Exiguobacterium Mexicanum Research Articles

Reclassification of Some Exiguobacterium Species Based on Genome Analysis.

The Exiguobacterium genus comprises Gram-stain-positive and facultatively anaerobic bacteria. Some Exiguobacterium species have previously shown significant high 16S rRNA gene sequence similarities with each other. This study evaluates the taxonomic classification of those Exiguobacterium species through comprehensive genome analysis. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were determined for various Exiguobacterium species pairs. The ANI and dDDH values between Exiguobacterium enclense and Exiguobacterium indicum, Exiguobacterium aquaticum and Exiguobacterium mexicanum, Exiguobacteriumsoliand Exiguobacterium antarcticum, and Exiguobacterium sibiricum and Exiguobacterium artemiae were above the cut-off level (95-96% for ANI and 70% for dDDH) for species delineation. Based on the findings, we propose to reclassify Exiguobacterium enclense as a later heterotypic synonym of Exiguobacterium indicum, Exiguobacterium aquaticum as a later heterotypic synonym of Exiguobacterium mexicanum, Exiguobacteriumsolias a later heterotypic synonym of Exiguobacterium antarcticum and Exiguobacterium sibiricum as a later heterotypic synonym of Exiguobacterium artemiae.

Differences of airborne and mural microorganisms in a 1,500-year-old Xu Xianxiu's Tomb, Taiyuan, China.

Microbial colonization represents one of the main threats to the conservation of subterranean cultural heritage sites. Recently, the microbial colonization on murals in tombs has gradually attracted attention. In this study, a total of 33 samples, including 27 aerosol samples and 6 mural painting samples, were collected from different sites of Xu Xianxiu's Tomb and analyzed using culture-dependent methods. We compared the diversities of culturable bacteria and fungi isolated from the air and murals and explored the potential impacts of microorganisms on the biodeterioration of the murals. Phylogenetic analyses revealed that the culturable bacteria belonged to Bacillus, Microbacterium, Lysobacter and Arthrobacter. And the most of fungal belonged to the Penicillium, Cladosporium and Aspergillus genera. The composition and structure of airborne bacteria and fungi outside the tomb were both significantly different from that inside the tomb. The variation trends of airborne bacterial and fungal concentrations at different sampling sites were remarkably similar. Bacillus frigoritolerans, Bacillus halotolerans, Bacillus safensis, Exiguobacterium mexicanum, Microbacterium trichothecenolyticum, and Micrococcus yunnanensis were bacterial species commonly isolated from both the mural and air environments. Fungal species commonly isolated from aerosol samples and mural painting samples were Alternaria alternata, Cladosporium cladosporioides, Penicillium brevicompactum, and Peyronellaea glomerata. The prediction of the ecological functions of the bacteria revealed that chemoheterotrophy or aerobic_chemoheterotrophy accounted for substantial relative proportions in all sample types. These results suggest that the aerosol circulation between the inside and outside environments of the tomb was weak and that the outside environment had yet to have an impact on the air microbial community inside the tomb. Selective colonization of microorganisms, which is mediated by interaction between microorganisms and special microenvironmental factors, is an important reason for the biodeterioration of murals.

Microbial Consortia Preparation for Amylase, Protease, Gelatinase and Lipase Production from Isolates Obtained from Organic Kitchen Waste

Households, restaurants, canteens, and hotel wastes constitute kitchen waste. Every day our growing cities generate more and more waste, which is overloading our municipal systems. The main aim of the present work was to prepare a microbial consortium that can effectively and rapidly bring about the degradation of kitchen wastes that can be used in agricultural soils. More than 100 different bacterial isolates were obtained from various kitchen waste dumping areas. The bacterial isolates were studied to produce enzymes like amylase, gelatinase, lipase, and protease on respective media plates. The best 20 isolates were subjected to enzyme quantification. The isolates showing maximum production for all four enzymes were selected for consortia preparation. The consortia of isolates were prepared by permutation combinations. Amongst all consortia prepared consortium No. 7 showed maximum enzymatic potential. The bacterial isolates in the best consortium (No. 7) were further characterized and identified as KW104 Serratia marcescens, KW37 Micrococcus luteus, KW128 Brevindimonas mediterranea, KW91 Bacillus tequilensis, and KW97 Exiguobacterium mexicanum. This consortium showed rapid degradation of waste as compared to others in 15 days duration of time showing good potential for compost formation when applied to plant growth.

