Abundance Of Total Bacteria Research Articles

Response of soil bacterial communities to polycyclic aromatic hydrocarbons during the phyto-microbial remediation of a contaminated soil

Rhizo-box experiments were conducted to analyze the phyto-microbial remediation potential of a grass (Lolium multiflorum L.) and a crop (Glycine max L.) combined with exogenous strain (Pseudomonas sp.) for polycyclic aromatic hydrocarbons (PAHs) contaminated soils. The dynamics of bacterial community composition, abundances of 16 S rDNA and ring hydroxylating dioxygenases (RHDα) genes, and removal of PAHs were evaluated and compared on four culture stages (days 0, 10, 20, and 30). The results showed that 8.65%–47.42% of Σ12 PAHs were removed after 30 days of cultivation. Quantitative polymerase chain reaction (qPCR) analysis indicated that treatments with soybean and ryegrass rhizosphere markedly increased the abundances of total bacteria and PAH-degraders, especially facilitated the growth of gram-negative degrading bacteria. Flavobacterium sp. and Pseudomonas sp. were the main and active strains in the control soil. However, the presence of plants and/or exogenous Pseudomonas sp. changed the soil bacterial community structure and modified the bacterial diversity of PAH-degraders. On the whole, this study showed that the high molecular weight PAHs removal efficiency of phyto-microbial remediation with ryegrass was better than those of remediation with soybean. Furthermore, the removals of PAHs strongly coincided with the abundance of PAH-degraders and bacterial community structure.

Size resolved characteristics of urban and suburban bacterial bioaerosols in Japan as assessed by 16S rRNA amplicon sequencing

To study the size-resolved characteristics of airborne bacterial community composition, diversity, and abundance, outdoor aerosol samples were analysed by 16S rRNA gene-targeted quantitative PCR and amplicon sequencing with Illumina MiSeq. The samples were collected using size-resolved samplers between August and October 2016, at a suburban site in Toyama City and an urban site in Yokohama City, Japan. The bacterial communities were found to be dominated by Actinobacteria, Firmicutes, and Proteobacteria. At the genus level, we found a high abundance of human skin-associated bacteria, such as Propionibacterium, Staphylococcus, and Corynebacterium, in the urban site. Whereas, a high abundance of bacteria associated with soil and plants, such as Methylobacterium and Sphingomonas, was observed in the suburban site. Furthermore, our data revealed a shift in the bacterial community structure, diversity, and abundance of total bacteria at a threshold of 1.1-µm diameter. Interestingly, we observed that Legionella spp., the causal agents of legionellosis in humans, were mainly detected in > 2.1 µm coarse particles. Our data indicate that local environmental factors including built environments could influence the outdoor airborne bacterial community at each site. These results provide a basis for understanding the size-resolved properties of bacterial community composition, diversity, and abundance in outdoor aerosol samples and their potential influence on human health.

Enhanced nitrogen removal by simultaneous nitrification-denitrification and further denitrification (SND-DN) in a moving bed and constructed wetland (MBCW) integrated bioreactor

With the main objective of improving the removal of nitrogen from domestic wastewater and more sustainably, a moving bed and constructed wetland (MBCW) integrated bioreactor was fabricated and evaluated with continuous and intermittent aeration operations. The hybrid system achieves average removal efficiencies up to 90.4 ± 0.8% of chemical oxygen demand (COD), 91.8 ± 1.2% of ammonia nitrogen (NH4+-N), and 77.0 ± 2.6% of total nitrogen (TN), respectively, through a simultaneous nitrification-denitrification and further denitrification (SND-DN) process. This occurs through an intermittent aeration operation followed by continuous aeration with a dissolved oxygen (DO) of 4.0 mg L−1 due to the complementary and coordinated action of mixed biocarriers. It has resulted in the improvement of the efficiency of SND from 5.9 to 35.3% and in the removal via wetland for DN, between 2.42 and 2.45 g m−2·d−1, respectively. The analysis of extracellular polymeric substances (EPS) and high-throughput sequencing demonstrated the enhanced SND mechanism and the evolution of microbial species within the biofilm structure. The total relative abundance of nitrifying bacteria, more aggregated outside the biofilm, decreased by 7.66% compared to denitrifying bacteria, mostly accumulated inside, which increased by 5.49%, respectively.

