Biofilm Abundance Research Articles

Potential of Prebiotic D-Tagatose for Prevention of Oral Disease.

Recent studies have shown phenotypic and metabolic heterogeneity in related species including Streptococcus oralis, a typical oral commensal bacterium, Streptococcus mutans, a cariogenic bacterium, and Streptococcus gordonii, which functions as an accessory pathogen in periodontopathic biofilm. In this study, metabolites characteristically contained in the saliva of individuals with good oral hygiene were determined, after which the effects of an identified prebiotic candidate, D-tagatose, on phenotype, gene expression, and metabolic profiles of those three key bacterial species were investigated. Examinations of the saliva metabolome of 18 systemically healthy volunteers identified salivary D-tagatose as associated with lower dental biofilm abundance in the oral cavity (Spearman’s correlation coefficient; r = -0.603, p = 0.008), then the effects of D-tagatose on oral streptococci were analyzed in vitro. In chemically defined medium (CDM) containing D-tagatose as the sole carbohydrate source, S. mutans and S. gordonii each showed negligible biofilm formation, whereas significant biofilms were formed in cultures of S. oralis. Furthermore, even in the presence of glucose, S. mutans and S. gordonii showed growth suppression and decreases in the final viable cell count in a D-tagatose concentration-dependent manner. In contrast, no inhibitory effects of D-tagatose on the growth of S. oralis were observed. To investigate species-specific inhibition by D-tagatose, the metabolomic profiles of D-tagatose-treated S. mutans, S. gordonii, and S. oralis cells were examined. The intracellular amounts of pyruvate-derived amino acids in S. mutans and S. gordonii, but not in S. oralis, such as branched-chain amino acids and alanine, tended to decrease in the presence of D-tagatose. This phenomenon indicates that D-tagatose inhibits growth of those bacteria by affecting glycolysis and its downstream metabolism. In conclusion, the present study provides evidence that D-tagatose is abundant in saliva of individuals with good oral health. Additionally, experimental results demonstrated that D-tagatose selectively inhibits growth of the oral pathogens S. mutans and S. gordonii. In contrast, the oral commensal S. oralis seemed to be negligibly affected, thus highlighting the potential of administration of D-tagatose as an oral prebiotic for its ability to manipulate the metabolism of those targeted oral streptococci.

Vertical distribution of biofilm communities along an injection wellbore in a deep petroleum reservoir

In petroleum production, microbial research has been widely carried out to serve different engineering applications. For instance, studies on microbial-induced corrosion (MIC) control and microbial-enhanced oil recovery (MEOR) focus on the microbial activities in surface pipelines and in subsurface strata (oil reservoirs), respectively. However, the living microorganisms attaching to the inner surfaces of vertical wells as biofilms has not attracted much attention In a normal water-flooded oil-production system, the water is transferred between the surface and subsurface reservoirs through the vertical wells so that the wellbore biofilms are able to constantly affect the surface and subsurface communities. Therefore, it is necessary to reveal the structure and function of the sessile community along the vertical wellbore. Since in situ sampling from underground vertical wells is technologically complex and expensive, in this study, biofilm samples were obtained during well workover from well tube segments corresponding to different original depths (approximately 0 m, 300 m, 800 m, and 1300 m). Moreover, the injection water was also sampled. The results of 16S rRNA gene library sequencing showed that the microbial community in the water phase was distinct from that found in the biofilms (dissimilarity 0.63–0.78), although they shared 200–272 OTUs. At the phylum level, the dominant phylum, Euryarchaeota , accounted for 21.5%–35.8% in the four biofilms, while only 11.7% in the water phase. Proteobacteria was the dominant phylum in the water phase (74.6%), while accounted for only 7.7%–20.1% in the biofilms. With increasing depth from 0 m to 1300 m, the richness and diversity of biofilms declined (Chao index of 608.8 to 442.4, Shannon index of 4.01 to 3.48), and the bacterial abundance of biofilms declined from 78.4% to 63.5%, while the archaeal abundance increased from 21.6% to 36.5%. The geothermal gradient, depleted oxygen and even turbulence were the significant factors affecting the depth-dependent variation in the communities. For instance, the relative abundance of the hydrogenotrophic genera increased from 8.62% to 28.8% with increasing depth. In addition, the sudden variation of wellbore biofilms suggested a presumed boundary of the microbial ecosystem around the depth of 1000 m, which is consistent with existing reports. This is the first study to directly investigate and reveal the depth-dependent distribution of the wellbore community along a deep well (depth >1300 m). The distinct and depth-dependent communities suggested that direct investigation is necessary for completely understanding and efficiently controlling microbial activities in oil production processes, including MIC control and MEOR. • Biofilms at different depths from an injection well were sampled during workover. • There are abundant microorganisms living in wellbore environments as biofilms. • Biofilm communities show a depth-dependent distribution along the deep well. • Those biofilms interact with the entire oil production system by fluid circulation. • Understanding wellbore biofilm is essential for corrosion control and oil recovery.

