Indigenous Microbes Research Articles

Conversion of chicken viscera into protein hydrolysate for palatant production

Flavor and aroma cannot be separated in food industries. The manipulation of the ingredients to increase the taste has started since early civilization. Common example of the earliest application of ingredients to increase the savory taste of the food is soy sauce production. The process of digging out the aroma and flavor includes frying, stewing, grilling as well as fermenting. Nowadays, much complex savory system in food can be achieved through several processes such as Maillard reaction and protein hydrolysate production. The food produced will not only be tasty but healthy. This concept was first focusing on human food production. However, the increasing number of pet owner for about 10% annually since 2008 as reported by US Pet Owner Society demands the same concept to be implemented in pet food industries. Since most pet owners considered their pets as part of their family, the pet food source from 4D (dead, dying, disable and diseased) animals are unacceptable. Therefore, the pet food industries are competing with human food industries to get the clean source of meat for food as well for flavor production. An alternative to overcome this is by utilizing the viscera of the slaughtered chicken for palatant or flavor production. Aside from meat, bones and feathers, viscera are also abundantly being considered as waste and were not fully utilized. They are rich in protein. The protein can be recovered using suitable process and later turned into a value-added product such as flavor. There is a study available for converting the protein waste into protein hydrolysate via chemical and physical technique. However, only few reports are available for the conversion process via indigenous microbes and enzymes. It is believed that the indigenous microbes and enzymes (protease, peptinase) can be utilized for protein hydrolysate production which will later can be utilized as palatant. The palatant produced should have Sulphur-based aroma compound such as 2-methyl-3-furanthiol and 2-furfuryl-thiol which serve as precursors for chicken aroma.

INDUCED DEGRADATION OF CRUDE OIL POLLUTED SOIL BY MICROBIAL AUGMENTATION

This study was aimed at assessing the effectiveness of indigenous microbes for remediation of hydrocarbon contaminated soil by first increasing the population of the indigenous microbes via bioaugmentation. Soil samples were treated using a consortium of bacteria: Bacillus substilis and Pseudomonas sp. which were isolated and cultured from the contaminated soil. The non-bacteria injected soil sample had the highest hydrocarbon content (THC) of 271.021 in comparison with the other soil samples. The THC percentage removal of B1 (96.885 %), B2 (97.562 %), B3 (98.835 %), B4 (99.594 %) and B5 (99.540 %) were higher than that of the control; indicating that biodegradation actually took place.

Mechanism of aerobic denitrifiers and calcium nitrate on urban river sediment remediation

Calcium nitrate, coupled with aerobic denitrifiers, were applied to reduce nitrogen and organic pollutants of urban river sediment. 115-day remediation tests showed that total nitrogen in the sediment decreased by 16.5%, while total transferable nitrogen increased from 0.097 to 0.109 mg/g. Increased urease activity and decreased protease showed a potential for further nitrogen degradation. Although the total organic carbon (TOC) content decreased slightly, the predominant organic pollutants were removed or converted to low molecular weight compounds through microbial biodegradation. Decreased phenol oxidase activity exhibited that low concentrations of recalcitrant aromatic compounds remained in the sediment. The high-throughput sequencing results reveals that the community diversity of bacteria markedly increased. Compared with the addition of calcium nitrate or aerobic denitrifiers alone, genera mainly removed nitrogen and organic compounds, especially recalcitrant compounds, following the treatment with the combination technology. Moreover, the concentrations of nitrogen and organic matter did not increase significantly in the overlying water, which was free of undesirable secondary pollution. During the process of remediation, dosing with nitrate may provide a more favorable environment for aerobic denitrifiers and indigenous microbes in the sediment. Furthermore, the introduced aerobic denitrifiers may improve nitrogen removal and have a collaborative effect with indigenous microbes.

