Populations Of Heterotrophic Bacteria Research Articles

Antibiotics Sensitivity Reaction of salmonella Species Isolated from Ready-to-Eat Porridge Beans Sold in Federal Polytechnic of Oil and Gas Bonny of Rivers State

Salmonella specie is one of the four key global causes of diarrhoeal diseases. In this research we investigated the frequency occurrence of salmonella species isolated from ready-to-eat porridge beans sold from vendors in the proximity of federal polytechnic of oil and gas bonny island. A total of 40 samples were purchased from four different food vendors in four different spots [vendor 1(The first spot), vendor 11(second spot), vendor 111(third spot) and vendor 1V (fourth spot)] between February and May 2024.All samples were processed and analysed using standard culturebased, biochemical methods and antibiotic susceptibility test assays to confirm salmonella isolates. The highest total occurrence of heterotrophic bacteria population densities were: vendor1 4.0.0×105CFU/g; vendor11 4.4×107CFU/g, vendor111 4.5×102CFU/g and vendor 1V 4.2×109CFU/g. The highest total occurrence of salmonella population density were, for vendor1 3.9×102, Vendor11 2.7×104 , Vendor111 4.1×105,Vendor1V 4.4×103 respectively. Antibiotics susceptibility test was performed for the isolates which exhibited that all of them were susceptible to Ciprofloxacin (CPR)-5 g, Nitrofurantoin (NIT)-30 g, Oflotaxin (OFL)-5 g, were susceptible to Salmonella species. While Gentamicin (GEN)-10 g, and Cefuroxime (CXM)-5 g, were intermediate and Finally, Augmentin (AUG)-30 g, Cefuroxime (CAZ)-30 g, and Cefuroxime (CRX)-30 g were resistant to Salmonella species. Therefore, it can be stated that ready-to-eat porridge beans sold in the proximity of FPOG environment are possible route of transmission for Salmonella species. However, due to lack of intense antibiotic resistance among these bacteria, most of them can be treated with the antibiotics available in the market. Nonetheless, strict monitoring and regular surveillance is necessary.

Simultaneous nitrification and denitrification pattern in aerated moving-bed sequencing batch reactor: Choosing appropriate SRT for different COD/N ratios

ABSTRACT The effect of chemical oxygen demand (COD)/N ratio and sludge retention time (SRT) on the simultaneous nitrification and denitrification (SND) process in an aerated moving-bed sequencing batch reactor (A-MBSBR), for treating synthetic municipal wastewater, was studied. Three lab-scale reactors with SRTs of 5, 10, and 15 days were operated under COD/N ratios of 10 (phase 1) and 20 (phase 2). The high correlation coefficients between nitrification and denitrification efficiencies in both phases demonstrated that the denitrification efficiency in A-MBSBRs was strongly affected by nitrification efficiency (nitrate concentration). A high COD/N ratio of 20 in phase 2 provided suitable conditions for the increase and dominance of the population of heterotrophic bacteria over autotrophic nitrifiers, which led to weak nitrification (29.6–39.1%) and consequently weak denitrification (15.8–27.9%) in all reactors. In phase 2, increasing SRT from 5 to 15 days was beneficial for both nitrification and denitrification reactions. Therefore, the optimal SND efficiency in phase 2 was expected to be achieved under SRTs higher than 15 days. Under the COD/N ratio of 10 in phase 1, a better balance between the population of heterotrophs and autotrophs resulted in higher nitrification and denitrification efficiencies (44.4–62.7% and 26.3–42.8%, respectively). In phase 1, the highest and the lowest nitrification and denitrification efficiencies were obtained at SRTs of 10 and 5 days, respectively.

