Indigenous Microbes Research Articles

Host habitat is the major determinant of the gut microbiome of fish

BackgroundOur understanding of the gut microbiota of animals is largely based on studies of mammals. To better understand the evolutionary basis of symbiotic relationships between animal hosts and indigenous microbes, it is necessary to investigate the gut microbiota of non-mammalian vertebrate species. In particular, fish have the highest species diversity among groups of vertebrates, with approximately 33,000 species. In this study, we comprehensively characterized gut bacterial communities in fish.ResultsWe analyzed 227 individual fish representing 14 orders, 42 families, 79 genera, and 85 species. The fish gut microbiota was dominated by Proteobacteria (51.7%) and Firmicutes (13.5%), different from the dominant taxa reported in terrestrial vertebrates (Firmicutes and Bacteroidetes). The gut microbial community in fish was more strongly shaped by host habitat than by host taxonomy or trophic level. Using a machine learning approach trained on the microbial community composition or predicted functional profiles, we found that the host habitat exhibited the highest classification accuracy. Principal coordinate analysis revealed that the gut bacterial community of fish differs significantly from those of other vertebrate classes (reptiles, birds, and mammals).ConclusionsCollectively, these data provide a reference for future studies of the gut microbiome of aquatic animals as well as insights into the relationship between fish and their gut bacteria, including the key role of host habitat and the distinct compositions in comparison with those of mammals, reptiles, and birds.2jWna3AEmgLMLS436bvUkuVideo

Methanogenic Biodegradation of iso-Alkanes by Indigenous Microbes from Two Different Oil Sands Tailings Ponds.

iso-Alkanes, a major fraction of the solvents used in bitumen extraction from oil sand ores, are slow to biodegrade in anaerobic tailings ponds. We investigated methanogenic biodegradation of iso-alkane mixtures comprising either three (2-methylbutane, 2-methylpentane, 3-methylpentane) or five (2-methylbutane, 2-methylpentane, 2-methylhexane, 2-methylheptane, 2-methyloctane) iso-alkanes representing paraffinic and naphtha solvents, respectively. Mature fine tailings (MFT) collected from two tailings ponds, having different residual solvents (paraffinic solvent in Canadian Natural Upgrading Limited (CNUL) and naphtha in Canadian Natural Resources Limited (CNRL)), were amended separately with the two mixtures and incubated in microcosms for ~1600 d. The indigenous microbes in CNUL MFT produced methane from the three-iso-alkane mixture after a lag of ~200 d, completely depleting 2-methylpentane while partially depleting 2-methylbutane and 3-methylpentane. CNRL MFT exhibited a similar degradation pattern for the three iso-alkanes after a lag phase of ~700 d, but required 1200 d before beginning to produce methane from the five-iso-alkane mixture, preferentially depleting components in the order of decreasing carbon chain length. Peptococcaceae members were key iso-alkane-degraders in both CNUL and CNRL MFT but were associated with different archaeal partners. Co-dominance of acetoclastic (Methanosaeta) and hydrogenotrophic (Methanolinea and Methanoregula) methanogens was observed in CNUL MFT during biodegradation of three-iso-alkanes whereas CNRL MFT was enriched in Methanoregula during biodegradation of three-iso-alkanes and in Methanosaeta with five-iso-alkanes. This study highlights the different responses of indigenous methanogenic microbial communities in different oil sands tailings ponds to iso-alkanes.

Soil concentrations, compositional profiles, sources and bioavailability of polychlorinated dibenzo dioxins/furans, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in open municipal dumpsites of Chennai city, India.

Several studies have reported the release of halogenated persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) associated with open burning of municipal solid waste. Considering soil as a sink for such organic contaminants, we conducted an in-depth study on the surface soil concentrations of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and sixteen USEPA enlisted PAHs collected from thirteen zones of the two major municipal dumpsites, Kodungaiyur dumpsite (KDS) and Perungudi dumpsite (PDS) of Chennai city. Indigenous microbes from dumpsite soil samples were isolated and identified based on 16S rRNA sequencing and phylogenetic analysis. Using indigenous microbes, we have elucidated the bioavailability of the targeted organic pollutants for each site.Range of Σ17PCDD/Fs, Σ25PCBs and ∑16PAHs varied between 3.96-612pg/g (96.0pg/g; median), ND-182ng/g (6.35ng/g; median) and 0.62-3649ng/g (64.3ng/g; median), respectively. All the dumpsite samples showed bioavailability for POPs and PAHs. Toxicity equivalent values (TEQs) associated with dioxin-like PCBs and PCDD/Fs from the zones where dumped municipal solid wastes were collected from electronic-waste/IT-corridor/port areas and toxic PAHs from the zone receiving wastes from the industrial corridor of the city were higher than the soil permissible limit prescribed by the World Health Organization.