The antioxidant potential of copper oxide nanoparticles synthesized from a new bacterial strain

Abstract. Alshami HGA, Al-Tamimi WH, Hateet RR. 2023. The antioxidant potential of copper oxide nanoparticles synthesized from a new bacterial strain. Biodiversitas 24: 2666-2673. Copper oxide nanoparticles (CuONPs) have recently gained much attention due to their potential in various fields. The present study aimed to screen nine bacterial strains (Klebsiella quasipneumoniae KP18-31, K. pneumoniae IOB-L, K. quasipneumoniae subsp. similipneumoniae 2437, Bacillus cereus DBA1, B. thuringiensis MSP51, Neobacillus drentensis ROA042, Enterococcus faecalis 2674, Exiguobacterium mexicanum AB201, and Acinetobacter lwoffii K34) isolated from produced water of oil field reservoirs for their ability to biosynthesize CuONPs, as well as characterize and evaluate the antioxidant potential of the manufactured CuONPs. Biosynthesized CuONPs were characterized using XRD, TEM, AFM, and zeta potential analysis. In addition, the DPPH method was used to analyze the antioxidant activity of CuONPs. The results revealed that five of the nine isolates could synthesize CuONPs. B. thuringiensis MSP5 was the best and most productive among them, and it was used for the first time in this present study as an oil field bacteria for the biosynthesis of CuONPs. The results showed that CuONPs have a spherical shape with an average size of 20, 33, and 75 nm based on XRD, TEM, and AFM analysis, respectively. The zeta potential value of the synthesized CuONPs was -12.4 mV. The antioxidant results demonstrated that CuONPs have a remarkable scavenging activity with an IC50 value of 141.68 ?g/mL. This study concluded that CuONPs were excellent free radical scavengers.

Characterizations of highly efficient moderately halophilic toluene degrading exiguobacterium mexicanum M7 strain isolated from Egyptian saline sediments

ABSTRACT Toluene and other monoaromatic compounds are released into the environment particularly saline habitats due to the inappropriate disposal methods of petroleum products. Studying the bio-removal strategy is required to clean up these hazardous hydrocarbons that threaten all ecosystem life using halophilic bacteria with higher biodegradation efficiency of monoaromatic compounds as a sole carbon and energy source. Therefore, sixteen pure halophilic bacterial isolates were obtained from saline soil of Wadi An Natrun, Egypt, which have the ability to degrade toluene and consume it as the only source of carbon and energy. Amongst these isolates, isolate M7 exhibited the best growth with considerable properties. This isolate was selected as the most potent strain and identified based on phenotypic and genotypic characterizations. The strain M7 was belonging to Exiguobacterium genus and founded to be closely matched to the Exiguobacterium mexicanum with a similarity of 99%. Using toluene as sole carbon source, strain M7 showed good growth at a wide range temperature degree (20–40ºC), pH (5–9), and salt concentrations (2.5–10%, w/v) with optimal growth conditions at 35ºC, pH 8, and 5%, respectively. The biodegradation ratio of toluene was estimated at above optimal conditions and analyzed using Purge-Trap GC-MS. The results showed that strain M7 has the potentiality to degraded 88.32% of toluene within greatly short time (48 h). The current study findings support the potential ability to use strain M7 as a biotechnological tool in many applications such as effluent treatment and toluene waste management.

