Number Of Bacterial Cells Research Articles

Isolation of Bacillus strains inhibition disease resistance of Acute Hepatopancreatic Necrosis Disease on the Shrimp in Can Gio, Vietnam

Recently, the outbreak and severe damage to the shrimp farming industry is Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Disease (AHPND). The selection of Bacillus strains inhibition disease resistance of the acute hepatopancreatic necrosis disease on the shrimp is a research filed that is much attention due to Bacillus subtilis is a group of beneficial bacteria that presents in the majority of biological products for aquaculture, especially for shrimp. Competitiveness of Bacillus subtilis towards the harmful bacteria firstly is the number of bacterial cells. Beside, Bacillus has capacity to create a large amount of extracellular enzymes aid digestion, antibiotics or the inhibitor has the characteristic for resistance to the strains of Vibrio Parahaemolyticus. In this work, the inhibition ability of the Bacillus strains for the AHPND on the brackish water shrimp is studied. In which, the Bacreria is isolated and filtered from shrimp farm in Can Gio province that contain the characteristic of antagonizing Vibrio parahaemolyticus, which cause AHPND on shrimp in laboratory conditions. The results show that Bacillus subtilis produced 2,5 – Diketopiperazines capable to inbihite the growth of pandemic strain of Vibrio parahaemolyticus in Landy media for hightest activity was 200 AU/mL after 24 h of culture. This research is create the possibility of using probiotics to control the pantogenic clones Vibrio parahaemolyticus that cause AHPND for brackish water shrimp farming in Can Gio province as well as other areas in Vietnam.

A novel retentive type of dental implant prosthesis: marginal fitness of the cementless double crown type implant prosthesis evaluated by bacterial penetration and viability.

PURPOSEThis study aims to compare the marginal fitness of two types of implant-supported fixed dental prosthesis, i.e., cementless fixation (CL.F) system and cement-retained type.MATERIALS AND METHODSIn each group, ten specimens were assessed. Each specimen comprised implant lab analog, titanium abutment fabricated with a 2-degree tapered axial wall, and zirconia crown. The crown of the CL.F system was retained by frictional force between abutment and relined composite resin. In the cement-retained type, zinc oxide eugenol cement was used to set crown and abutment. All specimens were sterilized with ethylene oxide, immersed in Prevotella intermedia culture in a 50 mL tube, and incubated with rotation. After 48 h, the specimens were washed thoroughly before separating the crown and abutment. The bacteria that penetrated into the crown-abutment interface were collected by washing with 500 µL of sterile saline. The bacterial cell number was quantified using the agar plate count technique. The BacTiter-Glo Microbial Cell Viability Assay Kit was used to measure bacterial adenosine triphosphate (ATP)-bioluminescence, which reflects the bacterial viability. The t-test was performed, and the significance level was set at 5%.RESULTSThe number of penetrating bacterial cells assessed by colony-forming units was approximately 33% lower in the CL.F system than in the cement-retained type (P<.05). ATP-bioluminescence was approximately 41% lower in the CL.F system than in the cement-retained type (P<.05).CONCLUSIONThe CL.F system is more resistant to bacterial penetration into the abutment-crown interface than the cement-retained type, thereby indicating a precise marginal fit.

Characterization of lytic activity of Phage SAvB14 on Staphylococcus aureus variant bovis.

Objective:The objective of this study was to investigate the intensity of phage infection caused by Phage SAvB14, which was isolated from dairy farms, depending on the initial number of Staphylococcus aureus cells in the medium.Material and methods:To evaluate the impact of the viable bacteria S. aureus var. bovis on the intensity of phage infection caused by Phage SAvB14, 1 mg of phagolysate (phage titer 105 CFU/ ml) was introduced in 9 ml of nutrient broth with an appropriate amount of daily culture of S. aureus var. bovis under study. The number of viable staphylococci was determined by total viable count/ml.Results:In this experiment, we found that the intensity of phages lytic activity was dependent on the number of sensitive bacterial cells in the volume of the culture medium. Effective phage therapy requires a high concentration of phages in the medium (inflammation foci) for rapid contact of the virus with bacteria.Conclusion:When developing a phage drug to treat subclinical mastitis, it is necessary to increase the phage titer in the drug or its dosage compared to the clinical form, as there is a lower probability of phage contact with a susceptible microbial cell. Besides, at a high concentration of bacteria, there is a gradual decrease in nutrients in the medium, resulting in phages going back to the condition of lysogeny.