Intercropping with Chinese leek decreasedMeloidogyne javanicapopulation and shifted microbial community structure in Sacha Inchi plantation

AbstractThe root-knot nematode,Meloidogyne javanica, is a major problem for the production of Sacha Inchi plants. We examined the effects of strip intercropping of Sacha Inchi/Chinese leek of 3–4 years on the seasonal dynamics of plant and soil traits in tropical China. Results indicated that in the intercropping system, a partially temporal divergence of belowground resource acquisition via niche separation occurred throughout the growing seasons, besides a complete spatially-separated plant height between the two crops. Compared with Sacha Inchi monoculture, the increased seed yield per unit area in the intercropping system was mainly attributed to the higher plant survival rate, rather than the enhanced plant traits of healthy plants. Intercropping greatly suppressedM. javanicapopulations only in the wet season, compared with monoculture; which may be associated with the combined effects of the direct allelopathy and indigenous microbe induced-suppressiveness. Intercropping did not affect microbial richness andα-diversity in the rhizosphere, except for the decreased fungal richness. Both bacterial and fungal composition and structure were diverged between monoculturev.intercropping system. The relative abundances of the dominant bacterial genera (Bacillus,Gaiellales,Lactococcus,MassiliaandLysobacter, etc.) differed significantly between the two cropping systems. For fungi, intercropping decreased the relative abundances ofFusariumandGibberella, but increased those ofNectriaceae_unclassified,Chaetomiaceae,HumicolaandMortierella. Overall, Sacha Inchi/Chinese leek intercropping suppressedM. javanicapopulations and shifted microbial compositions (especially decreased pathogen-containingFusarium). The increased yield and economic returns in this intercropping system provide valid information for the effective agricultural management.

Pemberdayaan Kelompok Tani Hortikultura di Lahan Pasir melalui Pemanfaatan Kayambang (Salvinia molesta) sebagai Trichokompos

Lebak swamp weeds such as Kayambang (Salvinia molesta) grow abundantly. They can be used as compost, which effectively improves soil fertility, increasing nutrients N, P, and P K quickly and environmentally friendly. The effectiveness of compost fertilizer needs to be increased by adding indigenous microbes as decomposers and biological agents to control plant diseases. The activities carried out to empower horticultural farmer groups on sandy land in Tanjung Pinang Village, Palangka Raya are through socialization, training in composting with three types of antagonist fungus Trichoderma sp. (Trichocompost), facilitate the procurement of weed chopping machines, assist farmers in horticultural crop cultivation, and increase farmers' independence in self-supporting organic fertilizers. The use of Kayambang as Trichocompost with microbial decomposers and indigenous biological agents is new knowledge for partner farmers. The application of Trichocompost on the demonstration plots shows that eggplant plant growth and yields are excellent, meaning that Trichocompost can improve the fertility of sandy soils. Farmers participating in the training stated that the use of Trichocompost could reduce farming costs because it can substitute for manure that has been used by farmers and can meet the self-help needs of organic fertilizers. Participants wanted an advanced mentoring program because the farmers had not yet mastered the isolation or propagation of biological agents and decomposer microbes.

PASTEURIZATION OF COCONUT WATER AND RICE WASHING WATER AS A SUPPLEMENT FOR EXTENDING THE LIFE OF OYSTER MUSHROOM CULTIVATION MEDIA

This study aims to determine the potential effect of pasteurization on the resistance of coconut water and cherry water as a nutritional supplement in the cultivation of oyster mushrooms ( Pluerotus ostreatus ) and to obtain information on the temperature range and duration of the pasteurization process which can increase nutrient resistance in rice washing water and coconut water so that it can be obtained. the potential use of it is known to extend the life of baglog in oyster mushroom cultivation. This research was conducted from May to October 2020 using the method of review and in-depth literature review. The results showed that the addition of nutrient water and coconut water to the baglog medium had no effect on the number of fruit bodies per clump, the diameter of the fruit caps, the length of the fruit hood stalks, the fruit body weight, and the fruit body weight/baglog of white oyster mushroom ( P. ostreatus ). Heating 80oC for 20 minutes against rice washingwater and heating 80oC for 20 minutes for coconut water has the potential to increase the life of the baglog because it can extend the resistance of the supplement material from premature destruction of indigenous contaminant microbes and environmental physical factors.