QS9: Host Biofilm Interaction In Breast Implant Illness

Purpose:Breast Implant Illness (BII) is patient-described constellation of symptoms that are believed to be related to their breast implant. The symptoms described include fibromyalgia, chronic fatigue and a host of other symptoms that are often associated with autoimmune illnesses. In this work, we report that bacterial biofilm associated with breast implant, metabolize fatty acid oleic acid present in the breast tissue milieu to oxylipins, one such oxylipin identified from this study is (10S)-hydroxy-(8E)-octadecenoic acid (10-HOME). We hypothesize that immunomodulatory effects of oxylipin 10-HOME produced by biofilm present on the implant could be correlated with BII pathogenesis.Methods:Capsulectomy and breast implants from clinically indicated procedures for patients requesting prosthetic removal were collected using clinical parameters outlined in previous studies, and questionnaire screened for the commonly reported symptoms associated with BII. Predictive variables included age, diabetes status, co-morbidities, nature and duration of implant. Scanning electron microscopy (SEM), Wheat Germ Agglutinin (WGA) and 16SrRNA sequencing were used for bacterial biofilm bacterial identification. 10-HOME was quantitated through targeted and untargeted lipidomic analyses using LC-MS-MS.Results:Sixty eight Implant, associated capsules and breast tissue specimen were collected for BII (n=46) and two control groups, group I, (non-BII, n=14) patients with breast implants, no BII symptoms. Group II (normal tissue, n = 8), patients without an implant, whose breast tissue was removed due to surgical procedures. Bacterial biofilm was detected through SEM in both BII and non BII cohorts. However, WGA analysis (quantitative analysis) indicated increased abundance of biofilm in the BII cohort (n=7, p=0.0036). 16SrRNA (genomic) sequencing identified increased abundance of Staphylococcus epidermidis (Fisher’s exact test, p<0.001) in the BII group (63.04%) compared to non-BII group (14.3%) and the normal group. The BII group was 9.8 times significantly more likely to have Staphylococcus epidermidis colonization compared to the non-BII group (p=0.003, logistic regression), compared to normal, it is 17.4 times significantly more likely to have Staphylococcus epidermidis (p=0.0021). Elevated levels of 10-HOME BII compared to non-BII samples, (p < 0.0001) were observed through mass spectrometry. Positive correlation was observed between bacterial abundance and concentration of 10-HOME in BII subjects (R2=0.88). Similar correlation was observed in BII subjects with Staphylococcus epidermidis (R2=0.77).Conclusion:This study investigated the biofilm hypothesis of breast implant illness through a host-pathogen interaction. The breast microenvironment led to formation of biofilm derived 10-HOME from host oleic acid. The study provides the first evidence of a possible correlation between bacterial biofilm and biofilm derived 10-HOME in the context of 10-HOME. In consideration of reports of biofilm association with other metal implants, the findings of this study can possibly explain autoimmune response associated with those implants.

Microbial degradation of polyhydroxybutyrate with embedded polyhexamethylene guanidine derivatives

The aim of this study was to isolate biofilm-forming bacteria that are capable of degrading polyhydroxybutyrate (PHB) with polyhexamethylene guanidine (PHMG) derivatives. The three types of derivatives incorporated in PHB and their concentration affected the biodegradability of the tested films in both water and compost. The PHMG derivative granular polyethylene wax at the highest concentration significantly inhibited BOD in both environments. At the same time, in water, PHB with PHMG stearate at 1% concentration was also found to inhibit biodegradation but to a lesser extent than PHMG polyethylene wax granulate. Analyzing the values of biofilm abundance and their hydrolytic activity in water, low concentrations of PHMG derivatives (0.2 and 0.6%) slightly inhibited biofilm abundance on the surface of the tested composites. Only granular polyethylene wax PHMG (at 1% concentration) significantly reduced biofilm formation and hydrolase activity in the compost to the greatest extent. Bacteria from biofilm were isolated and identified. Based on the 16S rRNA gene sequence, the strains belong to Bacillus toyonensis HW1 and Variovorax boronicumulans HK3. Introduction of the tested isolates to the environment can enhance composites degradation. However, this requires further research.