Screening for extracellular synthesis of silver nanoparticles by bacteria isolated from Al-Halfaya oil field reservoirs in Missan province, Iraq

Abstract. Alshami HGA, Al-Tamimi WH, Hateet RR. 2022. Screening for extracellular synthesis of silver nanoparticles by bacteria isolated from Al-Halfaya oil field reservoirs in Missan province, Iraq. Biodiversitas 23: 3462-3470. Microorganisms that live in deep environments are thought to be adapted to the conditions of these environments and possess enzymatic systems that can be useful in scientific and commercial applications. The study aimed to isolate, identify, and screening of silver nanoparticles (AgNPs)-producing bacteria from five samples of produced water of the Al-Halfaya oil field reservoirs in Missan governorate, Iraq. The results revealed a total of 22 bacterial isolates were isolated and identified by morphological features and amplification of the 16S rDNA gene. The isolates are belonging to nine species, including Bacillus cereus strain DBA1.1, Bacillus thuringiensis strain MSP51, Neobacillus drentensis strain ROA042, Enterococcus faecalis strain 2674, Exiguobacterium mexicanum strain AB201, Klebsiella quasipneumoniae strain KP18-31, Klebsiella quasipneumoniae subsp. similipneumoniae strain 2437, Klebsiella pneumoniae strain IOB-L, and Acinetobacter lwoffii strain K34. The Gram-positive bacteria were the most dominant (55.56%), and the most frequent isolate was Klebsiella quasipneumoniae strain KP18-31 (63.64%). Six species out of nine species were recognized as AgNPs producing bacteria and B. cereus strain DBA1 was the best and most potent isolate in the synthesis of AgNPs. The phylogenetic tree was constructed depending on 16S rDNA gene sequences to determine the evolutionary relationship among the isolated bacteria.

Production of Endoglucanase by Exiguobacterium mexicanum OB24 Using Waste Melon Peels as Substrate.

Millions of tons of agricultural waste are produced globally every year. A practical solution to this global problem is to convert this waste into value-added products. In this study, endoglucanase enzyme production was carried out by using waste melon peels as a carbon source. To use this important resource, its stubborn structure must be broken down. Rumen bacteria are regarded as unique for this job. Therefore, firstly endoglucanase producing rumen bacteria was isolated and the bacteria with the best activity (OB24) were identified by molecular methods (16S rRNA gene squencing). As a result of the sequence analysis, it was determined that isolate belonged to Exiguobacterium mexicanum. Then, by optimizing the culture conditions, the enzyme production potential was increased. The optimal conditions were determined as 50 g/L MPP, 2g/L yeast extract, 60 h incubation time, pH: 6.0, and 40°C temperature. Under optimized conditions the enzyme activity increased approximately 3.8-fold.

Reduction of hexavalent chromium by Exiguobacterium mexicanum isolated from chromite mines soil

Hexavalent chromium is a highly toxic element generated due to indiscriminate chromite mining in Sukinda, Odisha. In the present research investigation a relatively higher Cr(VI) resistant (900 mg L−1) bacterium CWB-54 was isolated from the chromite mine water. Based on the biochemical and molecular analysis the strain (CWB-54) was identified as Exiguobacterium mexicanum. When this bacterium was grown at 35 °C, 100 rpm, pH~8.0, and fructose as an electron donor, it could reduce the total hexavalent chromium (100 mg L−1) supplemented in the medium within 33 h of incubation period. Though experiment was carried out to study the effect of Mn, Ni, Cd, Hg and Zn on Cr(VI) reduction by the strain E. mexicanum it has been observed that in the presence of Cd and Hg, Cr(VI) reduction drastically decreased. Characterization of Cr(VI) reduced product by SEM-EDX and TEM analysis revealed intracellular and extracellular Cr(III) deposition in the bacterium, which is assumed to be Cr(OH)3 precipitate in nanometric size. But the extracellular chromate reductase enzyme production is found to be negligible as compared to the intracellular enzyme production. The increased concentration of Cr(VI) above (1000 mg L−1) also showed the genotoxic effect on the DNA. Several reports have been published on Exiguobacterium sp. on different scientific aspect but the current report on the reduction of toxic Cr(VI) by a new species E. mexicanum is a novel one which established the potentiality of this microorganism for a broad area of application.

Lentic and effluent water of Delhi-NCR: a reservoir of multidrug-resistant bacteria harbouring blaCTX-M, blaTEM and blaSHV type ESBL genes.