Diversity of reductive dechlorinating bacteria and archaea in herbicide/dioxin-contaminated soils from Bien Hoa airbase using metagenomic approach

Heavy herbicide/dioxin contamination of soil was derived a negative effect on the microbial biodiversity, soil quality, animal and human health in Central and South of Vietnam. This is the first time, the application metagenomic tools investigated soil microbial structural community of undetoxified (C - 21,605 ng TEQ/kg dry soil) and bioremediated (BHR - 13.2 ng TEQ/kg dry soil) which could not only help us to explore the potential risks associated with contaminated soils but also provide insights into possible soil bioremediation technology by stimulating indigenous microbes. Four methanogen genera, Methanosarcina (24 - 322 OTUs respectively C – BHR samples), Methanocella (13 - 63 OTUs), Methanosaeta (7 - 42 OTUs) and Methanococcus (6 - 69 OTUs) have been dominantly detected in both two metagenomes. Twenty genera of archaea belonging to the phylum Euryarchaeota were found. They could be clustered within 14 different families and nine archaeal genera including unclassified archaea (17 OTUs – C; 145 OTUs - BHR). In metagenome C and BHR, 12 genera of sulfate reducing bacteria (SRB) with different number (2 - 77; 61 - 904 OTUs) respectively were presented. Four SRB genera are dominated in C metagenome, it is linear also in BHR. The highest number is genus Desulfovibrio detected in both examined metagenomes. However, the relationship features of these bacterial groups need deeply investigation for understanding their role of reductive dechlorination, anaerobic degradation in herbicide/dioxin contaminated heavy soil and sediment. These results provide additional evidence to explain why heavy herbicide/dioxin contaminated soil was detoxified successfully at Bien Hoa airbase, Vietnam.

In-vessel composting of HMX and RDX contaminated sludge using microbes isolated from contaminated site

Current study was carried out with an objective to remediate highly contaminated sludge with HMX and RDX obtained from an explosive manufacturing facility in North India employing indigenous microbes, Arthrobacter subterraneus (isolate no. S2-TSB-17) and Bacillus sonorensis (isolate no. S8-TSB-4) which were isolated from the same contaminated site. In-vessel composting of the explosive contaminated sludge was performed in 12 different bioreactors using cow manure and garden waste as bulking agents. 78.5% degradation of HMX was observed in reactor no. 2 with Bacillus sonorensis having combination of 10% sludge, 70% cow manure and 20% garden waste on 80th day. Two secondary metabolites Bis(hydroxymethyl)nitramine and methylene dinitramine were identified while studying the degradation pathway. Similarly, degradation of 91.2% was observed for RDX in reactor no. 11 with consortia of Arthrobacter subterraneus and Bacillus sonorensis on 80th day. During the study, release of significant nitrate and nitrite ions were observed. It has already been established that RDX and HMX degradation leads to release of nitrite/nitrate ions. The highest nitrite (reactor no. 11) and nitrate (reactor no. 2) release observed were 24.02 ± 0.05 mg/kg and 30.65 ± 0.99 mg/kg on 50th and 70th day, respectively. Scanning electron microscopic studies confirmed the attachment and presence of microbes with solid surface and no deformation in structure was observed in the microbial cells due to contamination stress. Findings of the study concluded that in-vessel composting assisted with native bacterial species can be a potential technology for the treatment of explosive contaminated sludge at the contaminated sites.