Phytoremediation of pollutants in oil-contaminated soils by Alhagi camelorum: evaluation and modeling

Phytoremediation is a cost-effective and environmentally friendly method, offering a suitable alternative to chemical and physical approaches for the removal of pollutants from soil. This research explored the phytoremediation potential of Alhagi camelorum, a plant species, for total petroleum hydrocarbons (TPHs) and heavy metals (HMs), specifically lead (Pb), chromium (Cr), nickel (Ni), and cadmium (Cd), in oil-contaminated soil. A field-scale study spanning six months was conducted, involving the cultivation of A. camelorum seeds in a nursery and subsequent transplantation of seedlings onto prepared soil plots. Control plots, devoid of any plants, were also incorporated for comparison. Soil samples were analyzed throughout the study period using inductively coupled plasma-optical emission spectroscopy (ICP‒OES) for HMs and gas chromatography‒mass spectrometry (GC‒MS) for TPHs. The results showed that after six months, the average removal percentage was 53.6 ± 2.8% for TPHs and varying percentages observed for the HMs (Pb: 50 ± 2.1%, Cr: 47.6 ± 2.5%, Ni: 48.1 ± 1.6%, and Cd: 45.4 ± 3.5%). The upward trajectory in the population of heterotrophic bacteria and the level of microbial respiration, in contrast to the control plots, suggests that the presence of the plant plays a significant role in promoting soil microbial growth (P < 0.05). Moreover, kinetic rate models were examined to assess the rate of pollutant removal. The coefficient of determination consistently aligned with the first-order kinetic rate model for all the mentioned pollutants (R2 > 0.8). These results collectively suggest that phytoremediation employing A. camelorum can effectively reduce pollutants in oil-contaminated soils.

Determination of Starter Cultures (Organisms) in Fermentation of Cassava (Manihot esculenta), Used for Fufu Production

Fufu is a traditional Nigerian fermented cassava food product. Due to the production of objectionable odor, fermentation was done in the Laboratory using improved techniques. Sweet white, Yellow, bitter cassava varieties were used. Since a wet fufu mash is a product of the activities of various microorganisms, this study was aimed at determining the contents of the cassava mash for several days. The microbial, chemical and sensory changes during the fermentation were determined. Microbial counts were higher as retting progressed, but reduced at completion. Heterotrophic bacterial counts decreased from 2.65-2.46Log10CFU/mL, for sweet variety, but increased from 1.95-2.27 Log10CFU/mL for bitter variety; 2.28-2.59 Log10CFU/mL for yellow variety on Nutrient agar. Coliform counts decreased from 2.56 to 2.28Log10CFU/mL for sweet variety, but increased from 2.32 - 2.55Log10 CFU/mL for bitter variety, from 2.30 - 2.49Log10 CFU/ mL, for yellow variety on MacConkey agar and from 1.91 - 2.41Log10CFU/mL, for sweet variety, from day 2; 1.91- 2.23 Log10CFU/Ml, for bitter variety, from day 3), and 2.10 – 2.32 Log10CFU/mL (for yellow variety from day 3) for Fungi on SDA. The dominant Starter organisms were a mixed population of heterotrophic bacteria, Bacillus spp, yeasts and mould. Protein content of the sweet variety increased from 0.3- 5.25% and the yellow variety from 0.2- 4.375%, their cyanide contents reduced from 2.7- 0.01 mg/kg and from 4.3 - 0.04 mg/kg respectively, showing loss of hydrogen cyanide. Cyanide content of bitter variety remained 10.6mg/kg at the end of fermentation, since there was neither retting nor loss of hydrogen cyanide. The pH of the product reduced as the fermentation progressed. Sensory evaluation of the fermented samples accepted all the samples, but liked most, the sweet white variety. The bitter variety was not assessed because it did not ferment even on day 5. These organisms can be used as starter cultures to improve the protein content of fufu, and reduce the cyanide content to minimal level which makes it safer for consumption.

