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MINI REVIEW - Acinetobacter : environmental and biotechnological applications
Abstract
Among microbial communities involved in different ecosystems such as soil, freshwater, wastewater and solid wastes, several strains belonging to the genus of Acinetobacter have been attracting growing interest from medical, environmental and a biotechnological point of view. Bacteria of this genus are known to be involved in biodegradation, leaching and removal of several organic and inorganic man-made hazardous wastes. It is also well known that some of Acinetobacter strains produce important bioproducts. This review summarizes the usefulness and environmental applications of Acinetobacter strains.
... As seen in Figure 7, each group contained the genus Limnohabitans, the genus unclassified_f_Comamonadaceae, and the genus of the Hgcl_clade with a relatively high relative abundance. Compared with other groups, the species with significant differences in the Shapingba District were Acinetobacter [37], Vogesella, and Pseudomonas, all of which had a higher relative abundance, whereas Cavicella had a lower relative abundance. The species with significant differences in the Hechuan District were Aquabacterium, Novosphingobium, and Cavicella with a higher relative abundance, whereas norank_Vicinamibacteraceae had a lower relative abundance. ...
At present, research on the influence of human activities (especially urbanization) on the microbial diversity, structural composition, and spatial distribution of rivers is limited. In this paper, to explore the prokaryotic community structure and the relationship between the community and environmental factors in the Jialing River Basin of Chongqing, so as to provide a basis for monitoring microorganisms in the watershed. The V3–V4 region of the 16 S rRNA gene was analyzed by high-throughput sequencing and the microbial community of the waters of the Jialing River was analyzed for the diversity and composition of the prokaryotic community as well as the species difference of four samples and correlations with environmental factors. The main results of this study were as follows: (1) The diversity index showed that there were significant differences in the biodiversity among the four regions. At the genus level, Limnohabitans, unclassified_f_Comamonadaceae, and Hgcl_clade were the main dominant flora with a high abundance and evenness. (2) A Kruskal–Wallis H test was used to analyze the differences of species composition among the communities and the following conclusions were drawn: each group contained a relatively high abundance of Limnohabitans; the Shapingba District had a higher abundance of Limnohabitans, the Hechuan District had a wide range of unclassified_f_Comamonadaceae, and the Beibei District had a higher Hgcl_clade. (3) Through the determination of the physical and chemical indicators of the water—namely, total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll A, and an analysis by an RDA diagram, the results demonstrated that the distribution of microbial colonies was significantly affected by the environmental factors of the water. Chemical oxygen demand and ammonia nitrogen had a significant influence on the distribution of the colonies. Different biological colonies were also affected by different environmental factors.
... Bacteria of the genus Acinetobacter are non-motile, nonsporulating, Gram-negative, obligate aerobic coccobacilli (Dexter et al., 2015). They belong to the phylum Proteobacteria and family Moraxellaceae, and they are ubiquitous in many environments, including water, wastewater, soil and human skin (Abdel-el-haleem, 2003). Acinetobacter spp. ...
The aim of this study was to analyze the prevalence of carbapenem resistance genes in Acinetobacter spp. isolated from wastewater in a municipal WWTP and to determine their spread from treated wastewater to river water with the use of conventional and molecular microbiology methods (qualitative and quantitative PCR and metagenomic analysis). Samples of untreated and treated wastewater and samples of river water obtained upstream and downstream from the wastewater discharge point were collected in 3 seasons (February, June, and September) of 2019. Acinetobacter spp. isolates were obtained by the culture method on the CHROMagar™ Acinetobacter medium. Additionally, environmental DNA was extracted from the samples for metagenomic and qPCR analyses. The presence of beta-lactam resistance genes (Ambler class B and D), insertion sequence ISAba1, and class I, II, and III integron-integrase genes was determined, and the bacterial taxonomic structure and wastewater and river samples was analyzed. Out of the 301 isolates obtained on the CHROMagar™ Acinetobacter medium, 258 belonged to the genus Acinetobacter, including 21 isolates that were identified as Acinetobacter baumannii. The highest number of Acinetobacter spp. and A. baumannii isolates were obtained from wastewater and river water samples collected in June and September. The ISAba1/blaOXA-51 complex was identified in 13 isolates, which confirms the occurrence of carbapenem-resistance isolates in the analyzed samples. The number of Acinetobacter isolates carrying antibiotic resistance genes (ARGs) increased in river water samples collected downstream from the wastewater discharge point (48 out of 258 isolates – 18.6%) compared to river water samples collected upstream from the wastewater discharge point (34 out of 258 isolates – 13.2%), which suggests that WWTP is a source of pollution in the natural environment. The conducted research provides evidence that bacteria of the genus Acinetobacter may spread alarming beta-lactam resistance in the environment and, therefore, pose a serious epidemiological threat.
