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Vitreoscilla hemoglobin (VHb) is bacterial hemoglobin and has beneficial effects on heterologous organisms. The VHb/vgb system, in the advanced phases of the culture, transfers oxygen to the membrane transferases, giving the elderly cells the ability to better oxygen-uptake, grow and proliferate. In this study was investigated the intracellular and extracellular production of vitamin E in Erwinia herbicola and its recombinant strains (vgb- and vgb+). There was a significant increase the production of vitamin E in the vgb+ strain in the LB medium. Production of total vitamin E in the vgb+ recombinant strain had 2-fold higher than its host. The wild strain produced 0.06 μg/mL total vitamin E, whereas the recombinant bacteria carrying the vgb gene produced 0.12 μg/mL the product. In addition, production of vitamin E was investigated in the minimal medium (M9) including 1% concentrations of different carbon resources such as glucose, sucrose and fructose. It was recorded that the vitamin E levels produced by the recombinant strain in the culture containing 1% fructose were higher than with 1% glucose and sucrose cultures. The findings showed that the presence of vgb may provide an effective biotechnological method to increase yield of vitamin E.

In this study, the use of recombinant oxygen uptake system on production of ATP production, oxygen uptake and cell mass was investigated. Citrobacter freundii and their vgb recombinants were used. Citrobacter freundii, a broad host range plasmids Cf[pMK 79] and Cf[pUC 8:15] was used. Best ATP production by Cf[pMK 79] (0.17 mg/ g). C f[pMK 7 9] s train t he l evel o f o xygene u ptake w as h igher t han C f[pUC 8 :15]. Whereas Cf[pMK 79] the OD600 values have been falling at the end of 48 hours.

Given the well-established beneficial effects of Vitreoscilla hemoglobin (VHb) on heterologous organisms, the potential of this protein for the production of L-DOPA and dopamine in two bacteria, Citrobacter freundii and Erwinia herbicola, was investigated. The constructed recombinants bearing the VHb gene (vgb(+)) had substantially higher levels of cytoplasmic L-DOPA (112 mg/L for C. freundii and 97 mg/L for E. herbicola) than their respective hosts (30.4 and 33.8 mg/L) and the vgb(-) control strains (35.6 and 35.8 mg/L). Further, the vgb(+) recombinants of C. freundii and E. herbicola had 20-fold and about two orders of magnitude higher dopamine levels than their hosts, repectively. The activity of tyrosine phenol-lyase, the enzyme converting L-tyrosine to L-DOPA, was well-correlated to cytoplasmic L-DOPA levels. As cultures aged, higher tyrosine phenol-lyase activity of the vgb(+) strains was more apparent.

Tuberculosis (TB) is major health problem threatening many people worldwide. It is caused by Mycobacterium tuberculosis. M. tuberculosis changes its cellular environment with the mechanisms that have been evolved since prehistoric times. The interactions between the bacteria and the host environment have been studied well. But the studies at RNA level began to emerge recently. MicroRNAs (miRNAs) became a target for different diseases depending on their regulatory role on gene expression. As the data about the new class of small non-coding RNA called microRNAs accumulate researchers find more information about their regulatory role in biological processes including immune response to infectious agents like mycobacteria. Several studies detected the alterations in the expression levels of miRNAs in the individuals that are infected. Researchers are trying to find miRNA expression profiles for the infection either in latent or active state which can also be used as biomarkers for diagnosis or miRNA based therapy options. Here we try to summarize some of the studies that include M. tuberculosis and the possible functions of miRNAs during TB infection.

The production of antileukemic enzyme methionine γ-lyase (MGL) in distinctly related bacteria, Citrobacter freundii and in their recombinants expressing the Vitresocilla hemoglobin (VHb) has been studied. This study concerns the potential of Citrobacter freundii expressing the Vitreoscilla hemoglobin gene (vgb) for the methionine γ- liyase production. Methionine γ- liyase production by Citrobacter freundii and its vgb(-) and vgb(+) bearing recombinant strain was studied in shake-flasks under 200 rpm agitation, culture medium and 30 °C in a time-course manner. The vgb(+) and especially the carbon type had a dramatic effect on methionine γ- liyase production. The vgb(+) strain of C. freundii had about 2-fold and 3.1-fold higher levels of MGL than the host and vgb(-) strain, respectively.