Soil chemical properties and heterotrophic bacterial population in the rhizosphere of oil palm plantations under different ages

This study was carried out to determine the soil chemical properties and heterotrophic bacterial population and species that are predominant in the rhizosphere of oil palms (Elaeis guineensis. jack) and to compare the bacteria population in the rhizosphere of matured (10 years and above) fruit bearing palms with those present in young (3 – 6 years) palms that are just bearing fruits for the first few years. Four plantations of different ages were sampled at the Nigerian Institute for Oil Palm Research (NIFOR) main station located in Ovia North Local Government Area of Edo State at soil depth of; 0 – 15 cm, 15 – 30 cm, 30 – 45 cm and 45 – 60 cm. The soil samples obtained were analyzed for their physical, chemical and microbial compositions and the bacteria counts found in the various oil palm plantations were tested for significant differences (p ≤ 0.05) using Duncan multiple range test in a Completely Randomized Design. The soil texture of Field 52 (3 – 6 years) was sandy in both top and sub soil (0 – 60 cm) while the older plantations had sandy-loam and loamy-sand at some depth. The nitrogen, phosphorus and organic carbon content of the soil were also observed to increase with age. The investigation further showed a high presence of bacteria at the top soil (0 – 15 cm and 15 – 30 cm) than in the sub soils (30 – 45 cm and 45 – 60 cm). This was in close relationship with the high presence of carbon and other primary nutrients that were also more at the top soils. On the basis of plant age, the heterotrophic bacteria populations were greater in the older plantations than found in the young (3 - 6 years) plantations. The specific bacteria isolated from the rhizosphere soils were Pseudomonas aeroginosa, Micrococcus cereus, Staphylococcus aureus, and Coryrubacteria spp.

Evaluation of biofloc generation protocols to adopt high density nursery rearing of Penaeus vannamei for better growth performances, protective responses and immuno modulation in biofloc based technology

Biofloc (BFT) based nursery rearing system help provides an additional food source, healthy juvenile production with better survival and an avenue for nitrogen removal through eco-friendly approach. It should be cost and energy efficient with a quick turn over. However, many questions remain unanswered regarding mechanisms of action and induced antibacterial/antiviral immune responses in penaeid shrimp especially during nursery phase. The present experiment was designed to evaluate the effects of biofloc treatments generated and maintained through three approaches on growth performances, physico-chemical parameters, microbial dynamics, feed utilization and immunological assessments in P. vannamei nursery rearing. The experiment was conducted in 500 L FRP tanks stocked with PL-III stage of Pacific white shrimp for 30 days at a stocking density of 6000 nos/m3. The heterotrophic bacteria level of 1 × 107 CFU/ml was maintained through three approaches differing in their generation; 1) biofloc lyophilized powder (BFP), 2) biofloc matured water (BFW) and 3) biofloc consortium (BFC) and compared with that of the conventional nursery rearing without biofloc treatment (Control). BFT treatments showed significantly higher growth as observed in average body weight (ABW) (BFP - 0.357 g, BFW - 0.363 g & BFC - 0.391 g) compared to control (0.188 g). BFT groups showed significantly (P < 0.01) higher survival (BFP (81.47%), BFW (79.73%), and BFC (85.4%)), than control groups. The population of heterotrophic bacteria was significantly (P < 0.05) increased in treatments when compared to control. But higher Vibrio load was recorded in the control than BFT water samples. BFT based nursery rearing system improves the water quality parameters when compared to the control. The cumulative mortality rate of biofloc reared juveniles was significantly lowered when challenged with Vibrio whereas, in control, it was higher. Further, certain immune genes like the prophenoloxidase, crustin, MAS, serine protease, alpha-2-M, antiviral genes, and RAN were up-regulated in the BFT groups. All these findings indicate that BFT nursery rearing system gives optimal and better culture condition displaying better survival, growth, disease tolerance, immune activity during the nursery phase and can be managed with minimal water exchange and maximum biosecurity.

