Crystallization of Purple Bacterial Antenna Complexes
Hartmut Michel in Crystallization of Membrane Proteins, 1991
We are currently involved in trying to understand the molecular details of the light-harvesting process in purple photosynthetic bacteria. It is quite clear that in order to achieve this aim we need to obtain a high resolution three-dimensional structure for a bacterial antenna complex. Unfortunately, it is still true that the only reliable way to determine such a high-resolution structure for a protein is to use the methods of X-ray crystallography. This of course requires the production of suitably sized, well ordered crystals and this is why we began to try and crystallize the bacterial antenna complexes.1,2 In this chapter, after a brief introduction to bacterial antenna complexes, we shall describe some of our experiences in this area of crystallizing membrane proteins, with the hope that they will be of help to others who embark on a similar research program.
Water-based disease and microbial growth *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Cyanobacteria, photosynthetic bacteria and commonly referred to as blue-green algae, grow as blooms or mats, mostly within freshwater bodies, and like dinoflagellates are called harmful algal blooms (HABs). There are a large variety of species. Many of these produce potent toxins that are capable of causing acute and chronic disease in mammals, including humans. The toxins include microcystins, nodularins, anatoxins, saxitoxins, aplysiatoxins, cylindrospremopsins, beta-methyl-amino-l-alanine (BMAA) and lipopolysaccharides (see Table 9.1 in Chapter 9). Algal blooms are more commonly found in eutrophic inland waters (eutrophic waters have a high concentration of nutrients). Human health risks arise if the water is consumed untreated, if people bathe or participate in water contact sports in waters with a scum or heavy bloom and if contaminated water is used in renal dialysis. There have been some notable outbreaks of disease associated with cyanobacterial toxins with a high mortality rate in dialysis patients. The risks through long-term exposure to contaminated drinking water may be greater than occasional recreational exposure to cyanobacterial blooms while bathing in natural waters. More information on cyanobacteria and their toxins are presented in Chapter 9.
Organic Matter
Michael J. Kennish in Ecology of Estuaries Physical and Chemical Aspects, 2019
Green plants, via photosynthesis, supply most of the organic carbon production of estuaries. Photosynthetic bacteria, although potentially important in polluted and eutrophic systems, account for only a minor portion of the total organic carbon produced. Sulfate-reducing bacteria are obligate anaerobes (growing only in environments devoid of oxygen) frequently encountered at the upper edge of the reduced zone of tidal mudflat sediments and in anaerobic water masses. Chemosynthetic bacteria appear to be intermediate between autotrophs and heterotrophs,64 responsible for what is termed “secondary primary production”. Heterotrophs participate directly in carbon cycling by ingesting organic matter, converting plant organic carbon into animal organic carbon, and respiring or excreting metabolites and ultimately releasing elements subsequent to death and microbial decay.292 Various pathways of carbon transformation exist; however, carbon fixed by autotrophs ultimately enters abiotic carbon pools through respiration (CO2), mortality and defecation (POC), and secretion and degradation (DOC).24
An overview on cyanobacterial blooms and toxins production: their occurrence and influencing factors
Published in Toxin Reviews, 2022
Isaac Yaw Massey, Muwaffak Al osman, Fei Yang
The ancient cyanobacteria organisms, noticeable in rocks dating from the first thousand million years of the earth’s history and belong to the kingdom monera (Prokaryota), division eubacteria and class cyanobacteria (Ressom et al.1994, Omidi et al.2018), are a type of photosynthetic bacteria that live in water surface. As cyanobacteria colonies occur in shallow water, they appear in the fossil record in sedimentary rocks deposited in shallow seas and lakes. Cyanobacteria colonies identified as stromatolites emerge in rocks as fossilized mushroom shapes and sheets. Falconer (2005) reported that the Gunflint chert was one of the best stromatolite formations known in Lake Erie. It is of interest cyanobacteria was shown to possess a single circular chromosome completely sequenced in several species, plasmids and small circular strands of DNA (Schwabe 1988, Kaneko et al.1996). Whitton and Potts (2000) found that the chlorophyll-a and pigment phycocyanin observed in cyanobacteria photosynthetic membranes were responsible for the characteristic blue-green color of the many species. Pigments such as carotenoids and phycoerythrin which give a strong red color to some species may also be present (Bryant 1994).
Short-term succession of marine microbial fouling communities and the identification of primary and secondary colonizers
Published in Biofouling, 2019
Raeid M. M. Abed, Dhikra Al Fahdi, Thirumahal Muthukrishnan
Phototroph and macrofouler analyses within our one-week old bacterial biofilm re-affirms the fact that despite the establishment of a heterotrophic biofilm during the initial stages of biofouling, the motile and plocon growth forms of diatoms and brown macroalgae were indeed able to adhere to the primary layer of bacterial cells on the surface. Yet, these growth forms are prone to drifting from the biofilm matrix due to physico-chemical disturbances such as grazing, signs of which were evident after one week. Apparently, this indicates the formation of a biofilm attractive as food for fish and predatory organisms in the seawater (Lawrence et al. 2002). This in turn promotes the proliferation and survival of the diatoms with adnate growth forms as observed at day 7 and thereafter in the present biofilm (McLachlan et al. 2009; Svensson et al. 2014). The adnate growth forms such as Cocconeis sp. and Amphora sp. are the most tenacious of all growth forms owing to their abilities to firmly attach, survive in low-light conditions and resist rapid changes in water flow and grazing by various herbivores (Hoagland et al. 1993; Cardinale et al. 2006; Molino and Wetherbee 2008; Molino et al. 2009b; Totti et al. 2011; Svensson et al. 2014; Mejdandžić et al. 2015; Majewska and De Stefano 2015; Majewska et al. 2016).
Biofilm diversity, structure and matrix seasonality in a full-scale cooling tower
Published in Biofouling, 2018
L. Di Gregorio, R. Congestri, V. Tandoi, T. R. Neu, S. Rossetti, F. Di Pippo
The biodiversity and structure of phototrophic biofilms in the cooling tower varied with season, which only partially reflected seasonal variation in the source water and appeared to be mostly related to environmental changes. The tower operating conditions such as pH, water hardness and the presence of biocides most likely selected microorganisms from the source communities that were able to survive under specific conditions. Those capable of adhering to the available surfaces in the cooling tower, eg members of the bacterial families Sphingomonadaceae and Comamonadaceae, may initiate biofilm formation. Subsequently, seasonal variations in irradiance and water temperature shaped the communities and accounted for differences in biofilm assemblages observed over the year. In particular, the effect of these factors may have initially driven the composition of the phototrophic fraction that was dominated by diatoms in winter, green algae in summer and cyanobacteria in the period at intermediate temperatures. Later, the diversity of non-photosynthetic bacteria developed, being mainly affected by the interactions between microorganisms. The analysis of biofilms grown in microcosms under light and temperature control in order to mimic the operational conditions of cooling towers may provide further insight into the combined effect of abiotic conditions and biotic interactions on the diversity and structure of biofilms in industrial systems. Deciphering seasonal changes in the composition and structure of biofilms is crucial to defining specific control treatments in order to efficiently counter the dynamic evolution of biofouling in cooling towers.