The Degradation of Glyphosate and Its Effect on the Microbial Community of Agro-Sod–Podzolic Soil under Short-Term Model Experiment Conditions

Under laboratory conditions, the decomposition of glyphosate with the formation of aminomethylphosphonic acid (AMPA) and its effect on the total abundance of bacteria and fungi as well as the number of copies of genes encoding the enzymes C–P lyase of α-proteobacteria (phnJ), acid and alkaline phosphatase (phoC and phoD) and Fe protein of nitrogenase (nifH) in agro-sod-podzolic soil (Epialbic Retisol) were determined. It was shown that when applying glyphosate in recommended doses (5–10 mg/kg), only 5–7% of the introduced herbicide were detected after 14 days, but when the dose was increased to 100 mg/kg, this value increased up to 23%. Decreasing the rate of the herbicide degradation was observed only during the first week of incubation and was accompanied by a decrease in the number of copies of the phoC, phoD, and nifH genes and an increase in the abundance of fungi. The obtained results indicate that glyphosate was mainly degraded by means of C–P bond breaking and the formation of phosphates, and also suggest possible inhibition of the nitrogen fixation process. It is shown that at an application dose of glyphosate of 100 mg/kg may lead to the accumulation of AMPA, the first metabolite of the herbicide degradation pathway, formed after the C–N bond break. Bioassay using wheat showed that when applying glyphosate at a dose of 100 mg/kg, an inhibition of plant development was observed: the length of the roots and the biomass of the shoots reduced by 60 and 20% compared to the control, respectively. Based on the data obtained, it was proposed to use the reduction in the content of copies of the phoC gene and the increase in the number of copies of ITS rRNA as indicators of the predominant decomposition of glyphosate through the sarcosine pathway. The decrease in the number of copies of ITS rRNA gene by 40% or more can be used as an indicator of the possibility of AMPA accumulation during glyphosate degradation.

STRUCTURAL AND FUNCTIONAL INDICATORS OF BACTERIOPLANKTON OF THE SOUTH STRETCH OF LAKE MUNOZERO (KARELIA)

In article are presented the results of the state of the pelagic part of the south stretch of Lake Munozero (Karelia) according to microbiological indicators for the growing season of 2018. In the furtherance of this goal, 27 water samples were chosen in May, July and September at different strata. Munozero Lake is one of the unique lakes of Karelia due to its high salinity (100 mg/l), low-nutrient water sand organic substances. The total number, cell size dimensional structure and biomass of bacteria were determination by method of luminescence microscopy, by means of filtration through black nucleopore track membranes, after coloration bacteria by acridine orange. The total abundance of bacteria varied from 0,66 to 1,85 million cells/ml, and the biomass from 0,13 to 0,66 g/m3. The average cell volume varied in the range 0,18-0,34 μm3. Coccus form of bacteria prevailed in numbers. The doubling time and bacterial production were determined by the method of isolated samples. Bacterial production varied between 0,01 and 0,07 g/(m3•day-1). Specific growth rates (day-1) ranged around 0,05-0,2, giving doubling times of 70-364 h. The average daily production for the growing season was 0,65 g/m3•day-1. The physiological activity of bacteria was greatest at the end of the growing season. During the research period, the abundance of saprophytic bacteria growing on fish peptone agar was in the range of 19-550 CFU/ml. the abundance of oligotrophic bacteria growing on from starvation agar variable 200 to 850 CFU/ml. During the study period Water of the south stretch of the Lake Munozero was estimated as clean - moderately polluted with an intermediate quality class of 2-3. The south stretch of the Munozero is characterized as a mesotrophic water body.

Abundance of the species Clostridium butyricum in the gut microbiota contributes to differences in obesity phenotype in outbred Sprague-Dawley CD rats.

Gut microbiota profiles contribute to differences in obesity phenotype. We examined the abundance of the species Clostridium butyricum in relation to obesity phenotype. In outbred Sprague -Dawley rats we examined effects of dietary fat, resistant starch (RS), and a microbiota transplant on obesity phenotype. Using targeted qPCR, we examined the abundance of total gut bacteria and C. butyricum in relation to the propensity of obesity prone and obesity resistant rats to accumulate abdominal fat. Before inclusion of dietary RS, obesity resistant (OR) rats had higher amounts of total bacteria, and C. butyricum compared to obesity prone (OP) rats (P < 0.005 in study I, P < 0.0001 in study II). A high fat diet (HF) lowered C. butyricum levels while RS had no effect. Dietary RS elicited robust fermentation and increased total bacteria only in OP rats. In preparation for the transplant, antibiotics were administered to recipient rats. Four weeks thereafter, total bacteria levels were restored but, C. butyricum levels were not. The transplant between the two phenotypes had no effect on abundance of C. butyricum and obesity phenotype. While C. butyricum is a known saccharolytic, its proliferation is not enhanced by fermentation of resistant starch. C. butyricum maybe one of the species that constitute a core microbiota involved in energy storage and metabolism through mechanisms that are not yet known.

