Characterization of the promising poly(3-hydroxybutyrate) producing halophilic bacterium Halomonas halophila (original) (raw)
Related papers
Journal of Applied Microbiology, 2005
The objective of the present work was to enable the use of starch hydrolysate, generated by the action of a recombinant maltooligosaccharide forming amylase from Bacillus halodurans LBK 34, as the carbon source for the production of poly-b-hydroxybutyrate (PHB) by Halomonas boliviensis LC1. Methods and Results: In this work, different amounts of the a-amylase (Amy 34) were utilized for starch hydrolysis, resulting in the production of mixtures of maltooligosaccharides (G1-G6) at varying ratios. The highest PHB accumulation (56 wt%) by H. boliviensis cultivated in shake flasks (with agitation at 160 rev min)1) was obtained when 6AE4 U ml)1 of the amylase was used for starch hydrolysis. When H. boliviensis cells were grown in a fermentor with no oxygen limitation the accumulation of PHB was decreased to 35 wt%. Although some improvements in PHB accumulation and cell mass concentration were reached by the addition of peptone and phosphate, respectively, major enhancements were attained when oxygen limitation was induced in the fermentor. Conclusions: Halomonas boliviensis uses preferentially maltose for PHB formation from starch hydrolysate. It is also able to hydrolyse higher sugars if no other simpler carbon source is available but with a significantly lower polymer yield. Furthermore, H. boliviensis is able to adjust its metabolism to oxygen limitation, most probably by directing the excess NAD(P)H to PHB accumulation. Significance and Impact of the Study: There have been no reports related to PHB production amongst the members of the genus Halomonas. The use of a maltooligosaccharide forming a-amylase, which is active at a temperature and pH close to that required for growth of H. boliviensis, and the versatility of this bacterium in the selection of the carbon source may provide an attractive alternative for the utilization of starch-derived raw materials.
Poly(β-hydroxybutyrate) production by a moderate halophile, Halomonas boliviensis LC1
Enzyme and Microbial Technology, 2006
The moderate halophile Halomonas boliviensis, isolated from a Bolivian saline soil sample, was able to accumulate poly(-hydroxybutyrate) (PHB) when grown under conditions of nutrient limitation and excess carbon source. The concentration of sodium chloride in the medium influenced the cell-growth,-size, and rate of PHB accumulation. Cultivation in shake flasks led to a PHB accumulation of about 54 wt.% with respect to cell dry weight at 4.5% (w/v) NaCl in a medium with butyric acid and sodium acetate as carbon sources. The production of PHB was substantially improved to a maximum value of 88 wt.% during cultivation under controlled conditions of pH and oxygen concentration in a fermentor. The use of glucose and sucrose, respectively, as carbon source could also lead to the production of PHB at an average level of 55 wt.%.
Molecules
This work aims to characterize the haloarchaeal diversity of unexplored environmental salty samples from a hypersaline environment on the southern coast of Jeddah, Saudi Arabia, looking for new isolates able to produce polyhydroxyalkanoates (PHAs). Thus, the list of PHA producers has been extended by describing two species of Halolamina; Halolamina sediminis sp. strain NRS_35 and unclassified Halolamina sp. strain NRS_38. The growth and PHA-production were investigated in the presence of different carbon sources, (glucose, sucrose, starch, carboxymethyl cellulose (CMC), and glycerol), pH values, (5–9), temperature ranges (4–65 °C), and NaCl concentrations (100–350 g L−1). Fourier-transform infra-red analysis (FT-IR) and Liquid chromatography–mass spectrometry (LC-MS) were used for qualitative identification of the biopolymer. The highest yield of PHB was 33.4% and 27.29% by NRS_35 and NRS_38, respectively, using starch as a carbon source at 37 °C, pH 7, and 25% NaCl (w/v). The FT-IR...