An intrauterine device with potential to control fertility in feral equids

Fertility control of feral equids is difficult. A 4-month pilot study was conducted with a hormone-free intrauterine device (iUPOD). There was evaluation of i) device retention; ii) contraceptive efficacy; iii) fertility following device removal; iv) effects of device on estrous cycle periodicity and; v) abundance of biofilm on devices after removal from the uterus. The iUPODs were inserted trans-cervically in eight mares at random stages of the estrous cycle. Mares were confined in a paddock with a stallion the following day and remained with the stallion for 120 days. Transabdominal detection of the iUPOD, using a non-invasive handheld magnetic detector wand, was performed weekly. Mares were examined using transrectal ultrasonography on days 0 (Time at insertion = day 0), 14, and 30, and subsequently every third week to assess number and size of follicles, corpora lutea, and whether there was intrauterine fluid (IUF) present. The mares and stallion were observed daily for mating behavior. Weekly samples were assayed for progesterone (P4) at day 0 and until 3 weeks subsequent to stallion removal. None of the mares became pregnant while fitted with the iUPOD. Two of four mares conceived within 30 days subsequent to iUPOD removal. Three of eight mares fitted with the device had periods greater than 14 days with P4 concentrations <1 ng/mL, and seven of eight mares had periods greater than 14 days with P4 concentrations>1 ng/mL. There was a marked abundance of biofilm on devices of two mares at the time of device removal.

Turning down tolerance

Antimicrobial Drugs Persister cells, which are found in abundance in biofilms, adopt a quiescent state and survive antimicrobial treatments, seeding disease recurrence and incubating new resistance mutations. Building on work implicating the reactive small-molecule hydrogen sulfide in bacterial defense against antibiotics, Shatalin et al. conducted a structure-based screen for inhibitors of a bacterial hydrogen sulfide–producing enzyme and found a group of inhibitors that act through an allosteric mechanism (see the Perspective by Mah). These inhibitors potentiated bactericidal antibiotics in vitro and in mouse infection models. They also suppressed persister bacteria and disrupted biofilm formation. This strategy of taking out persister cells may be promising for treating recalcitrant infections and holding the line against drug-resistant bacteria. Science , abd8377, this issue p. [1169][1]; see also abj3062, p. [1153][2] [1]: /lookup/doi/10.1126/science.abd8377 [2]: /lookup/doi/10.1126/science.abj3062

Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

Temperature variation can promote physico-chemical and microbial changes in the water transported through distribution systems and influence the dynamics of biofilms attached to pipes, thus contributing to the release of pathogens into the bulk drinking water. An experimental real-scale chlorinated DWDS was used to study the effect of increasing temperature from 16 to 24°C on specific pathogens, bacterial-fungal communities (biofilm and water samples) and determine the risk of material accumulation and mobilisation from the pipes into the bulk water. Biofilm was developed for 30 days at both temperatures in the pipe walls, and after this growth phase, a flushing was performed applying 4 gradual steps by increasing the shear stress. The fungal-bacterial community characterised by Illumina MiSeq sequencing, and specific pathogens were studied using qPCR: Mycobacterium spp., Mycobacterium avium complex, Acanthamoeba spp., Pseudomonas aeruginosa, Legionella pneumophilia, and Stenotrophomonas maltophilia. Sequencing data showed that temperature variation significantly modified the structure of biofilm microbial communities from the early stages of biofilm development. Regarding bacteria, Pseudomonas increased its relative abundance in biofilms developed at 24°C, while fungal communities showed loss of diversity and richness, and the increase in dominance of Fusarium genus. After the mobilisation phase, Pseudomonas continued being the most abundant genus at 24°C, followed by Sphingobium and Sphingomonas. For biofilm fungal communities after the mobilisation phase, Helotiales incertae sedis and Fusarium were the most abundant taxa. Results from qPCR showed a higher relative abundance of Mycobacterium spp. on day 30 and M. avium complex throughout the growth phase within the biofilms at higher temperatures. The temperature impacts were not only microbial, with physical mobilisation showing higher discolouration response and metals release due to the increased temperature. While material accumulation was accelerated by temperature, it was not preferentially to either stronger or weaker biofilm layers, as turbidity results during the flushing steps showed. This research yields new understanding on microbial challenges that chlorinated DWDS will undergo as global temperature rises, this information is needed in order to protect drinking water quality and safety while travelling through distribution systems.

