Heterotrophic Bacterial Populations Research Articles

AMR Threat Perception Assessment of Heterotrophic Bacteria From Shrimp Aquaculture Through Epidemiological Cut off Values.

Emergence and dissemination of antibiotic resistance is one of the major risks associated with the rampant usage of antibiotics in food-producing animals including aquaculture. To determine Epidemiological Cut-OFF (ECOFF) values of heterotrophic bacterial populations from shrimp culture environments against five different antibiotics. In this present study, bacterial samples were isolated from Penaeus vannamei culture environment in different locations of Andhra Pradesh, which is the aquaculture hub of India. The bacterial isolates were assessed for antibiotic resistance towards five antibiotics belonging to different classes (oxytetracycline, chloramphenicol, erythromycin, ciprofloxacin, and co-trimoxazole) by the disc diffusion method. Determination of Epidemiological Cut-OFF (ECOFF) values and analysis by employing normalized resistance interpretation (NRI) was carried out. The most dominant bacterial populations from shrimp culture were Vibrio spp. (pathogenic bacteria) followed by Bacillus spp. (probiotic bacteria). The bacterial isolates showed highest resistance towards oxytetracycline (overall 23.38%) and in location L6 (59.4%) followed by co-trimoxazole (31.1%). ECOFF values calculated by employing NRI showed that the disc diffusion data were distributed in a normalized manner. The maximum ECOFF value was obtained for ciprofloxacin (23.32 mm), while the minimum value was observed for oxytetracycline (9.05 mm). The antibiotic resistant phenotypes showed that the majority of the heterotrophic bacterial isolates (>60%) belonged to the non-wild type phenotype and primarily towards oxytetracycline (90%). The presence of non-wild antibiotic-resistant phenotypes of heterotrophic bacterial populations (which include not only pathogenic bacteria but also probiotic bacteria) indicates that shrimp culture ponds may be a reservoir for drug-resistant bacteria and there is a greater risk associated with transmission of resistant genes across bacterial flora. NRI analysis of antibiotic disc diffusion data of heterotrophic bacterial populations in shrimp aquaculture environments revealed that majority of them belonged to non-wild type (90%) paticularly to oxytetracycline in comparison to other studied antibiotics (chloramphenicol, erythromycin, ciprofloxacin and co-trimoxazole).

Abundance of Heterotrophic Bacterial Population in Coastal Waters of Palghar Taluka, Maharashtra, India

The population density of total heterotrophic bacteria in coastal water at 4 different sites along Palghar taluka namely; Kelwa coast, Navapur coast, Dandi creek and Satpati coast were studied. Total heterotrophic bacterial count was found to range from 0.34×102 – 423.1× 102 CFUml-1 in coastal waters. Average heterotrophic bacterial abundance was noted higher during monsoon at all 4 sites in the study with 47.2× 102 ± 34.79 CFU ml1at Satpati coast, 281.55× 102 ± 148.45 CFU ml-1 at Dandi creek, 265.26× 102 ± 149.74 CFU ml-1 at Navapur coast, and 1.12 × 102 ± 0.54 CFU ml-1 at Kelwa coast. Dandi creek recorded highest bacterial count throughout study period irrespective of season.

Bioremediation of a crude oil contaminated soil using water lettuce (<i>Pistia stratiotes</i>)