Short-Term Effects of Eco-Friendly Fertilizers on a Soil Bacterial Community in the Topsoil and Rhizosphere of an Irrigated Agroecosystem

Fertilizer application to arable soils could be effective for soil nutrients. However, there are many negative effects in croplands with long-term chemical fertilizer application. Whether eco-friendly fertilizer addition could enhance soil quality and soil microbial activity has been investigated before; however, how top- and rhizosphere soil bacterial communities respond to their short-term effects is not well known. Here, we used Illumina MiSeq sequencing to determine the changes of bacterial community structure in both topsoil and rhizoshpere after one month of the addition of three different eco-friendly fertilizers—biochar (B), microbial fertilizer (MF), fertilizer synergist (FS) and selected soil base fertilizer (CK) as a control, in an irrigated agroecosystem of cabbage crop (Brassica oleracea L. var. capitata L.). The results show that three different eco-friendly fertilizers significantly enhanced cabbage growth. The Shannon and Ace indexes of the bacterial community significantly decreased under the FS treatment in both soils, but the total abundance of bacteria was maximal under the FS treatment in the topsoil and the MF treatment in the rhizosphere. The addition of the three fertilizers led to significant differences in the relative abundance of bacteria community at the phylum level, such as Proteobacteria, Acidobacteria, Rokubacteria and Planctomycetes in the topsoil, and Chloroflexi, Actinobacteria, Firmicutes and Rokubacteria in the rhizosphere. The same phylum showed the inconsistent changes under different fertilizer treatments in both topsoil and rhizosphere. The dominant genera, i.e., Nitrosospira and Massilia in the topsoil, and Flavobacterium, Nitrosospira and Pseudomonas in the rhizosphere, were much higher under the FS treatment than others. Redundancy analysis showed that total nitrogen and available phosphorus were the key factors that shaped the bacterial community in this ecosystem. These results highlighted that the short-term addition of eco-friendly fertilizer had an improvement effect on the quality of both topsoil and rhizosphere in croplands with long-term chemical fertilizer application.

Lactobacillus rhamnosus GG (ATCC 53103) for the Management of Infantile Colic: A Randomized Controlled Trial.

Background: The aim of this study was to investigate the efficacy of Lactobacillus rhamnosus ATCC 53103 together with the maternal diet avoidance of cow’s milk in treating infantile colic. Methods: Forty-five colicky breastfed infants were consecutively randomized to receive L. rhamnosus for 28 days at a dosage of 5 × 109 cfu per day or placebo. Faecal samples were collected from each subject before starting supplementation and at the end of the study period and were immediately analysed. Faecal calprotectin was detected via a quantitative assay. The total bacterial load and selected bacterial species were evaluated using real-time TaqMan PCR. Results: After supplementation for 28 days with Lactobacillus rhamnosus ATCC 53103, median full-force daily crying was reduced (104 versus 242 min, p < 0.001) and the values of faecal calprotectin decreased significantly (p = 0.026). Furthermore, the probiotic increased the abundance of Lactobacillus (p = 0.048) and total bacteria (p = 0.040); all these effects were not observed in the placebo group. Conclusion: Infants treated with Lactobacillus rhamnosus ATCC 53103 for 28 days, in association with the elimination of cow’s milk from the maternal diet, presented some interesting features related to the effect of this probiotic treatment: reductions in crying time and faecal calprotectin, with increased total bacteria and Lactobacillus. To validate these results, a double-blind, placebo-controlled trial on a larger cohort is required.