Reprocessing effectiveness of gastrointestinal endoscopes in western Algeria hospitals: Infectious risk and biofilm formation

The significant increase in endoscopic procedures can lead to a potential source of cross-infection accompanied by biofilm formation on the devices when the disinfection procedure is unsuitable. This study, the first in Algeria, aims to describe the microbiological quality of gastroscopes used in gastroin-testinal units of western Algeria hospitals and to implement some corrective measures. A total of 132samples from endoscopes were examined over a period of 2 years. Contamination level of samples was evaluated by CFU count. Identification of the isolates was made by MALDI Biotyper System. Biofilm formation was detected by Congo Red Agar and tissue Culture Plate method (TCP). The endoscope-drying effectiveness was analyzed by bacterial count and Scanning Electron Microscopy (SEM). Microbial growth was de-tected in 68.18%of endoscopes; 150strains were isolated: Gram-negative-bacilli (56%), Gram-positive-cocci (26.66%), Gram-positive-bacilli(17.33%); dominant species were Enterobacter cloacae, coagulase-negative Staphylo-cocci, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus. Forty one out of 132 samples collected after disinfection disclosed Enterobacteriaceae (41.93%), Pseudomonaceae (16.12%), Staphylococci (30.64%) and Bacillus (11.29%). Using TCP, 96 isolates were good biofilm-producers. The drying reduced significantly the rate of CFU growth for all channels with absence of indicators bacteria. Drying had a better inhibition on biofilm formation, SEM observation revealed a very low abundance of biofilms. Our study is the first in Algeria to describe microbiological findings of post-reprocessing-gastroscopes. Biofilms inside endoscope result in de-contamination failure. Rigorous cleaning/disinfection and drying with com-pressed air are essential elements that reduce the contamination level and biofilm formation inside endoscopes.

Impacts of two nitrogen concentrations on nutrients release and nitrogen cycle genes abundance in biofilm during &lt;i&gt;Hydrilla verticillata&lt;/i&gt; decomposition

氨氮是地表水常见污染物，尤其在农业区域，氮类化肥的不合理施用会导致周边水体氮浓度迅速升高并保持较高水平.然而，当前对高氮水平下沉水植物腐败和附着氮循环微生物的影响尚不清楚.以轮叶黑藻(Hydrilla verticillata)为研究用沉水植物，在实验室内模拟水体内8和16 mg/L氮浓度下轮叶黑藻腐解过程中营养盐释放及残体表面微生物氮循环功能基因丰度的变化.研究发现水体两种氮浓度下轮叶黑藻腐解过程中残体腐解及营养盐释放速率无显著差异；与对照相比，植物腐败初期水体内碳、磷浓度迅速增加，而溶解氧浓度及氧化还原电位迅速降低，随着时间的推移上述水质指标逐步恢复至初期状态(第146天)；水体荧光溶解性有机质主要包括紫外类富里酸、可见类富里酸、色氨酸类蛋白质和酪氨酸类蛋白质等类型.在5个氮循环相关基因中，氮负荷增加对轮叶黑藻残体生物膜内amoA、napA和narG的丰度有显著影响.冗余分析表明氮循环基因丰度受水体总氮浓度的影响较小，与植物总有机碳含量和水体化学需氧量及溶解氧浓度存在相关性.研究结果表明虽然当前氮水平对植物腐败过程影响不大、对氮循环基因丰度有一定影响，但是对该水生植被(尤其是植物腐败初期)和农业退水排放的管理仍需加强，以降低其对水体的影响.

Metal resistance genes enrichment in marine biofilm communities selected by biocide-containing surfaces in temperate and tropical coastal environments.