DIVERSIDAD BACTERIANA EN AGUAS MINEROMEDICINALES DEL BALNEARIO “URAUCO”. PICHINCHA. ECUADOR

The presence of mineromedicinal water springs in Ecuador is related to the large number of volcanoes that exist in the country, which have been used since ancient times as medicines by the population. However, it is unknown what bacterial biodiversity is present. Therefore, the objective of these work was to determine the bacterial biodi- versity of the mineromedicinal waters of “Urauco” spa located in Pichincha Provinces of Ecuador. Water samples of a volume of 1 liter were taken at two points in each spa studied. Sampling was done 2 times over a period of two year. To take and transport the samples, the Ecuadorian standards INEN 2 176-98 and INEN 2 169-98 were followed. For the determination of bacterial biodiversity, the techniques of planting, selection and identification of bacteria indicated by Barrow and Feltan (2004) and MacFfadin (2004) were used, complemented with the bio- chemical tests contained in the API (BioMérieux) galleries and Microgen (Microgen corp.). The results indicate a population of heterotrophic bacteria in the spa waters of 3.1 x 102 CFU / mL, with the prevalence of Gram negative bacteria of the Gamma Proteobacteria class. It was possible to isolate and identify 64 colonies of bacteria. The genera of bacteria were Acidovorax, Aeromonas, Bacillus, Brevundimonas, Budvicia, Citrobacter, Corynebacterium, Edwardsiella, Enterococcus, Ewingella, Flavobacterium, Kurthia, Micrococcus, Proteus, Pseudomonas, Psychrobacter, Ralstonia, Staphylococcus, Vibrio and Yokonella. The bacterial biodiversity observed was high, although low in number .

Long-term microbial community dynamics at two full-scale biotrickling filters treating pig house exhaust air.

SummaryIn this study, the microbial community structure of two full‐scale biotrickling filters treating exhaust air from a pig housing facility were evaluated using 16S metabarcoding. The effect of inoculation with activated sludge of a nearby domestic waste water treatment plant was investigated, which is a cheap procedure and easy to apply in practice. The study was performed at a three‐stage and a two‐stage full‐scale biotrickling filter; of which, only the latter was inoculated. Both biotrickling filters evolved towards a rather similar community over time, which differed from the one in the activated sludge used for inoculation. However, the bacterial population at both biotrickling filters showed small differences on the family level. A large population of heterotrophic bacteria, including denitrifying bacteria, was present in both biotrickling filters. In the non‐inoculated biotrickling filter, nitrite‐oxidizing bacteria (NOB) could not be detected, which corresponded with the incomplete nitrification leading to high nitrite accumulation observed in this system. Inoculation with the wide spectrum inoculum activated sludge had in this study a positive effect on the biotrickling filter performance (higher ammonia removal and lower nitrous oxide production). It could thus be beneficial to inoculate biotrickling filters in order to enrich NOB at the start‐up, making it easier to keep the free nitrous acid concentration low enough to not be inhibited by it.

GROWTH OF HETEROTROPHIC BACTERIA IN SEA WATER POLLUTED BY SURF DETERGENT

The research was conducted from February 2016 to April 2017, aimed to determine the effect of adding different concentrations of detergent namely SURF on the growth of bacterial populations in the seawater column. This research used experimental method with Completely Randomized Design. Seawater samples were analyzed at Marine Microbiology Laboratory, Fisheries and Marine Faculty of Riau University. Based on the results of the study, from day 0 untill day 10 after given detergent with different concentrations, bacteria experienced a decreasing trend of growth, in day 15 untill day 20, the trend of bacterial growth contaminated by detergent with different concentration relatively increased to stagnant. Based on the result of this study the addition of different detergent concentration in each treatment affect the growth of heterotrophic bacteria population in the sea water, where the higher concentration of detergent added the lower the ability of bacteria to grow and the ability of heterotrophic bacteria to survive at different concentrations of detergent, it can be concluded that the ability of heterotrophic bacteria to grow from days 0 to 20 has decreased in each of its concentrations.