Antimicrobial resistance is not restricted to clinics but also spreading fast in the aquatic environment. This study focused on the prevalence and diversity of extended-spectrum β-lactamase (ESBL) genes among bacteria from lentic and effluent water in Delhi-NCR, India. Phenotypic screening of 436 morphologically distinct bacterial isolates collected from diverse sites revealed that 106 (∼24%) isolates were ESBL positive. Antibiotic profiling showed that 42, 60, 78 and 59% ESBL producing isolates collected from Ghazipur slaughterhouse, Lodhi garden pond, Hauz Khas lake and Jasola wastewater treatment plant, respectively, were multidrug-resistant (MDR). The multiple antibiotic resistance (MAR) index varied from 0.20 to 0.32 among selected locations. The prevalence of ESBL gene variants blaSHV, blaTEM and blaCTX-M were found to be 17.64, 35.29 and 64%, respectively. Furthermore, the analysis of obtained gene sequences showed three variants of blaCTX-M (15, 152 and 205) and two variants of blaTEM (TEM-1 and TEM-116) among ESBL producers. The co-existence of 2-3 gene variants was recorded among 48% ESBL positive isolates. New reports from this study include the blaCTX-M gene in Acinetobacter lwoffii, Enterobacter ludwigii, Exiguobacterium mexicanum and Aeromonas caviae. Furthermore, the identification of blaTEM and blaSHV in an environmental isolate of A. caviae is a new report from India.

A novel halophilic Exiguobacterium mexicanum strain removes nitrogen from saline wastewater via heterotrophic nitrification and aerobic denitrification

The utilization of halophilic bioresources is limited due to a lack of isolation and characterization work. A halophilic bacterium strain SND-01 of Exiguobacterium mexicanum was isolated in this study, which is the first report on its novel function in heterotrophic nitrification-aerobic denitrification (HN-AD). The strain SND-01 is slightly halophilic, surviving at 0 up to 9% (w/v) salinity. When utilizing ammonium, nitrate or nitrite as the sole nitrogen source in aerobic conditions, the isolated strain showed the maximum nitrogen removal rate of 2.24 ± 0.14 mg/(L·h), 3.63 ± 0.21 mg/(L·h) and 2.30 ± 0.23 mg/(L·h), respectively. Functional genes and key enzymes involved in heterotrophic-aerobic nitrogen transformations were characterized, establishing the pathway of HN-AD. The nitrogen removal via HN-AD is dependent on the C/N ratio, salinity and temperature. The halophilic Exiguobacterium mexicanum strain SND-01 shows a significant potential in biotreatment of saline wastewater in an easy and cost-effective way.

Complete genome sequence of Exiguobacterium mexicanum A-EM, isolated from seafloor hydrothermal vents in Atlantic Ocean.

Exiguobacterium mexicanum A-EM was isolated from seafloor hydrothermal vents(Caifan field, 14.0S 14.4W) and was shown to degrade toxins and contaminants. Here, we present the complete genome sequence of A-EM, consisting of 2,412,492bp, with a GC content of 53.16%. A-EM sequence contains genes encoding enzymes that degrade toxins and contaminants. Complete genome sequence of the strain A-EM can further provide insights into microbial adaption to the seafloor hydrothermal system and the genomic basis for the biotechnological application of strain A-EM as an efficient agent to degrade environmental contaminants.

Functional and Genetic Diversity of Bacteria Associated with the Surfaces of Agronomic Plants

The main objective of this study was to evaluate the genetic diversity and agricultural significance of bacterial communities associated with the surfaces of selected agronomic plants (carrot, cabbage and turnip). The bacterial diversity of fresh agricultural produce was targeted to identify beneficial plant microflora or opportunistic human pathogens that may be associated with the surfaces of plants. Bacterial strains were screened in vitro for auxin production, biofilm formation and antibiotic resistance. 16S rRNA gene sequencing confirmed the presence of several bacterial genera including Citrobacter, Pseudomonas, Pantoea, Bacillus, Kluyvera, Lysinibacillus, Acinetobacter, Enterobacter, Serratia, Staphylococcus, Burkholderia, Exiguobacterium, Stenotrophomonas, Arthrobacter and Klebsiella. To address the biosafety issue, the antibiotic susceptibility pattern of strains was determined against different antibiotics. The majority of the strains were resistant to amoxicillin (25 µg) and nalidixic acid (30 µg). Strains were also screened for plant growth-promoting attributes to evaluate their positive interaction with colonized plants. Maximum auxin production was observed with Stenotrophomonas maltophilia MCt-1 (101 µg mL−1) and Bacillus cereus PCt-1 (97 µg mL−1). Arthrobacter nicotianae Lb-41 and Exiguobacterium mexicanum MCb-4 were strong biofilm producers. In conclusion, surfaces of raw vegetables were inhabited by different bacterial genera. Potential human pathogens such as Bacillus cereus, Bacillus anthracis, Enterobacter cloacae, Enterobacter amnigenus and Klebsiella pneumoniae were also isolated, which makes the biosafety of these vegetable a great concern for the local community. Nevertheless, these microbes also harbor beneficial plant growth-promoting traits that indicated their positive interaction with their host plants. In particular, bacterial auxin production may facilitate the growth of agronomic plants under natural conditions. Moreover, biofilm formation may help bacteria to colonize plant surfaces to show positive interactions with host plants.