Microorganisms able to form biofilms in marine ecosystems are selected depending on immersed surfaces and environmental conditions. Cell attachment directly on toxic surfaces like antifouling coatings suggests a selection of tolerant (or resistant) organisms with characteristics conferring adaptive advantages. We investigated if environment would drive metal resistance gene abundance in biofilms on artificial surfaces. Biofilms were sampled from three surfaces (a PVC reference and two antifouling coatings) deployed in three coastal waters with dissimilar characteristics: The Mediterranean Sea (Toulon) and Atlantic (Lorient) and Indian (Reunion) Oceans. The two coatings differed in metals composition, either Cu thiocyanate and Zn pyrithione (A3) or Cu2O (Hy). Metal resistance genes (MRG) specific to copper (cusA, copA, cueO) or other metals (czcA and pbrT) were monitored with qPCR in parallel to the microbial community using 16S rRNA gene metabarcoding. A lower α-diversity on A3 or Hy than on PVC was observed independent on the site. Weighted Unifrac suggested segregation of communities primarily by surface, with lower site effect. Metacoder log2 fold change ratio and LeFSe discrimination suggested Marinobacter to be specific of Hy and Altererythrobacter, Erythrobacter and Sphingorhabdus of A3. Likewise, the relative abundance of MRG (MRG/bacterial 16S rRNA) varied between surfaces and sites. A3 presented the greatest relative abundances for cusA, cueO and czcA. The latter could only be amplified from A3 communities, except at Toulon. Hy surface presented the highest relative abundance for copA, specifically at Lorient. These relative abundances were correlated with LeFSe discriminant taxa. Dasania correlated positively with all MRG except cueO. Marinobacter found in greater abundance in Hy biofilm communities correlated with the highest abundances of copA and Roseovarius with czcA. These results prove the selection of specific communities with abilities to tolerate metallic biocides forming biofilms over antifouling surfaces, and the secondary but significant influence of local environmental factors.

Measuring and reducing biofilm in mosquito rearing containers

BackgroundMosquito rearing containers contain organic-rich water that nourishes numerous bacteria, some of which are capable of forming biofilms. Biofilm is broadly an extracellular polymeric matrix (EPS) in which living bacteria occur, and the accumulation of biofilm is possible during routine stock-keeping as most of these containers are re-used. Whether biofilm has an effect on the mosquito rearing is not a question that has been investigated, nor have measures to reduce biofilm in this context been systematically studied.MethodsWe measured biofilm accumulation in standard rearing containers by staining with crystal violet and determining the OD using a spectrophotometer. We also treated rearing containers with 0.1% sodium hypochlorite to determine its effectiveness in reducing biofilm abundance. Lastly, we performed an analysis of the relationship between the occurrence of biofilm and the likelihood of microbial blooms that were associated with larval death during trials of larval diets.ResultsWe observed that soaking rearing containers overnight in 0.1% sodium hypochlorite greatly reduced biofilm, but we observed no relationship between the use of containers that had not been treated with bleach and subsequent microbial blooms.ConclusionsLarva rearing leaves detectable biofilm. While we were unable to correlate microbial blooms with the presence of biofilm, as a precaution, we recommend that plastic containers that are re-used be treated with 0.1% sodium hypochlorite occasionally.

Metagenomic and network analyses decipher profiles and co-occurrence patterns of antibiotic resistome and bacterial taxa in the reclaimed wastewater distribution system

Metagenomic and network analyses were applied to decipher the profiles and co-occurrence of resistome and microbial taxa in the reclaimed wastewater distribution system, including reclaimed wastewater and two types of biofilms, i.e., surface layer biofilms and inner layer biofilms. The effects of chlorination, UV irradiation and no disinfection treatment on ARG relative abundance and composition were systemically investigated. The reclaimed wastewater possesses more diverse and abundant ARGs than biofilms and total ARG relative abundance followed the order of reclaimed wastewater samples > surface layer biofilms > inner layer biofilms. Multidrug, bacitracin, sulfonamide, aminoglycoside, beta-lactam, and macrolide-lincosamide-streptogramin resistance genes were the six most dominant ARG types and their sum accounted for 90.1 %–96.0 % of the total ARG relative abundance in different samples. Beta-lactam resistance gene was the discriminative ARG type for reclaimed wastewater. Bacitracin resistance gene and bacA were the discriminative ARG type and subtype for biofilms. Chlorination significantly reduced ARG relative abundance in the reclaimed wastewater. Nevertheless, it could not reduce ARG relative abundance in biofilms. Regarding to the total ARG profiles, there were no obvious increasing or decreasing trends over time during one year period. Co-occurrence results revealed twenty-six genera were deduced as the potential hosts of twenty-two ARG subtypes.

