonas aeruginosa penicillin-binding protein 3 (PBP3) homolog (PBP3x) was cloned and analyzed to determine the regulation of pbpB and pbpC gene expression. Analysis of the Pseudomonas aeruginosa PBP3x indicated the presence of an amino acid sequence that was 41%-48% identical to Escherichia coli PBP3. The Pseudomonas aeruginosa PBP3 and PBP3x also exhibited similar functions and were upregulated during the stationary growth phase. Furthermore, the gene encoding PBP3 and PBP3x such as pbpB and pbpC were differentially regulated depending on the growth phase.

The functional properties of the Bacillus subtilis ftsH gene were analyzed to determine the activity of the FtsH protein during osmotic stress and spore formation. Analysis of Bacillus subtilis ftsH gene in ftsH::spc mutants indicated the role of the gene in proteolytic activity, membrane assembly and attainment of cell density during the stationary phase of cell growth. Furthermore, the FtsH protein also mediated cellular response to osmotic stress and promoted spore formation in Bacillus subtilis.

The relationship between leuB- reversion rates and steady-state ppGpp levels was analyzed during exponential growth in two Escherichia coli K-12 isogenic strains. Analysis of two isogenic multiple auxotrophs of Escherichia coli K-12 indicated the presence of two general classes of leu+ revertants that are produced by two distinct mechanisms during exponential growth. Furthermore, mutation rates correlated with ppGpp levels during the transitional period between the end of exponential growth and stationary phase.

The MDM12 gene in Saccharomyces cerevisiae encoded a 31-kilodalton protein that mediated the maintenance of the normal mitochondrial reticular network. Analysis of Saccharomyces cerevisiae cells exhibiting mdm12-1 mutations indicated the presence of abnormal mitochondrial morphology and distribution. Furthermore, Mdm12p was characterized as Saccharomyces cerevisiae protein that mediated the attachment of the mitochondria to cytoskeletal elements.

The expression of the stpA gene under a variety of conditions was analyzed in hns wild-type Escherichia coli cells to determine the specific conditions that induced the expression of the StpA H-NS-like protein. Escherichia coli cells that were cultured in a rich medium exhibited a transient burst of stpA expression during log phase. The expression of stpA was also dependent on the presence of the leucine-responsive regulatory protein, medium osmolality and growth temperature.

The synthesis of coenzyme F390 and the transcription of the ftsA gene were analyzed in Methanobacterium thermoautotrophicum under different growth conditions to determine their effects on the expression of methane genes. Analysis of growth phase-dependent methane gene regulation indicated the role of H2 availability in the transcription of mcr genes, methanogenesis and growth. Furthermore, the availability of H2 regulated maximum growth yield and growth rate.

The role of proteins encoded by cbbX, cbbY and cbbZ genes on autotropic metabolism was analyzed by insertional mutagenesis in Rhodobacter sphaeroides. Insertional mutations in the cbbX gene of Rhodobacter sphaeroides altered microbial photoautotrophic growth and attenuated phosphoglycolate phosphatase activity. However, cbbZ and cbbY mutations did not affect normal autotrophic growth in Rhodobacter sphaeroides.

The 7-kbp region of the Bacteroides thetaiotaomicron genome was cloned and analyzed to determine its role in the biosynthesis of starch. Analysis of the region located downstream of the susC gene indicated the presence of five Bacteroides thetaiotaomicron genes that encoded maltose-inducible outer membrane proteins. However, mutations in the novel genes such as susD, susE and susG did not affect the metabolism of starch during microbial growth.

The regulation of abrB gene expression in Bacillus subtilis was analyzed to determine the biochemical activity of the transition state regulator AbrB during microbial growth. The levels of abrB messenger RNA (mRNA) in Bacillus subtilis increased during the lag phase and early logarithmic phase of the growth cycle of Bacillus subtilis. However, abrB mRNA was reduced to undetectable levels before the mid-exponential phase of the growth cycle. Furthermore, the maximal level of AbrB nucleoid binding protein correlated with the maximal transcript level.