Effects of metam sodium fumigation on the abundance, activity, and diversity of soil bacterial communities

Metam sodium is a fumigant used as a crop pretreatment in agriculture to control a wide array of pests, and soil borne diseases that may adversely affect plant quantity and quality. This present study utilized control and treated field plots to examine the effects of metam sodium on indigenous soil microbes in terms of numbers, activity, and diversity. Following metam sodium application, culturable heterotrophic counts in all soils increased significantly for 24h, but quickly returned back to original levels. Application resulted in decreased microbial activity, detected by ATP-based assays, that was significantly lower in treated soils than control plots, but recovered quickly. High-throughput sequencing of the 16S rRNA gene showed that treated plots contained significantly lower numbers of observed OTUs, particularly 14, 21, and 28days after treatment. Soil bacterial communities were significantly altered by MS-treatment due to increased relative abundances of Actinomycetales, Bacilli, and Chloroflexi, as well as decreased Acidobacteria. These dominant taxa observed in MS-treated plots are major contributors to biological activity in various healthy soils and rhizospheres. Therefore, the increase in relative abundance of these biologically productive phyla coupled with abundant ATP production suggests that soil health recovered following MS-treatment and remained functionally intact.

Influence of organic matter, nutrients, and cyclodextrin on microbial and chemical herbicide and degradate dissipation in subsurface sediment slurries

Pesticides leaching from soil to surface and groundwater are a global threat for drinking water safety, as no cleaning methods occur for groundwater environment. We examined whether peat, compost-peat-sand (CPS) mixture, NH4NO3, NH4NO3 with sodium citrate (Na-citrate), and the surfactant methyl-β-cyclodextrin additions enhance atrazine, simazine, hexazinone, dichlobenil, and the degradate 2,6-dichlorobenzamide (BAM) dissipations in sediment slurries under aerobic and anaerobic conditions, with sterilized controls. The vadose zone sediment cores were drilled from a depth of 11.3–14.6m in an herbicide-contaminated groundwater area. The peat and CPS enhanced chemical atrazine and simazine dissipation, and the peat enhanced chemical hexazinone dissipation, all oxygen-independently. Dichlobenil dissipated under all conditions, while BAM dissipation was fairly slow and half-lives could not be calculated. The chemical dissipation rates could be associated with the chemical structures and properties of the herbicides, and additive compositions, not with pH. Microbial atrazine degradation was only observed in the Pseudomonas sp. ADP amended slurries, although the sediment slurries were known to contain atrazine-degrading microorganisms. The bioavailability of atrazine in the water phase seemed to be limited, which could be due to complex formation with organic and inorganic colloids. Atrazine degradation by indigenous microbes could not be stimulated by the surfactant methyl-β-cyclodextrin, or by the additives NH4NO3 and NH4NO3 with Na-citrate, although the nitrogen additives increased microbial growth.

Speciation, mobilization, and bioaccessibility of arsenic in geogenic soil profile from Hong Kong.

The behaviour of arsenic (As) from geogenic soil exposed to aerobic conditions is critical to predict the impact of As on the environment, which processes remain unresolved. The current study examined the depth profile of As in geologically derived subsoil cores from Hong Kong and investigated the mobilization, plant availability, and bioaccessibility of As in As-contaminated soil at different depths (0-45.8m). Results indicated significant heterogeneity, with high levels of As in three layers of soil reaching up to 505mg/kg at a depth of 5m, 404mg/kg at a depth of 15m, and 1510mg/kg at a depth of 27-32m. Arsenic in porewater samples was <11.5μg/L in the study site. X-ray absorption spectroscopy (XAS) indicated that main As species in soil was arsenate (As(V)), as adsorbed fraction to Fe oxides (41-69% on goethite and 0-8% on ferrihydrite) or the mineral form scorodite (30-57%). Sequential extraction procedure demonstrated that 0.5±0.4% of As was exchangeable. Aerobic incubation experiments exhibited that a very small amount (0.14-0.48mg/kg) of As was desorbed from the soil because of the stable As(V) complex structure on abundant Fe oxides (mainly goethite), where indigenous microbes partly (59±18%) contributed to the release of As comparing with the sterilized control. Furthermore, no As toxicity in the soil was observed with the growth of ryegrass. The bioaccessibility of As was <27% in the surface soil using simplified bioaccessibility extraction test. Our systematic evaluation indicated that As in the geogenic soil profile from Hong Kong is relatively stable exposing to aerobic environment. Nevertheless, children and workers should avoid incidental contact with excavated soil, because high concentration of As was present in the digestive solution (<0.1-268μg/L).