Data highlighting phenotypic diversity of urine-associated Escherichia coli isolates.

This article provides a reusable dataset describing detailed phenotypic and associated clinical parameters in n=303 clinical isolates of urinary Escherichia coli collected at Vanderbilt University Medical Center. De-identified clinical data collected with each isolate are detailed here and correlated to biofilm abundance and metabolomics data. Biofilm-abundance data were collected for each isolate under different in vitro conditions along with datasets quantifying biofilm abundance of each isolate under different conditions. Metabolomics data were collected from a subset of bacterial strains isolated from uncomplicated cases of cystitis or cases with no apparent symptoms accompanying colonization. For more insight, please see “Defining a Molecular Signature for Uropathogenic versus Urocolonizing Escherichia coli: The Status of the Field and New Clinical Opportunities” [1].

Advanced biofilm analysis in streams receiving organic deicer runoff.

Prolific heterotrophic biofilm growth is a common occurrence in airport receiving streams containing deicers and anti-icers, which are composed of low-molecular weight organic compounds. This study investigated biofilm spatiotemporal patterns and responses to concurrent and antecedent (i.e., preceding biofilm sampling) environmental conditions at stream sites upstream and downstream from Milwaukee Mitchell International Airport in Milwaukee, Wisconsin, during two deicing seasons (2009-2010; 2010-2011). Biofilm abundance and community composition were investigated along spatial and temporal gradients using field surveys and microarray analyses, respectively. Given the recognized role of Sphaerotilus in organically enriched environments, additional analyses were pursued to specifically characterize its abundance: a consensus sthA sequence was determined via comparison of whole metagenome sequences with a previously identified sthA sequence, the primers developed for this gene were used to characterize relative Sphaerotilus abundance using quantitative real-time PCR, and a Sphaerotilus strain was isolated to validate the determined sthA sequence. Results indicated that biofilm abundance was stimulated by elevated antecedent chemical oxygen demand concentrations, a surrogate for deicer concentrations, with minimal biofilm volumes observed when antecedent chemical oxygen demand concentrations remained below 48 mg/L. Biofilms were composed of diverse communities (including sheathed bacterium Thiothrix) whose composition appeared to shift in relation to antecedent temperature and chemical oxygen demand. The relative abundance of sthA correlated most strongly with heterotrophic biofilm volume (positive) and dissolved oxygen (negative), indicating that Sphaerotilus was likely a consistent biofilm member and thrived under low oxygen conditions. Additional investigations identified the isolate as a new strain of Sphaerotilus montanus (strain KMKE) able to use deicer components as carbon sources and found that stream dissolved oxygen concentrations related inversely to biofilm volume as well as to antecedent temperature and chemical oxygen demand. The airport setting provides insight into potential consequences of widescale adoption of organic deicers for roadway deicing.

Variability of the nitrifying bacteria in the biofilm and water column of a recirculating aquaculture system for tilapia ( Oreochromis niloticus ) production

The aim of this study was to evaluate variability of nitrifying bacterial community in the biofilm and in the water of a recirculating aquaculture systems (RAS) in a tilapia farming in order to determine if nitrification process is dependent, or not, of nitrifying bacteria abundance. Biofilm and water samples were collected periodically for 30 days and analysed with the fluorescent in situ hybridization (FISH) technique, used to quantify ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). Ammonia presented the peak in the first week, while the nitrite's maximum was recorded in the second week. Nitrate increased steadily, indicating nitrification activity. Total bacterial abundance in biofilm increased continuously, while in water, it did not change significantly. In the biofilm, number of AOB was high at beginning, decreased after few days and increased again following augment of ammonia. Number of NOB also showed an increase in abundance in biofilm following the increment of nitrite and nitrate. In water, AOB and NOB did not show major variability. Relative abundance of nitrifying bacteria represented more than 30% of total bacteria in biofilm at beginning of the experiment. Their contribution decreased to >3% in last days. It indicates that nitrifying bacteria are biofilm colonizers, and that their activity seems to be directly related to the concentration of nitrogen compounds. However, contribution of nitrifying bacteria did not vary much along the time. We may conclude that the biofilm-nitrifying bacteria plays major role in nitrification process in RAS and that the activity of these organisms is dependent of their abundance in response to the concentration of nitrogen compounds.

