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Bacterial Chemotaxis, Current Knowledge and Future Need for Application in Hydrocarbon Remediation Technologies
Published in Wael Ahmed Ismail, Jonathan Van Hamme, Hydrocarbon Biotechnology, 2023
Nisenbaum Melina, Georgina Corti-Monzón, Silvia E. Murialdo
Some studies (Clancy et al., 1981; Zhulin et al., 1997; Alexandre et al., 2000) suggested that metabolism-dependent chemotaxis shares the signaling pathway with other behavioral responses collectively known as energy taxis. Energy taxis are broadly defined as a behavioral response to stimuli that affect (Zhulin et al., 1993) electron transport and energy generation, such as air taxis, phototaxis, redox taxis, and taxis to alternative electron acceptors. Changes in the speed of electron transport (or a related parameter) act as the signal that gives rise to this type of behavior. A few energy taxis studies towards HCs and aromatic compounds have been reported (Sarand et al., 2008; Rabinovitch-Deere et al., 2012; Luu et al., 2013; Hughes et al., 2017). Taylor and Zhulin (1998) proposed that when bacteria sense a decrease in intracellular energy, energy taxis override chemotaxis, giving bacteria the opportunity to escape to an environment that supports optimal energy levels. This is a versatile response that can be triggered by any condition that impairs cellular energy.
UV-B Radiation and the Green Tide-forming Macroalga Ulva
Published in Donat-P. Häder, Kunshan Gao, Aquatic Ecosystems in a Changing Climate, 2018
Jihae Park, Murray T. Brown, Hojun Lee, Christophe Vieira, Lalit K. Pandey, Eunmi Choi, Stephen Depuydt, Donat-P. Häder, Taejun Han
For UV-B irradiated Ulva spores, blue light was the most effective for reactivation of germination (Han et al. 2004). The lack of discernible germination in red light eliminates the involvement of photosynthetic pigments for the reactivation process. Similar reactivation by blue light has been reported for cyanobacteria (Saito and Werbin 1970, O’Brien and Houghton 1982, Eker et al. 1990). In Ulva spp., the phototaxis of zoospores is guided by blue light but not by green and red light (Callow and Callow 2000). The action spectrum of the photoreactivation of germination in U. pertusa spores irradiated with UV-B shows a large peak at 435 nm and a smaller but significant peak at 385 nm (Han et al. 2004). The improving effect of blue light on the germination of U. pertusa exposed to UV-B radiation seems to be related to the presence of a photoreactivation system that is similar to that found in other organisms. The action spectrum is similar to the DNA photoreactivation of cyanobacteria (van Baalen and O’Donnell 1972, Eker et al. 1990), with a major peak at 436 nm, and that of the higher plant, Zea mays, with a broad single peak at 385 nm (Ikenaga et al. 1974). The similarity between the action spectra suggests that the mechanism of photoreactivation may require DNA repair, and that the UV-B target involved in the Ulva spore germination may be DNA.
Cells and Cellular Aggregates
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
The elongated rod-shaped cell (bacterium) is an adaptation to a heterogenic non-viscous environment with gradients of nutrients. It is the most abundant shape of prokaryotes. The elongated shape increases the vector of directional movement (called chemotaxis or phototaxis) of cells toward a source of nutrients. An example of this environment with gradients of nutrients is an aquatic microenvironment close to the surface of the solid matter of soil particles, to suspended particles, to bottom sediments, or to animal or plant tissue surfaces.
Diversity of algal species present in waste stabilisation ponds and different factors affecting its enrichment and phototaxis
Published in Chemistry and Ecology, 2021
Swati Dahiya, Aparajita Shilpie, Gowtham Balasundaram, Raja Chowdhury, Pradeep Kumar, Arun Kumar Mishra
Algae have long been associated with wastewater treatment. Waste stabilisation ponds, where a mixture of algae and heterotrophic bacteria coexist for the treatment, have been used for centuries and are being used widely nowadays [1–3]. Algae play a polishing role by removing nutrients from the effluent streams of wastewater treatment plants (WWTPs) [4]. Many studies have focused on wastewater treatment through algae. Chlorella, Scenedesmus and Euglena are reported to be the dominant species present in the waste stabilisation ponds used for wastewater treatment [5]. Woertz et al. [6] noted that algae-based municipal wastewater treatment could be an energy efficient and less costly alternative for aerobic wastewater treatment. The potential for biofuel production and resource recovery from algae provide additional incentives [7]. However, the selection of effective algal strains is essential for developing new technologies on resource recovery from wastewater [8]. Mixed cultures provide a higher biomass growth, nutrient and organic carbon removal from wastewater than pure cultures. A mutualistic relationship most likely exists among numerous algal species present in a consortium [9–12]. Several algal species show different removal efficiency of nutrients present in wastewater. Algae are highly sensitive to parameters such as pH, temperature, nutrient concentration and light. Various stress conditions (i.e. pH, temperature and nutrients) and the presence of trace elements ultimately influence the proliferation of one algal species over the others [13]. Some algal strains require high-intensity light to increase their metabolic activity; hence, they traverse towards the source of light to utilise it for food production through photosynthesis [14]. However, some algal strains are sensitive to high-intensity light; thus, they move away from high-intensity light sources. This movement of algae towards and away from a light source is called phototaxis. This movement can be positive (towards light) or negative (opposite to light). Hence, to enrich algal species, different stress conditions were studied to analyse their effect on various algal species. Fistarol et al. [15] used a flow cytometry-based approach to sort microalgal species. This method can be used to sort numerous species within a short period of time. Moreover, microbiomes were analysed using second-generation sequencing (SGS) to evaluate algal diversity and detect novel and unpredicted species [16]. Current SGS methods that use the MiSeq platform (Illumina, San Diego, CA, USA) can be employed to generate N5 million 150-base DNA sequences in approximately 24 h [17,18]. Sequences of hypervariable regions in rRNA genes provide the measures of community diversity and the relative abundance of both prokaryotes [19,20] and eukaryotes [21]. Employing methods for the multiple sample analyses in a single lane in a rapid sequencer (i.e. multiplexing) can provide a quick analysis applicable for estimating the algal species present in the samples.