Novel bacteria capable of degrading phenanthrene in activated sludge revealed by stable-isotope probing coupled with high-throughput sequencing.

The indigenous microorganisms responsible for degrading phenanthrene (PHE) in activated biosludge were identified using DNA-based stable isotope probing. Besides the well-known PHE degraders Burkholderia, Ralstonia, Sinobacteraceae and Arthrobacter, we for the first time linked the taxa Paraburkholderia and Kaistobacter with in situ PHE biodegradation. Analysis of PAH-RHDα gene detected in the heavy DNA fraction of 13C-PHE treatment suggested the mechanisms of horizontal gene transfer or inter-species hybridisation in PAH-RHD gene spread within the microbial community. Additionally, three cultivable PHE degraders, Microbacterium sp. PHE-1, Rhodanobacter sp. PHE-2 and Rhodococcus sp. PHE-3, were isolated from the same activated biosludge. Among them, Rhodanobacter sp. PHE-2 is the first identified strain in its genus with PHE-degrading ability. However, the involvement of these strains in PHE degradation in situ was questionable, due to their limited enrichment in the heavy DNA fraction of 13C-PHE treatment and lack of PAH-RHDα gene found in these isolates. Collectively, our findings provide a deeper understanding of the diversity and functions of indigenous microbes in PHE degradation.

Disease Suppressive Soils: New Insights from the Soil Microbiome

Soils suppressive to soilborne pathogens have been identified worldwide for almost 60 years and attributed mainly to suppressive or antagonistic microorganisms. Rather than identifying, testing and applying potential biocontrol agents in an inundative fashion, research into suppressive soils has attempted to understand how indigenous microbiomes can reduce disease, even in the presence of the pathogen, susceptible host, and favorable environment. Recent advances in next-generation sequencing of microbiomes have provided new tools to reexamine and further characterize the nature of these soils. Two general types of suppression have been described: specific and general suppression, and theories have been developed around these two models. In this review, we will present three examples of currently-studied model systems with features representative of specific and general suppressiveness: suppression to take-all (Gaeumannomyces graminis var. tritici), Rhizoctonia bare patch of wheat (Rhizoctonia solani AG-8), and Streptomyces. To compare and contrast the two models of general versus specific suppression, we propose a number of hypotheses about the nature and ecology of microbial populations and communities of suppressive soils. We outline the potential and limitations of new molecular techniques that can provide novel ways of testing these hypotheses. Finally, we consider how this greater understanding of the phytobiome can facilitate sustainable disease management in agriculture by harnessing the potential of indigenous soil microbes.

Coupling metagenomics with cultivation to select host-specific probiotic micro-organisms for subtropical aquaculture.

To demonstrate a nonempirical workflow to select host-specific probiotics for aquaculture industry. Using both culture-dependent and culture-independent methods, we have systematically investigated, for the first time, the gut microbiota of twelve subtropical aquatic animal species. We found that the diversity, abundance and distribution of gut micro-organisms of these animals were host-specific and that lactic acid bacteria (LAB) were predominant among the indigenous probiotic microbes. Using culturing method, we isolated and characterized ninety-eight LAB strains; however, only a few strains was representative of the dominant LAB OTUs recovered by culture-independent analysis. Two cultured LAB strains, Enterococcus faecalis LS1-2 and Enterococcus faecium Z1-2, capturing the major LAB OTUs in the sequencing data set of the most animal samples and showing significant antimicrobial activities against shrimp pathogens, were suggested to be the candidates of shrimp probiotics. Disease outbreak and the consequential abuse of antibiotics have been the constraints to the aquaculture industry. However, the selection of probiotic bacteria is currently still an empirical process due to our limited knowledge on the gastrointestinal microbiota of aquatic organisms. Our study points to a nonempirical selection process by which host-specific probiotics can be developed.

