Biosynthesis of poly-beta-hydroxyalkanoates by Sphingopyxis chilensis S37 and Wautersia sp. PZK cultured in cellulose pulp mill effluents containing 2,4,6-trichlorophenol

Getting Value from Pulp and Paper Industry Wastes: On the Way to Sustainability and Circular Economy

The pulp and paper industry is recognized as a well-established sector, which throughout its process, generates a vast amount of waste streams with the capacity to be valorized. Typically, these residues are burned for energy purposes, but their use as substrates for biological processes could be a more efficient and sustainable alternative. With this aim, it is essential to identify and characterize each type of waste to determine its biotechnological potential. In this context, this research highlights possible alternatives with lower environmental impact and higher revenues. The bio-based pathway should be a promising alternative for the valorization of pulp and paper industry wastes, in particular for bioproduct production such as bioethanol, polyhydroxyalkanoates (PHA), and biogas. This article focuses on state of the art regarding the identification and characterization of these wastes, their main applied deconstruction technologies and the valorization pathways reported for the production of the abovementioned bioproducts.

The genus Sphingopyxis: Systematics, ecology, and bioremediation potential - A review

The genus Sphingopyxis was first reported in the year 2001. Phylogenetically, Sphingopyxis is well delineated from other genera Sphingobium, Sphingomonas and Novosphingobium of sphingomonads group, family Sphingomonadaceae of Proteobacteria. To date (at the time of writing), the genus Sphingopyxis comprises of twenty validly published species available in List of Prokaryotic Names with Standing in Nomenclature. Sphingopyxis spp. have been isolated from diverse niches including, agricultural soil, marine and fresh water, caves, activated sludge, thermal spring, oil and pesticide contaminated soil, and heavy metal contaminated sites. Sphingopyxis species have drawn considerable attention not only for their ability to survive under extreme environments, but also for their potential to degrade number of xenobiotics and other environmental contaminants that impose serious threat to human health. At present, genome sequence of both cultivable and non-cultivable strains (metagenome assembled genome) are available in the public databases (NCBI) and genome wide studies confirms the presence of mobile genetic elements and plethora of degradation genes and pathways making them a potential candidate for bioremediation. Beside genome wide predictions there are number of experimental evidences confirm the degradation potential of bacteria belonging to genus Sphingopyxis and also the production of different secondary metabolites that help them interact and survive in their ecological niches. This review provides detailed information on ecology, general characteristic and the significant implications of Sphingopyxis species in environmental management along with the bio-synthetic potential.

Synthesis of Short-Chain-Length and Medium-Chain-Length Polyhydroxyalkanoate Blends from Activated Sludge by Manipulating Octanoic Acid and Nonanoic Acid as Carbon Sources

The effects of octanoic acid/nonanoic acid and acclimation time on the synthesis of short-chain-length and medium-chain-length PHA blends from activated sludge were investigated. An increased concentration (847-1366 mg/L) of PHAs resulted from 4-month acclimation compared with the concentration derived from 2-month acclimation (450-1126 mg/L). The content of octanoic acid had a positive linear relationship with the content of even-numbered carbon monomers among the PHAs. The blending products were identified mainly with scl-PHAs during the 2-month acclimation period and were thereafter dominated by mcl-PHAs until 4 months of acclimation. Thermal properties analysis demonstrated that the products derived from 4-month acclimation were a mixture of scl-PHAs and mcl-PHAs rather than a copolymer of scl-PHAs and mcl-PHAs. High-throughput sequencing results indicated that Pseudofulvimonas, Paracoccus, and Blastocatella were the dominant genera that might be responsible for scl-PHAs production during the 2-month acclimation period, whereas Comamonas and Pseudomonas that were responsible for mcl-PHAs production then became the dominant genera after 4-months acclimation.

Performance and microbial characteristics of biomass in a full-scale aerobic granular sludge wastewater treatment plant

By modification of the operational conditions of batch reactors, a municipal wastewater treatment plant was upgraded from activated sludge to aerobic granular sludge (AGS) technology. After upgrading, the volume of the biological reactors was reduced by 30%, but the quality of the effluent substantially improved. The concentration of biomass in the reactors increased twofold; the average biomass yield was 0.6 g MLVSS/g COD, and excess granular sludge was efficiently stabilized in aerobic conditions. Canonical correspondence analysis based on the results of next-generation sequencing showed that the time of adaptation significantly influenced the microbial composition of the granules. In mature granules, the abundance of ammonium-oxidizing bacteria was very low, while the abundance of the nitrite-oxidizing bacteria Nitrospira sp. was 0.5 ± 0.1%. The core genera were Tetrasphaera, Sphingopyxis, Dechloromonas, Flavobacterium, and Ohtaekwangia. Bacteria belonging to these genera produce extracellular polymeric substances, which stabilize granule structure and accumulate phosphorus. The results of this study will be useful for designers of AGS wastewater treatment plants, and molecular data given here provide insight into the ecology of mature aerobic granules from a full-scale facility.