Two groESL1 heat shock operons from Rhodobacter sphaeroides were cloned and analyzed to determine the mechanisms of chaperonin-mediated ribulose bisphosphate carboxylase/oxygenase folding. Southern blot analysis of the Rhodobacter sphaeroides groESL1 operons indicated the presence of groES1 and groEL1 heat shock genes that exhibited a conserved upstream hairpin loop structure. Furthermore, the levels of groESL1 genes were reduced during photoautotrophic growth conditions.

The role of catalases and alkylhydroperoxidases in the maintenance of intracellular hydrogen peroxide was analyzed in Escherichia coli cells during exponential growth. Analysis of H2O2 levels in Escherichia coli cells during aerobic growth indicated the role of the katG-encoded bifunctional catalase hydroperoxidase I in the transcriptional regulation of H2O2 homeostasis. Furthermore, the high levels of intracellular H2O2 during exponential growth was associated with the increased frequency of spontaneous mutations and oxidative DNA damage.

The metabolic pathways involved in the catabolism of dicarboxylic acid substrates in Bradyrhizobium japonicum was analyzed in alpha-ketoglutarate dehydrogenase-deficient mutants. The absence of alpha-ketoglutarate dehydrogenase did not alter the ability of the Bradyrhizobium japonicum mutant strain to grow on a wide variety of carbon sources. However, the ability of the mutant to utilize glutamate was impaired. Furthermore, the ability of the mutant to grow on succinate and malate indicated the presence of other metabolic pathways that compensate for the loss of the enzyme.

The narQ regulatory gene of Escherichia coli was analyzed to determine the presence of nitrate-responsive sensor-transmitter proteins. Nucleotide sequencing of the naQ gene indicated the presence of an open reading frame in the 53.0 min. region of the Escherichia coli chromosome which encodes a protein that is similar to the beta subunit of glutamate synthase. Furthermore, the expression of narQ is regulated by the anaerobically-expressed gene A (aegA) which is activated by anaerobiosis and fnr, narXL and narQ gene products.

The biochemical activity of leucine-responsive regulatory (Lrp) protein in Escherichia coli cultured in chemically rich mediums is studied. The levels of Lrp in Escherichia coli cells in minimal medium decreased during the logarithmic growth phase of the microbial culture. However, Lrp levels decreased significantly in microbial cells that were cultured in a chemically-rich nutrient medium during the log phase. The reduced levels of Lrp during the logarithmic growth phase is also attributed to low levels of ppGpp nucleotides.

The SNZ1 gene is a highly conserved stationary-phase gene in Saccharomyces cerevisiae which is activated by nutrient limitation and growth arrest. Analysis of the biochemical activity and structure of the gene in Saccharomyces cerevisiae indicated the role of the protein product as a component of a specific growth arrests response. The SNZ1 also exhibited a broad phylogenetic conservation that is not activated by induced starvation or heat shock.

Stigmatella aurantiaca transposon mutants exhibiting defective fruiting body formation have been induced with the Tn5lacZ promotor probe transposon to determine the genes that mediate microbial morphogenesis. The mutants exhibited defective fruiting body formation due to the inactivation of the fbfB gene by the transposon insertion of AP182. The fbfB gene acts as a component of the signal-transducing pathway that promotes the spatial aggregation of cells which is necessary for stabilizing microbial morphologic structure.

The HYR1 gene of Candida albicans is specifically expressed during the yeast-to-hypha transition and encodes a nonessential cell wall protein component. The pH-responsive genes and serum-induced genes of Candida albicans encode proteins that are needed for microbial metabolism. The HYR1 gene is composed of a putative N-terminal signal sequence and a putative C-terminal GPI-anchoring domain. The gene encodes a hypha-specific cell surface glycoprotein during hyphal development.