Establishment and application of a novel fluorescence-based analytical method for the rapid detection of viable bacteria in different samples.

A rapid method for readily detecting the total numbers of viable bacterial cells in numerous samples (including surface water, solid inoculants, and soil samples) is reported using a newly developed hand-held fluorometer and a fluorescent dye Calcein UltraGreen™ AM. Compared to the traditional plate counting method that requires 48 hours of cultivation, the newly established method does not require any incubation time, making the detection method faster and more convenient. The portable rapid detection fluorometer has a wide dynamic range of relative fluorescence intensity from 45 to 30 133. It can detect bacterial concentration ranging from 105 to 1010 cells per mL. This newly established method has good applicability for accurately and quickly detecting the cell number of viable bacteria in various samples. The results of the fluorescence-based method were compared with those of the traditional plate counting method, and it was found that the relative standard deviation was less than 6%. This new rapid measurement system provides a robust method for the rapid on-site detection of viable bacteria.

Study of soil microbial activity in different silvi-horti-agricultural system under rainfed plateau conditions of Jharkhand

An attempt was made at ICAR RCER, Research Centre, Ranchi to study the microbial population in soil in an already established 4 years old silvi-horti-agricultural system during 2018-2019. The study was laid out in split plot design with four treatments and four replications. Results revealed that the microbial population was significantly affected under different systems due to the presence of filler crops and the agricultural crops under different silvi-horti-agricultural system. The maximum number of fungal colonies and bacterial cells were observed under all silvi-horti-agricultural systems in comparison to the fallow/sole crop system. Among the different silvi-horti-agricultural system, mango + mahogany + peach system has the highest value. The highest dehydrogenase activity was recorded in mango + mahogany + peach system (11.25 micro gram TPF 24 hr-1 gm-1).

Preparation of Silver Sulfadiazine Loaded Pectin-Zinc Nanocomposites for Improvement of Antioxidant, Antibacterial and Care Cutaneous Wound Care During the Perioperative Period

Medicinal care for cutaneous wound becomes difficult due to the emergence of antibiotic resistant bacteria. The development of a new cost-effective drug based on silver sulfadiazine loaded with pectin-zinc nanocomposites offers better therapeutics in wound healing besides its role in enhancing antioxidant and antibacterial activities. In this study, silver sulfadiazine loaded with pectin-zinc nanocomposites (AgSD-PC-Zn) was produced and its antioxidant and antimicrobial properties were tested against wound infection causing bacterial pathogens (S. aureus and E. coli). The synthesized AgSD-PC-Zn composite was biophysically characterized. TEM analysis confirmed the spherical shape of NPs. AgSD-PC-Zn composite exhibited a greater antibacterial effect against S. aureus and E. coli. The number of dead bacterial cells was higher after exposure to AgSD-PC-Zn composite. Furthermore, in vitro antioxidant enzyme activities (DPPH and H2O2) were increased with AgSDPC-Zn composite. A rapid healing of the skin wounds in mouse was noticed with AgSD-PC-Zn composite treatment. This study concludes that the newly formed AgSD-PC-Zn composite will act as a strong antimicrobial and antioxidant agents for treating skin wound infection.

