Growth In Broth Research Articles

A heterodinuclear complex of s-d block containing sodium(I), manganese(II) and the enrofloxacinate anion: Preparation, crystal structure and antibacterial activity

In the present work, the first manganese(II) heterodinuclear complex with enrofloxacin (Henro) has been synthesized and characterized using the following methods: elemental analysis, FT-IR, Raman, ultraviolet–visible (UV–Vis) spectroscopy, molar conductivity and single-crystal X-ray diffraction. In the complex structure, the deprotonated bidentate enrofloxacin ligands (Enrofloxacinate, Enro) are coordinated to manganese(II) via the pyridone oxygens and carboxylato oxygens. Sodium(I) is surrounded by carboxylate oxygens from three Enro ligands and oxygens from three water molecules. It should also be noted that, manganese(II) and sodium(I) have the distorted octahedral coordination geometry. Binuclear Na(I)⋯Mn(II) unit is linked by three carboxylate oxygens of Enro ligands. This crystal structure is the first example of a binuclear complex of sodium(I) and manganese(II) with carboxylate bridge. The antimicrobial activity of the complex was evaluated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) strains by using broth microdilution, well diffusion, and growth inhibition methods. In all experiments, a higher antimicrobial activity of the complex was observed compared to the free ligand.

Global gene expression profiling of a virulent Klebsiella pneumoniae strain during pulmonary infection

Background Klebsiella pneumoniae (Kpn) is an important respiratory pathogen associated with significant mortality, fierce inflammatory responses and high rates of antimicrobial resistance. The increasing incidence of multidrug resistant Kpn has significantly narrowed the therapeutic options available; as such, there is an urgent need to better understand Kpn pathophysiology to identify novel therapeutic targets. Here we performed an in vivo transcriptomic analysis of Kpn isolated from a mammalian host with pulmonary infection. Methods C57BL/6 mice were intranasally inoculated with the virulent Kp52.145 strain (serotype O1:K2); with lungs extracted, homogenised and pooled (n=3; in duplicate) at 32 h post-infection for bacterial RNA purification and RNA-Seq (Illumina). Differential gene expression (analysed using Degust [Voom/Limma]; FDR cut-off =0.01, abs log-FC=2) was assessed in comparison with mid-log phase growth in Lennox broth. Results Overall, we identified >900 differentially expressed genes (DEGs), comprising ∼17 % of the combined chromosomal and plasmid coding sequence repertoire. 52 % of the DEGs were upregulated during infection, including several siderophore-independent iron-, manganese- and zinc-uptake systems (e.g. hmuRSTUV, sitABCD, mntH and znuACB). We also observed a marked in vivo oxidative stress signal, with several Kpn oxidative stress response genes (e.g. oxyR, katE, katG) upregulated during infection. In contrast, expression of mgrB, a negative-regulator of the PhoPQ two-component system associated with resistance to host antimicrobial peptides was downregulated. Conclusion This study provides a novel insight into Kpn gene expression during pulmonary infection. Overall, our data suggest that adaptation to metal starvation, oxidative stress and innate immune defenses are critical for the success of Kpn lung infection.

Ginger and its component shogaol inhibit Vibrio biofilm formation in vitro and orally protect shrimp against acute hepatopancreatic necrosis disease (AHPND)

Specific isolates of Vibrio parahaemolyticus bacteria that cause acute hepatopancreatic necrosis disease (AHPND) colonize and form biofilms on the chitin lining of the shrimp stomach where they release toxins that cause necrosis in the adjacent hepatopancreas. One potential strategy to prevent AHPND is to inhibit biofilm formation in the stomach using feed additives. Thus, we tested ethanolic extracts of ginger (0.2 mg/ml and 2 mg/ml) for their ability to inhibit biofilm formation by an AHPND-causing isolate of V. parahaemolyticus (3HP) using chitosan coated 96-well polystyrene plastic plates to mimic the shrimp stomach lining. The extract significantly (p < .05) inhibited biofilm formation in those plates but did not inhibit cell growth in broth culture in parallel uncoated plates. Subsequent in vivo immersion-challenge experiments using 3HP (106 CFU/ml) showed that use of extract-supplemented feed (0.2 mg/g and 2 mg/g) for 7 days prior to challenge protected whiteleg shrimp (Penaeus vannamei) against mortality (40%–60% higher survival) when compared to control shrimp fed un-supplemented feed. Extract supplementation had no apparent negative effect on feed palatability or on shrimp growth. Three potentially bioactive compounds known to occur in ginger extracts (6-gingerol, 8-gingerol, and 6-shogaol) were also tested for efficacy in biofilm inhibition in vitro, and 6-shogaol was found to be the most potent followed by the others in descending order. None were found to affect bacterial growth in broth. The results of this study suggested that the use of ginger-based or other feed additives that inhibit biofilm formation may constitute a practical approach to reduce the negative impact of AHPND in shrimp aquaculture.