Effects of alpha cypermethrin and imidacloprid on soil bacteria in pot experiments of rice (Oryza sativa var. G 98–135) using soil collected from rice fields (Mahaica, Guyana)

This project endeavored to determine the effect of pesticides commonly used in rice cultivation in Guyana, on populations of heterotrophic soil bacteria as well as their effects on Azotobacter, Nitrosomonas and Nitrobacter. This experiment used Fastac, with an active ingredient of Alpha-Cypermethrin and Pronto, with an active ingredient of Imidacloprid, at recommended rates. Alpha-Cypermethrin was applied at a rate of 100 ml per acre (5 g a.i. acre−1) while Imidacloprid was applied at a rate of 15 g per acre (10.5 g a.i. acre−1). The effects of these pesticides were examined using a potted experiment in which soil was placed and then treated using a treatment regimen utilized by local rice farmers. The effect on populations of heterotrophic soil bacteria was determined by culturing on agar plates followed by enumeration of colonies grown. Azotobacter was grown using Ashby's medium while Nitrosomonas was cultured using a modified Winogradsky medium while Nitrobacter was grown using a similar, specialized medium. The results show that, at recommended concentrations, Alpha-Cypermethrin and Imidacloprid had no significant effects on the populations of heterotrophic bacteria. Similarly, the pesticides applied showed no significant effects on the populations Azotobacter and Nitrobacter. However, the results showed that the application of these pesticides resulted in increases in the population of Nitrosomonas indicating interactive behavior of soil microbes with minimum use of chemical pesticides. The research work highlights the integrated approach to cultivation of rice for sustainable crop productivity.

Persulfate treatments of phenanthrene-contaminated soil: Effect of the application parameters

The aim of this work was to study the effects of the parameters involved in persulfate (PS) application, namely, the cation counterion, mode of persulfate addition and soil-moisture content, to optimize the use of low doses of PS coupled with bioremediation technologies. Soil microcosms were contaminated with 110±20mg of phenanthrene per kilogram of dry soil. The efficiency of each treatment in phenanthrene elimination was evaluated. Additionally, the impact on cultivable autochthonous heterotrophic bacteria populations was examined.The addition of sodium persulfate in successive doses (14.9g/kgDS) showed the greatest efficiency in phenanthrene elimination (36%) after 7days of treatment, but inhibited further bioremediation. Sodium persulfate was more efficient than ammonium. Increased moisture enhanced the bioremediation but inhibited the oxidative treatment. The persulfate-ion decomposition rate decreased at high moisture levels, possibly through diluting activators within the soil.The results suggest that, for oxidative treatments of contaminated soil, the application of low doses of sodium PS at low soil-moisture levels is the most effective option for an elimination of phenanthrene that is compatible with bioremediation.

Isolation and characterization of antibiotic susceptibility profile of &lt;i&gt;Salmonella&lt;/i&gt; species isolated from abattoir environment

In this study we investigated the antibiogramic profile of Salmonella species isolated from abattoir environment. A total of 72 samples were collected from three different stations [station A (the drainage), station B (stagnant water in potholes and floors around the abattoir) and station C (water used for washing the meat slaughtered at the abattoir)] between January and June 2017. All samples were processed and analysed using standard culturebased and polymerase chain reaction (PCR) methods. The mean total heterotrophic bacteria population densities were: station A 2.0×1010 ± 0.02 CFU/ml; station B 1.6×1010 ± 0.10 CFU/ml and station C 3.9×109 ± 0.05 CFU/ml. The mean total salmonellae population density were 2.4×105 ± 0.14 CFU/ml,1.3×105 ± 0.15 CFU/ml, and 1.0×104 ± 0.06 CFU/ml for station A, station B and station C respectively. A total of 50 confirmed salmonellae, using PCR identification system, were subjected to antimicrobial profiling using the disc diffusion method. The resistance profile of the isolates revealed that 24 (48%) of the isolates were resistant to piperacillin, 50 (100%) to gentamycin, 50 (100%) were resistant to tetracycline, while 22 (44%) of the isolates were resistant to aztreonam. Multidrug resistance (MDR) profile of the isolates revealed that 22 (44%) of the isolates were resistant to piperacillin, gentamycin, tetracycline, and aztreonam belonging to four antimicrobial class. Our findings revealed that abattoir environments could be a potential reservoir of multi-antibiotic resistant Salmonella species.Keywords: Abattoir, Salmonellae, Antibiogramic Profile, Multi-Drug Resistance, Effluent

