Alba Ena

The recovery of polyphenols from olive mill waste using two adsorbing vegetable matrices

Olive mill wastewater (OMW) is considered one of the most pollutive waste materials in the Mediterranean basin. However, its phenolic fraction should be recovered, since it has been shown to have incredible benefits for health. In the present study, the adsorbent and desorbent capacities of Azolla and granular activated carbon (GAC) were investigated. The GAC was found to be more efficient than Azolla in both the adsorption and the desorption of phenols. The total characterization of two powder products obtained from Azolla and GAC desorption is reported, together with their antioxidant and antiradical activities. In the Azolla powder product, total polyphenols were more than twice as numerous as those found in the GAC powder product. The GAC powder contained hydroxytyrosol in concentrations that were 3.5 times higher than those of Azolla. On the other hand, both powder products showed great antiradical activities: the IC₅₀ was found to be 102 mg ml⁻¹ for the Azolla and 199 mg ml⁻¹ for the GAC powders respectively. The oxygen radical absorbance capacity was very high: 4097 μmol TE g⁻¹ Azolla powder product and 1277 μmol TE g⁻¹ of GAC powder products.

H and poly-β-hydroxybutyrate, two alternative chemicals from purple non sulfur bacteria

The feasibility of a process for the photoproduction of both H 2 and poly-b-hydroxybutyrate (PHB)-containing biomass has been tested utilizing semi-continuous cultures of Rhodopseudomonas palustris growing in a tubular system with limiting amounts of fixed nitrogen. A two-stage batch process, consisting in a first period of nitrogen-limited cell growth followed by a second period of cell cultivation under conditions of phosphorus shortage, showed the possibility to separate the H production phase from the PHB accumulation phase, making possible to carry out processes that otherwise would be in competition.

Assessment of the potential of Nostoc strains from the Pasteur Culture Collection for the production of polysaccharides of applied interest

The exocellular polysaccharides released during thephotoautotrophic growth by 25 Nostoc strainsbelonging to the Pasteur Culture Collection (PCC) wereinvestigated with regard to their chemical andrheological properties in order to assess theirpotential for the production of polysaccharides ofindustrial interest.All the released polysaccharides (RPSs) were complexanionic heteropolymers, composed of a number ofmonosaccharides ranging from six to nine, alwaysincluding glucose and fucose, and most frequentlygalactose. Ribose, rarely reported to be present incyanobacterial RPSs, was found in seven polymers. TheRPSs were shown to possess an anionic charge due tothe presence of uronic acids and in most cases also ofpyruvil and sulphate groups. Moreover, a large numberof polymers showed the presence of significant amountsof constituents such as acetyl groups, peptidicmoieties and deoxysugars, that may contribute to thehydrophobicity of the macromolecules. The viscositydependence on the shear rate of aqueous solutions ofthe RPSs was, in three cases, comparable with that ofxanthan gum, and one RPS showed a very satisfactorystability of the viscosity over a wide range of pH,temperature and salinity values. The most promisingPCC Nostoc strains for the production of RPSsfor specific applications were thus singled out, basedon the characteristics of their polymers.

Production of bio-fuels (hydrogen and lipids) through a photofermentation process.

The purple non-sulfur photosynthetic bacteria Rhodopseudomonas palustris (strain 42OL) was investigated for a co-production of both bio-H(2) and biodiesel (lipids). The investigation was carried out using malic and glutamic acids in a fed-batch cultivation system under continuous irradiances of 36, 56, 75, 151, 320, 500, and 803 W m(-2). Boltzmanns sigmoidal regression model was used to determine growth kinetic parameters during hydrogen photoevolution. The upper limit of volumetric hydrogen photoevolution was 15.5 + or - 0.9 ml l(-1) h(-1). During the entire cultivation period (408 h), the highest average hydrogen production rate (HPR(av)) of 11.1 + or - 3.1 ml l(-1) h(-1) was achieved at an irradiance of 320 W m(-2). Biomasses stored at the end of each experimental set were analyzed in order to determine lipid content, which ranged from a minimum of 22 + or - 1% to a maximum of 39 + or - 2% of biomass dry weight.