Laboratory-scale studies were carried out using a nutrient formula produced from Pistia stratiotes plant to achieve bioremediation of crude oil impacted loamy soil. This study assessed the efficacy of powdered Pistia stratiotes as potential bio stimulant in the remediation of crude oil contaminated soil using three test treatments (20ml, 60ml and 100ml) at three test concentrations (20g, 40g and 60g) of nutrient and a control (0g). The remediation process was monitored by assaying the total hydrocarbon content (THC) and soil pH before and after amendment with the powdered P. stratiotes for 90 days. The result showed increase in soil pH and THC in comparison with the control due to soil contamination by crude oil. However, there was a significant reduction (p < 0.05) in soil pH and THC with the introduction of powdered P. stratiotes at different concentrations. Contaminated soil amended with 40g of P. stratiotes had the highest THC loss of (30%) on the final day of remediation. In a 90 day study, the control set-up had its total culturable heterotrophic bacterial population of the P. stratiotes recipe increase from 1.4×107 Cfu/g to 2.8×107 Cfu/g, while the total culturable heterotrophic fungal count in the P. stratiotes treatment ranged from 7.0×104 Cfu/g to 4.0×104 Cfu/g. Statistical analyses showed significant difference at p ≤ 0.05 level for the two conditions (Pistia stratiotes nutrient treated soil and control). The total culturable hydrocarbon utilizing bacteria in P. stratiotes treated polluted soil increased from 1.0×106 Cfu/g to 6.8×105 Cfu/g, while the total culturable hydrocarbon utilising fungal counts increased significantly from 1.9×104 Cfu/g to 4.8×104 Cfu/g for P. stratiotes treatment. The results from this research demonstrated that powdered P. stratiotes is an effective agent that can be used to decrease the pH of contaminated soil and improve soil properties, hence aids in remediating a crude oil contaminated soil.

Herotrophic Bacterial Populations and Primary Production In Fish Ponds Under Different Manaement Practices

The aerobic heterotrophic bacterial populations in the water and sediment media and primary production levels with reference to the physicochemi cal conditions of carp polyculture ponds under different management practices, viz. , fortnightly application of cowdung in heaps, spray-application of cowdung on alternate days, gradual leaching of inorganic fertilizers, manual raking of pond bottom and bioturbation by common carp, were studied, along with observations on the growth characteristics of bacterial populations under simulated conditions. The bacterial counts were maximal in the ponds with agitated bottom, inspite of the absence of allochthonous organic enrichment. The generation time and generation number of the populations in the water and sediment media were in the ranges of 0.9-24.8 h, 0.7-21.2 h and 0.2-5.3, 0.2-6.4 respectively, indicating intense bacterial activities . Primary production levels in the ponds were moderate (1.13-3 6.77 g c/m3/d ) , comprising high (31.27-139.82%) respiration values. The results brought out the significance of the heterotrophic food chain in f i s h pond ecosystems and demonstrated the positive effects of simple pond environmental man ipu l a t ion measures like bottom raking on sediment-water interactions .

Assessment of the Potentials of Water Hyacinth (Eichhornia crassipes) as Raw Material for Biofertilizer

This research investigated the potentials of water hyacinth as raw material for biofertilizers. Water hyacinth was collected from Alape River in Ilaje Local Government Area of Ondo State and processed for microbiological, proximate and physicochemical analyses by standard methods. Results revealed that the total heterotrophic bacterial and fungal populations were 5.0 x 107 (CFU/g) and 3.5 x 105 (CFU/g) and 3.6 x 102 SFU/g and 3.0 x 102 (SFU/g) for root and leaf parts respectively. The population of phosphate solubilizing bacteria, Azospirillum spp., Azotobacter spp. and Rhizobium spp. were 3.5 x 104 - 1.3 x 106 CFU/g, 1.4 x 103- 2.6 x 104 (CFU/g), 3.4 x 103 – 1.7 x 104 (CFU/g) and 1.2 x 103 – 1.1 x 104 (CFU/g) respectively. 16S rRNA gene sequencing revealed the presence of Enterobacter cloacae (LT 221670.1 -53%) and Bacillus safensis (AB711138.1 -99%), Pseudomonas mendocina (LN 881702.1 – 99%) and Aeromonas veroni (LC 487867.1 – 97%) from the root and leaf respectively. Aspergillus spp., Fusarium sp., Rhizopus sp., Trichoderma sp. Cladosporium sp. were among the fungi from the water weed parts. The proximate, nutrient and heavy metal constituents of water hyacinth vary among the leaf, stem and root. The proximate values for moisture (65.45%), protein (12.18%) and carbohydrate (5.30%) were highest in the leaf part compared to the stem and roots. Also, the highest values of ash (18.48%), fat (3.84%) and crude fibre (12.50%) were obtained in the plant root relative to leaf and stem. Apart from magnesium and phosphorous, mineral elements such as sodium, calcium and potassium were more abundant in the leaf. Among the heavy metal, Lead, Cadmium, Nickel, Arsenic and Cobalt had undetectable values for all parts. This study concludes that the presence of microbial biofertilizer and micro and macro nutrients on water hyacinth suggests its potential as raw material for biofertilizer and can be used to promote plant growth without negative consequences.