Изменения морфологии S. aureus в условиях их культивирования в присутствии антибактериальных препаратов

The search for new methods for identifying the pathogen in biological material, including microscopic, remains relevant. The study of ultrastructural changes of microorganisms as a result of exposure to various groups of antibiotics is important, because the morphology of the bacterial cell varies considerably depending on the conditions of cultivation. The purpose of the study: 1. To identify the nature of changes in the ultrastructure of preserved bacterial cells of S. aureus, cultivated in the presence of antibiotics. 2. To determine the viability of that part of the population of S. aureus, which remained exposed to suppressive concentrations of antibacterial drugs. 3. To determine whether the ultrastructural changes of the reference strain S. aureus ATCC 25923 in the proposed conditions completely reflect the nature of these changes for strains isolated from clinical material. Materials and methods. Three strains of S. aureus isolated from biological material and the reference strain S. aureus ATCC 25923 were used to investigate the S. aureus ultrastructure. The analysis was carried out on the basis of data obtained using scanning electron microscopy (SEM). In the process of sample preparation, the technique of imprinting bacteria from agarized nutrient medium was applied. Results and conclusions. The most common feature for the strains of clinical isolates of S. aureus was the formation of a large number of bacterial cells of a specific disc-shaped form in zones of influence of bacteriostatic antibiotics. In terms of the use of bactericidal drugs, part of the population remained spherical, the other part had irregular contours. Changes in the size of bacterial cells in growth suppression zones were multidirectional. Cultivation of bacteria under conditions of exposure to suppressive concentrations of antibacterial drugs stimulated the production of exocellular matrix. The ultrastructural changes of phenotypic variability of the reference strain S. aureus ATCC 25923 did not fully correspond to changes in the morphology of the bacterial cells of the strains of clinical isolates. The viability of bacteria remaining in the zones of growth suppression has been confirmed in all cases of antibiotic exposure, except gentamicin. Thus, the study revealed the nature of changes in the ultrastructure of S. aureus as manifestations of phenotypic variability of microorganisms in response to the presence of antibacterial drugs with different mechanisms of action.

Ecological–microbiological studies of lake Beloe in winter and spring with the use of innovation test-systems

Chlorophyll a concentration, the total abundance of bacteria, the number of bacterial cells with active metabolism, and the abundance of saprotrophic bacteria were studied in the surface and bottom water layers of Lake Beloe in winter and spring 20152016. The abundance of sanitary-indicator microorganisms was determined for the first time with the use of Petrifilm test-systems (3MTM Petrifilm). In most cases, Lake Beloe water in spring and winter was found to correspond to eutrophic level (in terms of chlorophyll a concentration in water) and polysaprobic status (in terms of microbiological indices). By its sanitary-microbiological characteristics, the lake is clearthe values of the total microbial count, determined with the use of test-systems 3M Petrifilm Aqua (AQHC), were 1000 CFU/mL, and the abundance of coliform bacteria, determined with the use of test-systems 3M Petrifilm Aqua (AQСC), varied from 20 to 135 CFU/100 mL. Coliform bacteria were mostly found in the bottom water layer. It was shown that, in the organization of ecologicalmicrobiological studies, special attention is to be paid to the bottom horizons of water bodies.

SOME PROPERTIES OF ADSORPTIVE CARBON DRESSING APPLICABLE TO QUESTIONS OF POSTOPERATIVE TREATMENT OF WOUNDS IN RATS WITH GUERIN CARCINOMA

Abstract. Aim — еvaluation of the adsorptive potential of carbon dressing, including its activity towards microbial cells of clinical strains with high antimicrobial resistance, and its effect on the course of wound process after removing a massive tumor in Guerin's rats. Materials and Methods. Microbial cell adsorption of S. aureus, A. baumannii and K. Pneumoniae cultures were studied in vitro. Woundplanimetry, photo-monitoring, and odor control on a verbal rating scale were carried out to control the state of wounds. Results: 1-hour contact of cell cultures with adsorptive carbon dressing ensured the decrease in the number of bacterial cells by 60.6-96.3%.Theuse of dressing after removing the tumor permitted to stop quickly capillary bleeding, stop/reduce traumatic edema, lower the risk of infectingthe wounds under recurrence of carcinoma growth and increase the average lifespan of animals by 1.5 times. Conclusion: adsorptive carbon dressing with high adsorption potential can be considered asa promising application means for the prevention and treatment of wound infection.