Long-Term Fertilization with Potassium Modifies Soil Biological Quality in K-Rich Soils

Imbalanced fertilization without potassium (K) is a worldwide phenomenon in K-rich soils, but its long-term effects on soil quality are poorly understood. Here, in a wheat–fallow system with K-rich soil, soil nutrients and enzyme activities involved in C, N, P, and S cycling and microbial community composition were studied in a 27-year field study with three treatments: no fertilizer (CK); mineral N and P fertilizer (NP); and mineral N, P, and K fertilizer (NPK). Results revealed that long-term NP and NPK fertilization significantly increased soil quality index (SQI) scores and wheat grain yield by mediating soil fertility, which was characterized by a significant decline in soil pH and increase in soil organic carbon (SOC), total N, available N (AN), available P (AP), enzymatic activities, and the abundance of total bacteria, fungi, and actinomycetes, when compared to CK. NP exhibited significantly higher SOC, AN, AP, microbial biomass C (MBC) and N (MBN), N-acetyl-glucosaminidase, total bacteria, and fungi values compared to NPK; the opposite was true for soil pH and available K. Notably, the differences in wheat grain yield were not statistically significant, while SQI scores in NP (0.86 ± 0.02) were appreciably higher than NPK (0.79 ± 0.03), which was attributed to the differences in MBC, MBN, and microbial communities. Redundancy analysis (RDA) indicated that SOC was the key variable affecting enzymatic activities and microbial community composition. The partial least squares path model (PLS-PM) revealed that fertilization-induced changes in SQI were primarily associated with soil microbiological properties (e.g., microbial community composition), while fertilization-driven increases in wheat grain yield were regulated by the soil nutrients. These results suggest that long-term NPK fertilization decreases soil biological quality in K-rich soils, and further studies are required to elucidate the underlying mechanisms by which K affects soil quality in agricultural systems.

Wastewater Treatment using the “Sulfate Reduction, DenitrificationAnammox and Partial Nitrification (SRDAPN)” Process

Although nitrogen removal from wastewater is essential to prevent eutrophication, the biological processes employed to this end are characterized by several disadvantages, including high energy consumption and the production of large quantities of sludge. Thus, in this study, the organic matter and nitrogen removal efficiencies of the new sulfate reduction, denitrification/anammox and partial nitrification (SRDAPN) process were examined using an anaerobic-anoxic-oxic biofilter reactor. The results showed that the organic matter removal efficiency of the new process at loading rate 1.0 kg COD/m3 per day was 97%. With a circulation flow from the oxic to the anoxic column that was 3 times influent, the nitrogen removal efficiency of the sulfur denitrification and nitrification (SRDN) process without anammox, was 66%, while that of the SRDAPN process with anammox was 76%. Additionally, nitrogen consumption by the anammox reaction in the anoxic column was 13.8% for nitrite-nitrogen and 10.5% for ammonium-nitrogen, and the withdrawal of excess sludge was not required throughout the 170 days of operation. Microbial community analysis showed that acetogenic sulfate reducing bacteria and acetoclastic methanogens coexisted in the anaerobic column, and in the anoxic column, the total relative abundance of anammox bacteria, including Candidatus Brocadia, which coexisted with heterotrophic denitrifying bacteria and sulfur denitrifying bacteria, was 17-18%. Thus, this study established the SRDAPN process as an energy saving and high removal efficiency process.

Evaluating the impact of turf-care products on soil biological health.

Golf courses require extensive use of inputs to meet the needs of playability and aesthetics. The impact of these inputs on soil biological health is largely unknown. Two field trials were conducted at a golf course in Georgia to evaluate short-term effects of wetting agents (Cascade Plus and Duplex [C+D], Revolution [Rev]), plant growth regulators (PrimoMaxx [PM] and Cutless [CL]), and a product called PlantHelper (PH) on soil biological health by measuring microbial abundance and function. Quantitative polymerase chain reaction was used to measure microbial abundance, which included total bacteria, total fungi, and ammonia-oxidizing prokaryotes. Soil respiration and enzyme assays were used as additional indicators of soil health. In bentgrass putting green, total bacteria and ammonia-oxidizing bacteria decreased in abundance in response to the wetting agents and PH, indicating their sensitivity to the products. Whereas C+D stimulated urease activity, Rev and PH caused a short-lived but immediate increase in respiration, indicating that they acted as labile carbon sources. In a bermudagrass fairway, PM was the only product that caused an increase in total bacteria abundance. PrimoMaxx and CL caused a delayed increase in respiration, suggesting that they may have affected the microorganisms indirectly through their impact on root growth and exudate production later. Although CL caused a decrease in urease activity, none of the products significantly affected phosphatase activity. Overall, the products did not seem to have a lasting impact on soil biological health, although long-term studies are needed to confirm these observations.