Frontiers in Bioengineering and Biotechnology
Microbial polyhydroxyalkanoates (PHA) are biodegradable and biocompatible bio-based polyesters, which are used in various applications including packaging, medical and coating materials. In this study, an extremophilic hydrocarbonoclastic bacterium, previously isolated from saline sediment in the Tunisian desert, has been investigated for PHA production. The accumulation of intracellular PHA granules in Halomonas desertis G11 was detected by Nile blue A staining of the colonies. To achieve maximum PHA yield by the strain G11, the culture conditions were optimized through response surface methodology (RSM) employing a Box-Behnken Design (BBD) with three independent variables, namely, substrate concentration (1–5%), inoculum size (1–5%) and incubation time (5–15 days). Under optimized conditions, G11 strain produced 1.5 g/L (68% of DCW) of PHA using glycerol as a substrate. Application of NMR (1H and 13C) and FTIR spectroscopies showed that H. desertis accumulated PHA is a poly-3-hydr...
International Journal of Bioassays, 2016
PHB is a biodegradable plastic which is becoming an environmentally friendly substitute to the synthetic plastics that are persistent and accumulate in large amounts and are non-degradable. PHB is a class of Polyhydroxyalkanoate which are similar to commercial plastics like polypropylene but with an added advantage of being biodegradable. To overcome the problem of commercializing PHB production by microorganisms because of the high cost involved, Halotolerant organisms can be used as they are easier to cultivate and do not require strict sterile conditions. In this present study PHB producing halotolerant bacterial strains were isolated from a marine environment and cultivated under saline conditions. The growth conditions of the bacterial strains were optimized for maximum production of PHB. The parameters such as pH, temperature, NaCl concentration, carbon sources, nitrogen sources and carbon and nitrogen ratio were optimized and studied. The growth conditions for each of the pa...
Effects of Culture Conditions on Poly(β-Hydroxybutyric Acid) Production by Haloferax mediterranei
Applied and Environmental Microbiology, 1990
The halobacterium Haloferax mediterranei accumulates poly(β-hydroxybutyrate) (PHB) as intracellular granules. The conditions for PHB production in batch and continuous cultures have been studied and optimized. Phosphate limitation is essential for PHB accumulation in large quantities. Glucose and starch are the best carbon sources. With 2% starch, 0.00375% KH 2 PO 4 , and 0.2% NH 4 Cl in batch culture, a production of ca. 6 g of PHB per liter was reached, being 60% of the total biomass dry weight, and giving a yield over the carbon source of 0.33 g/g. The PHB production in continuous cultures was stable over a 3-month period. Our results demonstrate that H. mediterranei is an interesting candidate for industrial production of biological polyesters.
Fermentation
The global production of fossil-based plastics has reached critical levels, and their substitution with bio-based polymers is an urgent requirement. Poly(3-hydroxybutyrate) (PHB) is a biopolymer that can be produced via microbial cultivation, but efficient microorganisms and low-cost substrates are required. Halomonas boliviensis LC1, a moderately halophilic bacterium, is an effective PHB producer, and hydrolysates of the residual stalks of quinoa (Chenopodium quinoa Willd.) can be considered a cheap source of sugars for microbial fermentation processes in quinoa-producing countries. In this study, H. boliviensis LC1 was adapted to a cellulosic hydrolysate of quinoa stalks obtained via acid-catalyzed hydrothermal pretreatment and enzymatic saccharification. The adapted strain was cultivated in hydrolysates and synthetic media, each of them with two different initial concentrations of glucose. Cell growth, glucose consumption, and PHB formation during cultivation were assessed. The c...
Indian Journal of Agricultural Sciences, 2021
An experiment was conducted at the Indian Agricultural Research Institute, New Delhi (2017-18) to report the identification of halophilic poly-ß-hydroxybutyrate (PHB) producing bacteria and optimization of process parameters for maximum PHB recovery. The phylogenetic analysis classified the isolates into bacterial phylum α, γ-Proteobacteria, and Firmicutes. Halomonas sp. KB7 and Stenotrophomonas maltophila B11 produced maximum PHB in mineral salt media having optimized C and N concentration with 10% NaCl. Optimizing media increased PHB production from 23.80-73.7% w/w for Halomonas sp and 29.5-78.3 % w/w for S. maltophila.