Germination of desiccated aged akinetes of alkaliphilic cyanobacteria

Morphological and biochemical changes associated with synchronous germination of mature, aged and desiccated akinetes of two alkaliphilic cyanobacteria, Cyanospira rippkae and Cyanospira capsulata, are described. Akinetes of both strains proved to be highly resistant to desiccation, being able to germinate, in the presence of either N2 or nitrate as nitrogen source, with a germination frequency of more than 90% after seven years of storage in a dried state. The first cell division occurred after 8–10 h of incubation, thereafter the germlings of the two strains followed a different pattern of cell differentiation. Heterocysts were first noted, in a terminal position, at 16–18 h in three-celled germlings of C. capsulata and at 21–24 h in C. rippkae, when germlings were at least seven cells in length. Akinetes of both species possessed, on a per cell basis, almost identical amounts of all photosynthetic pigments but, under nitrogen fixing conditions, photosynthetic activity (oxygen evolution) was detected only after new proteins had been synthesized, before a functional heterocyst was developed and while total nitrogen remained constant. With energy provided by aerobic respiration, a wide range of intracellular amino acids characteristic of proteins was utilised to sustain the new protein synthesis. The end of this biosynthetic activity coincided with the timing of the first cell division. From this stage on, no changes in protein concentration occurred until mature heterocysts were developed. In the presence of nitrate, no significant changes in the major germination events were observed.

Fatty acid composition of Antarctic cyanobacteria

Pushparaj B., Buccioni A., Paperi R., Piccardi R., Ena A., Carlozzi P., and Sili C. 2008. Fatty acid composition of Antarctic cyanobacteria. Phycologia 47: 430–435. DOI: 10.2216/07-90.1 The 31 Antarctic cyanobacterial strains, object of this study, were isolated from south polar lake sediments, soil and lichen associations and belong to the genera of Cyanothece, Chondrocystis, Leptolyngbya, Pseudophormidium, Phormidium, Hormoscilla and Nostoc. They are maintained in the Culture Collection of the Istituto per lo Studio degli Ecosistemi (ISE-CNR, Florence). The fatty acid composition varied among the strains, with relatively high quantities of polyunsaturated fatty acids. Arachidonic acid was found in two strains of Phormidium pseudopristleyi at 24% and 32% of the total fatty acid content. The total lipid content and the C/N ratio varied among strains from 13% to 9% and 3.7 to 11.2, respectively. The diversity of saturated and unsaturated fatty acid composition among the Antarctic strains and their possible application as nutrient supplements are discussed.

Ammonia photoproduction byCyanospira rippkae cells ‘entrapped’ in dialysis tube

The photoproduction of ammonia by cells of the heterocystous cyanobacteriumCyanospira rippkae in the presence of the glutamine synthetase inhibitor, L-methionine D,L-sulfoximine (MSX), was investigated. The time course of changes in protein, pigment and carbohydrate concentrations and the C2H2-reducing activity of nitrogenase in MSX treated and untreated filament suspensions was also determined. The results show that nearly 40 h after MSX addition the cells are able to recover from the nitrogen starvation induced by the inhibitor by themselves, without the removal of MSX or the addition of nitrogenous compounds. Biliproteins, mobilized as a consequence of MSX addition, seem to play a key role in the process of cell recovery. These findings were exploited in a semicontinuous ammonia producing process with cells ‘immobilized’ in a dialysis tube photobioreactor.

Hydrodynamic alterations during cyanobacteria (Arthrospira platensis) growth from low to high biomass concentration inside tubular photobioreactors.

The rheological behavior of an Arthrospira culture was studied from low to high biomass concentration. Two tubular undulating row photobioreactors (TURP‐5r and TURP‐10r), with a very short light path of 1.0 cm, were used during batch growth. In TURP‐5r, the biomass concentration increased to 14.5 g(dw) L−1, and alterations of the physical properties and hydrodynamic behavior occurred as a result. In the past, the rheological characteristics of photosynthetic‐microbe cultures were rarely investigated because of the low biomass concentration attained in the systems. Developing closed photobioreactor technologies, the optimum biomass concentration rises and the viscosity, the generalized Reynolds number (N′Re), and the power required for culture recycling are also subject to alteration. Starting from a biomass concentration of 4.1 g(dw) L−1, the Arthrospira culture already exhibits the characteristics of a non‐Newtonian fluid. As a result of culture recycling from 2.0 to 20.5 g(dw) L−1 and an available power of 1.67 W row−1, we demonstrated that N′Re is reduced from 6265 to 1148. Our experimental results showed that N′Re of 2345 can be reached only at a cell concentration below 11.1 g(dw) L−1, while at a cell concentration below 4.1 g(dw) L−1 N′Re = 4080 was reached. The power consumption (Pc) for culture recycling increased noticeably when the cell concentration rose; the highest Pc increase attained was from 2.0 to 4.1 g(dw) L−1. This is the range within which the Arthrospira culture changes from a Newtonian to a non‐Newtonian fluid.