Mixotrophy in the marine red-tide cryptophyte Teleaulax amphioxeia and ingestion and grazing impact of cryptophytes on natural populations of bacteria in Korean coastal waters

Cryptophytes are ubiquitous and one of the major phototrophic components in marine plankton communities. They often cause red tides in the waters of many countries. Understanding the bloom dynamics of cryptophytes is, therefore, of great importance. A critical step in this understanding is unveiling their trophic modes. Prior to this study, several freshwater cryptophyte species and marine Cryptomonas sp. and Geminifera cryophila were revealed to be mixotrophic. The trophic mode of the common marine cryptophyte species, Teleaulax amphioxeia has not been investigated yet. Thus, to explore the mixotrophic ability of T. amphioxeia by assessing the types of prey species that this species is able to feed on, the protoplasms of T. amphioxeia cells were carefully examined under an epifluorescence microscope and a transmission electron microscope after adding each of the diverse prey species. Furthermore, T. amphioxeia ingestion rates heterotrophic bacteria and the cyanobacterium Synechococcus sp. were measured as a function of prey concentration. Moreover, the feeding of natural populations of cryptophytes on natural populations of heterotrophic bacteria was assessed in Masan Bay in April 2006. This study reported for the first time, to our knowledge, that T. amphioxeia is a mixotrophic species. Among the prey organisms offered, T. amphioxeia fed only on heterotrophic bacteria and Synechococcus sp. The ingestion rates of T. amphioxeia on heterotrophic bacteria or Synechococcus sp. rapidly increased with increasing prey concentrations up to 8.6×106 cells ml−1, but slowly at higher prey concentrations. The maximum ingestion rates of T. amphioxeia on heterotrophic bacteria and Synechococcus sp. reached 0.7 and 0.3 cells predator−1 h−1, respectively. During the field experiments, the ingestion rates and grazing coefficients of cryptophytes on natural populations of heterotrophic bacteria were 0.3–8.3 cells predator−1h−1 and 0.012–0.033d−1, respectively. Marine cryptophytes, including T. amphioxeia, are known to be favorite prey species for many mixotrophic and heterotrophic dinoflagellates and ciliates. Cryptophytes, therefore, likely play important roles in marine food webs and may exert a considerable potential grazing impact on the populations of marine bacteria.

Biogenic oxidation of the high-viscosity oil of the Ashal’chinskoe field and its hetero compounds

Biodegradation of high-viscosity oil of the Ashal’chinskoe field by indigenous microflora of soil on the basis of fen peat and humus with a high concentration of nutrients and microorganisms has been studied under laboratory conditions on model soil systems. It has been shown that after the adaptation period of ten days, the total population of heterotrophic bacteria increases by two orders of magnitude and the activity of soil enzymes increases by a factor of 2–3.5. Oil utilization was 84% over 180 days of the experiment. During this period of time, all petroleum hydrocarbons: alkanes, naphthenes, and arenes, are oxidized by 68–99%; the total biodegradation of resins and asphaltenes making 85.6 and 55.2%, respectively; i.e., the resins are oxidized easier that the asphaltenes. It has been found that the biotransformation of the high-molecular-weight hetero compounds resins and asphaltenes results in partial degradation of saturated structures and accumulation of oxygen in the composition of average molecules, with the average size of the block decreasing and naphthene structures partially degrading.

Characterization of an autotrophic bioreactor microbial consortium degrading thiocyanate.

