A novel two-phase bioprocess for the production of Arthrospira (Spirulina) maxima LJGR1 at pilot plant scale during different seasons and for phycocyanin induction under controlled conditions.

A two-phase outdoor cultivation bioprocess for Arthrospira maxima LJGR1 combined with phycocyanin induction in concentrated cultures under controlled conditions was evaluated using a modified low-cost Zarrouk medium. Growth was monitored during 4 cycles in 2018 and 4 cycles in 2019. Biomass was harvested and concentrated using membrane technology at the end of each cycle for further phycocyanin induction using blue LED light (controlled conditions, 24 h). The highest biomass productivity was observed during spring and summer cycles (13.63-18.97 gDWm-2 d-1); during mid-fall and mid-end fall, a decrease was observed (9.93-7.76 gDWm-2 d-1). Under favorable growth conditions, phycocyanin induction was successful. However, during cycles with unfavorable growth condition, phycocyanin induction was not observed. Reactive-grade phycocyanin (3.72 ± 0.14) was recovered and purified using microfiltration and ultrafiltration technologies.

Biotransformation of water lettuce (Pistia stratiotes) to biohydrogen by Rhodopseudomonas palustris.

AIMS: Aim of the paper was to assess the feasibility of producing hydrogen as a biofuel by photofermentation of fermented water lettuce (Pistia stratiotes L.) waste biomass, after a nitrogen-stripping treatment. METHODS AND RESULTS: A natural (42OL) and an engineered strain (CGA676, with low-ammonium sensitivity) of Rhodopseudomonas palustris were used for producing hydrogen. The stripping procedure was highly effective for ammonium removal, with an acceptable selectivity (91% of ammonium was removed; only 14% of total organic acids were lost). Both strains were able to produce hydrogen only in the nitrogen-stripped substrate. The natural strain R. palustris 42OL showed a higher Biochemical Hydrogen Potential (1224 ml l-1 vs 720 ml l-1 ; 50·0 mol m-3 vs 29·4 mol m-3 ), but at a lower rate (5·6 ml l-1  h-1 vs 7·3 ml l-1  h-1 ; 0·23 mol m-3  h-1 vs 0·29 mol m-3  h-1 ) than strain CGA676. CONCLUSIONS: Water lettuce waste biomass can be used for biofuel production, after hydrolization, fermentation and nitrogen stripping. SIGNIFICANCE AND IMPACT OF THE STUDY: The investigation on novel, low cost and sustainable biomasses as feedstocks for biofuel production is a priority. Aquatic plants do not compete for arable land. Moreover, water lettuce is a floating and invasive weed, thus its biomass must be harvested when detrimental, and can now be biotransformed in clean hydrogen.

Biosorption of heavy metals influenced by the chemical composition of Spirulina sp. (Arthrospira) biomass.

The capacity of Spirulina sp. cells with different chemical composition for Pb (II), Cd (II) and Cr (VI) sorption, was evaluated. Four different types of Spirulina biomass with a different chemical composition were tested. Two of them contained a high percentage of protein (68.95 +/- 0.30 and 63.73 +/- 0.25%) as a result of being cultivated in Zarrouk medium and exposedat two light intensities (66 micromol photon m(-2) s(-1) and 144 micromol photon m(-2) s(-1)) in batch cultures. A third type of biomass, cultivated in a "Complex" medium and exposed at 66 micromol photon (m-2) s(-1), contained a high percentage of lipids (30.08 +/- 1.92. Finally, the fourth type of biomass was enriched in polysaccharides (25.54 +/- 0.51%) as a result of being cultivated in the "Complex" medium, but exposed at 144 micromol photon m(-2) s(-1). It was found that the chemical composition of Spirulina sp. cells did have a strong influence on their adsorption capacity. The maximum adsorption capacities (q(max)) for Pb and Cd were highest (172.41 and 54.05 mg g(-1) of cells, at pH 5.0 and 4.5 respectively) when cells exhibited the higher polysaccharide content. In the case of Cr VI, the highest q(max), was exhibited by cells cultivated in Zarrouk medium and showing the higher protein content (at pH 2.0). pH did not affect the adsorption of Pb II in the range of 3 to 5.5, nor of Cd in the range of 4 to 7. For Cr VI, adsorption was observed only at a pH equal to 2 or lower.