Varying ensiling conditions affect the fermentation quality and abundance of bacterial key players in lucerne silages

AbstractThe successful ensiling of lucerne (Medicago sativa L.) depends on a rapid acidification in the silo and consequently relies on a sufficient proliferation of, particularly homofermentative, lactic acid bacteria. Similarly, growth of spoilage bacteria, such as enterobacteria and clostridia, must be suppressed and silage additives are therefore frequently applied to promote favourable conditions during ensiling. Three silage additives or soil were applied during lucerne ensiling and investigated for their effects on silage quality characteristics and abundances of total bacteria as well as the bacterial key players Lactobacillus spp., homofermentative Lact. plantarum, heterofermentative Lact. buchneri, Clostridium spp. and Enterobacteriaceae after 30 days of storage. Inoculation with viable Lact. plantarum resulted in highest concentration of this species and excellent silage quality, i.e. high lactic acid concentration coupled with low acetic acid and ammonia-nitrogen concentrations. A sodium nitrite and hexamine-based additive did not support growth of lactic acid bacteria, which was also apparent by higher pH and low lactic acid concentration. No effect of treatments was found on spoilage-related enterobacteria and clostridia, even not when adding soil to lucerne to increase initial clostridial contamination. However, soil treatment resulted in increased ammonia-nitrogen and acetic acid concentrations. Consequently, among the bacterial key players, lactic acid bacteria concentrations were related to silage quality. Regarding spoilage bacteria, however, alterations in silage quality characteristics were not reflected in the abundances of enterobacteria and clostridia. Future investigations should underpin the present findings and help to understand how silage additives affect microbial key players and silage fermentation.

Soil biology characteristics of oil palm land endemic to Ganoderma after four years conversion to sugarcane

Basal stem rot disease is the primary disease in oil palm production. One of the control methods to keep the disease severity low is through crop rotation by planting non-host crops for a certain period to reduce the pathogen population. This study aimed to evaluate the biological and molecular characteristics of Ganoderma endemic land after converted to sugarcane for four years. Results showed that the total abundance of bacteria in the land ranged from 3.5 × 102–6.1 × 108 CFU/g, whereas phosphates solubilizing bacteria, was in the range of 101–1.0 × 106 CFU/g and N fixing bacteria was 101–2.4 × 104 CFU/g. The genus dominated mycorrhizal fungi from Glomus and Acaulospora with spore population of 1 to 135 spores per 25 g of soil. Another soil biota analyzed was Trichoderma sp. that had population range between 102 to 105 CFU/g. Based on PCR analyses using specific primers Gan2 and Gan3, Ganoderma fungi were still detected in selected soil samples and the remaining roots in the field. Nevertheless, the productivity of sugarcane up to 4 ratoons remained high, i.e. more than 90 t/ha.

Anti-inflammatory effects of Lactobacillus johnsonii L531 in a pig model of Salmonella Infantis infection involves modulation of CCR6+ T cell responses and ER stress

Probiotic pretreatment is an effective non-antibiotic strategy for preventing or controlling Salmonella infections. We found that Lactobacillus johnsonii L531, isolated from the colon of a clinically healthy weaned piglet, effectively prevented infection with Salmonella enterica serovar Infantis in a pig model. Newly weaned piglets were intragastrically administered Lactobacillus johnsonii L531 at 1.0 × 1010 CFU/day for 1 week before S. Infantis challenge. Pretreatment with L. johnsonii L531 lessened the severity of diarrhea and ileal inflammation in S. Infantis–infected piglets. Lactobacilli were more abundant in the ileum than jejunum after L. johnsonii L531 pretreatment. Treatment with L. johnsonii L531 reduced the abundance of total bacteria in the ileal mucosa and the production of lipocalin 2 in the jejunum of piglets challenged with Salmonella. Both intestinal morphology and transmission electron microscopy results indicated that L. johnsonii L531 alleviated intestinal tissue damage following S. Infantis challenge, especially in the villus and endoplasmic reticulum (ER). ER stress induced by S. Infantis was attenuated by L. johnsonii L531 treatment. The number of CD4− CCR6+ T cells decreased following S. Infantis challenge, but the percentage of CCR6− IFNγ+ T cells in peripheral blood increased. In intestinal mesenteric lymph nodes, S. Infantis increased the proportion of CCR6+ IFNγ+ T cells, whereas L. johnsonii L531 induced an increase in the proportion of CD4+ CCR6+ T cells in response to S. Infantis infection. Our data thus suggest that L. johnsonii L531 contributes to the maintenance of intestinal homeostasis by modulating T-cell responses and ER stress.