Maximizing nutrient recovery from aquaponics wastewater with autotrophic or heterotrophic management strategies

Aquaponics uses bacterial processes and plant nutrient uptake to recover nutrients from aquaculture wastewater. However, little is known about which wastewater management strategy is best suited for nutrient recovery. We compared four aquaponics water management strategies: pH 6 or pH 7 with autotrophic bacterial populations (pH 6, pH 7), and pH 6 or 7 with heterotrophic bacterial populations (pH6M, pH 7 M). The results indicated that nutrients recovered with greater efficiency in pH 6 and pH 6 M than in pH 7, with higher plant biomass and food quality. pH 6 displayed the highest nitrogen (N) use efficiency (NUE = 65.5 %) and the lowest N loss as gas (34.5 %), followed by pH 6 M, suggesting that lower pH in aquaponics could enhance NUE and reduce N loss. pH 6 M had the highest phosphorus (P) use efficiency (PUE = 65.0 %) suggesting that lower pH and heterotrophic bacterial populations facilitate P recovery from wastewater. Plant nutrient uptake was improved when heterotrophic bacterial populations were established in an environmental pH of 6.

Interspecific variations in leaf litter decomposition and nutrient release from tropical mangroves

Efficient nutrient cycling through decomposition of leaf litter often regulates the high productivity and subsequent carbon sequestration of mangrove ecosystems along the land-ocean boundary. To understand the characteristics and the potentials of mangrove leaf litter in supplying organic carbon and nutrients to the coastal waters, four major mangrove species (A. officinalis, R. mucronata, H. littoralis and S. apetala) of Bhitarkanika mangrove forest, Odisha, India, were examined in controlled environmental conditions. Half-life time (t0.5), estimated for decomposition of those mangrove leaf litter materials ranged from 18 to 52 days. During the incubation experiment, organic carbon from mangrove leaf litter was released primarily through physical processes and was available for heterotrophic respiration. Among the four species, leaf litter of S. apetala with the lowest initial C/N ratios, released organic carbon with low molecular weight (labile substances) that has a relatively higher potential to support the aquatic food web. On the contrary, leaf litter of R. mucronata released organic material with relatively higher molecular weight (humic substances, higher aromaticity), which revealed its superior non-labile characteristics in this unique environment. The mean total heterotrophic bacterial (THB) population in the incubation was around nine-fold higher than the control. THB population growth and Chromophoric Dissolved Organic Matter (CDOM) spectral data further suggested the rapid release of highly labile and recalcitrant carbon from S. apetala and R. mucronata (between 7th and 21st day of incubation), respectively. The mean litter fall from the Bhitarkanika mangrove forest was estimated to be 11.32 ± 1.57 Mg ha−1 y−1 and its corresponding carbon content was 5.43 ± 0.75 Mg C ha−1. The study revealed the role of leaf litter leachates as an important food source to microbial communities in the adjacent coastal waters, in addition to a potential carbon sequesterer through long-term burial in mangrove soil and export to the deep sea.

