Production of Polyhydroxyalkanoates (PHAs) by Vibrio alginolyticus Strains Isolated from Salt Fields.

Hong-Fei Li,Lin-Yue Tian,Zheng-Jun Li,Meng-Ru Wang

doi:10.3390/molecules26206283

Hong-Fei Li, Lin-Yue Tian + Show 2 more

Open Access

https://doi.org/10.3390/molecules26206283

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Abstract

Vibrio alginolyticus is a halophilic organism usually found in marine environments. It has attracted attention as an opportunistic pathogen of aquatic animals and humans, but there are very few reports on polyhydroxyalkanoate (PHA) production using V. alginolyticus as the host. In this study, two V. alginolyticus strains, LHF01 and LHF02, isolated from water samples collected from salt fields were found to produce poly(3-hydroxybutyrate) (PHB) from a variety of sugars and organic acids. Glycerol was the best carbon source and yielded the highest PHB titer in both strains. Further optimization of the NaCl concentration and culture temperature improved the PHB titer from 1.87 to 5.08 g/L in V. alginolyticus LHF01. In addition, the use of propionate as a secondary carbon source resulted in the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). V. alginolyticus LHF01 may be a promising host for PHA production using cheap waste glycerol from biodiesel refining.

Highlights

Plastic pollution is a severe and increasing global problem, affecting almost every marine and freshwater ecosystem in the world
The results showed that V. alginolyticus LHF01 could synthesize PHB from a series of carbon sources including glucose, sucrose, soluble starch, acetate, butyrate, glycerol, oleic acid, and linoleic acid, while V. alginolyticus LHF02 produced PHB only using soluble starch and glycerol (Figure 3)
Strain LHF01 accumulated PHB when grown on sucrose, soluble starch, acetate, butyrate, glycerol, oleic acid, and linoleic acid, among which glycerol yielded the highest PHB titer of 1.87 g/L

Summary

Introduction

Plastic pollution is a severe and increasing global problem, affecting almost every marine and freshwater ecosystem in the world. Various research teams attempted to reduce the production cost of PHA by increasing the yield of strains, using cheap materials, and developing non-sterile fermentation technology [5,9,11]. Several species of Vibrio strains including V. harveyi [21,22], V. natriegens [23], V. azureus [24], and V. fischeri [25] were identified for PHA production. As salt-tolerant bacteria from the marine environment can survive in high-salt media with low contamination, they do not require certain steps such as antibiotic treatment or sterilization to provide an economical biological process for PHA production [22]. Marine microorganisms may become strong candidates for the production of PHA due to their adaptation to high-salt conditions and the potential to utilize cost-effective seawater as a culture medium [26]. When 4 g/L of propionate was added, V. alginolyticus LHF01 produced 1.44 g/L of P(3HB-co-24.42 mol% 3HV)

Sample Collection and Strain Screenings

Culture Conditions for PHA Production

Quantification of PHA and Cell Growth

PHA Extraction and Molecular Weight Determination

Conclusions