Degradation of BDE-47 in mangrove sediments with amendment of extra carbon sources

Polybrominated diphenyl ethers (PBDEs) are widely detected in coastal wetlands but their remediation is still difficult. In this study, different carbon sources, namely formate, acetate, pyruvate, lactate, succinate, methanol and ethanol, were added to mangrove sediments contaminated with BDE-47, a common PBDE congener, to enhance its degradation. After 2-month incubation, all carbon addition significantly enhanced degradation percentages. The residual BDE-47 percentage significantly correlated with the abundance of total bacteria and Dehalococcoides spp. The addition of methanol, acetate and succinate also achieved significantly higher degradation rates and shorter half-lives than sediments without carbon amendment at the end of 5-month incubation, although degradation percentages were comparable between sediments with and without extra carbon. The degradation pathway based on the profiles of degradation products was also similar among treatments. The results indicated the stimulatory effect of extra carbon sources on BDE-47 degradation in contaminated sediments was carbon- and time-specific.

Microbial community composition in different carbon source types of biofilm A/O-MBR systems with complete sludge retention

ABSTRACT In this study, the three biofilm-anoxic-oxic-MBR systems were operated in parallel using different carbon source feed types. The three systems were operated with complete sludge retention to compare microbial community composition and system efficiency. High average removal of ammonia and COD was obtained in the three reactors. However, total nitrogen and total phosphorus removal efficiency were significantly higher in the VFAs feed systems when compared with the glucose feed system. The highest and most stable BNR efficiency was observed when acetate was used as a carbon source. The qPCR analysis revealed that ammonium oxidizing bacteria, denitrifiers and total bacteria were all highest in the acetate feed system followed by the propionate feed system. Moreover, among all carbon source types, the PUS-biofilm could maintain a higher degree of abundance of total bacteria than the sludge biomass. Meanwhile, ammonium oxidizing bacteria and denitrifiers were enriched in the sludge biomass rather than in the PUS-biofilm. The results of illumina sequencing revealed that acetate followed by propionate were favourable to the growth of microorganisms that were associated with the BNR process, which was the main reason for the high efficiency of nutrient removal in the acetate and propionate feed systems.

Substrate availability and soil microbes drive temperature sensitivity of soil organic carbon mineralization to warming along an elevation gradient in subtropical Asia

Subtropical forest soil exerts a large, but uncertain effect on terrestrial carbon (C) cycling. Global warming is anticipated to alter subtropical soil C cycling but currently, there is no consensus on how warming will affect soil C at different elevations. We conducted a short-term laboratory soil warming incubation experiment (ambient temperature +4 °C) along an elevational gradient in Wuyi Mountains of southeastern China to examine the response of soil organic carbon (SOC) mineralization to rising temperatures. Soil samples were collected from three elevations (630 m, 1450 m and 2130 m), and microbial community composition was determined using phospholipid fatty acids (PLFAs). The SOC mineralization increased with rising mean annual temperature (i.e., with decreasing elevation) and with experimental warming. Unlike most other similar experimental studies, we found that the temperature sensitivity (Q10) of SOC mineralization to short-term experimental warming significantly decreased with increasing elevation. We also found that temperature sensitivity of SOC mineralization in response to warming depends on substrate availability, as indicated by the significant relationship between dissolved organic carbon (DOC) and Q10 values. In addition, soil microbial biomass increased significantly with increasing elevations, but was not significantly affected by short-term experimental warming. Experimental warming reduced the abundance of total PLFAs, bacteria, fungi, and actinomycetes in the low-elevation soil. Experimental warming significantly changed soil microbial community composition at low elevation, with increases in the ratios of cyclopropyl to monoenoic precursor fatty acids (cy:pre), saturated to monounsaturated fatty acids (sat:mono), and isomers to trans-isomers fatty acids (i:a), all of which are stress indicators, indicating that warming treatment increased microbial respiration rather than microbial growth, because the microbial respiration per biomass increases under environmental stress. Microorganisms likely altered their membrane fatty acid components and mass in response to changes in available C. The differences in Q10 associated with short-term warming and among elevations with long-term temperature differences indicate that the effect of warming on SOC mineralization may change through time and this should be taken into account when predicting SOC mineralization in response to continual rising temperatures.