Genomics Tools and Microbiota: Applications to Response in Coastal Ecosystems

Abstract Microorganisms are central and cross-cutting to oil spill response strategies. Biodegradation mediated by indigenous microbial communities is the ultimate fate of the majority of petroleum (oil and gas) that enters the marine environment. Key ecosystem services provided by microbes, such as organic matter and nutrient cycling, may be adversely affected by oil contamination. The Deepwater Horizon (DWH) oil spill was the first large scale environmental disaster to which the methods of genomics were applied to determine microbial response to a major perturbation. Here we present a case study on coastal ecosystems to highlight the knowledge gained by application of genomics tools to interrogate mechanisms of petroleum hydrocarbon degradation and to elucidate impacts of oil exposure on ecosystem health and functioning. At Pensacola Beach, results showed that oiling led to a large increase in the growth of indigenous microbes in the form of a series of bacterial blooms. Oil contamination strongly selected for microbial groups capable of hydrocarbon degradation. Oil was degraded and benthic microbial communities returned to near baseline levels approximately one year after oil came ashore. These results indicate that when small particles (< 1 cm) of weathered light oil are buried in the coastal zone, biodegradation by indigenous microbial communities is sufficient for the rapid mitigation of oil contamination after a major spill, whereas larger sand-oil-aggregates take longer to completely degrade because of their unfavorable surface to volume ratio. “Operation Deep Clean” removed these aggregates and enhanced biodegradation insofar as many larger oil aggregates were broken down into smaller ones thereby increasing the surface area available for microbial attack. For environmental managers, these results suggest that biodegradation in beach sands is relatively rapid because oxygen can easily penetrate to the buried oil, and resources may be better placed elsewhere in environments where degradation is limited by oxygen availability or microbial access to hydrocarbons. While specialist microbial groups such as nitrifiers show promise as bioindicators of oil contamination in coastal ecosystems, more work is needed to further validate these biomarkers. Despite substantial progress, a predictive understanding of the fate and impacts of oil spills remains hampered by challenges in interpreting the in situ activity and ecosystem response of benthic microbial populations. To advance this understanding, a dedicated funding mechanism is needed to support fundamental research. A polyphasic approach is encouraged that employs metagenomics in the field along with cultivation and microcosm or mesocosm experiments in the laboratory. Further, research during future disasters would be greatly facilitated by improved coordination between the emergency responders directing mitigation efforts and scientists investigating the success of those efforts.

Optimization and Degradation Studies on Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) with Selected Indigenous Microbes under Aerobic Conditions

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) a nitramine explosive, which has contaminated various military sites during its use, storage and manufacturing worldwide. As RDX is a recalcitrant, less soluble and toxic to human beings and other organisms, it is essential to remediate the contaminated sites. In the current investigation, authors have explored the potential of two indigenous microbes i.e., Bacillus toyonensis (isolate No. WS4-TSB-3, MTCC No. 12857) and Paenibacillus dendritiformis (isolate No. S10-TSA-3, MTCC No. 12859) isolated from an explosive manufacturing facility in north India, for the degradation of RDX in aqueous medium. Furthermore, RDX degradation has been optimized using response surface methodology (RSM) in a 15 days experiment at concentration of 20, 40, and 60 mg/L. It was found that various factors such as initial concentration of RDX, inoculum volume (2, 4 and 6%) and time (5, 10 and 15 days) had impact on transformation and degradation of contaminant. Samples were analyzed using high performance liquid chromatography (HPLC) and intermediate products were identified using LC-MS/MS. Maximum RDX removal of 81.6 ± 1.3 and 84.7 ± 0.9% for Bacillus toyonensis (isolate No. WS4-TSB-3) and Paenibacillus dendritiformis (isolate No. S10-TSA-3), respectively, was observed on 15th day at 40 mg/L initial concentration. During the degradation Hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), Hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), 4-Nitro-2,4-diazabutanal, Bis(hydroxymethyl)nitramine and nitrite were identified as intermediate products. The findings of the investigation suggest that both the microbes have the potential to degrade RDX in the aqueous medium and can be used for up-scaling the degradation of RDX on explosive contaminated sites.

High level of conservation and diversity among the endophytic seed bacteriome in eight alpine grassland species growing at the Qinghai Tibetan Plateau.