Habitat and indigenous gut microbes contribute to the plasticity of gut microbiome in oriental river prawn during rapid environmental change.

Growing evidence points out that the capacity of organisms to acclimate or adapt to new habitat conditions basically depends on their phenomic plasticity attributes, of which their gut commensal microbiota might be an essential impact factor. Especially in aquatic organisms, which are in direct and continual contact with the aquatic environment, the complex and dynamic microbiota have significant effects on health and development. However, an understanding of the relative contribution of internal sorting (host genetic) and colonization (environmental) processes is still unclear. To understand how microbial communities differ in response to rapid environmental change, we surveyed and studied the environmental and gut microbiota of native and habitat-exchanged shrimp (Macrobrachium nipponense) using 16S rRNA amplicon sequencing on the Illumina MiSeq platform. Corresponding with microbial diversity of their living water areas, the divergence in gut microbes of lake-to-river shrimp (CK) increased, while that of river-to-lake shrimp (KC) decreased. Importantly, among the candidate environment specific gut microbes in habitat-exchanged shrimp, over half of reads were associated with the indigenous bacteria in native shrimp gut, yet more candidates presented in CK may reflect the complexity of new environment. Our results suggest that shrimp gut microbiota has high plasticity when its host faces environmental changes, even over short timescales. Further, the changes in external environment might influence the gut microbiome not just by providing environment-associated microbes directly, but also by interfering with the composition of indigenous gut bacteria indirectly.

Biocontrol potential of vermicompost through antifungal volatiles produced by indigenous bacteria

As a practical manner for improving soil quality, controlling pathogens and pests, and promoting plant growth, vermicompost is increasingly used in agriculture during these decades. Compared with chemical fungicides, vermicompost exhibits a promising potential for controlling fungal plant pathogens for its effectiveness and environmental friendliness. While as a hotspot for isolating beneficial microorganisms, little is known about the mechanisms underlying the interactions between indigenous beneficial microbes and phytopathogenic fungi. In this study, ten plant pathogenic fungi were used to screen antagonistic bacteria from vermicompost. Then, the antagonistic bacteria were identified based on its morphological, physiological and biochemical characteristics, and 16S rDNA gene sequence analysis, the strain M29 which belongs to Bacillus subtilis showed the broadest spectrum of antifungal ability was selected. The antagonistic effect of the mixed volatile organic compounds (VOCs) released by M29 showed significant inhibitory activity against Botrytis cinerea (BC). Based on the GC–MS analysis, eleven VOCs including alcohols, acids, ketones, esters, ethers and hydrocarbons were identified, and the antifungal activity of purified compounds was tested against BC in different concentrations. 1-butanol, acetic acid butyl ester, 1-heptylene-4-alcohol and 3-methyl-3-hexanol completely inhibited the mycelia growth in vitro at a low concentration of 50μL per dish, while furan-tetrahydro-2,5-dimethyl completely inhibited mycelia growth only at a high concentration of 100μL per dish. Although 2,6-diisocyanato-1-methyl-benzene, 1-propoxy-2-propanol and benzophenone had limited antagonistic effects on suppressing mycelial growth, they could destroy normal hyphae morphology and induce mycelial fragmentation and crumpling as other prominent compounds. Through this study, we demonstrated that as a biocontrol agent, vermicompost can inhibited the development of fungal pathogens through the VOCs released by symbiotic microbes, which may promote more reasonable and effective utilizations of vermicompost in the future.