Diversity and seasonal prevalence of starch hydrolysing, phosphate solubilizing and nitrogen-fixing bacterial groups of rooted and un-rooted regions of tropical mangrove sediments of Sundarbans, West Bengal, India

ABSTRACT The Sundarbans mangrove is a transitional zone between terrestrial land and sea, a unique location in our global geography. This study identifies the richness and population dynamics of bacterial populations along different seasons in the rooted and unrooted regions of soil sediments in Sundarbans, West Bengal. Throughout the year, bacterial populations were higher in the rooted sediment zone, than the unrooted area. The rooted zone contains more silt and clay but the unrooted zone harbours more silty, sandy soil. Salinity is lower in the unrooted zone. The heterotrophic bacterial populations were higher than other types of bacteria in both regions irrespective of seasonal variation. The results revealed that the most varied seasons were the monsoon season in the rooted and unrooted sediment region. The changes identified in this study were most likely due to variances in the microhabitat associated with mangrove root, physicochemical parameters and seasonal fluctuations.

Current Concentrations of Zn, Cu, and As in Piggery Wastewater Compromise Nutrient Removals in Microalgae-Bacteria Photobioreactors Due to Altered Microbial Communities.

Simple SummaryPhotobioreactor systems based on consortia of microalgae and bacteria are a promising, efficient and sustainable alternative for treatment of wastewaters with high nitrogen content, such as piggery wastewater. In these biological systems, microorganisms play a key role in wastewater treatment by degradation of organic matter and accumulation of nutrients into the generated biomass. However, these wastewaters often contain high concentrations of zinc, copper and arsenic, which can severely affect the activity and growth of microorganisms, and so, the wastewater treatment performance. This article studies the effect of high concentrations of zinc, copper and arsenic on microbial communities, specifically microalgae and bacteria, in photobioreactors treating piggery wastewater, with the aim of elucidating their impact on wastewater treatment performance. For this purpose, the growth of microalgae and the composition and structure of bacterial communities exposed to these pollutants were studied. The performance of the reactors was also evaluated by determining the removal of nutrients, zinc, copper and arsenic. The results showed that high concentrations of zinc, copper and arsenic in piggery wastewater significantly affect the microbiome of the reactors without recovery after exposure to these contaminants, resulting in poorer performance of the reactors and compromising the environmental and health impact of treated effluents.The treatment of pig manure is a major environmental issue, and photobioreactors containing consortia of microalgae and bacteria have proven to be a promising and sustainable treatment alternative. This work studies the effect of Cu, Zn and As, three toxic elements frequently present in piggery wastewater, on the performance and microbiome of photobioreactors. After dopage with Zn (100 mg/L), Cu (100 mg/L), and As (500 µg/L), the high biomass uptake of Zn (69–81%) and Cu (81–83%) decreased the carbon removal in the photobioreactors, inhibited the growth of Chlorella sp., and affected heterotrophic bacterial populations. The biomass As uptake result was low (19%) and actually promoted microalgae growth. The presence of Cu and As decreased nitrogen removal, reducing the abundance of denitrifying bacterial populations. The results showed that metal(loid)s significantly affected 24 bacterial genera and that they did not recover after exposure. Therefore, this study makes an important contribution on the impact of the presence of metal(loid)s in piggery wastewater that compromises the overall performance of PBRs, and so, the environmental and health impact of treated effluents.

Effects of Seasonal Variations on Microorganisms on Paint-Polluted Soil in Nigeria

