Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Brown Coconut Husks as Media Within an Anaerobic Filter for Improving On-Site Wastewater Treatment(MDPI (Basel, Switzerland), 2025-02-13) Brown N; Edwards J; Yarita S; Chia S; Miino MC; Ruíz LM; Gómez MÁMany small communities rely on on-site wastewater treatment systems such as septic tanks; however, there are concerns regarding the level of wastewater treatment being achieved. Appropriate solutions for these communities are needed to upgrade existing septic tanks. Anaerobic filters are a potential solution, which can be added downstream of the septic tank and operate by containing media which allow a biofilm to form. Ideally, this media would be easily accessible and affordable. In this work, the use of brown coconut husks is investigated, and it is found that 68% of the chemical oxygen demand (COD) can be removed by these systems. Nutrient levels were also monitored in the effluent to determine whether the leaching of nutrients from the coconut husks is a concern. It was found that initially some nitrogen and phosphorus had leached but these were washed out of the reactor very quickly and had a minimal impact on the effluent concentrations. Examination of the coconut husks after 10 months of operation showed no signs of the coconut husks beginning to break down, suggesting that the use of coconut husks as media in anaerobic filters should be investigated further.Item Polyphosphate accumulation in microalgae and cyanobacteria: recent advances and opportunities for phosphorus upcycling.(Elsevier B.V., 2024-09-19) Plouviez M; Brown N; Blank L; Pratt CPhosphorus (P) must continuously be added to soils as it is lost in the food chain and via leaching. Unfortunately, the mining and import of P to produce fertiliser is unsustainable and costly. Potential solutions to the global issues of P rock depletion and pollution lie in microalgae and cyanobacteria. With an ability to intracellularly store P as polyphosphates, microalgae and cyanobacteria could provide the basis for removing P from water streams, thereby mitigating eutrophication, and even enabling P recovery as P-rich biomass. Metabolic engineering or changes in growing conditions have been demonstrated to improve P removal and recovery by triggering polyphosphates synthesis in the laboratory. This now needs to be replicated at full scale.Item Polyphosphate synthesis is an evolutionarily ancient phosphorus storage strategy in microalgae(Elsevier B.V., 2023-06-02) Cliff A; Guieysse B; Brown N; Lockhart P; Dubreucq E; Plouviez MTo assess the ubiquity of the potential for inorganic polyphosphate (polyP) synthesis in microalgae, we searched databases for algal homologues to the polyP polymerase VTC4 of Chlamydomonas reinhardtii. Homologues of this protein were found within >40 species of microalgae known to inhabit marine, freshwater, and terrestrial environments. Phylogenetic analysis demonstrated that these proteins were organized into clades aligning with their taxonomic relationships. These similarities and evolutionary relationships suggest that polyP synthesis represents an ancient ability that has evolved with species as the microalgal lineage has spread out over time. Based on these results and prior knowledge on P metabolism, C. reinhardtii, Chlorella vulgaris, Desmodesmus cf. armatus, Gonium pectorale, and Microcystis aeruginosa were further tested in bioassays known to trigger the synthesis of polyP within dense granules, by addition of P following a period of P depletion. While the cellular P content of C. reinhardtii, G. pectorale, M. aeruginosa, and D. cf. armatus increased to similar maxima, ranging from 2.6 ± 0.5 % to 3.6 ± 1.3 % 24 h after P repletion, P content only reached 1.2 ± 0.2 % in C. vulgaris, suggesting a lesser ability to accumulate polyP than the strains of the other species. Models of predicted VTC4 proteins were generated from the four eukaryotic species tested and showed that the microalgae share the conserved VTC catalytic core and SPX phosphate-sensing domains found in the yeast VTC4 proteins. This confirms the role of microalgal VTC4 as polyP polymerase and suggests a similar regulation of VTC4 proteins to the one described in yeast. Further work is now needed to uncover the assembly of the microalgal VTC complex and its regulation. A deeper study of the microalgal VTC structure could also help to understand whether differences in VTC structures can explain observed differences in P accumulation kinetics.