Seasonal Abundance of Acanthamoeba rhysodes (Singh, 1952) (Protozoa: Gymnamoebia) in a Mangrove Litter‐Soil Ecosystem of Gangetic‐Estuary, India,
01 Nov 1987-Journal of Eukaryotic Microbiology (Blackwell Publishing Ltd)-Vol. 34, Iss: 4, pp 403-405
TL;DR: It has been found that the overall number of organisms per gram of soil attains peak value during the monsoon period, and this value comes down in post-monsoon samples and is the least in pre- monsoon ones.
Abstract: Acanthamoeba rhysodes has been found to be a predominant intertidal benthic gymnamoeba in the mangrove ecosystem of Sundarbans of lower deltaic Bengal, facing the Bay. The sampling zones under study were the highest high tide regions, with characteristic mangrove litter-soil, inundated twice per month during the highest ebb of spring tide. Population abundance of this species, both in its trophic and cystic forms in the three distinct seasonal periods of pre-monsoon (March to June), monsoon (July to October), and post-monsoon (November to February) has been surveyed for over two years. These seasonal periods affect the physico-chemical parameters of the habitat substrata, including temperature, pH, and salinity. It has been found that the overall number of organisms per gram of soil attains peak value during the monsoon period. This value comes down in post-monsoon samples and is the least in pre-monsoon ones.
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TL;DR: Small free-living amoebae (FLA) are the main predators controlling bacterial populations in soils; however, they may spread deeper, reaching the vadose zone of groundwater systems, especially where bacterial populations get to high densities.
Abstract: Small free-living amoebae (FLA) are the main predators controlling bacterial populations in soils. They are distributed in the rhizospheric zone and the surrounding bulk soil; however, they may spread deeper, reaching the vadose zone of groundwater systems, especially where bacterial populations get to high densities. Soil texture is the physical factor controlling the distribution of FLA because it determines the mean bore pore of soil aggregates and other important physical factors. FLA help maintain the high bacterial mineralization rate of organic matter through predation. As attachment onto a surface is necessary for feeding, the quantity of available surfaces is very important for developing this activity. However, the role of protozoa on plant growth promotion is still unclear because they may increase this effect by feeding on both fungi and bacteria. Small FLA are found in soils or sediments, as well as attached to suspended particulate matter in water columns, in the first 30 pm of water surface, or on the bodies of submerged animals and plants. These microor- ganisms do not distinguish between terrestrial or aquatic environments because they live in the interfaces between them. However, their importance in aquatic systems has been considered as negligible because they are outcompeted by free swimmers. The water conditions affecting amoebae survival are pH, temperature, concentration of sulfhydric acid and salinity. These factors have a strong influence on the structure of amoebae communities in aquatic environments. FLA are considered cosmopolitan as a group, and they live inside vertebrates, in soils, freshwater, marine waters, and on the aerial parts of plants and animals. These microbes, are spread by wind and water currents. Once in the air, cysts and trophozoites behave like any other suspended particulate matter. Therefore, suspension, transportation, and removal depend on atmospheric dynamics rather than on their own mechanisms. Ultraviolet light and drought are the main causes of losing viability, but much needs to be learned about the effects of air contaminants on amoebal survival. Naked amoebae also live in the phyllosphere as part of phylloplane community, but their importance and participation in this environment remain unknown. Some species belonging to the genera Acantharnoebae, Naegleria, and Balamuthia cause fatal diseases in humans and are carriers of other pathogens such as Legionella pneumophilia. However, FLA communities can be of some utility in sewage treatment works based in soil filters. %A's predatory activity in the root zone method may be of greater importance than previously thought, because this is their natural or more favorable environment. Research on the feeding behavior of FLA species, their rate of biomass transformation, and growth rate changes in response to environmental stresses are still needed in order to clarify their importance in both sewage system works and agricultural fields, where both bacteria and amoebae are involved.
423 citations
TL;DR: Evidence indicates that perhaps only a limited number of species cause ocular disease, and that the presence of Acanthamoeba strains that grow at lower temperatures may also contribute to infection, thereby increasing the number of possibly infectious amebas.
Abstract: Acanthamoeba is a free-living ameba that is present in all types of environments throughout the world. The recent increase in cases of keratitis, especially in relation to an increase in the use of contact lenses, is probably due to the omnipresence of the organism as a result of the pronounced resistance of its cysts to disinfection and desiccation. The temperature of the eye is lower than that of the rest of the human body. Therefore, the presence of Acanthamoeba strains that grow at lower temperatures may also contribute to infection, thereby increasing the number of possibly infectious amebas. Recent evidence, however, indicates that perhaps only a limited number of species cause ocular disease. Delineation of the exact species of Acanthamoeba that cause keratitis is a prerequisite for the study of the ecology of the keratitis-producing amebas.
138 citations
TL;DR: Fastidious cleaning and disinfection of contact lenses, with particular care in lens storage, are necessary in the control of Acanthamoeba keratitis.