Adverse impacts of paints effluents from industries improperly disposed into the environment caused pollution, a lot of carcinogenic, mutagenic, physiological alterations resulting in debilitating health effects on humans. The study was aimed at the effects of seasonal variations on soil microorganisms’ dominant at paint effluent disposal sites in lagos. A total of one hundred soil samples each were collected at different seasons of the disposal sites of two paint companies and analysed using standard microbiological methods. Results obtained shows paint effluents caused a significant decrease (p≤0.05) in the population of the microbial groups studied in the different seasons. Total heterotrophic bacterial population decreased from 7.7x108±0.19 to 6.4x107±0.01 in the dry season, and 5.3x108±0.08 to 6.5x107±0.15 during the rainy season. A total of eleven bacterial and eight fungal genera were identified. The identified bacterial genera included Bacillus, Pseudomonas, Staphylococcus, Micrococcus, Serratia, Arthrobacter., Aeromonas, Citrobacter, Alcaligenes, Flavobacterium, and Enterobacter. The fungal genera included Aspergillus, Penicillium, Fusarium, Mucor, Rhodotorula, Cladosporium, Trichophyton, and Geotricum. The most predominant bacteria and fungi were Bacillus (30.0%) and Pseudomonas (16,7%) species and Aspergillus (38.5%) species respectively. This study has confirmed the presence of different microbial species associated with acrylic paint-impacted sites. It, therefore, suggests that improvement of antimicrobial additives of paints may be a promising approach to reduce contamination.

CMIP6 Simulations With the CMCC Earth System Model (CMCC‐ESM2)

AbstractThis article introduces the second generation CMCC Earth System Model (CMCC‐ESM2) that extends a number of marine and terrestrial biogeochemical processes with respect to its CMIP5 predecessor. In particular, land biogeochemistry was extended to a wider set of carbon pools and plant functional types, along with a prognostic representation of the nitrogen cycle. The marine ecosystem representation was reshaped toward an intermediate complexity of lower trophic level interactions, including an interactive benthic compartment and a new formulation of heterotrophic bacterial population. Details are provided on the model setup and implementation for the different experiments performed as contribution to the sixth phase of the Coupled Model Intercomparison Project. CMCC‐ESM2 shows an equilibrium climate sensitivity of 3.57°C and a transient climate response of 1.97°C which are close to the CMIP5 and CMIP6 multi‐model averages. The evaluation of the coupled climate‐carbon response in the historical period against available observational datasets show a consistent representation of both physical and biogeochemical quantities. However, the land carbon sink is found to be weaker than the current global carbon estimates and the simulated marine primary production is slightly below the satellite‐based average over recent decades. Future projections coherently show a prominent global warming over the northern hemisphere with intensified precipitations at high latitudes. The expected ranges of variability for oceanic pH and oxygen, as well as land carbon and nitrogen soil storage, compare favorably with those assessed from other CMIP6 models.

Effect of heterotrophic bacteria on the growth of tilapia (Oreochromis niloticus) cultivated in brackish water

Tilapia is a commercial fish cultivated in both fresh water and seawater frequently attacked by pathogenic bacteria. Some bacteria have become probiotics and help overcome this problem. This study aimed to examined the effect of heterotrophic bacteria administration on survival rate and absolute weight growth of the fish, heterotrophic bacterial population growth and the water quality. The study used a factorial experimental design a x b, where a factor was the method of administering heterotrophic bacteria and b factor was the species of isolate used. Factor a consists of an introduction to fish via feed (a1) and via water test media (a2). Factor b consisted of b1 (diet without heterotrophic bacterial treatment), b2 (diet with heterotrophic bacterial isolate J), b3 (diet with heterotrophic bacterial isolate N), b4 (diet with heterotrophic bacterial combined isolates B, C, D, J (Vagococcus fluvialis), H, N; Bacillus cereus). The fishes were reared in a 60 l container. Administering via a feed of heterotrophic bacteria showed no significant effect to survival rate of tilapia. While administering via water showed a significant influence on the survival rate. Both administration methods caused a better absolute growth rate. However, administration of the bacteria did not affect the heterotrophic bacterial populations in the water.

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.