Biocalcification by halophilic bacteria for remediation of concrete structures in marine environment.

Microbial carbonate precipitation has emerged as a promising technology for remediation and restoration of concrete structures. Deterioration of reinforced concrete structures in marine environments is a major concern due to chloride-induced corrosion. In the current study, halophilic bacteria Exiguobacterium mexicanum was isolated from sea water and tested for biomineralization potential under different salt stress conditions. The growth, urease and carbonic anhydrase production significantly increased under salt stress conditions. Maximum calcium carbonate precipitation was recorded at 5% NaCl concentration. Application of E. mexicanum on concrete specimens significantly increased the compressive strength (23.5%) and reduced water absorption about five times under 5% salt stress conditions compared to control specimens. SEM and XRD analysis of bacterial-treated concrete specimens confirmed the precipitation of calcite. The present study results support the potential of this technology for improving the strength and durability properties of building structures in marine environments.

Distribution of bacteria in Lake Qarun, AL Fayoum, Egypt (2014 -2015) in relation to its physical and hydrochemical characterization.

The bacteriological monitoring of Lake Qarun water and sediment (aerobic heterotrophs, Staphylococcus sp., Vibrio sp. Aeromonas sp., S. feacalis, E. coli, and total coliform sp.) through the period of study (2014-2015) was carried out. Six common bacterial isolates were fully identified as; Bacillus firmus, Bacillus stratosphericus, Exiguobacterium mexicanum, Stenotrophomonas rhizophila, Halomonas stevensii, and Halomonas korlensis based on partial sequencing of 16Sr DNA. In addition, physical and chemical analyses of Lake Qarun water and sediment (pH, temperature, salinity, dissolved oxygen, BOD, COD, and nutrients) were estimated. The pH varied between 7.08 at sit I and 8.73 at sit V. The temperature varied between 15.6oC at sit VIII and 32.2oC at sit I. The salinity ranged between 3.18% at sit I and 51.72% at sit III. The dissolved oxygen fluctuated between 3.89 md/l at sit VI and 8.96 md/l at sit IV. The BOD ranged between 1.08 mg/l at sit VIII and 6.47 mg/l at sit IV. The COD varied between 11.36 mg/l at sit I and 53.64 mg/l at sit VIII. The phosphate in lake water varied between 1.453.4 μg/l at sit VIII and 498.4 μg/l at sit I. The ammonia ranged between 14.73 μg/l at sit II and 1485 μg/l at sit I. The nitrite varied between 4.10 μg/l at sit IV and 646.5 μg/l at sit I. The nitrate varied between 14.79 μg/l at sit III and 2138 μg/l at sit I. The silicate fluctuated between 894.6 μg/l at sit VI and 4682 μg/l at sit VII.Distribution of bacteria, physical characterization, hydrochemical characterization, Lake Qarun.

