https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:50088  twofold) than ammonium, while the bacterial strain cultured with ammonium alone exhibited a > 1.3-fold increase in growth than nitrate. Co-culturing performed higher growth at combined nitrate and ammonium supply as compared to the single cultures. The same ratio of nitrate and ammonium resulted in superior growth of microalgae (> 1.7-fold) and the bacterium (> 4.1-fold) as compared to the monocultures. Uptake of NO3–N, NH4–N and PO4–P by monocultures or co-cultures depended on the ratio of two inorganic nitrogen sources used. The composition of organic acids, amino acids and simple sugars in exudates from monocultures varied with the ratios of nitrate and ammonium in the medium. Thus, the present novel study demonstrates that the release of exudates is affected both qualitatively and quantitatively during mutualistic interactions in microalgal‒bacterial co-cultures under the impact of inorganic nitrogen sources. Our results suggest that the variables such as inorganic nitrogen sources and extracellular metabolites released need to be considered while using co-cultures for effective bioremediation of wastewaters.]]> Thu 13 Jul 2023 10:13:24 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20307 Sat 24 Mar 2018 07:55:13 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30000 4, FeCl₃ and Fe(NO₃)₃) was evaluated towards three soil microalgal isolates, Chlorella sp. MM3, Chlamydomonas sp. MM7 and Chlorococcum sp. MM11. Interestingly, all the three iron salts gave different EC50 concentrations; however, ferric nitrate was found to be significantly more toxic followed by ferrous sulphate and ferric chloride. The EC₅₀ analysis revealed that Chlorella sp. was significantly resistant to iron compared to other microalgae. However, almost 900 µg g^-1 iron was accumulated by Chlamydomonas sp. grown with 12 mg L^-1 ferric nitrate as an iron source when compared to other algae and iron salts. The time-course bioaccumulation confirmed that all the three microalgae adsorb the ferric salts such as ferric nitrate and ferric chloride more rapidly than ferrous salt, whereas intracellular accumulation was found to be rapid for ferrous salts. However, the amount of iron accumulated or adsorbed by algae, irrespective of species, from ferrous sulphate medium is comparatively lower than ferric chloride and ferric nitrate medium. The Fourier transform infrared spectroscopy (FTIR) analysis shows that the oxygen atom and P = O group of polysaccharides present in the cell wall of algae played a major role in the bioaccumulation of iron ions by algae.]]> Sat 24 Mar 2018 07:28:52 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26960 Diplosphaera sp. and was designated strain MM1. The growth of this strain was evaluated in different diluted dairy and winery wastewaters. The highest algal biomass production (up to 2.3 g L^-1) was obtained in dairy wastewater (D3; dairy wastewater 1:2 deionised water) after 14 days of culture. However, for winery wastewater, the highest algal biomass production (up to 1.46 g L^-1) was obtained in wastewater combination W2 (winery wastewater 1:1 deionised water) after 14 days of culture. Turbid dairy wastewater with high concentration of nitrogen and phosphorous slowed down the initial growth of the alga. However, at the end of day 14, biomass production was nearly twofold higher than that of winery wastewater. The findings from both types of wastewater suggest that Diplosphaera sp. MM1 has potential for its application in generating biomass with simultaneous remediation of nutrient-rich wastewater.]]> Sat 24 Mar 2018 07:27:01 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:45523 Mon 31 Oct 2022 14:16:56 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:33068 Hormosira banksii for total phenolic content (TPC) and antioxidant activities including total antioxidant capacity (ABTS), DPPH free radical scavenging capacity (DPPH) and ferric reducing antioxidant power (FRAP) using response surface methodology (RSM). Box–Behnken design was employed to assess the effect of ultrasonic temperature, time and power on the TPC and antioxidant activities of the extracts. The results showed that RSM was an accurate and reliable method in predicting TPC and antioxidant activities (ABTS, DPPH and FRAP) of the extracts with R² values of 0.97, 0.96, 0.92 and 0.94, respectively. The ultrasonic temperature and time had the significant impact on TPC and antioxidant capacities. The optimal UAE conditions for the maximal values of TPC and antioxidant activities were of 30 °C, 60 min and power 60%, or 150 W. The values of TPC and antioxidant activities (ABTS, DPPH, FRAP) achieved under these parameters were 23.12 (mg GAE g⁻¹), 85.64 (mg TE g⁻¹), 47.24 (mg TE g⁻¹) and 12.56 (mg TE g⁻¹), respectively. UAE was found to be more efficient in comparison to conventional extraction, with shorter time for extraction and higher of TPC level and antioxidant activities. Therefore, ultrasonic-assisted extraction using RSM is effective for extraction and further isolation and purification of phenolic compounds from H. banksii. In addition, this alga could be a potential rich source of natural antioxidants applied in food and pharmaceutical fields.]]> Fri 24 Aug 2018 13:44:59 AEST ]]>