Bacteria and archaea on Earth and their abundance in biofilms.

Biofilms are a form of collective life with emergent properties that confer many advantages on their inhabitants, and they represent a much higher level of organization than single cells do. However, to date, no global analysis on biofilm abundance exists. We offer a critical discussion of the definition of biofilms and compile current estimates of global cell numbers in major microbial habitats, mindful of the associated uncertainty. Most bacteria and archaea on Earth (1.2 × 1030 cells) exist in the 'big five' habitats: deep oceanic subsurface (4 × 1029), upper oceanic sediment (5 × 1028), deep continental subsurface (3 × 1029), soil (3 × 1029) and oceans (1 × 1029). The remaining habitats, including groundwater, the atmosphere, the ocean surface microlayer, humans, animals and the phyllosphere, account for fewer cells by orders of magnitude. Biofilms dominate in all habitats on the surface of the Earth, except in the oceans, accounting for ~80% of bacterial and archaeal cells. In the deep subsurface, however, they cannot always be distinguished from single sessile cells; we estimate that 20-80% of cells in the subsurface exist as biofilms. Hence, overall, 40-80% of cells on Earth reside in biofilms. We conclude that biofilms drive all biogeochemical processes and represent the main way of active bacterial and archaeal life.

Effects of Chloramine and Coupon Material on Biofilm Abundance and Community Composition in Bench-Scale Simulated Water Distribution Systems and Comparison with Full-Scale Water Mains.

The vast majority of bacteria in drinking water distribution systems (DWDSs) reside in biofilms on the interior walls of water mains. Little is known about how water quality conditions affect water-main biofilms because of the inherent limitations in experimenting with drinking water supplies and accessing the water mains for sampling. Bench-scale reactors permit experimentation and ease of biofilm sampling, yet questions remain as to how well biofilms in laboratory reactors represent those on water mains. In this study, the effects of DWDS pipe materials and chloramine residual on biofilms were investigated by cultivating biofilms on cement, polyvinyl chloride, and high density polyethylene coupons in CDC reactors for up to 28 months in the presence of chloraminated or dechlorinated tap water. The bench-scale biofilm microbiomes were then compared with the microbiome on a water main from the full-scale system that supplied the water to the reactors. The presence of a chloramine residual (1.74 ± 0.21 mg/L) suppressed biofilm accumulation and selected for Mycobacterium-like and Sphingopyxis-like operational taxonomic units (OTUs) while the destruction of the chloramine residual resulted in a significant increase in biomass quantity and a shift toward a more diverse community dominated by Nitrospira-like OTUs, which, our results suggest, may be complete ammonia oxidizers (comammox). Coupon material, however, had a relatively minor effect on the abundance and community composition of the biofilm bacteria. Although biofilm communities from the chloraminated water reactor and the water mains shared some dominant populations (namely, Mycobacterium- and Nitrosomonas-like OTUs), the communities were significantly different. This manuscript provides novel insights into the effects of dechlorination and pipe material on biofilm community composition. Furthermore, to our knowledge, it is the first study to compare biofilm in a tap water-fed, bench-scale simulated distribution system to biofilm on water mains from the full-scale system supplying the tap water.