Isolation and characterization of dipropyl-, S-propyl ester from Exiguobacterium mexicanum (MSSRF-S9) against larvae of malaria and dengue vectors

ObjectiveTo evaluate the insecticidal property of the compound dipropyl-, S-propyl ester extracted from the Gram-positive rhizosphere bacterium against the fourth instars larvae of malaria vector, Anopheles culicifacies (An. culicifacies) and dengue vector, Aedes albopictus (Ae. albopictus). MethodsBacteria were taxonomically identified as Exiguobacterium mexicanum (E. mexicanum) and different crude solvent extracts were examined for its larvicidal potential against mosquito vectors. The crude extract was eluted in silica gel column chromatography and the pure compound was identified. ResultsThe highest larvicidal activity against An. culicifacies was exhibited by ethyl acetate extract. The bacterium of E. mexicanum extract at 150, 300, 450, 600, 750 mg/L caused against both vector mosquito species. Hexane, chloroform, acetone, methanol and ethyl acetate caused moderate considerable mortality. The highest larval mortality was observed in ethyl acetate extract. ConclusionsThe results of the bacterial extract of E. mexicanum are promising as potential larvicidal compound against the mosquito vectors (An. culicifacies and Ae. albopictus). Therefore, this study provides first report on the larvicidal activity with dipropyl-, S-propyl ester compound from India.

Broad spectrum antimicrobial compounds from the bacterium Exiguobacterium mexicanum MSSRFS9

Clinical bacterial pathogens front a major challenge for the clinical researchers and physicians. In particular microbial pathogens like Escherichia coli, Shigella flexneri, Klebsiella pneumonia and Salmonella enterica are apparelled with systemic machineries to bring down the human immune system as well as proliferate dramatically in a short period which in turn cause a pronounced ailment to the human health. In vitro evaluation of four purified compounds isolated from rhizosphere bacterium Exiguobacterium mexicanum tested against clinical pathogens mentioned above by disc diffusion method showed the two compounds viz., 3,6,18-trione, 9,10-dihydro-12′-hydroxyl-2methyl-5-(phenyl methyl) (5′-alpha, 10-alpha)-dihydroergotamine (C3) and dipropyl – S-propyl ester (C4) exhibit antibacterial property against all the tested pathogens. Among the four clinical pathogens tested, compound C3 has shown higher zone of inhibition against S. enterica with 17±0mm, followed by S. flexneri with 16.5±0.7mm, E. coli with 15±0mm and K. pneumoniae with 14±0mm, respectively. The compound C4 has shown higher antimicrobial activity against S. enterica with 21.5±0.7mm zone of inhibition, followed by S. flexneri with 19.5±0.7mm, E. coli with 17±0mm and K. pneumoniae with 16±0mm, these two compounds were found to be safer when subjected to rat haematological and enzymatic analysis.

Culturable and culture-independent bacterial diversity and the prevalence of cold-adapted enzymes from the Himalayan mountain ranges of India and Nepal.

Bacterial diversity of soil samples collected from different geographical regions of Himalayan mountains was studied through culturable (13 samples) and culture-independent approaches (5 samples based on abundance of diversity indices in each ecological niche). Shannon-Wiener diversity index and total bacterial count ranged from 1.50 ± 0.1 to 2.57 ± 0.15 and 7.8 ± 1.6 × 10(5) to 30.9 ± 1.7 × 10(5) cfu ml(-1) of soil, respectively. Based on morphology and pigmentation, 406 isolates were selected by culturing in different cultivable media at various strengths and concentrations. All the strains were subjected to amplified ribosomal DNA restriction analysis and the representative isolates from each cluster were chosen for 16S rRNA gene sequence-based identification. Soil habitat in Himalayan foot hills was dominated by the genera Arthrobacter, Exiguobacterium, Bacillus, Cedecea, Erwinia, and Pseudomonas. Five 16S rRNA gene libraries from the selected five samples yielded 268 clones and were grouped into 53 phylotypes covering 25 genera including the genus of Ferribacterium, Rothia, and Wautersiella, which were reported for the first time in Himalayan tracks. Principal coordinates analysis indicates that all the clone libraries were clearly separated and found to be significantly different from each other. Further, extracellular investigation of cold-active enzymes showed activity of cellulase (23.71%), pectinase (20.24%), amylase (17.32%), phytase (13.87%), protease (12.72%), and lipase (23.71%) among the isolates. Four isolates namely Exiguobacterium mexicanum (BSa14), Exiguobacterium sibiricum (BZa11), Micrococcus antarcticus (BSb10), and Bacillus simplex (BZb3) showed multiple enzyme activity for five different types of enzymes. In addition, various genera like Exiguobacterium, Erwinia, Mycetecola, Cedecea, Pantoea, and Trichococcus have also shown novel hydrolytic enzyme activity in the Himalayan foothills.