Thiocyanate (SCN-) forms as a by-product of cyanidation during gold ore processing and can be degraded by a variety of microorganisms utilizing it as an energy, nitrogen, sulphur and/or carbon source. In complex consortia inhabiting bioreactor systems, a range of metabolisms are sustained by SCN- degradation; however, despite the addition or presence of labile carbon sources in most bioreactor designs to date, autotrophic bacteria have been found to dominate key metabolic functions. In this study, we cultured an autotrophic SCN--degrading consortium directly from gold mine tailings. In a batch-mode bioreactor experiment, this consortium degraded 22mM SCN-, accumulating ammonium (NH4+) and sulphate (SO42-) as the major end products. The consortium consisted of a diverse microbial community comprised of chemolithoautotrophic members, and despite the absence of an added organic carbon substrate, a significant population of heterotrophic bacteria. The role of eukaryotes in bioreactor systems is often poorly understood; however, we found their 18S rRNA genes to be most closely related to sequences from bacterivorous Amoebozoa. Through combined chemical and phylogenetic analyses, we were able to infer roles for key microbial consortium members during SCN- biodegradation. This study provides a basis for understanding the behaviour of a SCN- degrading bioreactor under autotrophic conditions, an anticipated approach to remediating SCN- at contemporary gold mines.

Molecular Diversity of Sea Spray Aerosol Particles: Impact of Ocean Biology on Particle Composition and Hygroscopicity

The impact of sea spray aerosol (SSA) on climate depends on the size and chemical composition of individual particles that make up the total SSA ensemble. There remains a lack of understanding as to the composition of individual particles within the SSA ensemble and how it changes in response to dynamic ocean biology. Here, we characterize the classes of organic compounds as well as specific molecules within individual SSA particles. The diversity of molecules within the organic fraction was observed to vary between submicrometer- and supermicrometer-sized particles and included contributions from fatty acids, monosaccharides, polysaccharides, and siliceous material. Significant changes in this molecular diversity were observed to coincide with the rise and fall of phytoplankton and heterotrophic bacteria populations within the seawater. Furthermore, the water uptake of individual particles was affected, as learned from studying the hygroscopicity of model systems composed of representative mixtures of salts and organic compounds.

Harnessing fertilizer potential of human urine in a mesocosm system: a novel test case for linking the loop between sanitation and aquaculture.

Human urine (HU) is a biogenic fertilizer which has raised immense interest owing to its capacity of combining sanitation and nutrient recovery. In search of an alternative organic fertilizer for fish culture, the nutrient potential of HU was evaluated. Fries of Indian carps and larvae of freshwater prawn were reared for 120days under six conditions: (a) aerated and (b) non-aerated fresh HU (0.01%), (c) cattle manure (CM; 1.8kgtank-1), mixed treatment with CM and HU under (d) iso-phosphorus and (e) iso-nitrogenous condition and (f) control. Monitoring of water quality and biological parameters revealed that total fish yield was the highest in CM (621.5gtank-1) followed by mixed treatments under iso-nitrogenous (428gtank-1) and iso-phosphorus (333gtank-1) conditions, aerated HU (321gtank-1) and HU (319gtank-1). The gross primary productivity (GPP) in HU was satisfactory (601.8mgCm-2h-1) and superior to all but CM treatment. The abundance of heterotrophic bacteria (HB) was highest in CM and lowest in HU. Both GPP and HB population were correlated positively with fish yield per tank. Although pH in all treatments remained high (pH 8.4-8.9), no ammonia toxicity was observed. No E. coli infestation in any fish muscle was encountered. The concentrations of cadmium and lead in fish muscle were within respective safe level. The study established that high fertilizer potential of HU could be exploited as an alternative organic fertilizer or as a candidate to be blended with cattle manure.

Distribution pattern of picoplankton carbon biomass linked to mesoscale dynamics in the southern gulf of Mexico during winter conditions