The origin of clay-coated sand grains and sediment heterogeneity in tidal flats

The presence and distribution of clay minerals attached to grain surfaces as coats (also known as rims) are of great interest because they affect petroleum reservoir quality via the inhibition of the porosity-occluding quartz cement during prolonged burial and heating. Being able to predict the distribution of clay-coated sand grains in petroleum reservoirs is thus important to help find and exploit anomalously high porosity sandstones deep in sedimentary basins. The few studies focused on the distribution of clay coats in marginal marine sediments derive from surface sediment-based data sets, with limited emphasis placed on the preservation of the surface trends in sediment undergoing eodiagenesis in the near-surface environments. The post-depositional processes of bioturbation (sediment homogenization) and infiltration of clay into sand-grade sediment have been widely invoked as potential mechanisms that produce clay coats in modern sands and ancient sandstones. However, the potential for such processes to alter surface trends and govern clay-coat distribution in the subsurface remains unconstrained. In this study, we report the development of a novel, quantitative model of clay-coat coverage in order to identify the controlling mechanisms that govern clay-coat distributions. This study has focused on surface and near-surface sediments in the Saltcoats tidal flat deposits of the Ravenglass Estuary, UK. This unique bio-sedimentary study involved geomorphic mapping, core logging, a range of scanning electron microscopy techniques, and quantification of grain-size, clay fraction content, biofilm abundance (total carbohydrate and biomarker analysis), clay-coat coverage, and clay-coat mineralogy. In this study, against established convention, we demonstrate that infiltration and bioturbation do not significantly affect clay-coat grain coverage in near-surface sediments. Instead, we show that the extent, distribution, and mineralogy of clay coats in near-surface sediment are governed by the surface-based hydrological segregation of the clay mineral assemblage and biological clay-coat formation.

Impacts of bleach on bryozoans: A framework to distinguish direct and indirect effects using chemical and physical manipulations

Chemical disturbances, caused by contamination, are a global issue and can cause changes in the abundance of populations of one or more species via direct and/or indirect effects. This, in turn, can have profound consequences on assemblages and/or systems. Understanding how contaminants affect functional groups or taxa, i.e. which ecological or biological processes are being affected, is necessary to better predict their consequences. To distinguish between direct and indirect effects of contaminants, however, specific experiments, physically manipulating the changing variable (in this case, biofilm) as well as the contaminant, are necessary. Here, I tested which processes were affected by bleach, a biocide commonly found in urban run-offs that caused a decrease in covers of bryozoans. Effects of bleach on recruitment and growth of bryozoans were variable, suggesting that impacts are complex. Nevertheless, results indicate that bleach reduced recruitment of bryozoans. Therefore, manipulative field experiments were done to test whether these effects were direct or indirect, through changes in the abundance of photosynthetic biofilms. Responses of biofilms varied with the duration and exposure to bleach, as well as the timing of experiments. Abundance of biofilms did not seem, however, to affect the number of recruits of bryozoans, which could suggest a direct effect of bleach on bryozoan recruitment. Given that bryozoans are a major component of subtidal benthic assemblages and an important food source for >300 species, decreases in their abundance, as those observed here, might have important knock-on effects on marine systems due to trophic cascades.Capsule.In situ manipulative experiments showed that bleach decreased covers of bryozoans, which is possibly due to a combination of effects on their growth and recruitment. Manual removals and chemically induced removals are necessary to disentangle direct and indirect effects of contaminants.

Antimicrobial Activity of Polyhexamethylene Guanidine Derivatives Introduced into Polycaprolactone

The research was aimed at determining the abundance of biofilm formation by Escherichia coli and Staphylococcus aureus on the surface of polycaprolactone (PCL) with polyhexamethylene guanidine (PHMG) derivatives and effect of the derivatives on extracellular hydrolytic enzymes and intracellular dehydrogenases. Biofilm abundance was determined by spectrophotometry, using crystal violet staining. Hydrolytic enzymes after contact with the film were determined with the use of non-specific substrate—fluorscein diacetate. The effect of PHMG derivatives on dehydrogenases activity was assessed using the test, where triphenyltetrazolium chloride (TTC) is reduced to triphenylformazan (TF). The PCL containing PHMG granular polyethylene wax and salt of sulfanilic acid (0.6–1% wt.) strongest inhibited biofilm formation. PHMG derivatives introduced into PCL were found to slightly affect hydrolases activity in both E. coli and S. aureus at a concentration of 0.2 and 0.6%. It was also found that dehydrogenases activity was inhibited by PCL films containing PHMG derivatives. PCL containing 1% of PHMG sulfanilate strongest inhibited hydrolases activity, whereas PCL modified with 1% of PHMG granular polyethylene wax showed the highest inhibitory effect on the activity of both enzymes. W-PCL and A-PCL composites (at concentration of 0.6%) have optimal combination of antibiofilm activity and biodegradability.