Seed borne microorganisms play an important role in plant biology. Concerns have recently been raised about loss of seed microbial diversity by seed treatments, crop domestication and plant breeding. Information on the seed microbiomes of native plants growing in natural ecosystems is beneficial as they provide the best settings to detect indigenous plant microbe interactions. Here, we characterized the seed bacterial community of 8 native alpine grassland plants. First, seed bacterial diversity was examined using Illumina DNA sequencing, then 28 cultivable bacteria were isolated and potential functions were explored. Across 8 plant species, 343 different bacterial genera were identified as seed endophytes, 31 of those were found in all plant species, indicating a high level of conservation. Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Chloroflexi were the top five dominant phyla. Plant species identity was a key determinant shaping the seed endophytic bacteriome. ACC deaminase activity, siderophores production and secretion of lytic enzymes were common functions shown by isolated bacteria. Our results demonstrate that highly diverse and beneficial bacterial populations are hosted by seeds of alpine grassland species to ensure the establishment of best bacterial symbionts for the next generation. This information is useful for crop improvement by reinstating beneficial seed microbial diversities for high-quality forage and crop seeds.

Soil fertility and rice productivity in shifting cultivation: impact of fallow lengths and soil amendments in Lengpui, Mizoram northeast India

An exponential increase in the human population has drastically reduced the length of fallow period (<5 years) in widely spread shifting cultivation (Jhum). This has increased the invasion of weeds and decreased soil fertility and crop productivity, and consequently raised concern of food security for the local farming communities. The present study was conducted in two jhum fallows (FL-10 and FL-15) to understand the response of fallow length and applications of indigenous soil microbes and rock phosphate on the levels of soil fertility and crop productivity. The results showed greater soil physicochemical properties in FL-15 compared to FL-10. Burning significantly increased the levels of soil pH, avail P, avail N in the soil, whereas, the same decreased the levels of soil C, MBC and SM in both the sites. Among treatments, the synergistic effect of rock phosphate and microbial inocula showed greater improvement in soil biochemical properties, and showed a climactic increase over control in crop productivity and rice yield in all sites. Maximum rice grain yield and productivity was recorded in FL-15 followed by FL-10. This study concludes that a mixture of rock phosphate and microbial inocula from the rhizosphere soil of early regenerating plant is effective in increasing soil fertility and crop productivity, and can be used as an important tool to sustain crop productivity and food security in the region.

Co-existing siderite alleviates the Fe(II) oxidation-induced inactivation of Fe(III)-reducing bacteria.

Abiotic Fe (II) oxidation widely occurs in the natural subsurface environment and engineered dynamic processes, which possibly impacts the growth of indigenous microbes. As previously discovered, the oxidation of aqueous Fe2+ at neutral pH effectively inactivates iron-reducing bacteria Shewanella oneidensis strain MR-1 (MR-1). Herein, the impacts of co-existing iron mineral on the oxidation of aqueous Fe2+ and the subsequent disinfection activity on MR-1 were investigated with siderite selected as a representative iron mineral in the subsurface environment. The oxidation rate of aqueous Fe2+ and the amount of generated OH radical increased as the content of siderite increased, while the MR-1 inactivation was alleviated. An initial concentration of 2.0 × 106 CFU/mL MR-1 was inactivated by about 2.7 orders of magnitude during oxidation of 0.2 mM FeSO4 alone for 30 min, which was reduced to only about 0.6 orders of magnitude in the presence of 4.3 mM co-existing siderite. ROS scavenging results confirmed that the OH radical generated in the bulk solution was not the leading role for the inactivation of MR-1. Morphological changes of the cells observed by SEM demonstrated that the disruption of the cell membrane was alleviated by siderite, which was further supported by the XRD and FTIR spectra. The underlying mechanism was proposed to be the reduced contact time of Fe2+ and MR-1 cells due to the accelerated oxidation. This work provides new insights into the disinfection behavior of heterogeneous Fe (II) oxidation on iron cycling bacterial in the natural environment.

Arsenic reduction and mobilization cycle via microbial activities prevailing in the Holocene aquifers of Brahmaputra flood plain

Arsenic mobilization and immobilization are primarily controlled via hydrogeological and microbiological activity in an alluvial flood plain. In this study, two distinctly different high (HAsCR) and low (LAsCR) arsenic contaminated regions were selected. Morphological analysis of sediment samples showed the presence of authigenic (viz. magnetite) in HAsCR whereas detrital minerals (viz. flaky muscovite) morphology observed in the LAsCR study area. Indigenous arsenic-reducing microbes were isolated from groundwater samples of both study areas. The identified microbial species are Lysinibacillus sphaericus,Acinetobacter nosocomialis,Pseudomonas aeruginosa and Bacillus licheniformis showed a significant As tolerance limit and depicted their capability to enhance the dissolved arsenate [As(V)] concentration in the study area groundwater aquifers. This collective study for sediment color and microbiology analysis of two representative alluvial regions, suggested that the redox aquifer condition is favorable for the reductive dissolution mechanism of iron along with arsenate-reducing microorganism, which found main cause for the heterogeneous distribution of dissolved arsenic. This study bridges the knowledge gap between causes for heterogeneous concentration distribution of As in alluvial aquifer and the role of arsenate reducing bacteria in high and low As contaminated groundwater regions.