... Among microbial communities involved in different ecosystems such as soil, freshwater, wastewater and solid wastes, several strains belonging to the genus of Acinetobacter have been attracting growing interest from medical, environmental and a biotechnological point of view [12]. Bacteriaof this genus are known to be involved in biodegradation, leaching and removal of several organic and inorganic manmadehazardous wastes [13]. ...
The emergence of multiple metal/antibiotic resistance among bacterial populations poses a potential threat to human health. Heavy metal and antibiotic resistance have been shown to have a strong correlation in nature, and their interrelation is an important subject of study. The present study had an objective to isolate and identify multiple metal/antibiotic resistant bacteria from industrial wastewater of a Plastic Factory at Hafar Al Baten governorate, Saudi Arabia. Initially a total of 14 bacterial cultures (coded HAF-1 to HAF-14) were isolated on nutrient agar plates supplemented with different concentrations; 10, 15, 25, 25 and 30 mg/l of the five heavy metals; Hg 2+ , Pb 2+ , Cd 2+ , As 5+ and Cr 6+ respectively. Out of 14 isolates, 5 (35.71 %) isolates (HAF-2, HAF-6, HAF-7, HAF-9 & HAF-13) were selected as a multiple heavy metal resistant (MHMR) organisms with maximum tolerable concentrations (MTCs); 75-100 mg/l for Hg 2+ , 125-175 mg/l for Pb 2+ , 200 mg/l for Cd 2+ and 200-250 mg/l for Cr 6+ and As 5+. Antibiotic resistance pattern of the selected MHMR isolates was determined by Kirby-Bauer disc diffusion method against 15 different antibiotics belonging to 10 classes. Out of 5 isolates, 4 (80 %) isolates were multiple antibiotic resistance (MAR) with varying degrees. Among them isolate, HAF-13 showed a wide range of resistance to all tested antibiotics; Amikacin, Augmentin, Ceftazidime, Chloramphenicol, Ciprofloxacin, Clindamycin, Cotrimoxazole, Erythromycin, Gentamicin, Levofloxacin, Oxacillin, Tetracycline, Vancomycin and Penicillin Gexcept Imipenem. Strain HAF-13 was selected for its multiple metal/antibiotic resistance and identified by morphological, physiological and biochemical characteristics in addition to the phylogenetic analysis of the nucleotide sequence of 16S rRNA gene, which indicated that this strain is belonged to the genus Acinetobacter with high similarity 98% to Acinetobacter baumannii (accession number KU310899.1) and designated Acinetobacter baumannii strain HAF-13.
... Indeed, Lactobacillus members, which are present in our sediment communities and in FRG2, have this ability to bind and sequester metals, providing local safe spots where other sensitive community members could be protected [62]. Other members from FRG2 and FRG4 are known to be able to ensure metal removal like Clostridium [48], Rhodobacter [69] and Acinetobacter [97]. Our results based on FRGs strongly suggest that such local microscale facilitation mechanisms could indeed enhance the survival of sensitive and/or new comers toward metals, contributing to an overall increase in diversity. ...