The effect of low light flux and nitrogen deficiency on the chemical composition of Spirulina sp. (Arthrospira) grown on digested pig waste.

Evaluation of the effect of low light flux and nitrogen deficiency on growth and chemical composition of Spirulina sp. (straight filaments strain, SF) in batch cultures utilizing a complex medium containing sea-water supplemented with anaerobic effluents from digested pig waste, was undertaken. Cultivation was carried out either at a light flux of 66 (lower) or 144 micromol photon m(-2) s(-1) (higher), utilizing bench raceways. Biomass concentration (as dry weight) after 12 days of cultivation in the complex medium was similar (P < 0.05) to the one observed in a chemically defined medium (Zarrouk), regardless of the light intensity. Protein content of the biomass in the complex medium was significantly lower (P < 0.05), compared to the Zarrouk medium, regardless of the light flux. However, biomass from the complex medium was enriched in total lipids (28.6%), when cultures were exposed to the lower light flux. On the other hand, the palmitoleic acid percentage of total fatty acids was significantly higher (P < 0.05) at a higher light intensity and a high level of gamma linolenic acid (GLA) as a percentage of total fatty acids was observed (28.13%) in the biomass harvested from the complex medium at the lower light intensity. Finally, polysaccharide content was significantly higher (P < 0.05) at the high light intensity and a very high content of total polysaccharides (28.41%) was observed in the complex medium.

Accelerated coffee pulp composting.

The effect of two abundant, easily available and very low-cost agro-industrial organic residues, i.e., filter cake from the sugar industry and poultry litter, on the composting stabilization time of coffee pulp and on the quality of the produced compost, was evaluated. Piles of one cubic meter were built and monitored within the facilities of a coffee processing plant in the Coatepec region of the State of Veracruz, Mexico. Manual aeration was carried out once a week. A longer thermophilic period (28 days) and a much lower C/N ratio (in the range of 6.9-9.1) were observed in the piles containing the amendments, as compared to the control pile containing only coffee pulp (14 days and a C/N ratio of 14.4, respectively). The maximum assimilation rate of the reducing sugars was 1.6 g kg-1 d-1 (from 7.5 to 5.3%) during the first two weeks when accelerators were present in the proportion of 20% filter cake plus 20% poultry litter, while they accumulated at a rate of 1.2 g kg-1 d-1 (from 7.4 to 9.13%) during the same period in the control pile. The best combination of amendments was 30% filter cake with 20% poultry litter, resulting in a final nitrogen content as high as 4.81%. The second best combination was 20% filter cake with 10% poultry litter, resulting in a compost which also contained a high level of total nitrogen (4.54%). It was concluded that the use of these two residues enhanced the composting process of coffee pulp, promoting a shorter stabilization period and yielding a higher quality of compost.

Simultaneous high-biomass protein production and nutrient removal using Spirulina maxima in sea water supplemented with anaerobic effluents.

Maximum protein accumulation (71%, w/w) and nutrient removal by a mutant strain of Spirulina maxima growing on sea water supplemented with anaerobically treated pig slurry was achieved at 30°C with constant illumination (60 to 70 µEm(-2)s(-1)), using a flow rate of 14.5 cm s(-1) (20 rev. min(-1) of a paddle wheel). Total phosphates were decreased by 99% and all ammonia-N was removed under these conditions.

Accelerated food waste composting.

Experiments on food waste composting under the temperate and dry conditions of Mexico City showed that the waste stabilized faster (within 2 months) if an 'accelerator' (chopped orange peel and carrot bagasse) was used. The relatively cool and humid conditions prevailing during similar experiments in Xalapa City inhibited decomposition, and stabilization of waste, with or without accelerator, was generally slower than in Mexico City. However, addition of wood chips as a bulking agent greatly improved composting in Xalapa, leading to stabilization in just 35 days.Use of the accelerator increases the initial C/N ratio in the waste. This permits rapid utilization of any easily degradable sugars, which in turn supports rapid multiplication of mesophilic microorganisms.