Naphthalene degradation studies using Pseudomonas sp. strain SA3 from Alang-Sosiya ship breaking yard, Gujarat

Polycyclic aromatic hydrocarbons (PAHs) remediation has received considerable attention due to their significant health concern and environmental pollution. However, PAHs contaminated sites also contain indigenous microbes that can potentially degrade naphthalene. Therefore, this study aimed to isolate, characterise and optimise process parameters for efficient naphthalene degradation. A total of 50 naphthalene degrading bacteria were isolated from Alang-Sosiya ship breaking yard, Bhavnagar, Gujarat and screened for their naphthalene degrading capacity. The selected isolate, Pseudomonas sp. strain SA3 was found to degrade 98.74 ± 0.00% naphthalene at a concentration of 500 ppm after 96 h. Further, optimisation of environmental parameters using one factor at a time approach using different inoculum sizes (v/v), pH, salinity, temperature, carbon and nitrogen source greatly accelerated the degradation process attaining 98.6 ± 0.46% naphthalene degradation after 72 h. The optimised parameters for maximum naphthalene degradation were pH 8, 0.1% peptone as nitrogen source, 8% salinity and 1% (v/v) inoculum size.

Nutrient Stimulation of Indigenous Microorganisms for Oil-in-Water Emulsion in a Medium Temperature Petroleum Reservoir with Ca2+-Rich Brine

One of the challenges indigenous microbial enhanced oil recovery (MEOR) is facing is the high percentage of divalent ions, which obstruct the growth and metabolism of microorganisms and destabilize the oil-in-water (o/w) emulsion. Six formulas were selected for the stimulation of indigenous microbes and to compare their performances on the oil emulsification and oil spreading in the Luliang oilfield containing Ca2+-rich brine. Illumina MiSeq sequencing of 16S rRNA genes was applied to investigate the structural response of microbial communities to various formulas. The results showed that the addition of proper organic phosphorus and the optimal P/N ratio (0.01) can facilitate production of biosurfactant and create stable o/w emulsion with specific reservoir condition containing Ca2+-rich brine, through direct stimulation of certain functional microbes. This study provides a promising path for direct enrichment of biosurfactant-producing and oil-degrading Dietzia genus and a potential instructional approach of indigenous MEOR in Luliang oilfield.

Stingless Bee-Collected Pollen (Bee Bread): Chemical and Microbiology Properties and Health Benefits.

Stingless bee-collected pollen (bee bread) is a mixture of bee pollen, bee salivary enzymes, and regurgitated honey, fermented by indigenous microbes during storage in the cerumen pot. Current literature data for bee bread is overshadowed by bee pollen, particularly of honeybee Apis. In regions such as South America, Australia, and Southeast Asia, information on stingless bee bee bread is mainly sought to promote the meliponiculture industry for socioeconomic development. This review aims to highlight the physicochemical properties and health benefits of bee bread from the stingless bee. In addition, it describes the current progress on identification of beneficial microbes associated with bee bread and its relation to the bee gut. This review provides the basis for promoting research on stingless bee bee bread, its nutrients, and microbes for application in the food and pharmaceutical industries.