Metal contamination poses serious biotoxicity and bioaccumulation issues, affecting both abiotic conditions and biological activity in ecosystem trophic levels, especially sediments. The MetalEurop foundry released metals directly into the French river “la Deûle” during a century, contaminating sediments with a 30-fold increase compared to upstream unpolluted areas (Férin, Sensée canal). Previous metaproteogenomic work revealed phylogenetically analogous, but functionally different microbial communities between the two locations. However, their potential activity status in situ remains unknown. The present study respectively compares the structures of both total and active fractions of sediment prokaryotic microbiomes by coupling DNA and RNA-based sequencing approaches at the polluted MetalEurop site and its upstream control. We applied the innovative ecological concept of Functional Response Groups (FRGs) to decipher the adaptive tolerance range of the communities through characterization of microbial lifestyles and strategists. The complementing use of DNA and RNA sequencing revealed indications that metals selected for mechanisms such as microbial facilitation via “public-good” providing bacteria, Horizontal Gene Transfer (HGT) and community coalescence, overall resulting in an unexpected higher microbial diversity at the polluted site.
... Acinetobacter are known to be involved in biodegradation, leaching and removal of several organic and inorganic man-made hazardous wastes (Abdel-El-Haleem, 2003). According to Baumann (1968), the genus Acinetobacter is usually isolated from water and soil with the species haemolyticus reported to be isolated mostly from soil. ...
Chromium (Cr), especially Cr(VI) is of particular environmental concern owing to its high solubility, bioavailability and toxicity. The reduction of Cr(VI) to innocuous Cr(III) is an important step in the remediation of Cr(VI)-contaminated environments. The understanding of how microorganisms resist metals can provide insight into strategies for their detoxification or removal from the environment. The present investigation was undertaken to study the Cr(VI) resistance mechanisms by Acinetobacter haemolyticus, a strain isolated from Cr(VI)-containing textile wastewater. In preliminary studies, the strain was shown to be able to tolerate Cr(VI) concentrations of 30 and 90 mg L-1 in Luria-Bertani (LB) agar and broth respectively. The Cr(VI) reduction capacity of A. haemolyticus was found to be greater when grown in higher percentage of LB broth than minimal salts broth. The Cr(VI) reduction also increased with lower initial concentration of Cr(VI) added after 5 hours. The x-ray absorption fine structure (XAFS) analysis displayed the ability of the strain to reduce Cr(VI) to Cr(III) which was octahedrally coordinated to oxygen. The Cr(III) was most likely to form complexes with carboxyl (COO-) groups from the biomass based on Fourier-transform infrared (FTIR) analysis. The FTIR analysis also showed interactions of chromium with amino and hydroxyl groups. Field-emission scanning electron microscope (FESEM) showed that cells grown in the presence of Cr(VI) had a wrinkled appearance with a significant increase in size. No precipitates were found on the cell surface. However, precipitates were observed in the cytoplasmic region of the cells via transmission electron microscope (TEM) analysis, suggesting the transport of Cr(VI) into the cytoplasm and intracellular Cr(VI) reduction. Intracellular reduction of Cr(VI) was supported by a reductase test using soluble crude cell - free extracts. The specific reductase activity obtained was 0.52 μg Cr(VI) reduced per mg of protein an hour at pH 7.2 and 37 ˚C. In plasmid screenings, the strain was found to harbor a plasmid of about 12 kb. The findings showed that Cr(VI) resistance mechanisms of A. haemolyticus include the reduction of Cr(VI) to Cr(III), and intra- and extracellular sequestration of chromium.
Anthropogenic pollution often leads to the generation of technosols, technogenic soils with inhospitable conditions for all living organisms including microbiota. Aluminum production near Ziar nad Hronom (Slovakia) resulted in the creation of a highly alkaline and heavy-metal-rich brown mud landfill, from which a bacterial strain of a likely new species of the genus Acinetobacter, Acinetobacter sp. K1, was isolated. The whole-genome sequence analysis of this strain confirmed the presence of operon units enabling tolerance to the heavy metals copper, zinc, cobalt, cadmium, chromium, and metalloid arsenic, which are functionally active. Despite the predominance of plasmid-related sequences in the K1 genome, the results indicate that most of the resistance genes are chromosomally encoded. No significant alkali tolerance of Acinetobacter sp. K1 was observed in vitro, suggesting that community level mechanisms are responsible for the survival of this strain in the highly alkaline, brown mud bacterial community.