Translocating subtropical forest soils to a warmer region alters microbial communities and increases the decomposition of mineral-associated organic carbon

It is not clear how soil organic carbon (SOC) and its related microbial processes respond to climate warming in subtropical forest, which limits our ability to predict the response and feedback of such forests to future warming. Here, we translocated a forest microcosm from a high-elevation site to a low-elevation site (600 m–30 m a.s.l.) in a subtropical forest, to study the responses of SOC fractions, microbial communities and enzyme activities to increases in soil temperature (ca. 1.69 °C). Results showed that translocation to a warmer region significantly decreased the total SOC content by an average of 21.1% after three years of soil warming. Warming non-significantly decreased the particulate organic C (POC) and microbial C (MBC) content by 15.7% and 15.2%, respectively, and increased the light fraction organic C (LFOC) and dissolved organic C (DOC) content by 15.5% and 2.3%, respectively. By contrast, warming significantly decreased the <53 μm fraction organic C (N-POC, −15.3%) and heavy fraction organic C (HFOC, −14.8%) content. Warming significantly decreased the relative abundance of total bacteria (−2.7%), G+ bacteria (−6.1%), G− bacteria (−6.6%) and actinomycetes (−10.8%), but increased the relative abundance of fungi (+22%). The oxidase and mass-specific oxidase activities were significantly increased by 32–70% in the warming soils. The decline in the N-POC was highly correlated to the increases in the relative abundance of fungi, the ratio of fungal to bacterial biomass (F:B), oxidase and mass-specific oxidase activities. Our results suggest that climate warming may increase the potential for fungal decomposition of mineral-associated organic C by increasing oxidase activities, leading to greater C losses in the subtropical forest than previously estimated.

Abundance and Spatial Distribution of Aerobic Anoxygenic Phototrophic Bacteria in Tama River, Japan

Aerobic anoxygenic phototrophic bacteria (AAnPB) are widely distributed and regarded as key players driving the carbon cycle in surface water of global oceans, coastal and estuary areas and in other freshwater environments (e.g., ponds and lakes). However, the abundance and spatial distribution of AAnPB in rivers is much less well-known. Here we investigated the variation of the absolute cell abundances of the total bacteria, AAnPB and cyanobacteria, at four different sites in Tama River, Japan, and the spatial distribution (i.e., free-living or particle-attached existence form) of AAnPB at two out of the four sites using infra-red epifluorescence microscopy. Free-living cell abundances for the total bacteria, AAnPB and cyanobacteria were 1.6–3 × 105, 1.5–4.4 × 104 and &lt;3.2 × 104 cells mL−1, respectively. The free-living AAnPB accounted for 6.1%–19.6% of the total bacterial abundance in the river. The peaks of the AAnPB and cyanobacteria abundances were found at the same site, suggesting that the AAnPB could potentially coexist with cyanobacteria. Meanwhile, the particle-attached AAnPB were observed at the two sites of the river, accounting for 52.2% of the total bacteria abundance in the particle. Our results showed the existence and aggregation form of AAnPB in the riverine environment.

Incident of algae blooms of Lake Svyatozero (Karelia, Russia)

The article presents results of the investigation of the littoral zone state in the northern part of Lake Svyatozero (Karelia) according to microbiological and phytoplankton indicators. We studied the causes of the appearance of a bloom spot in September 2019. The total abundance of bacteria was 6.42106 cells/ml, the abundance of saprophytic bacteria growing at 22 was 20.3103 CFU/ml, saprophytic bacteria growing at 37 was 1.74103 CFU/ml. The development of bacteria indicated that self-purification processes were completed. The total abundance of phytoplankton was 198712.5103 cells/l, and the total biomass was 14.945 mg/l. A total of 17 phytoplankton species were identified, 14 of which were ranked Cyanophyta (96.7% of the total abundance and 99.8% of the total biomass). Microcystis aeruginosa inhibiting the development of bacterioplankton was found in the water. Blooming of blue-green algae was apparently due to secondary pollution of the water body following low water level, wind intensity, waterborne soil movement, and warm weather. During the study period, water from the littoral zone in the northern part of Lake Svyatozero was estimated as highly polluted with the quality class 4 and was characterized as a stopgap measure from mesotrophic to the eutrophic water body.