Microbial inoculation elicited changes in phyllosphere microbial communities and host immunity suppress Magnaporthe oryzae in a susceptible rice cultivar

The hemibiotrophic fungal pathogen Magnaporthe oryzae causes serious crop losses in rice. As phyllospheric microbes share a common habitat with this foliar pathogen, they can be deployed as the change-agents for engineering desired phyllospheric microbial communities to inhibit the disease progression. Comparative evaluation of a set of native microbes, when applied as foliar spray or soil drench was undertaken, showed significant interactive effects on the concentrations of chlorophyll a and b, and carotenoids. A significant enhancement was recorded in the activities of chitosanase, β-1,3-endoglucanase and β-1,4-endoglucanase (CMCase) in the disease challenged plants, as compared to healthy plants. Among the treatments, Bacillus sp. (B1) inoculation recorded lowest values of the activities of all three hydrolytic enzymes, while Bacillus sp. (B4) and Nostoc-Anabaena consortium (C1) led to 30–60% decreases, both as foliar and soil drench modes of application. Distinct changes in the abundances of eubacterial and phylum Cyanobacterial 16S rRNA gene copies, nifH and bacterial amoA illustrated the significance of foliar over the soil drench method. The nifH gene copies were significantly higher due to the foliar method of Calothrix sp. (C2) inoculation, and values were significantly at par values with both the soil drench application of B1 (Bacillus sp.) and C1 (Nostoc-Anabaena consortium) treatments. This study illustrates the significance of the root-shoot linkages in the effective biocontrol of these promising, indigenous microbes, applied as soil drench or foliar agents, which can be useful in abating the incidence of the fungal pathogen in an environment –friendly manner.

Fructans with Varying Degree of Polymerization Enhance the Selective Growth of Bifidobacterium animalis subsp. lactis BB-12 in the Human Gut Microbiome In Vitro

Synbiotics aim to improve gastrointestinal health by combining pre- and probiotics. This study evaluated combinations of Bifidobacterium animalis subsp. lactis BB-12 with seven fructans: oligofructoses (OF1-OF2; low degree of polymerization (DP)), inulins (IN1-IN2-IN3; high DP) and OF/IN mixtures (OF/IN1-OF/IN2). During monoculture incubations, all fructans were fermented by BB-12 as followed from increased BB-12 numbers and increased acetate and lactate concentrations, with most pronounced fermentation for low DP fructans (OF1-OF2). Further, short-term colonic incubations for three human donors revealed that also in presence of a complex microbiota, all fructans (particularly OF1) consistently selectively enhanced the growth of BB-12. While each fructan as such already increased Bifidobacteriaceae numbers with 0.94–1.26 log(cells/mL), BB-12 co-supplementation additionally increased Bifidobacteriaceae with 0.17–0.46 log(cells/mL). Further, when co-supplemented with fructans, BB-12 decreased Enterobacteriaceae numbers (significant except for IN1-IN3). At metabolic level, all fructans decreased pH due to increased acetate and lactate production, while OF/IN2-IN1-IN2-IN3 also stimulated propionate and butyrate production. BB-12 co-supplementation further increased propionate and butyrate for OF/IN2-IN3 and IN1-IN2, respectively. Overall, combinations of BB-12 with fructans are promising synbiotic concepts, likely due to intracellular consumption of low DP-fructans by BB-12 (either present in starting product or released upon fermentation by indigenous microbes), thereby enhancing effects of the co-administered fructan.

Dynamic variations of dissolved organic matter from treated wastewater effluent in the receiving water: Photo- and bio-degradation kinetics and its environmental implications

Dissolved effluent organic matter (dEfOM) from wastewater treatment plants (WWTPs) is bound to encounter photo- and bio-degradation as discharged into the receiving water body. However, the comprehensive variations of dEfOM by photo- and bio-degradation are not well unveiled because of its compositional heterogeneity. In this work, dissolved organic carbon (DOC) concentrations, UV–Vis and fluorescent spectra combined with fluorescence regional integration (FRI) analysis were used to investigate the changes in bulk dEfOM and its fluorescent components during photo- and bio-degradation processes in the receiving water body. Results showed that 48.49%–69.62% of the discharged dEfOM was decomposed by ultra violet (UV)-irradiation and indigenous microbes, while the others (33%–45%) were recalcitrant and stable in the receiving water body. Specifically, the photo- and bio-degradation of chromophoric, fluorescent dEfOM and its components were found to follow the single or double exponential kinetic model, and the differences in photo- and bio-degradability of each components shifted its composition. Furthermore, results of bio-degradation after UV-irradiated dEfOM indicated that there was overlapping of photo- and bio-degradable fractions in dEfOM, and photoreactions could improve the self-production of natural organic matter in the receiving water body. These results could improve the understanding the fate of discharged dEfOM in the receiving water body, and we proposed some cost-effective strategies for discharging WWTPs effluent.