Cities are widely recognized as environments which can present risks to humans. Risks to health and well-being are measured in three groups of indices: physiological, emotional, and cognitive. The environmental factors discussed in studies include physical factors such as noise, heat load, and air pollution, and social factors include feelings of discomfort, crime, transportation, and access to health services. Some studies even argue that stress and health risks are intrinsic to urban environments and that restoration is intrinsic to green environments. This Topic aims to discuss what spaces can be greened and the effect this has on urban environments. It also discusses the effect of the size and layout of parks, vegetation on the walls and roofs of houses, and the effects of different types of vegetation, building materials, and energy-efficient design. Today’s environment demands new design processes, construction techniques, occupancy practices, and management strategies to increase the resilience of the built environment to extreme, uncontrollable, and unpredictable events while providing healthy and sustainable environments for people. This Topic reflects on what the new concept of sustainability for the built environment should be and how to guide new research directions.
Based on phylogenetic analyses, strain M2a isolated from honey, an unexpected source of acinetobacters, was classified as Acinetobacter lwoffii. The genome of this strain is strikingly crowded with mobile genetic elements. It harbours more than 250 IS elements of 15 IS-families, several unit and compound transposons and 15 different plasmids. These IS elements, including 30 newly identified ones, could be classified into at least 53 IS species. Regarding the plasmids, 13 of the 15 belong to the Rep-3 superfamily and only one plasmid, belonging to the “Low-GC” family, possesses a seemingly complete conjugative system. The other plasmids, with one exception, have a mobilization region of common pattern, consisting of the divergent mobA/mobL-family and mobS-, mobC- or traD-like genes separated by an oriT-like sequence. Although two plasmids of M2a are almost identical to those of A. lwoffi strains isolated from gold mine or Pleistocene sediments, most of them have no close relatives. The presence of numerous plasmid-borne and chromosomal metal resistance determinants suggests that M2a previously has also evolved in a metal-polluted environment. The numerous, possibly transferable, plasmids and the outstanding number of transposable elements may reflect the high potential of M2a for rapid evolution.
Acinetobacter sp. strain W-17, immobilized on porous sintered glass completely degraded 500 mg phenol l–1 in 40 h, but free cells required 120 h for this to be achieved. Immobilized cells can be used 7 times without losing their activity.
Polyphosphate-accumulating gram-negative bacteria were isolated from different anaerobic-aerobic activated sludge systems with diverse processes for enhanced biological phosphorus (P) elimination. Of 22 isolates, 10 were allocated to the genus Acinetobacter by using multiple-test systems and soluble protein and polyamine patterns. As diaminopropane (DAP) appears to be the characteristic main polyamine compound produced by Acinetobacter spp., it was used as a biomarker for the genus. The high DAP contents of representative samples from municipal wastes with enhanced biological P elimination indicated that Acinetobacter spp. can be dominant organisms in sewage treatment plants with low organic loading and nitrification and denitrification steps. Contrary to accepted opinion, sludge from treatment plants with efficient P removal and high organic loading had a low DAP content, indicating that bacteria other than Acinetobacter spp. are responsible for enhanced biological P elimination in these plants.
The genus Acinetobacter is defined as Gram-negative, nonmotile, nonpigmented, oxidase-negative saprophytes [1]. A genus-specific DNA transformation assay provides further demonstration for inclusion in this genus [2]. Strains belonging to the genus Acinetobacter produce a variety of extracellular polymers that bind to and change the surface properties of water-insoluble organic and inorganic compounds. A survey of several independently-isolated Acinetobacter strains indicated that most produced extracellular surface-active polymers [3]. Several of these microbially produced surface active polymers will be discussed here. All of these are complex, high molecular weight anionic heteropolysaccharides that may require additional components (lipids or proteins) for their maximum surface activity.
Electron microscopy combined with the energy dispersive analysis of X-rays (EDX) has been used to examine the nature of the phosphorus accumulated in sludges from seven activated sludge plants exhibiting enhanced phosphorus removal. Large phosphorus accumulations were located in identical structures in the sludges examined. The phosphorus was located in large electron-dense bodies, within large bacterial cells which were characteristically grouped in clusters. The calcium:phosphorus ratio of these electron-dense bodies precluded them from being any form of calcium phosphate precipitate. Quantitative analysis indicated that the electron-dense bodies contained an excess of 30% phosphorus. The results obtained are supportive of a biological mechanism of enhanced phosphorus uptake in activated sludge.