Fabrication of Mixed-Charge Polypeptide Coating for Enhanced Hemocompatibility and Anti-Infective Effect.

Medical catheters are prone to fouling by protein adsorption and platelet adhesion/activation due to their hydrophobic surface, resulting in bacterial adhesion/biofilm formation, associated infection, and thrombosis. Hence, an ultralow-fouling and exceptional infection-resistant coating on devices is urgently needed. Herein, we synthesized mussel-inspired cationic polypeptide (cPep) and mixed-charge polypeptide (mPep) via an N-carboxyanhydride ring opening polymerization method. In the view of the chemical structure, in addition to the catechol group of levodopa, the cationic group of l-lysine (K), and the hydrophobic group of l-phenylalanine (F), the mPep, comparing with cPep, contains the anionic group of l-glutamic acid (E) since the negatively charge amino acid sequence is newly introduced, so as to guarantee its bactericidal ability, low toxicity, and surface self-deposition. Both cPep and mPep coatings are conveniently obtained by a dopamine-assisted codeposition technique. Compared with the cPep coating, the mPep coating has a similar antibacterial activity level (>99%) against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Meanwhile, it is demonstrated that the mPep coating has most effective antibiofilm activity (>3 days) and protein/platelet-resistant ability in vitro, as well as improving hemocompatibility. Furthermore, the mPep-coated silicone catheter induces no inflammatory response and significantly lowers the bacterial cell number with 6 log reduction in a mouse model of infection. Consequently, the rationally designed mPep with a simple coating technique has great potential in combating against medical catheter-related clinical infections.

Isolation of bacteria at different points of Pleurotus ostreatus cultivation and their influence in mycelial growth

Pleurotus ostreatus is one of the most cultivated edible mushrooms worldwide and few approaches have been done to analyze bacterial influence during its cultivation. Therefore, bacteria from commercial spawn, mycelial-colonized straw and fruiting bodies from healthy productive samples were counted, isolated and tested for their mycelial growth promoting ability. Bacterial cell numbers at different steps of the process showed low bacterial cell numbers in spawn and in fruiting bodies inner tissue compared to the high concentration in mycelial-colonized straw. The majority of the 38 isolates belonged to phyla Firmicutes and Actinobacteria were identified as Bacillus, Paenibacillus and Micromonospora species. Similarly, 16S rRNA gene bacterial clones obtained from mycelial biomass DNA samples showed bacterial presence of various genera including Bacillus and Paenibacillus.In the mycelial growth promoting ability tests, 30 isolates negatively affected mycelial growth, two isolates showed no effect on mycelial growth, and six isolates promoted mycelial growth. Moreover, mycelial thickness was influenced in different ways by the bacterial growth. In general, nearly all isolates growth-preventing were isolated from healthy spawn and mycelial-colonized straw, whereas fruiting bodies were the best source for isolation of mycelial growth-promoting bacteria. Characterization of bacterial isolates revealed that growth-preventing isolates exhibited various enzymatic activities in comparison with positive influencing bacteria that exhibited none or weak enzymatic activities. In addition, the influence of volatile compounds being present in the headspace of bi-plate co-cultures on P. ostreatus mycelial growth was demonstrated.The effect of isolates, that promoted mycelial growth in co-cultivation, to reduce P. ostreatus spawn running time, was evaluated on sterilized rye seeds. Results showed that not all mycelial promoted isolates were able to significantly promote P. ostreatus colonization. However, isolate M46F identified as Micromonospora lupini significantly reduce spawn running time. This is one of few studies to estimate cultivable bacteria from healthy samples of P. ostreatus cultivation, to evaluate a bacterial effect on mycelial growth, to show that fruiting bodies are a good source for mycelia growth-promoting isolates, and the first to report a shorter P. ostreatus spawn running time due to bacterial inoculation.