The PCC 7120 strain of Anabaenaexhibit reduced growth rate under conditions promoting nitrogen fixation. This mutant strain is complemented by the patB gene the gene product of which, PatB,bears similarity to prokaryotic and eukaryotic transcription regulators. The amino terminal of the 529-amino acid residue PatB bears resemblance to the ferredoxin while the carboxy terminal contains a helix-turn-helix domain. The PCC 7120 strain is a product of a deletion mutation in the patB gene that resulted in the loss of 62 amino acid residues from the carboxy terminal.

Thiobacillus ferrooxidans AP19-3 expresses a novel membrane-localized sulfite oxidase which uses Fe(III) as an electron acceptor. This enzyme was purified to homogeneity, resulting in the isolation of a 650-kDa enzyme with an optimum pH of 6.5. Further analysis showed that this oxidoreductase is inhibited by Fe(II), indicating that it plays a major role in the regulation of sulfur use in T. ferrooxidans.

The Saccharomces cerevisiae byp1-3 mutants are defective in the signal transduction pathway involved in the transition from growth on a nonfermentable carbon source to a glucose-containing medium. Such mutants are deficient in fructose-2,6-bisphosphate formation as well as inactivation of fructose-1,6-disphosphatase. These mutants were also defective in the induction of pyruvate decarboxylase. A complementary gene correcting growth initiation defects was isolated from a yeast gene library. The gene was identified as the zince finger transcription repressor MIG1.

The Escherichia coli ispB-disrupted mutants were analyzed to determine the function of the ispB gene and its octaprenyl diphosphate synthase in microbial growth. The defects of the ispB-disrupted mutants were complemented by Haemophilus influenzae and Synechocystis sp. strain PCC6803 ispB homologs. Furthermore, the viability of the ispB gene disruptants was dependent on the presence of a plasmid-borne copy of the ispB gene.

The growth rate-related expression of ilvGMEDA operon on Escherichia coli K-12 strain was analyzed to characterize the transcriptional activity of the ivlpE and ivlpG promoters. Analysis of Escherichia coli ilvGMEDA operon indicated the growth rate-related expression of the operon via a transcriptional mechanism that was independent of the integration host factor or ilvpG promoter activity. Furthermore, the growth rate-related expression of the Escherichia coli ilvGMEDA operon was not regulated at the transcriptional level.

The in vivo expression of the Lactobacillus brevis surface (S)-layer protein (SlpA) was analyzed based on the measurement of the half-life of slpA transcripts and expression of the slpA gene. Analysis of SlpA expression in Lactobacillus brevis indicated the presence of high levels of transcripts derived from the P2 promoter of slpA during the entire growth phase. Furthermore, the two S-layer messenger RNAs exhibited long half-lives due to the high stability of their messenger RNAs.

The biochemical role of Escherichia coli mutant rpoC397 gene in the synthesis of ribonucleic acid (RNA) was analyzed in Escherichia coli 397c strains. The mutation of the rpoC gene has a shorter RNA polymerase beta' subunit compared to the wild type RNA polymerase betaprime subunit. Furthermore, the premature termination of genetic transcription contributed to the formation of the shorter betaprime subunit of RNA polymerase in the mutant strains.

Research has been conducted on Mycobacterium avium subsp. paratuberculosis Australian sheep strains. The authors describe the development of the method which uses growth indices from radiometric BACTEC cultures for the enumeration of these strains.

Research has been conducted on Pyrococcus furiosus which grows on chitin. The authors report that chitin is a growth substrate for P. furiosus, and that the biochemical features of chitinase family have been determined for their recombinant forms.

Research has been conducted on Lactococcus lactis growth in milk. The authors have demonstrated that double inactivation of aminotransferases AraT and BcaT, isolated from L. lactis, reduce L. lactis growth in milk.

Research has been conducted on microbial communities attached to the agar spheres. The authorts have investigated the dynamics of these communities and the processes of their colonization, detachment, growth and grazing mortality.

Research has been conducted on mucoid Pseudomonas aeruginosa FRD1 growth under low oxygen conditions. Results demonstrate that non-mucoid isolates emerging from P. aeruginosa FRD1 static growth are motile.