The impact of oil spills on land is reviewed. In terrestrial environments the lateral spread of spilled oil is relatively easy to control and the consequent ecological damage is typically localized. Special problems arise due to the movement of spilled oil into the soil water table. These problems are discussed in the context of the biodegradation of petroleum in soils. Petroleum prospecting, accidental petroleum spills on land, and intentional waste oil disposal on land are reviewed.
Cultivation of Acinetobacter radioresistens on n-hexadecane for lipase production was investigated with repeated batch culture in the presence of a hydrophobic nonwoven fabric. Lipase production followed the growth-associated model, and the repeated batch culture could achieve both high enzyme yield and increased volumetric productivity. The fabric was shown to be able to disperse n-hexadecane, to adsorb the unused hydrocarbon, and to retain bioemulsifiers excreted from the cells; therefore, it enhanced cell growth and, in turn, lipase production. In the repeated batch culture in the absence of the fabric, lipase yield and volumetric productivity were found to be 21 U/mL and 875 U/L · h, respectively. However, if the fabric was equipped in the fermentor, lipase yield and volumetric productivity increased to 30 U/mL and 2500 U/L · h, respectively. The lipase production profile could be further improved by raising the amount of nitrogen source and, as a result, a lipase yield of 54 U/mL and a volumetric productivity of 2250 U/L · h were obtained. In this study we assess the beneficial effects of nonwoven fabric on lipase production. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 214–218, 2001.
The influence of oxygen on alkaline lipase production by Acinetobacter radioresistens was studied under two operating modes: controlled dissolved oxygen (DO) concentration and controlled aeration rate. Compared with cell growth, the lipase production depended more extensively on oxygen. The intrinsic factor determining cell growth and lipase production was oxygen transfer rate (OTR) rather than DO concentration. Improvements in OTR, either by aeration or agitation, resulted in an increase in lipase yield and/or a reduction in fermentation time. The formation of A. radioresistens lipase could be described by a mixed-growth-associated model, and the enzyme was mainly a growth-associated product. The overall productivity for the lipase, which depended more strongly on agitation than aeration, could be related with kLa. DO concentration could not be employed in this correlation, though it has been useful as a criterion for ensuring no oxygen limitation in an aerobic fermentation. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 311–316, 1999.
Two identical sized laboratory-scale biofilters, filled with the same type of packing material, consisting of a mixture of peat and glass beads in a 4:1 volume ratio, are investigated for the purification of toluene and styrene-containing off-gas streams. One of the biofilters was inoculated with a toluene-degrading strain of Acinetobacter sp. NCIMB 9689, and the other with a styrene-degrading strain of Rhodococcusrhodochrous AL NCIMB 13259. For both pollutants, different sets of continuous experiments were conducted in the biofilter columns, varying both the inlet pollutant concentration and the superficial gas velocity. Maximum elimination capacities of 242 and 63 g mpacking material−3 h−1 packing material were recorded for toluene and styrene, respectively. Furthermore, the deodorization (defined as the achievement of a pollutant concentration in the effluent gas below the pollutant olfactory threshold value) of toluene and styrene-containing waste-gases was also considered. This was achieved, operating at maximum inlet concentrations of 1.99 and 0.20 g m−3 and at superficial gas velocities of 17.8 and 122 m h−1, respectively.
Complete degradation of the lignin model compound veratrylglycerol-beta-(o-methoxyphenyl) ether is accomplished mutualistically by a two-membered bacterial culture. Bacterial isolate E1, which has been tentatively identified as an Acinetobacter, grows on veratrylglycerol-beta-(o-methoxyphenyl) ether producing guaiacol (o-methoxyphenol) as a non-metabolizable, bacteriocidal by-product. When Nocardia corallina (strain A81) is also present in media containing veratrylglycerol-beta-(o-methoxyphenyl) ether as the only carbon/energy source, it is able to grow on the guaiacol produced from veratrylglycerol-beta-(o-methoxyphenyl) ether by isolate E1. Strain A81 alone does not grow on veratrylglycerol-beta-(o-methoxyphenyl) ether. In the absence of strain A81, isolate E1 is rapidly killed by accumulated guaiacol. In the presence of the Nocardia, isolate E1 maintains its viability.