Antimicrobial activity of Titanium dioxide and Zinc oxide nanoparticles supported in 4A zeolite and evaluation the morphological characteristic

In this study, the antimicrobial activity of titanium dioxide (TiO2), zinc oxide (ZnO), and TiO2/ZnO nanoparticles supported into 4A zeolite (4A z) was assessed. Based on antimicrobial experiments, minimum inhibitory concentration (MIC90), minimum bactericidal concentration (MBC), fractional inhibitory concentration (FIC) and disc diffusion test were determined after 24 h of contact with the prepared nanocomposites. These results are in agreements with the results of disc diffusion test. During the experiments, the numbers of viable bacterial cells of Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes and Escherichia coli O157:H7 decreased significantly. The crystallinity and morphology of nanoparticles were investigated by X-ray diffraction patterns (XRD), elemental mapping at the microstructural level by scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM). As a result, it was demonstrated that TiO2/ZnO nanoparticles supported in 4A zeolite could lead to an optimum activity as antimicrobial agents.

Characterization of the Cultivable Microbiota in Fresh and Stored Mature Human Breast Milk.

Besides nutritional components, breast milk contains diverse microbes, which may be involved in colonization of the infant gut. Expressed milk is often stored for few days in the refrigerator. The aim of this study was to determine the abundance, prevalence and diversity of facultative and strict anaerobic bacteria using culture-dependent and -independent methods, and to determine changes in milk microbial and chemical composition during storage. Samples of mature breast milk from 21 women were collected 3–6 months post-partum and were analyzed fresh or after anaerobic storage for 6 days at 4°C. The cultivable bacterial population was analyzed using the most probable number (MPN) method or plate counts and different media. The abundance of major bacterial groups was determined using quantitative PCR and 16S rRNA gene sequencing. Lactose, lactate, short chain fatty acids (SCFA) and human milk oligosaccharides (HMO) were analyzed using chromatography techniques. Highest mean viable cell counts were obtained in yeast casitone fatty acids (YCFA) broth supplied with mucin (log 4.2 ± 1.8 cells/ml) and lactose (log 3.9 ± 1.4 cells/ml), or Columbia broth (log 3.0 ± 0.7 cells/ml). Mean total bacterial counts estimated by qPCR was 5.3 ± 0.6 log cells/ml, with Firmicutes being the most abundant phylum. The most prevalent bacterial groups were Streptococcus spp. (15/19 samples), Enterobacteriaceae (13/19) and Lactobacillus/Lactococcus/Pediococcus group (12/19). While the average total number of bacterial cells did not change significantly during storage, the prevalence of strict anaerobic Bacteroidetes increased threefold, from 3/19 to 9/19, while in 7 samples Clostridium clusters IV or XIVa became detectable after storage. Major HMO were not degraded. Lactate was present in 18/21 samples after storage (2.3–18.0 mM). Butyrate was detected in 15/21 and 18/21 samples before and after storage, respectively, at concentrations ranging from 2.5 to 5.7 mM. We demonstrate enhanced prevalence and/or abundance of viable strict anaerobes from the Bacteroidetes and Clostridiales after 6-day anaerobic storage of human milk. Our data indicate that anaerobic cold storage did not markedly change total viable bacterial load, while HMO profiles were stable. Anaerobic cold storage of human milk for up to 6 days may be suitable for preserving milk quality for potential microbial transfer to the infant gut.

Ecological–Microbiological Studies of Lake Beloe in Winter and Spring with the Use of Innovation Test-Systems

Chlorophyll a concentration, the total abundance of bacteria, the number of bacterial cells with active metabolism, and the abundance of saprotrophic bacteria were studied in the surface and bottom water layers of Lake Beloe in winter and spring 2015–2016. The abundance of sanitary-indicator microorganisms was determined for the first time with the use of Petrifilm test-systems (3MTM Petrifilm™). In most cases, Lake Beloe water in spring and winter was found to correspond to eutrophic level (in terms of chlorophyll a concentration in water) and polysaprobic status (in terms of microbiological indices). By its sanitary-microbiological characteristics, the lake is clear—the values of the total microbial count, determined with the use of test-systems 3M™ Petrifilm™ Aqua (AQHC), were <1000 CFU/mL, and the abundance of coliform bacteria, determined with the use of test-systems 3M™ Petrifilm™ Aqua (AQСC), varied from 20 to 135 CFU/100 mL. Coliform bacteria were mostly found in the bottom water layer. It was shown that, in the organization of ecological–microbiological studies, special attention is to be paid to the bottom horizons of water bodies.

