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Optimizing Downstream Processing of scl-PHAs: A Comprehensive Approach to Bio-Extraction and Quality Assessment

Muniyoor, Chaithra LU (2025) KBTM01 20251
Biotechnology (MSc)
Abstract
Polyhydroxybutyrate-co-valerate (PHBV), a biodegradable biopolymer, holds promise as a sustainable alternative to petroleum-based plastics. In this study, PHBV was biosynthesized and extracted, followed by an extensive evaluation of various downstream purification methods focusing on surfactant-based washing protocols. Different conditions of sodium dodecyl sulphate (SDS) washing varying in temperature, duration, and number of water and ethanol rinses were assessed for their impact on polymer purity, molecular weight, ash content, and thermal stability. The highest purity (97.94 ± 0.20%) and lowest ash content (0.02 ± 0.01%) were achieved using 1:5 SDS: cell mass ratio reaction at 70 °C and simple single water wash, while ethanol-based... (More)
Polyhydroxybutyrate-co-valerate (PHBV), a biodegradable biopolymer, holds promise as a sustainable alternative to petroleum-based plastics. In this study, PHBV was biosynthesized and extracted, followed by an extensive evaluation of various downstream purification methods focusing on surfactant-based washing protocols. Different conditions of sodium dodecyl sulphate (SDS) washing varying in temperature, duration, and number of water and ethanol rinses were assessed for their impact on polymer purity, molecular weight, ash content, and thermal stability. The highest purity (97.94 ± 0.20%) and lowest ash content (0.02 ± 0.01%) were achieved using 1:5 SDS: cell mass ratio reaction at 70 °C and simple single water wash, while ethanol-based methods resulted in lower purity and compromised thermal stability. Gel Permeation Chromatography (GPC) analysis confirmed that the molecular weight distribution remained consistent across most samples, although higher ethanol exposure correlated with slight degradation. Gas Chromatography-Flame Ionization Detection (GC-FID) confirmed the polymer composition as PHBV with an average of ~5.1± 0.4 wt% hydroxyvalerate (HV). Future work could focus on scaling up the optimized SDS and water-only washing protocols to pilot-scale operations, evaluating their economic viability and environmental sustainability in large-scale PHA production. (Less)
Popular Abstract
Plastics are everywhere in our daily lives from packaging to textiles but most are made from fossil fuels and take hundreds of years to degrade. Bioplastics, biodegradable like polyhydroxyalkanoates (PHAs), offer a more sustainable alternative. Among them, PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is especially promising as it offers enhanced thermal and mechanical properties making it highly suitable for a variety of applications. PHBV can be produced intracellularly by microorganisms as energy storage. However, extracting and purifying PHBV from bacterial cells in a clean, efficient, and cost-effective way remains a major challenge.
This thesis focused on improving the purification process of PHBV using sodium dodecyl sulphate... (More)
Plastics are everywhere in our daily lives from packaging to textiles but most are made from fossil fuels and take hundreds of years to degrade. Bioplastics, biodegradable like polyhydroxyalkanoates (PHAs), offer a more sustainable alternative. Among them, PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is especially promising as it offers enhanced thermal and mechanical properties making it highly suitable for a variety of applications. PHBV can be produced intracellularly by microorganisms as energy storage. However, extracting and purifying PHBV from bacterial cells in a clean, efficient, and cost-effective way remains a major challenge.
This thesis focused on improving the purification process of PHBV using sodium dodecyl sulphate (SDS), a common industrial detergent, along with water and ethanol washes. The goal was to find a simple washing method that gives high-purity polymer without damaging its properties. Through various experiments, it was found that using just SDS and water at moderate temperatures could achieve excellent purity and thermal stability, sometimes even better than more complex methods involving ethanol. These findings suggest that simpler is better: a straightforward, water-based approach can reduce chemical use, lower costs, and still deliver high-quality bioplastic.
To understand the impact of different washing methods on PHBV properties, analytical techniques like gas chromatography, thermogravimetric analysis, and gel permeation chromatography were used. These helped assess not only purity, but also the polymer’s thermal stability and the integrity of its molecular structure. Results showed that with the right conditions, washing with SDS and water alone can remove impurities effectively while preserving PHBV’s strength and quality.
In the future, this optimized process could be scaled up to larger volumes to see if it remains practical and environmentally friendly on an industrial level. Additional research could also explore how other detergents might work in combination with SDS to further improve the extraction process. Ultimately, this work brings us one step closer to making sustainable plastics more accessible and industrially viable. (Less)
Please use this url to cite or link to this publication:
author
Muniyoor, Chaithra LU
supervisor
organization
course
KBTM01 20251
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Biopolymers, Bioprocess, PHA, Downstream Processing, Biotechnology
language
English
id
9198384
date added to LUP
2025-06-16 13:29:38
date last changed
2025-06-16 13:29:38
@misc{9198384,
  abstract     = {{Polyhydroxybutyrate-co-valerate (PHBV), a biodegradable biopolymer, holds promise as a sustainable alternative to petroleum-based plastics. In this study, PHBV was biosynthesized and extracted, followed by an extensive evaluation of various downstream purification methods focusing on surfactant-based washing protocols. Different conditions of sodium dodecyl sulphate (SDS) washing varying in temperature, duration, and number of water and ethanol rinses were assessed for their impact on polymer purity, molecular weight, ash content, and thermal stability. The highest purity (97.94 ± 0.20%) and lowest ash content (0.02 ± 0.01%) were achieved using 1:5 SDS: cell mass ratio reaction at 70 °C and simple single water wash, while ethanol-based methods resulted in lower purity and compromised thermal stability. Gel Permeation Chromatography (GPC) analysis confirmed that the molecular weight distribution remained consistent across most samples, although higher ethanol exposure correlated with slight degradation. Gas Chromatography-Flame Ionization Detection (GC-FID) confirmed the polymer composition as PHBV with an average of ~5.1± 0.4 wt% hydroxyvalerate (HV). Future work could focus on scaling up the optimized SDS and water-only washing protocols to pilot-scale operations, evaluating their economic viability and environmental sustainability in large-scale PHA production.}},
  author       = {{Muniyoor, Chaithra}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Optimizing Downstream Processing of scl-PHAs: A Comprehensive Approach to Bio-Extraction and Quality Assessment}},
  year         = {{2025}},
}