Magnetotactic bacteria

About: Magnetotactic bacteria is a research topic. Over the lifetime, 1118 publications have been published within this topic receiving 43741 citations.

Ultraviolet-B Radiation Effects on the Community, Physiology, and Mineralization of Magnetotactic Bacteria

Abstract: Solar radiation reaching the Earth can be divided into solar particle flux and electromagnetic waves (Iqbal, 1983). The Earth’s magnetic field shields most charged particles, but solar electromagnetic radiation can partially penetrate the Earth’s atmosphere and thus impact life on Earth (Cox et al., 1964; Crain, 1971; Glassmeier et al., 2009; Hays, 1971). Although it contributes only ∼8% to the whole solar electromagnetic spectrum, ultraviolet radiation (UVR) – which has wavelengths between 200 and 400 nm and is composed of ultraviolet-A (UVA; 320– 400 nm), ultraviolet-B (UVB; 290–320 nm), and ultraviolet-C (UVC; 200–290 nm) – can induce a variety of biological damages, such as damage to DNA, proteins, enzymes, and lipids (Cockell, 2000; Garcia-Pichel, 1998; Häder and Sinha, 2005; Jagger, 1985; Singh et al., 2010). Therefore, studies of UVR’s effects on life are of fundamental importance for understanding the origin and evolution of the biosphere on Earth and searching for extraterrestrial life. The oxidative state of Earth can be roughly divided into the anoxic period and oxic period corresponding to, respectively, before and after the great oxygenic event (GOE) at ∼2.5 Ga (Figure 8.3.1) (Bekker et al., 2004; Berner et al., 2003; Carver, 1981; Kasting, 1993; Kasting and Donahue, 1980; Kump, 2008). During the early stage, the biological effects of UVR were estimated to be about threefold higher in magnitude than in the present time, and the short-wavelength UVR has been known to be lethal for cells and a strong DNA mutagenic agent (Cockell, 1998). With the later formation of a natural UVR filter (i.e., the stratospheric ozone layer), UVR flux on the Earth’s surface could be significantly reduced in the Earth’s oxic period. However, the ozone layer protection is somehow unstable. For example, the instability of the ozone layer may be partially attributed to the variation of the geomagnetic field, which is an important shelter for life on Earth but changes over geological time (Glassmeier et al., 2009; Guyodo and Valet, 1999; Juarez et al., 1998; Pan and Zhu, 2011). During geomagnetic field reversal or excursion, the field is tilting, and its dipolar field strength drops to about 10–20% of the value of the present-day field (e.g., Cox et al., 1964; Glassmeier and Vogt, 2010; Mochizuki et al., 2011; Zhu et al., 2000). In this case, high-energy particles can penetrate into the middle atmosphere and photocatalyze nitrogen and oxygen into nitric oxide (a ozone depletion agent), thus depleting the ozone layer (Kerr and McElroy, 1993; Ma and Guicherit, 1997; Solomon, 1999). Numerical models also have been proposed that a decrease in the geomagnetic field results in an enhancement of UVR reaching the Earth’s surface (Glassmeier et al., 2009; Laštovička, 2003; Lee and Kodama, 2009; Sinnhuber et al., 2003; Winkler et al., 2008). Microbes might have existed on Earth for at least ∼3.5 Ga and thus have coevolved with the Earth’s surface environments (Abrevaya et al., 2013; Cockell and Raven, 2007; Ehling-Schulz and Scherer, 1999; Glikson, 2014; Mojzsis et al., 1996; Sagan, 1973; Schopf, 2006, 2012). To avoid deleterious or lethal UVR, microbes have developed multiple strategies to mitigate its harmful effects, such as possessing a fast escape ability, DNA damage repair systems (see Chapters 8.2, 8.4), reactive oxygen species (ROS)-scavenging enzymes (see Section 10), and synthesis of UV-absorbing chemical compounds or protecting sheaths (Ehling-Schulz and Scherer, 1999; Gao and Garcia-Pichel, 2011; Goosen and Moolenaar, 2008; Häder et al., 1998; Phoenix and Konhauser, 2008; Sinha and Häder, 2002a,b, 2008). For

Separation of magnetotactic bacterium and apparatus therefor

Abstract: PURPOSE:To carry out the separation and recovery of magnetotactic bacteria from a liquid containing said bacteria in high purity at a high speed, by placing a liquid containing magnetotactic bacteria in a high magnetic field, attracting and fixing the magnetotactic bacteria to a polar surface generating magnetic force line at a high speed and releasing the fixed bacteria by eliminating the magnetic field. CONSTITUTION:In the 1st step, a process for contacting a stock liquid containing magnetotactic bacteria with a surface 2 generating magnetic force line of >=1,000 Gauss to effect the adsorption of the bacteria to the surface 2 and a process for cleaning the bacteria adsorbed to the surface 2 with a cleaning liquid 7 under the influence of the magnetic force line are repeated once or more. In the 2nd step, the surface 2 washed in the 1st step is made to contact with a desorption liquid 7 under a condition free from magnetic field to transfer the bacteria into the desorption liquid 7. Finally, the desorption liquid produced by the 2nd step is taken out of the system in the 3rd step. The magnetotactic bacteria can be separated by this process from the stock liquid containing said bacteria in high speed, recovery and purity with magnetic force.

The Magnetosomes of Magnetotactic Bacteria May be Used as Drug-carriers for Targeted Therapy

Abstract: Magnetotactic bacteria can form uniform nanometer sized magnetic particles(megnetosomes)within the bacterial cells and each particle is enveloped in a membraneThe purified magnetosomes are compatible and less toxic to SD ratIt may be used as a carrier to link with certain antibiotics and larger molecular compounds for treatment of tumorsHere we described the properties of the magnetosnmes and the strategies for linking drugsWe also discussed the possibility to establish the system of targeted therapy for cancers nsing drug-loaded magnetosumes