Characterization of hydrocarbon utilizing bacteria in waste engine oil-impacted sites

Changes in soil physicochemical properties and bacterial species present in soil contaminated with waste engine oil were evaluated at three auto-mechanical workshops in Uyo, Nigeria. This work was aimed at isolating and identifying hydrocarbon degrading bacteria from waste engine oil polluted soil, and assessing their hydrocarbon-utilizing ability. Waste engine oil pollution affected soils significantly with increases in soil physicochemical properties, and heterotrophic bacterial population counts. Eight bacterial species Corynebacterium kutscheri, Pseudomonas aeruginosa, Flavobacterium aquatile, Serratia odorifera, Micrococcus agilis, Staphylococcus aureus, Micrococcus luteus and Bacillus substilis were isolated by the selective enrichment technique and screened for hydrocarbon utilization capability in mineral salt media with 1% (v/v) waste engine oil as a sole carbon and energy source. The extent of bacterial growth observed was related to the ability of organisms to biodegrade hydrocarbons present in the medium bacterium species, which showed varying hydrocarbon utilization during the 15 days of incubation. Growth in hydrocarbon medium was the most efficient in cultures of Corynebacterium kutscheri. All isolates also showed variable emulsification ability, with Corynebacterium kutscheri, showing the highest ability. These results demonstrate the presence of indigenous bacteria in hydrocarbon-polluted soils and the potential toward the remediation of hydrocarbons.

Application of cowdung and sawdust as biostimulants for enhanced bioremediation of diesel contaminated soil

The study was aimed at exploring the use of cow dung (CD) and sawdust (SD) as bio stimulants for enhanced ex-situ bioremediation of diesel fuel contaminated soil. Results of the microbial populations in a gram of soil showed that diesel polluted soil amended with CD had the highest total culturable heterotrophic bacterial (TCHB) population range (1.42 x 106 - 1.56 x 107Cfu/g), total fungal (TF) (1.0 x 106 – 1.60x107Cfu/g), hydrocarbon utilizing bacteria (HUB) (4.5 x 106 – 2.05 x 107Cfu/g) and hydrocarbon utilizing fungi (HUF) (3.5 x 106 – 1.3 x 107Cfu/g) respectively during the study. Diesel polluted soil amended with SD had lower TCHB populations (1.32 x 106 – 2.0 x 107Cfu/g), TF (6.0 x 106 – 3.6 x 107 Cfu/g), HUB (5.4 x 106 – 1.28 x 107Cfu/g) and HUF (1.2 x 106 – 2.0 x 106Cfu/g) respectively, while the microbial populations in option C (control) were TCHB (1.14 x 106 – 1.18 x 107Cfu/g), TF (1.7 x 106 – 7.0 x 106Cfu/g), HUB (4.2 x 106 – 7.8 x 106Cfu/g) and HUF (1.1 x 106 – 5.0 x 107Cfu/g) respectively. Changes in pH values showed reductions in CD (7.10 – 6.20) and SD (5.78 – 4.88) amended soils. Percentage losses in TPH from chromatography results showed diesel polluted soil amended with CD (61.30%), SD (41%) and control (4.11%) respectively. Characterization and identification tests of bacterial isolates revealed that a microbial consortium comprising of the following HUB genera; Bacillus, Pseudomonas, Proteus, Alcaligenes, Klebsiella, Enterobacter, Citrobacter, Corynebacterium and Escherichia coli was implicated in the biodegradation process. Similarly, the HUF encountered were Fusarium, Aspergillus, Microsporium, Penicilium and Mucor. The results suggest that the application of cow dung as biostimulant will enhance the bioremediation of diesel contaminated soil than the application of sawdust.Keywords: Cowdung, Sawdust, Bioremediation, Biostimulation

Microbial community analysis and correlation with 2-methylisoborneol occurrence in landscape lakes of Beijing