MITIGATION OF THE TOXIC EFFECTS OF XENOBIOTICS IN MUNG SEEDLINGS BY PLANT SYNERGISTIC BACTERIA

In today’s world, the problems due to the rising pollution are inevitable. A major contributor to this pollution is due to the effluents released by textile industries, chemical factories and others. They adversely affect the agricultural lands nearby leading to the accumulation of xenobiotics and heavy metals in the soil followed by barrenness. A great amount of effort had directed towards the exploration of remedial approach by various workers. Employing the indigenous microbes with degradative capabilities in situ had been a solution to it. Engineering of microbes is the latest trend for degrading a vast spectrum of compounds. The present study aims to isolate bacteria capable of degrading Phenol, Hexane, Toluene and Xylene to test their synergism with the test plant, Vigna radiata. We collected our soil sample from petroleum station. Three-gram negative bacteria (Proteus sp., Pseudomonas sp and Aeromonas sp) and two-gram positive bacteria (Enterococcus sp and Streptococcus sp) were isolated and identified with test compound degradative potential. They were further used to assess their synergism with the study plant by employing hydroponics technique at 100 ppm concentration of test compound. StreptococcusspandProteusspgave a promising result followed by Enterococcus sp. The seedlings experienced a negative inhibitory effect with Aeromonas sp and Pseudomonas sp.

Quantification of Chemotaxis-Related Alkane Accumulation in Acinetobacter baylyi Using Raman Microspectroscopy.

Alkanes are one of the most widespread contaminants in the natural environment, primarily as a consequence of biological synthesis and oil spills. Many indigenous microbes metabolize alkanes, and the chemotaxis and accumulation in some strains has been identified. For the first time, we apply Raman microspectroscopy to identify such chemotaxis-related affinity, and quantify the alkane concentrations via spectral alterations. Raman spectral alterations were only found for the alkane chemo-attractant bacteria Acinetobacter baylyi ADP1, not for Pseudomonas fluorescence, which exhibits limited chemotaxis toward alkane. The significant alterations were attributed to the strong chemotactic ability of A.baylyi enhancing the affinity and accumulation of alkane molecules on cell membranes or cellular internalization. Spectral fingerprints of A.baylyi significantly altered after 1-h exposure to pure alkanes (dodecane or tetradecane) and alkane mixtures (mineral oil or crude oil), but not monocyclic aromatic hydrocarbons (MAHs) or polycyclic aromatic hydrocarbons (PAHs). A semilog linear regression relationship between Raman spectral alterations and alkane concentrations showed its feasibility in quantifying alkane concentration in environmental samples. Pure alkanes or alkane mixtures exhibited different limits of detection and regression slopes, indicating that the chemotaxis-related alkane accumulation in A.baylyi is dependent on the carbon chain length. This work provides a novel biospectroscopy approach to characterize the chemotaxis-related alkane bioaccumulation, and has immense potential for fast and high-throughput screening bacterial chemotaxis.

Characterization of microbial communities during start-up of integrated fixed-film activated sludge (IFAS) systems for the treatment of oil sands process-affected water (OSPW)

In this study, integrated fixed-film activated sludge (IFAS) microbial development and degradation efficiency were investigated for oil sands process-affected water (OSPW) remediation. IFAS microbial community was characterized using 454 high-throughput 16S rRNA gene pyrosequencing that revealed that the IFAS seed sludge (activated sludge [AS] from the Gold Bar Wastewater Treatment Plant [GBWTP]) showed the greatest richness and evenness of bacterial community, as compare to other biomass samples. The Chao 1 value and the Shannon diversity index showed that the bacterial richness and microbial diversity in biofilms were significantly higher than those in flocs in both IFAS systems. Proteobacteria, Nitrospirae, Acidobacteria, and Bacteroidetes were dominant phyla in both flocs and biofilms in IFAS reactors. It is also noted that the phyla and class distributions of flocs and biofilms were significantly different. Principal coordinate analysis (PCoA) indicated that there were substantial differences between OSPW indigenous microbes and flocs and biofilm microbes in IFAS. Overall, a relatively low ozone dose (30mg/L utilized) combined with IFAS reactor treatment significantly increased the organic contaminants removal. The combined ozonation and IFAS system showed the promise for OSPW treatment.

The potential of indigenous Paenibacillus ehimensis BS1 for recovering heavy crude oil by biotransformation to light fractions.