Polyhydroxyalkanoate biosynthesis from paper mill wastewater treated by a moving bed biofilm reactor

Polyhydroxyalkanoate (PHA) biosynthesis in paper mill wastewater treated by a Moving Bed Biofilm Reactor (MBBR) was evaluated. A MBBR was operated during 300 d. The increasing effect of the Organic Load Rate (OLR) from 0.13 kg BOD(5)/m(3)·d to 2.99 kg BOD(5)/m(3)·d and the influence of two relationship of BOD(5:) N: P (100: 5: 1 and 100: 1: 0.3) on the PHA biosynthesis were evaluated. With an OLR of 0.13 kg BOD(5)/m(3)·d, the maximum organic matter removal measure as Biochemical Oxygen Demand (BOD(5)) was 98.7% for a BOD(5:) N: P relationship of 100: 5: 1. Meanwhile for BOD(5): N: P relationship of 100: 1: 0.3, the maximum efficiency was 87.2% (OLR: 2.99 kg BOD(5)/m(3)·d). The behaviour of the Chemical Oxygen Demand (COD) and total phenolic compound removal efficiencies were below 65.0% and 41.0%, respectively. PHA biosynthesis was measured as a percentage of cells that accumulate PHA, where the maximum percentage was 85.1% and 78.7% when MBBR was operated under a BOD(5): N: P relationship of 100: 5: 1 and 100: 1: 0.3, respectively. Finally, the PHA yields in this study were estimated to range between 0.11 to 0.72 mg PHA/mg VSS and 0.06 to 0.15 mg PHA/mg COD.

Biosynthesis of polyhydroxyalkanoate by Gamma proteobacterium WD-3 from volatile fatty acids

The production of copolymers of poly-β-hydroxyalkanoates (PHA) is generally a high cost process. To reduce the production costs, inexpensive carbon sources such as volatile fatty acids (VFAs) from acidified wastewater can be used. Therefore, isolation of bacterial strains that can produce PHA copolymers using VFAs as a sole carbon source would be a beneficial alternative. In this study, a strain of PHA accumulating bacterium was isolated from the wastewater treatment plant of a soybean processing facility in Harbin. The strain was identified as γ-proteobacterium according to its 16S rDNA information and was originally named as strain WD-3. The strain accumulated a mass of PHA up to 45% of its dry cell weight when it was cultured under the optimum fermentation condition in this study when butyrate was used as the carbon source. In addition, WD-3 could synthesize PHA copolymers of poly-hydroxybutyrate and poly-hydroxyvalerate (PHV) either from C-even substrates or from C-odd substrates, and one-third of the copolymer was PHV. Results from this study demonstrated that small molecule organic acids can be used by the strain of WD-3 as the carbon source for growth and PHA production. The maximum PHA yield in the study was 0.45 g g(-1) dry cell.

Biosynthesis of poly-β-hydroxyalkanoate by Brevundimonas vesicularis LMG P-23615 and Sphingopyxis macrogoltabida LMG 17324 using acid-hydrolyzed sawdust as carbon source

Poly-beta-hydroxyalkanoate (PHA) is a biodegradable polymer accumulated in intracellular granules by different bacterial species. Its physical and chemical properties are similar to those of petroleum-derived plastics. Material generated by the acid hydrolysis of wood was evaluated for use in the bacterial synthesis of PHA. Acid-hydrolyzed sawdust was prepared and adjusted to pH 7. Mineral salts with carbon:nitrogen (C:N) proportions of 100:1, 100:3.5, 100:10, 100:30, or 100:50 and trace elements were added and these solutions were inoculated with a bacterial strain Brevundimonas vesicularis LMG P-23615 or Sphingopyxis macrogoltabida LMG 17324. The percentage of cells accumulating PHA was evaluated by flow cytometry. The hydrolyzed sawdust composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The organic material (601.5 mg l(-1)) contained 112.5 mg l(-1) sugars. Over 96% of these sugars were consumed and more than 90% of the bacterial cells accumulated PHA. The 100:3.5 C:N proportion was optimal for growth and PHA synthesis, with yields ranging from 64% to 72% of the dry cell weight. The results suggest that acid-hydrolyzed sawdust can be used by bacteria as a carbon source for growth and PHA production. This forestry by sub-product offers a low-cost alternative for obtaining biodegradable plastics (e.g., PHA) synthesized by bacteria.