Isolasi Mikroba Dari Air Asam Tambang Pada Area Pertambangan Tembaga Di Pulau Wetar, Provinsi Maluku

This research was conducted to find bacteria from the genus Acidithiobacillus ferrooxidans which isolated from mine acid water in the copper mining area on Wetar Island, Maluku Province. This bacterium will be utilized in the biohidrometallurgical process (bioleaching) for copper extraction in mining area. The results of this study indicate that bacteria can be isolated from mine acid water samples by enrichment method that was use liquid media from Leathen which is optimized using Trypton Soya Broth (TSB) and bacterial growth on solid media. The presence of Thiobacillussp bacteria was confirmed by the results of gene analysis using a 16S rRNA sequence showing the presence of mixed bacterial colonies but not a single colony.

Escape band in Escherichia coli chemotaxis in opposing attractant and nutrient gradients

It is commonly believed that bacterial chemotaxis helps cells find food. However, not all attractants are nutrients, and not all nutrients are strong attractants. Here, by using microfluidic experiments, we studied Escherichia coli chemotaxis behavior in the presence of a strong chemoattractant (e.g., aspartate or methylaspartate) gradient and an opposing gradient of diluted tryptone broth (TB) growth medium. Our experiments showed that cells initially accumulate near the strong attractant source. However, after the peak cell density (h) reaches a critical value [Formula: see text], the cells form a "escape band" (EB) that moves toward the chemotactically weaker but metabolically richer nutrient source. By using various mutant strains and varying experimental conditions, we showed that the competition between Tap and Tar receptors is the key molecular mechanism underlying the formation of the escape band. A mathematical model combining chemotaxis signaling and cell growth was developed to explain the experiments quantitatively. The model also predicted that the width w and the peak position [Formula: see text] of EB satisfy two scaling relations: [Formula: see text] and [Formula: see text], where l is the channel length. Both scaling relations were verified by experiments. Our study shows that the combination of nutrient consumption, population growth, and chemotaxis with multiple receptors allows cells to search for optimal growth condition in complex environments with conflicting sources.

Acinetobacter as a potentially important producer of urocanic acid in chub mackerel, a histidine metabolite of emerging health concern

Urocanic acid, deaminated histidine and the first intermediate in the histidine utilization (Hut) pathway in bacteria, has recently been suggested to have adverse health effects by inducing scombrotoxicosis and immunosuppression after trans–cis isomerization. This work aimed to shed some light on the microbiology of its formation in scombroid fish, given that such information is very scarce. The isolation of urocanic acid producers from chub mackerel was basically based on enrichment of bacteria possessing the Hut pathway with histidine as the sole source of carbon, energy, and nitrogen. Morphological and molecular identification revealed that the isolates (n = 12), taken from the skin, gills, and intestine, were comprised entirely of Acinetobacter from at least five species. This implies that the Hut pathway in the microbes can be particularly active and as such conferred a growth advantage. Dynamic monitoring of bacterial growth and urocanic acid production in fish juice broth indicated that urocanic acid is a primary metabolite and its production is a closely growth-associated process. This in turn implies that its production can be controlled directly by suppressing the bacterial growth. Several potential methods are proposed through a study of the growth characteristics and preservative susceptibility of representative isolates. In conclusion, this work suggests that Acinetobacter can constitute a potentially important group of urocanic acid producers in chub mackerel.

Identification of Candida albicans using different culture media and its association in leukoplakia and oral squamous cell carcinoma.