Microbial Enhanced Oil Recovery (MEOR) is a potential technology for residual heavy oil recovery. Many heavy oil fields in Oman and elsewhere have difficulty in crude oil recovery because it is expensive due to its high viscosity. Indigenous microbes are capable of improving the fluidity of heavy oil, by changing its high viscosity and producing lighter oil fractions. Many spore-forming bacteria were isolated from soil samples collected from oil fields in Oman. Among the isolates, an autochthonous spore-forming bacterium was found to enhance heavy oil recovery, which was identified by 16S rDNA sequencing as Paenibacillus ehimensis BS1. The isolate showed maximum growth at high heavy oil concentrations within four days of incubation. Biotransformation of heavy crude oil to light aliphatic and aromatic compounds and its potential in EOR was analyzed under aerobic and anaerobic reservoir conditions. The isolates were grown aerobically in Bushnell-Haas medium with 1% (w/v) heavy crude oil. The crude oil analyzed by GC-MS showed a significant biotransformation from the ninth day of incubation under aerobic conditions. The total biotransformation of heavy crude oil was 67.1% with 45.9% in aliphatic and 85.3% in aromatic fractions. Core flooding experiments were carried out by injecting the isolates in brine supplemented with Bushnell-Haas medium into Berea sandstone cores and were incubated for twelve days under oil reservoir conditions (50°C). The extra recovered oil was analyzed by GC-MS. The residual oil recovered from core flood experiments ranged between 10–13% compared to the control experiment. The GC-MS analyses of the extra recovered oil showed 38.99% biotransformation of heavy to light oil. The results also indicated the presence of 22.9% extra aliphatic compounds in the residual crude oil recovered compared to that of a control. The most abundant compound in the extra recovered crude oil was identified as 1-bromoeicosane. The investigations showed the potential of P. ehimensis BS1 in MEOR technology by the biotransformation of heavy to lighter crude oil under aerobic and reservoir conditions. Heavy oil recovery and biotransformation to lighter components are of great economic value and a few studies have been done.

Chitinolytic microbes confer Meloidogyne incognita resistance and augment secondary metabolites in Bacopa monnieri (L.) Pennell

Meloidogyne incognita (Kofoid and White) Chitwood a calamitous plant pathogen affects almost all the commercial crops, especially medicinal plants viz. Bacopa monnieri L. In this study, the efficacy of indigenous chitinolytic microbes against M. incognita in B. monnieri was evaluated under sterilised and natural soil conditions. The plant growth was observed for various parameters viz. nutrient uptake, phytochemical activities and secondary metabolites (bacoside). In the natural soil under green house conditions, the isolates significantly (P ≤ 0.05) reduced M. incognita infestation (1.38–2.78-folds) with significant increase in secondary metabolites (1.28–1.88-fold) over the untreated control. The potential strains were identified through 16S-rRNA as Streptomyces sp., Microbacterium arabinogalactanolyticum, Cellulosimicrobium cellulans, Actinomycetales bacterium, Chitiniphilus sp. and Flavobacterium johnsoniae. These findings thus highlight the potential of indigenous chitinolytic microbes that can be utilised for overall fitness of the plant along with the reduced root-knot nematode infestation in B. monnieri.

The effects of rice straw biochar on indigenous microbial community and enzymes activity in heavy metal-contaminated sediment

Owning to the potential in carbon sequestration and other environmental benefits, biochar has been widely used for in-situ environmental remediation. Understanding the biological effects of biochar is essential. The goal of this study was to explore the response of indigenous microbes under the stress of different concentrations of biochar. The results showed that biochar could significantly change physicochemical properties, enzymes activity and microbial community composition depending on biochar concentration and incubation time. When the concentration of biochar was 50 mg kg−1, the activities of invertase and alkaline phosphatase were obviously inhibited. Meanwhile, bacterial 16S rRNA and fungal 18S rRNA coding gene copies were decreased by 74% and 25%, respectively after 90 days of incubation. Additionally, the bacterial community succession occurred and the relative intensity of dominant species decreased when treated with high concentration of biochar. However, the activity of urease and alkaline phosphatase, as well as bacterial and fungal abundance, were increased when sediment was treated with 10 mg kg−1 biochar. Relationships among physicochemical properties, heavy metals and microbes were analyzed by correlation analysis and redundancy analysis (RDA). Correlations between invertase activity and pH value in the experiment were significantly negative. Redundancy analysis showed physicochemical properties and heavy metals explained 92% of the variation in the bacterial DGGE profiles and organic matter content explained the majority (45%) of the variation. This study indicated that indigenous microbes could be affected by biochar either directly or indirectly via changing the physicochemical properties and heavy metals of sediment.