In order to characterize the carbon biomass spatial distribution of autotrophic and heterotrophic picoplankton populations linked to mesoscale dynamics, an investigation over an extensive open-ocean region of the southern Gulf of Mexico (GM) was conducted. Seawater samples from the mixed layer were collected during wintertime (February–March 2013). Picoplankton populations were counted and sorted using flow cytometry analyses. Carbon biomass was assessed based on in situ cell abundances and conversion factors from the literature. Approximately 46% of the total picoplankton biomass was composed of three autotrophic populations (Prochlorococcus, Synechococcus, and pico-eukaryotes), while 54% consisted of heterotrophic bacteria populations. Prochlorococcus spp. was the most abundant pico-primary producer (>80%), and accounted for more than 60% of the total pico-autotrophic biomass. The distribution patterns of picoplankton biomass were strongly associated with the mesoscale dynamics that modulated the hydrographic conditions of the surface mixed layer. The main features of the carbon distribution pattern were: (1) the deepening of picoplankton biomass to layers closer to the nitracline base in anticyclonic eddies; (2) the shoaling of picoplankton biomass in cyclonic eddies, constraining the autoprokaryote biomasses to the upper layers, as well as accumulating the pico-eukaryote biomass in the cold core of the eddies; and (3) the increase of heterotrophic bacteria biomass in frontal regions between counter-paired anticyclonic and cyclonic eddies. Factors related to nutrient preferences and light conditions may as well have contributed to the distribution pattern of the microbial populations. The findings reveal the great influence of the mesoscale dynamics on the distribution of picoplankton populations within the mixed layer. Moreover, the significance of microbial components (especially Prochlorococcus) in the southern GM during winter conditions was revealed, indicating that they may play an important role in the pelagic food web, and that they may have a substantial impact on the carbon cycle in oligotrophic regions.

Heterotrophic Bacterial Population in Water, Sediment and Fish Tissues Collected From Koka Reservoir and Awash River, Ethiopia

The quantitative estimation of total heterotrophic bacteria in the water, sediment and body tissues is helpful in predicting the quality of the fish as well as the status of the water body. The bacterial population in the water of Koka Reservoir and the Awash River, studied monthly for a period of one year, showed variation from 0.0.2×10 4 cfu/ml to 2.6×10 4 cfu/ml. Whereas, in the sediment the highest population density was 2.6 cfu/g and the lowest was 0.98×10 4 cfu /g. The highest population density in the reservoir was recorded in the sediment in January, while in the water was in August. The heterotrophic bacteria population in the river water and sediment was lower than the reservoir. During the non rainy season (February and March) the sediment bacteria increased with increase in water temperature and reduced rate of water level. The bacteria in the river water greatly reduced during February even though a regular pattern was not evident throughout the study period. The total bacterial population in different tissues of Cyprinus carpio and Oreochromis niloticus showed maximum population in intestine, followed by gill, skin, kidney and liver

Quorum sensing signal production and microbial interactions in a polymicrobial disease of corals and the coral surface mucopolysaccharide layer.

Black band disease (BBD) of corals is a complex polymicrobial disease considered to be a threat to coral reef health, as it can lead to mortality of massive reef-building corals. The BBD community is dominated by gliding, filamentous cyanobacteria with a highly diverse population of heterotrophic bacteria. Microbial interactions such as quorum sensing (QS) and antimicrobial production may be involved in BBD disease pathogenesis. In this study, BBD (whole community) samples, as well as 199 bacterial isolates from BBD, the surface mucopolysaccharide layer (SML) of apparently healthy corals, and SML of apparently healthy areas of BBD-infected corals were screened for the production of acyl homoserine lactones (AHLs) and for autoinducer-2 (AI-2) activity using three bacterial reporter strains. AHLs were detected in all BBD (intact community) samples tested and in cultures of 5.5% of BBD bacterial isolates. Over half of a subset (153) of the isolates were positive for AI-2 activity. AHL-producing isolates were further analyzed using LC-MS/MS to determine AHL chemical structure and the concentration of (S)-4,5-dihydroxy-2,3-pentanedione (DPD), the biosynthetic precursor of AI-2. C6-HSL was the most common AHL variant detected, followed by 3OC4-HSL. In addition to QS assays, 342 growth challenges were conducted among a subset of the isolates, with 27% of isolates eliciting growth inhibition and 2% growth stimulation. 24% of BBD isolates elicited growth inhibition as compared to 26% and 32% of the bacteria from the two SML sources. With one exception, only isolates that exhibited AI-2 activity or produced DPD inhibited growth of test strains. These findings demonstrate for the first time that AHLs are present in an active coral disease. It is possible that AI-2 production among BBD and coral SML bacteria may structure the microbial communities of both a polymicrobial infection and the healthy coral microbiome.