The microbial community is an important factor influencing the health of the water ecosystem in landscape lakes; in particular, proliferation of some cyanobacteria could cause odor problems. Exploring the microbial community is important for water quality management. In this study, focusing on seven landscape lakes in Beijing, the microbial communities were investigated based on 16S rRNA gene amplicon sequencing, and typical odor-causing compounds and interfering factors were identified. The results showed that 2-methylisoborneol (MIB) was the major odor-causing compound responsible for the earthy/musty odor in landscape lakes. For algal communities, Chlorella and Diatoms were the main eukaryote algae in the water. The bacterial community was dominated by Proteobacteria at the phylum level, and then Cyanobacteria, Actinobacteria, and Firmicutes, etc., most of which were the major phyla of the heterotrophic bacterial population. The richness and diversity of bacteria in natural-water-source lakes were higher than those in reclaimed-water-source lakes. Synechococcus (Cyanobacteria) and GKS98 (Proteobacteria) in reclaimed-water-source lakes were higher than those in natural-water-source lakes, however, CL500-29 (Actinobacteria) in natural-water-source lakes was higher than that in reclaimed-water-source lakes. These bacteria also had significantly positive correlations with MIB. Cyanobacteria and Actinobacteria were the main MIB compound contributors to the variability of MIB in the landscape lakes in Beijing.

Colonization of enzymatic bacterial flora in biofloc grown shrimp Penaeus vannamei and evaluation of their beneficial effect

Experiments were conducted to explore the colonization of beneficial bacteria in shrimp Penaeus vannamei grown in different sources of biofloc and clear water. Beneficial effect in terms of extracellular enzyme production and antibiofilm activity of the isolated strains was determined. Heterotrophic bacterial population were isolated by using different agar plates and resulted in isolation of 94 isolates in total. Extracellular enzyme production such as amylase, protease, lipase, cellulase, xylanase, and pectinase were screened. Antibiofilm activity of culture supernatants of enzymatic strains against pathogenic Vibrio was also determined. Out of 94 strains screened, 36 strains were found to produce amylase enzyme, 20 strains protease, 27 strains lipase, 6 strains cellulase, and 8 strains xylanase. Totally, 21 isolates selected for further identification and different species of Cobetia, Exiguobacterium, Bacillus, Marinilactibacillus, Staphyllococcus, and Novosphingobium genera from biofloc treatments were identified. In control group animals, strains of Bacillus and Exiguobacterium were isolated and identified. The genus Exiguobacterium was found common in all the different treatments and control. The result showed that shrimp grown on biofloc system allows colonizing more beneficial bacteria in gut than control. Few promising strains under Bacillus genus were found to produce all the extracellular enzymes along with antibiofilm activity.

Comparative Studies on the Bioremediation of Used Engine Oil Contaminated Soil using Urea Fertilizer (UF), Goat Manure (GM), Pig Manure (PM) and Brewery Spent Grain (BSG)

The focus of the study was to evaluate and compare the performance of urea fertilizer, goat manure, pig manure and brewery spent grain for the bioremediation of used engine oil contaminated soil. Soil with no pollution history was collected and subjected to detailed laboratory analysis to determine the total heterotrophic bacterial population, pH, moisture content, total organic carbon, total nitrogen and total hydrocarbon content. Used engine oil contaminated soil was prepared by adding 250g of used engine oil into a clean dry plastic bucket containing 1kg of unpolluted soil. The mixture was properly mixed and covered with aluminium foil paper before use. The used engine oil contaminated soil was left for a period of four (4) days for stabilization before the commencement of treatment. The entire setup and its content was open throughout the period of experimentation to allow for the influence of atmospheric oxidation. The setup was monitored for twelve (12) weeks and sampling/analysis of the samples was done on a weekly basis to ascertain the progress of treatment. The residual hydrocarbon content after each treatment was determined using Atomic Absorption Spectrophotometer. Results obtained shows that pig manure is the best substrate for the clean-up of used engine oil contaminated soil with calculated removal efficiency of 64.4% followed by BSG with 51.4% removal efficiency, Goat Manure with removal efficiency of 39.9% and Urea Fertilizer with 33.7% efficiency. The kinetic modelling shows that experimental data fitted well with pseudo-first order kinetic model with calculated error sum of square (SSE) values of (0.0002, 0.0005, 0.0012 and 0.0072) and root mean square errors (RMSE) of (0.0028, 0.0073, 0.0082 and 0.0481). On the accurate prediction of the optimum remediation time, it was observed that the non-linear regression model gave higher coefficient of determination of 0.9824, 0.9812, 0.9886 and 0.9899 compared to linear regression.