Biomediated synthesis of silver nanoparticles using Exiguobacterium mexicanum.

Biomediated silver nanoparticle were synthesized using a cell free extract of a soil bacterium, Exiguobacterium mexicanum PR 10.6. The silver nanoparticles were characterised using UV-Vis spectroscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. The nanoparticles ranged from 5 to 40 nm. Extracellular polymeric substance played a critical role in the reduction of silver ion and nanoparticle stabilisation when using the cell free extract. The synthesis using E. mexicanum is an effective eco-friendly, rapid method for silver nanoparticle synthesis within 1 h.

Microbial Diversity Analysis of Fermented Mung Beans (Lu-Doh-Huang) by Using Pyrosequencing and Culture Methods

In Taiwanese alternative medicine Lu-doh-huang (also called Pracparatum mungo), mung beans are mixed with various herbal medicines and undergo a 4-stage process of anaerobic fermentation. Here we used high-throughput sequencing of the 16S rRNA gene to profile the bacterial community structure of Lu-doh-huang samples. Pyrosequencing of samples obtained at 7 points during fermentation revealed 9 phyla, 264 genera, and 586 species of bacteria. While mung beans were inside bamboo sections (stages 1 and 2 of the fermentation process), family Lactobacillaceae and genus Lactobacillus emerged in highest abundance; Lactobacillus plantarum was broadly distributed among these samples. During stage 3, the bacterial distribution shifted to family Porphyromonadaceae, and Butyricimonas virosa became the predominant microbial component. Thereafter, bacterial counts decreased dramatically, and organisms were too few to be detected during stage 4. In addition, the microbial compositions of the liquids used for soaking bamboo sections were dramatically different: Exiguobacterium mexicanum predominated in the fermented soybean solution whereas B. virosa was predominant in running spring water. Furthermore, our results from pyrosequencing paralleled those we obtained by using the traditional culture method, which targets lactic acid bacteria. In conclusion, the microbial communities during Lu-doh-huang fermentation were markedly diverse, and pyrosequencing revealed a complete picture of the microbial consortium.

Exiguobacterium himgiriensis sp. nov. a novel member of the genus Exiguobacterium, isolated from the Indian Himalayas

The taxonomic position of an orange coloured bacterium, strain K22-26(T) isolated from a soil sample was studied using a polyphasic approach. The organism had phenotypic and chemotaxonomic properties consistent with its allocation into the genus Exiguobacterium. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain K22-26(T) belongs to the genus Exiguobacterium and was related to Exiguobacterium aurantiacum DSM 6208(T) (99.0 %) Exiguobacterium mexicanum DSM 16483(T) (98.6 %), Exiguobacterium aquaticum (98.6 %), Exiguobacterium aestuarii DSM 16306(T) (98.1 %), Exiguobacterium profundum DSM 17289(T) (98.1 %) and Exiguobacterium marinum DSM 16483(T) (97.9 %), whereas sequence similarity values with respect to other Exiguobacterium species with validly published names were between 92.5-94.0 %. The major polar lipids detected were phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The major menaquinone was determined to be MK-7 (83 %) whereas MK-8 (11 %) and MK-6 (6 %) occur in smaller amounts. The peptidoglycan of the strain was found to contain L-lysine as the diagnostic diamino acid. The major fatty acids detected were iso C13:0 (11.2 %), anteiso C13:0 (15.4 %), iso C15:0 (13.2 %) and iso C17:0 (16.1 %). However, analysis of the DNA-DNA relatedness confirmed that strain K22-26(T) belongs to a novel species. The G + C content of the strain K22-26(T) was determined to be 50.1 mol %. The novel strain was distinguished from closely related type species of the genus Exiguobacterium using DNA-DNA relatedness and phenotypic data. Based on these differences, the strain K22-26(T) should be classified as a novel species of the genus Exiguobacterium, for which the name Exiguobacterium himgiriensis sp. nov. strain K22-26(T) (= MTCC 7628(T) = JCM 14260(T)) is proposed.