Hydrogen production using Purple Non-Sulfur Bacteria (PNSB) cultivated under natural or artificial light conditions with synthetic or fermentation derived substrates

The aim of this thesis was to verify the feasibility of the hydrogen production process with purple non sulfur bacteria both under sunlight irradiation in an up-scaled system and with the use of low cost substrates. Among the products offermentations tested the best results were obtained with a medium derived from vegetable wastes. The use of a genetically modified strain of Rhodopseudomonas palustris insensitive to ammonium opened the way towards the use of wastes with attainment of high hydrogen yields also in inhibiting conditions. The experimentation carried out under natural irradiation demonstrated the full feasibility of the process using sunlight instead of artificial light in a semi-pilot reactor: the production rates were the highest so far reported for comparable outdoor systems

Drought-tolerant cyanobacteria and mosses as biotechnological tools to attain land degradation neutrality

Abstract. The induction of biocrusts through inoculation-based techniques has gained increasing scientific attention in the last 2 decades due to its potential to address issues related to soil degradation and desertification. The technology has shown the most rapid advances in the use of biocrust organisms, particularly cyanobacteria and mosses, as inoculants and biocrust initiators. Cyanobacteria and mosses are poikilohydric organisms – i.e., desiccation-tolerant organisms capable of reactivating their metabolism upon rehydration – that can settle on bare soils in abiotically stressing habitats, provided that selected species are used and an appropriate and customized protocol is applied. The success of inoculation of cyanobacteria and mosses depends on the inoculant's physiology, but also on the ability of the practitioner to identify and control, with appropriate technical approaches in each case study, those environmental factors that most influence the inoculant settlement and its ability to develop biocrusts. This review illustrates the current knowledge and results of biocrust induction biotechnologies that use cyanobacteria or mosses as inoculants. At the same time, this review's purpose is to highlight the current technological gaps that hinder an efficient application of the technology in the field

Cyanoremediation and phyconanotechnology: cyanobacteria for metal biosorption toward a circular economy

Cyanobacteria are widespread phototrophic microorganisms that represent a promising biotechnological tool to satisfy current sustainability and circularity requirements. They are potential bio-factories of a wide range of compounds that can be exploited in several fields including bioremediation and nanotechnology sectors. This article aims to illustrate the most recent trends in the use of cyanobacteria for the bioremoval (i.e., cyanoremediation) of heavy metals and metal recovery and reuse. Heavy metal biosorption by cyanobacteria can be combined with the consecutive valorization of the obtained metal-organic materials to get added-value compounds, including metal nanoparticles, opening the field of phyconanotechnology. It is thus possible that the use of combined approaches could increase the environmental and economic feasibility of cyanobacteria-based processes, promoting the transition toward a circular economy

Draft genome sequence and overview of the purple non sulfur bacterium Rhodopseudomonas palustris 42OL

Rhodopseudomonas palustris strain 42OL was isolated in 1973 from a sugar refinery waste treatment pond. The strain has been prevalently used for hydrogen production processes using a wide variety of waste-derived substrates, and cultured both indoors and outdoors, either freely suspended or immobilized. R. palustris 42OL was suitable for many other applications and capable of growing in very different culturing conditions, revealing a wide metabolic versatility. The analysis of the genome sequence allowed to identify the metabolic pathways for hydrogen and poly-β-hydroxy-butyrate production, and confirmed the ability of using a wide range of organic acids as substrates

Cyanoflan: A cyanobacterial sulfated carbohydrate polymer with emulsifying properties

Abstract The extracellular polysaccharides produced by cyanobacteria have distinctive characteristics that make them promising for applications ranging from bioremediation to biomedicine. In this study, a sulfated polysaccharide produced by a marine cyanobacterial strain and named cyanoflan was characterized in terms of morphology, chemical composition, and rheological and emulsifying properties. Cyanoflan has a 71% carbohydrate content, with 11% of sulfated residues, while the protein account for 4% of dry weight. The glycosidic-substitution analysis revealed a highly branched complex chemical structure with a large number of sugar residues. The cyanoflan high molecular mass fractions (above 1 MDa) and entangled structure is consistent with its high apparent viscosity in aqueous solutions and high emulsifying activity. It showed to be a typical non-Newtonian fluid with pseudoplastic behavior. Altogether, these results confirm that cyanoflan is a versatile carbohydrate polymer that can be used in different biotechnological applications, such as emulsifying/thickening agent in food or cosmetic industries

Assessing the antitumor potential of variants of the extracellular carbohydrate polymer from synechocystis ΔsigF mutant

Cancer is a leading cause of death worldwide with a huge societal and economic impact. Clinically effective and less expensive anticancer agents derived from natural sources can help to overcome limitations and negative side effects of chemotherapy and radiotherapy. Previously, we showed that the extracellular carbohydrate polymer of a Synechocystis ΔsigF overproducing mutant displayed a strong antitumor activity towards several human tumor cell lines, by inducing high levels of apoptosis through p53 and caspase-3 activation. Here, the ΔsigF polymer was manipulated to obtain variants that were tested in a human melanoma (Mewo) cell line. Our results demonstrated that high molecular mass fractions were important for the polymer bioactivity, and that the reduction of the peptide content generated a variant with enhanced in vitro antitumor activity. This variant, and the original ΔsigF polymer, were further tested in vivo using the chick chorioallantoic membrane (CAM) assay. Both polymers significantly decreased xenografted CAM tumor growth and affected tumor morphology, by promoting less compact tumors, validating their antitumor potential in vivo. This work contributes with strategies for the design and testing tailored cyanobacterial extracellular polymers and further strengths the relevance of evaluating this type of polymers for biotechnological/biomedical applications.info:eu-repo/semantics/publishedVersio

Editorial: Women in aquatic microbiology: 2022

3 pagesThere is a notable underrepresentation of female scientists in STEM research fields. Pursuing an academic career in the sciences requires persistence, perseverance, and courage. Despite awareness and implementation of measures to counteract them, women in STEM often face persistent challenges, including gender bias, stereotypes, unequal access to opportunities, and limited mentorship (Shen, 2013; Charlesworth and Banaji, 2019; Avolio et al., 2020; Jebsen et al., 2022; Freedman et al., 2023; Lathifa, 2023). Women juggle multiple roles in the workplace as researchers, teachers, and mentors, on top of administrative duties, and at home, women often shoulder much of the caregiving (Cech and Blair-Loy, 2019; Allen et al., 2023). The COVID-19 pandemic intensified these difficulties, adversely impacting work productivity, mental health, the pursuit of leadership positions, and an essential aspect for conducting outstanding research: achieving a healthy work-life balance (Gewin, 2020; Krukowski et al., 2021; National Academies of Sciences and Medicine, 2021; Lawson et al., 2023). [...]Peer reviewe

Hydrogen production using Purple Non-Sulfur Bacteria (PNSB) cultivated under natural or artificial light conditions with synthetic or fermentation derived substrates

The aim of this thesis was to verify the feasibility of the hydrogen production process with purple non sulfur bacteria both under sunlight irradiation in an up-scaled system and with the use of low cost substrates. Among the products offermentations tested the best results were obtained with a medium derived from vegetable wastes. The use of a genetically modified strain of Rhodopseudomonas palustris insensitive to ammonium opened the way towards the use of wastes with attainment of high hydrogen yields also in inhibiting conditions. The experimentation carried out under natural irradiation demonstrated the full feasibility of the process using sunlight instead of artificial light in a semi-pilot reactor: the production rates were the highest so far reported for comparable outdoor systems