Improvement of glycerol waste utilization by co-feedstock with palm oil decanter cake on biohydrogen fermentation

Co-feedstock of palm oil decanter cake with the both functions of substrate and microbial source in biogas fermentation was examined in this study. Decanter cake with the characteristic of high biodegradable organic contents and nutrient rich compositions is an attractive feedstock for biogas production. The various types of bacteria of the indigenous microbes from decanter cake resulted in the enhancement of the biogas productivity based on biogas potential production (Hmax) and energy recovery including glycerol waste utilization. Decanter cake with 2% TS w v−1 used as co-feedstock with varying glycerol waste concentration in the range of 7.5–45 g L−1 were used for the biogas production in 0.5 L batch reactors under the condition of initial pH 7 and 37 °C. Comparative performance of the biogas production using combined decanter cake as co-feedstock and indigenous microbes and sole glycerol waste fermentation with anaerobic sludge as inocula was evaluated. Types of inoculum seeds displayed strong effect on the biogas compositions and glycerol waste utilization. CH4 was the predominant biogas composition, while no H2 was observed in the sole glycerol waste fermentation. H2 production was predominantly detected in the combined decanter cake fermentation. The presence of the anaerobic sludge appeared to promote only methanogenesis resulting shorter fermentation period, lower glycerol waste utilization and biogas production potential (Hmax). The increase of the glycerol waste concentration depressed CH4 production and glycerol waste utilization. On the contrary, this work demonstrated the addition of decanter cake as co-feedstock and microbial source, containing hydrolytic and acedogenic bacteria, yielded a better performance in the biogas production and simulate glycerol waste utilization at the same time.

Identification Of Potential Indigenous Microbe From Local Fermented Vegetables With Antimicrobial Activity

Identification Of Potential Indigenous Microbe From Local Fermented Vegetables With Antimicrobial Activity

Characterization of red mud as a structural fill and embankment material using bioremediation

Red mud (Bauxite residue), a by-product of aluminum industry possess very serious and alarming environmental concern. Globally, 120 million tonne of red mud is generated per year. Disposal of red mud requires huge land, abundant earth material, high cost and further monitoring. And also, it has a potential to pollute nearby water, air and land due to its high toxicity. The most important barrier to remediate, re-use and long term red mud/bauxite residue management is its high alkalinity having pH range of 10–13. Hence, in the present study, bio-neutralization, an eco-friendly approach on red mud is attempted using various indigenous and non-indigenous microbes. In this study, the effect of bio-neutralization on morphological, physical and geotechnical properties of red mud due to the biogeochemical reactions are investigated and compared with raw red mud. Results indicated that reduction in pH value to nearly 7.5 from high alkalinity value of 10.06 is achieved by adding dairy waste product, sugar molasses and rice water in red mud, which act as a cost effective source of microorganism's nutrient. Further, geotechnical characterization as consistency of the red mud is improved in terms of plasticity index. The compaction characteristic is improved in terms of low optimum moisture content and compressive strength after bio-treatment increased marginally. The unconfined compressive strength (UCS) value of bio-treated red mud increased up to 298.6 kPa compared to 136.5 kPa for untreated red mud. The observation made is not only an option to neutralize red mud but also assist in effective utilization of the bauxite residue and various industrial wastes as dairy waste, sugar molasses and etc. The present study shows that bio-treatment of red mud provides an ample opportunity to use it in huge quantities as a structural fill and embankment material.