A Novel Approach of Curcumin Loaded Chitosan/Dextran Nanocomposite for the Management of Complicated Abdominal Wound Dehiscence

In recent times, about 35% of patients suffered from post laparotomy wound dehiscence and the effective management of wound is highly inevitable. Natural polymers such as chitosan and dextran have excellent biodegradability and biocompatibility. These features make them an ideal candidate for biomedical applications. The present study is aimed to synthesize curcumin loaded chitosan/dextran nanocomposite and to evaluate its antibacterial and abdominal wound healing properties. The curcumin loaded chitosan/dextran nanocomposite was characterized by UV–vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Zeta potential. FTIR results inferred the strong interaction between the three components. The surface morphology of curcumin loaded chitosan/dextran nanocomposite was spherical shaped which are firmly anchored on the polymer matrix. TEM analysis also confirmed the formation of the composite. The XRD analysis confirmed the presence of crystalline material. The curcumin loaded chitosan/dextran nanocomposite recorded greater antibacterial effects on S. mutans and E. coli. The number of dead bacterial cells was significantly higher in curcumin loaded chitosan/dextran nanocomposite. Moreover, curcumin loaded chitosan/dextran nanocomposite stimulated the regeneration of new tissues and promoted the wound healing efficiency in the mouse. Therefore, the developed materials have a potential role as antimicrobial and abdominal wound healing in biomedical fields.

Improving Proteome Coverage for Small Sample Amounts: An Advanced Method for Proteomics Approaches with Low Bacterial Cell Numbers

Proteome analyses are often hampered by the low amount of available starting material like a low bacterial cell number obtained from in vivo settings. Here, the single pot solid-phase enhanced sample preparation (SP3) protocol is adapted and combined with effective cell disruption using detergents for the proteome analysis of bacteria available in limited numbers only. Using this optimized protocol, identification of peptides and proteins for different Gram-positive and Gram-negative species can be dramatically increased and, reliable quantification can also be ensured. This adapted method is compared to already established strain-specific sample processing protocols for Staphylococcus aureus, Streptococcus suis, and Legionella pneumophila. The highest species-specific increase in identifications is observed using the adapted method with L. pneumophila samples by increasing protein and peptide identifications up to 300% and 620%, respectively. This increase is accompanied by an improvement in reproducibility of protein quantification and data completeness between replicates. Thus, this protocol is of interest for performing comprehensive proteomics analyses of low bacterial cell numbers from different settings ranging from infection assays to environmental samples.

Enhanced and Balanced Microalgal Wastewater Treatment (COD, N, and P) by Interval Inoculation of Activated Sludge.

Although chemical oxygen demand (COD) is an important issue for wastewater treatment, COD reduction with microalgae has been less studied compared to nitrogen or phosphorus removal. COD removal is not efficient in conventional wastewater treatment using microalgae, because the algae release organic compounds, thereby finally increasing the COD level. This study focused on enhancing COD removal and meeting the effluent standard for discharge by optimizing sludge inoculation timing, which was an important factor in forming a desirable algae/bacteria consortium for more efficient COD removal and higher biomass productivity. Activated sludge has been added to reduce COD in many studies, but its inoculation was done at the start of cultivation. However, when the sludge was added after 3 days of cultivation, at which point the COD concentration started to increase again, the algal growth and biomass productivity were higher than those of the initial sludge inoculation and control (without sludge). Algal and bacterial cell numbers measured by qPCR were also higher with sludge inoculation at 3 days later. In a semi-continuous cultivation system, a hydraulic retention time of 5 days with sludge inoculation resulted in the highest biomass productivity and N/P removal. This study achieved a further improved COD removal than the conventional microalgal wastewater treatment, by introducing bacteria in activated sludge at optimized timing.