Abstract: Publisher Summary The chapter introduces Acanthamoeba Keratitis as a small filose, free-living amoeba with a cyst stage with ostioles. Acanthamoeba species are voracious predators of various Gram-negative bacteria, cyanobacteria, and fungi. Species are cannibalistic or pathogenic and grows in axenic enrichment culture and on defined media. The chapter discusses its taxonomy and various strains and culture conditions. The chapter also discusses the infectious nature of the amoeba. Acanthamoeba species cause the disease of the central nervous system which occurs primarily among the immunosuppressed or chronically ill, particularly AIDS patients. Acanthamoeba keratitis occurs most commonly among healthy normal individuals and seems associated with the minor trauma to the eye that accompanies contact lens wear. Failure to comply with proper hygienic procedures for cleaning and disinfecting lenses appears to be the major factor in most contact-lens-related eye infections. Species of Acanthamoeba dwell in damp soils and upper zones of mud in rivers and lakes and in anthropogenic water reservoirs. Cysts and trophozoites are carried by humans and distributed by wind, water, and animals. Species of Acanthamoeba readily colonize surface biofilms in swimming pools, hot tubs, heating-, ventilation-, and air-conditioning systems, and domestic water taps and eye-wash stations. The chapter also discusses disinfecting methods such as isopropyl alcohol cleaning system an “O 2 conditioner” which can kill both cysts and trophozoites within 30 minutes of exposure. Various reports indicate that trophozoites adhere preferentially over cysts to contact lenses and that various species and strains differentially adhere to the four Food and Drug administration (FDA) hydrogel lens groups. Both cysts and trophozoites show greater adherence to the higher-water-content lenses. Fastidious cleaning and disinfection of contact lenses, with particular care in lens storage, are necessary in the control of Acanthamoeba keratitis .
37 citations
TL;DR: A Half-century of Research on Free-living Amoebae (1965-2017): Review of Biogeographic, Ecological and Physiological Studies
Abstract: A Half-century of Research on Free-living Amoebae (1965-2017): Review of Biogeographic, Ecological and Physiological Studies
17 citations
Cites background from "Seasonal Abundance of Acanthamoeba ..."
...Fewer reports were recovered for tropical locales, and were largely from lakes, lagoons, and mangroves (e.g. Amin et al. 2008, Finlay et al. 1987, Bhattacharya et al. 1987)....
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...Lakes and lagoons Amin et al. (2008), Bagatini et al. (2013), Finlay et al. (1987), Garstecki & Arndt (2000), Lugo et al. (1998) Mangroves Bhattacharya et al. (1987), Rogerson & Gwaltney (2000)...
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TL;DR: A review of previous studies on various diversified soil organisms of mangroves and a listing of the references available until date providing a comprehensive bibliography can be found in this article.
Abstract: The dynamic mangrove ecosystem is complemented by the activities of its soil organisms. Much study has been conducted in the various mangroves in India and the literature is scettered. This review provides an analysis of previous studies on various diversified soil organisms of mangroves and a listing of the references available until date providing a comprehensive bibliography.
16 citations
References
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TL;DR: After 24 days the nematode populations in the treatments without carbon additions were dominated by resistant dauer larvae indicating the unavailability of food, and the adult component of the population was still increasing at the end of the 24-day experiment.
Abstract: Bacteria (Pseudomonas), amoebae (Acanthamoeba), and nematodes (Mesodiplogaster) were raised in soil microcosms with and without glucose additions. Nematode and amoebal grazing on bacteria significantly reduced bacterial populations by the end of a 24-day incubation period. Amoebal numbers decreased in the presence of nematodes with a corresponding increase in nematode numbers which reached a maximum of 230 nematodes/g of soil in the treatment with amoebae and glucose additions. After 24 days the nematode populations in the treatments without carbon additions were dominated by resistant dauer larvae indicating the unavailability of food. Although larval numbers were high in the treatments with glucose additions, the adult component of the population was still increasing at the end of the 24-day experiment. The effect of the presence of amoebae on nematode abundance was of the same magnitude as addition of 600Μg glucose-C.
102 citations
TL;DR: The contributions of various components of soil microflora and microfauna to rhizosphere phosphatase activity were determined with hydroponic cultures and properties of additional activity were identical to properties of plant acid phosphat enzyme.
Abstract: The contributions of various components of soil microflora and microfauna to rhizosphere phosphatase activity were determined with hydroponic cultures. Three treatments were employed: (i) plants alone (Bouteloua gracilis (H.B.K.) Lag. ex Steud.) (ii) plants plus bacteria (Pseudomonas sp.), and (iii) plants plus bacteria plus amoebae (Acanthamoeba sp.). No alkaline phosphatase was detected, but an appreciable amount of acid phosphatase activity (120 to 500 nmol of p-nitrophenylphosphate hydrolyzed per h per plant) was found in the root culture solutions. The presence of bacteria or bacteria and amoebae increased the amount of acid phosphatase in solution, and properties of additional activity were identical to properties of plant acid phosphatase. The presence of bacteria or bacteria and amoebae increased both solution and root phosphatase activities at most initial phosphate concentrations.
18 citations
01 Jul 1986
TL;DR: Six strains of amoebae belonging to two species, vizAcunthamoeba culbertsoni and CanthamoEBa rhysodes, were isolated during the 3 prominent seasonal periods of premonsoon, monsoon and postmonsoon from the south of Sagar Island facing Bay of Bengal.
Abstract: Six strains of amoebae belonging to two species, vizAcunthamoeba culbertsoni andAcanthamoeba rhysodes, were isolated during the 3 prominent seasonal periods of premonsoon, monsoon and postmonsoon from the south of Sagar Island facing Bay of Bengal (21°56′ to 21°88′ N and 88°08′ to 88°16′E). The actual sampling sites were the lowest low tide belt areas. They were co-cultured in pairs, for respective seasonal periods, in 20‰ saline distilled water agar medium with their habitat associated microbiota as food. Dominance of all the seasonal isolates ofAcanthamoeba culbertsoni over the corresponding strains ofAcanthamoeba rhysodes arising out of competitive growth has been observed. Thus in laboratory maintained cultural conditions, strains ofAcanthamoeba culbertsoni show remarkable adaptive superiority over those ofAcanthamoeba rhysodes.
3 citations