Table 1.
Candidate strains of photosynthetic purple bacteria.
Fig 1.
PHA content (wt%) of photosynthetic purple bacteria.
Photosynthetic purple bacteria strains were cultured in growth medium until the cell cultures reached an approximate OD660 value of 1.0 and then diluted to an OD660 of 0.1 in nitrogen-limited media supplemented with 0.5% sodium acetate and/or 0.1% NaHCO3. After 7 days, the cells were harvested, and intracellular PHA levels were characterized using GC-MS. Intracellular PHAs under growth conditions were analyzed using cells showing approximately OD660 = 1.0 without supplementation and depletion. Data are the mean ± SD of at least three cultures. *Values that show significant differences compared to the growth conditions (p<0.05).
Fig 2.
TEM images of intracellular PHA granules in Mch. bheemlicum and Rdv. visakhapatnamense.
Mch. bheemlicum cells were cultured in growth medium (a) and in nitrogen-limited medium containing sodium acetate (b). Rdv. visakhapatnamense cells were cultured in growth medium (c) and in nitrogen-limited medium containing sodium acetate (d).
Fig 3.
Expression levels of phaC, phaP and phaZ genes under nitrogen-limited conditions.
RNA of Rdv. sulfidophilum was extracted under growth condition which cells were in the log phase and nitrogen-limited conditions which cells were cultured in nitrogen-limited medium for 7 days. rpoD gene was used as a housekeeping gene for normalizing the expression of target genes. The expression levels were shown as the relative values compared with those of growth conditions. *Values with significant differences compared with the growth conditions (p<0.05). Data are the mean ± SD from at least three cultures.
Fig 4.
1H-NMR spectra of purified PHA.
1H-NMR analysis was carried out using purified PHA from the cells of Thc. marinavi (a) Mch. bheemlicum (b), Rdv. tesquicola (c) and Ros. goensis (d).
Table 2.
PHA composition (mol%) under growth and nitrogen-limited conditions.
Table 3.
Number-average molecular weight and PDI of the purified PHAs.
Fig 5.
PHA content (wt%) of photosynthetic bacteria cultured in seawater.
Rdv.sulfidophilum cells were cultured in growth medium until the cell cultures reached an approximate OD660 value of 1.0 and then diluted to an OD660 of 0.1 in s supplemented with 0.5% sodium acetate and/or 0.4 g/L of yeast extract. After 7 days, the cells were harvested, and intracellular PHA levels were characterized using GC-MS. Intracellular PHAs under growth conditions were analyzed using cells showing approximately OD660 = 1.0. n. d., not detected. Data are the mean ± SD of at least three cultures. *Values that show significant differences compared to the growth conditions (p<0.05).