Methods for the diagnosis of bacterial fish diseases

The diagnosis of bacterial fish diseases has progressed from traditional culture-dependent methods involving the recovery of pathogens on agar-containing media and identification by examination of phenotypic traits. Newer approaches centre on culture-independent approaches. A problem with culturing is that it lacks sensitivity, tends to be slow, and its success depends on the composition of the media and incubation conditions employed. In contrast, culture-independent methods, now centring on molecular methods, are highly specific and sensitive. This raises an important issue that detection of very low numbers of bacterial cells does not necessarily imply the presence of clinical disease. Positivity could reflect background populations of the pathogen that may be present in the aquatic environment.

Shift of biofilm and suspended bacterial communities with changes in anode potential in a microbial electrolysis cell treating primary sludge

This study, for the first time, documented microbial community shifts in response to the changes in anode potential in a microbial electrolysis cell (MEC) operated with primary sludge. At an anode potential of −0.4 V vs. Ag/AgCl, the MEC showed COD and VSS removal efficiencies of 73 ± 1% and 75 ± 2%, respectively. The volumetric current density and specific hydrogen production rate were 23 ± 1.2 A/m3, and 145 ± 4.1 L/m3-d, respectively. The anodic microbial community was consisted of various fermentative/hydrolytic bacteria (e.g., Bacteroides and Dysgonomonas) and anode-respiring bacteria (Geobacter), while different hydrolytic/fermentative bacteria were abundant in suspension. The MEC showed substantially inferior performance along with a higher accumulation of various volatile fatty acids when the anode potential was switched to more positive values (0 V and +0.4 V). Both biofilms and suspended communities were also shifted when the anode potential was changed. Notably, at +0.4 V, Geobacter genus entirely disappeared from the biofilms, while Paludibacter species (known fermentative bacteria) were selectively enriched in biofilms. Also, the relative abundance of genus Bacteroides (known hydrolytic bacteria) substantially decreased in both biofilms and suspension, which was correlated with the inferior hydrolysis of VSS. Quantitative comparison of biofilms and suspended microbial communities at different anode potentials revealed a sharp decrease in bacterial cell numbers in anode biofilms after changing anode potential from −0.4 V to +0.4 V. By contrast, bacterial cell numbers in suspension were slightly decreased. Collectively, these results provide new insights into the role of anode potential in shaping key microbial players associated with hydrolysis/fermentation and anodic respiration processes when MECs are operated with real biowastes.

Komunitas Bakteri pada Saluran Pencernaan Lobster Mutiara (Panulirus ornatus)

The presence of microbial communities in the digestive tract affects the physiological functions of digestion. The purpose of this study is to determine the bacterial community in the digestive tract of lobsters, especially pearl lobsters. This research is descriptive explorative. Samples were taken from the lobster digestive tract which was divided into 3, namely the cardiac, pylorus and intestinal sections and each part was counted for the total bacteria using the TPC (Total Plate Count) method. Then isolated from the Sea Water Complex media and partially characterized. The results showed that the total number of bacterial cells in cardiac, piloric and intestinal cells were 41.91 x 108 cfu.ml-1, 18.26 x 108 cfu.ml-1 and 14.10 x 108 cfu.ml-1 respectively. The number of bacterial isolates obtained from the lobster pearl digestive tract were 51 isolates with details of 18 cardiac isolates, 16 isolates in piloric, and 17 isolates in the intestine. Phenotypic isolates obtained from lobster digestive tract bacteria consisted of monococcus 37.25%, diplococcus 27.45%, streptococcus 29.41%, staphylococcus 1.96%, and long baccil 3.92%, while gram positive 62.65 % and gram negative at 37.25%