Optimal iron concentrations for growth-associated polyhydroxyalkanoate biosynthesis in the marine photosynthetic purple bacterium Rhodovulum sulfidophilum under photoheterotrophic condition

Abstract

Polyhydroxyalkanoates (PHAs) are a group of natural biopolyesters that resemble petroleum-derived plastics in terms of physical properties but are less harmful biologically to the environment and humans. Most of the current PHA producers are heterotrophs, which require expensive feeding materials and thus contribute to the high price of PHAs. Marine photosynthetic bacteria are promising alternative microbial cell factories for cost-effective, carbon neutral and sustainable production of PHAs. In this study, Rhodovulum sulfidophilum , a marine photosynthetic purple nonsulfur bacterium with a high metabolic versatility, was evaluated for cell growth and PHA production under the influence of various media components found in previous studies. We evaluated iron, using ferric citrate, as another essential factor for cell growth and efficient PHA production and confirmed that PHA production in R . sulfidophilum was growth-associated under microaerobic and photoheterotrophic conditions. In fact, a subtle amount of iron (1 to 2 μM) was sufficient to promote rapid cell growth and biomass accumulation, as well as a high PHA volumetric productivity during the logarithmic phase. However, an excess amount of iron did not enhance the growth rate or PHA productivity. Thus, we successfully confirmed that an optimum concentration of iron, an essential nutrient, promotes cell growth in R . sulfidophilum and also enhances PHA utilization.

Marine Purple Photosynthetic Bacteria as Sustainable Microbial Production Hosts

“…Marine purple sulfur bacteria are categorized to the first group, whereas purple non-sulfur bacteria belong to the second group. We also found that iron concentrations (ferric citrate) affect the cell growth and PHA production in R. sulfidophilum (Foong et al, 2019). Very low concentrations of iron (1–2 μM) was sufficient to promote cell growth and a high PHA yield (1,000 mg/L) during the logarithmic phase.…”

Bacterial community composition of the sea grape Caulerpa lentillifera: a comparison between healthy and diseased states

“…Rhodovulum and particularly Paracoccus are Rhodobacteraceae with potential beneficial roles for C. lentillifera. Rhodovulum species have a high metabolic versatility with the capability to degrade organic pollutants, to produce polymers and to contribute with photosynthetic functions (Khandavalli et al ., 2018; Foong et al ., 2019; Baker et al ., 2021). Paracoccus is a common genus among seaweed-associated bacteria with a key role in the cycle of nitrogen and in the production of siderophores (Mei et al ., 2019).…”

An overview of anoxygenic phototrophic bacteria and their applications in environmental biotechnology for sustainable Resource recovery

“…However, during log phase the expression of phaC1 transcript and phaZ increased which consequently led to a decrease in PHA accumulation. Marine PNSB Rhodovulum sulfidophilum [ 147 ] Nutrient Syngas devoid of carbon monoxide and phosphorous, in fed- batch cultivation with controlled acetate input 30 % w/w PHB produced. CO was converted to carbon dioxide via the action of CO dehydrogenase.…”