High-throughput DNA sequencing reveals the dominance of pico- and other filamentous cyanobacteria in an urban freshwater Lake

The current study presents findings related to algal blooms in a fresh water lake, which has been experiencing severe cyanobacterial blooms (CyanoHABs). Primarily, picocyanobacteria belonging to the genus Synechococcus and filamentous cyanobacterial group belonging to Aphanizomenon and Dolichospermum dominated top water column during non-bloom and bloom periods respectively. The dominance of Synechococcus in early summer informs that blooming in Utah Lake starts in early summer and then later is taken over by other bloom-forming cyanobacteria, such as species belonging to the genus Aphanizomenon. A strong negative correlation (r = −0.9, p < 0.001) was found between the occurrence of Aphanizomenon and Synechococcus which correlates very well with the fact that the blooms of these two different cyanobacteria never coexisted. The predominance of cyanobacteria in 2017 was attributed more to temperature (r = 0.18, p < 0.001). The Actinobacteria was negatively correlated with primary production and high chlorophyll a concentration. Flavobacterium and Limnohabitans were the main phytoplankton colonizers and predators detected that could secrete extracellular enzymes to degrade algal exudates (such as proteins and polysaccharides). Additionally, cyanotoxins producers Microcystis aeruginosa and Planktothrix accounted for up to 12.43% and 7.04% of total cyanobacteria abundance during blooms. The relative abundance of chloroplast reads was overall lower than the cyanobacteria reads, except for the May 5th sampling in 2017. There was inter-annual variability in the bloom-associated heterotrophic bacterial populations, but these populations were consistent with bloom-associated bacterial populations found in other lakes. Community diversity analysis for both Shannon and Simpson indices indicated lower community diversity during the bloom period. The beta diversity conducted by PCoA and UPGMA trees suggested the significant temporal rather than spatial impacts on shaping the phytoplankton community structures during the summer season.

Assessing the cellulase enzyme heterogeneity of bacterial strains and their feedback to cattle manure degradation in a greenhouse model of in vivo pond ecosystem.

The responses of cellulase enzymes of three bacterial isolates and their impacts on cattle manure decomposition were assessed in a greenhouse model in vivo pond ecosystem. Fifty grams of fresh cattle manure was placed in a fastened nylon bag (mesh size ~ 50μm dia.) and placed in triplicate in a plastic bucket with 10 l of pond water which was hung inside the enclosed polyhouse, semi-closed and open systems for 4weeks. Samples of manure residue directly from nylon bag and water from manure leached bucket water, water, and soil from the enclosed polyhouse were collected for enzymatic assays, enumeration of aerobic cellulose decomposing and heterotrophic bacteria, and determination of water and soil quality parameters. Responses of cellulases to different temperatures in situ were also elucidated. The values of test bacteria, endoglucanase, exoglucanase and β-glucosidase, and organic carbon were significantly (P˂0.05) higher in the closed system compared to semi-closed or open system. Priming of all the enzymes coupled with the peak of aerobic cellulose decomposing bacteria and heterotrophic bacterial populations occurred on the day 14 or 21 in vivo. Since the peaks of three cellulases of bacterial isolates (KUPH1, KUPH6, and KUPH8) were demonstrated between 35 and 40°C, and that temperature coincided with temperature of the greenhouse model, this temperature range appeared to favor the growth of cellulose decomposing bacterial populations and involved cellulase enzymes.