Context:Candida, leukoplakia and oral squamous cell carcinoma.Aims:The aim of the present study has assessed the association of Candida albicans with normal control group, leukoplakia and oral squamous cell carcinoma lesions of the oral cavity by using cornmeal broth +5% milk and milk serum liquid culture media.Settings and Design:Thepresent study comprised of total 80 patients, which included, 30 patients of Leukoplakia, 30 patients of oral squamous cell carcinoma and normal control group comprised of 20 healthy individuals who were not having any relevant medical, dental and habit history.Subjects and Methods:Saliva and Biopsy was taken from clinically suspected leukoplakia and oral squamous cell carcinoma lesions for the confirmation of histopathological diagnosis. Saliva samples were inoculated for fungal growth in Sabouraud Dextrose Agar, and culture-positive samples had undergone for the germ tube test. Germ tube-positive samples were further taken for chlamydospore production in milk serum and cornmeal broth +5% milk media separately at 8 and 16 h.Statistical Analysis Used:Chi-square test, Fischer extract test.Results:In the normal control group, no fungus growth was found; however, leukoplakia and oral squamous cell carcinoma showed fungus growth with positive germ tube test and chlamydospore formation; the result also showed rapid and quantitatively more chlamydospore formation in cornmeal broth +5% milk in comparison to serum milk culture media. There was no growth of Candida in mild and moderate form of leukoplakia. Whereas in a severe form of leukoplakia, there was more quantitative chlamydospore growth in cornmeal broth +5% milk liquid media.Conclusions:In this study, we have tried to compare the efficacy of cornmeal broth +5% milk and milk serum for the identification of C. albicans. Both the culture media were able to promote the growth of chlamydospore in C. albicans. Among different grades of leukoplakia, the growth of C. albicans was seen in severe dysplastic patient only while mild and moderate dysplasia showed no Candidal growth.

Comprehensive Study of the Boundaries of Enterotoxin A Production and Growth of Staphylococcus aureus at Various Temperatures and Salt Concentrations.

Staphylococcus aureus food poisoning, which is still a serious health problem worldwide, is caused by the intoxication of staphylococcal enterotoxin (SE). Among many types of SE, staphylococcal enterotoxin type A (SEA) is known to be the most responsible for S. aureus food poisoning worldwide. Several researchers have reported the modeling of growth/no growth boundaries for S. aureus with a logistic regression model. In this study, the boundaries of SEA production and S. aureus growth in broth were first performed with the logistic regression model, to evaluate the effects of environmental factors of temperature and salt. Consequently, the boundaries of SEA production and growth of S. aureus in temperature and salt concentration could be produced with the model in shaking and stationary cultures. The area where S. aureus cells would grow, but not produce SEA could be shown between the boundaries of SEA production and growth. Internal and external validations showed that the model could well describe and predict experimental results. Further, the maximum concentrations of SEA and cell population under various conditions of temperature and salt concentration were also compared between the shaking and stationary cultures. These results obtained in this study would become useful information in food industry to prevent S. aureus food poisoning outbreaks. PRACTICAL APPLICATION: Production/no production of staphylococcal enterotoxin A at various temperatures and salt concentrations in shaking and stationary cultures could be estimated well with a logistic regression model. Growth/no growth of staphylococcal cells under the same conditions was also well estimated with the model. The area where S. aureus cells would grow, but not produce SEA could be shown with the model. This present analysis would provide useful information in food industry to prevent staphylococcal food poisoning outbreaks.

2090. Decontamination of Fusarium oxysporon from a Central Line Needleless Access Device Using a 70% Isopropyl Alcohol Impregnated Port Protector

Background Fusarium species, pervasive environmental fungi, cause disseminated infection in immunocompromised hosts including central line-associated bloodstream infections (CLABSIs), with a 75% mortality rate. Many hospitals utilize 70% isopropyl alcohol impregnated port protectors over needleless access devices (NADs) to reduce CLABSIs (Figure 1). These port protectors achieve ≥4-log reduction in colony-forming units (CFU’s) of S. aureus, S. epidermidis, E. coli, C. albicans, P. aeruginosa and C. glabrata. The effect against F. oxysporon has not been reported.Figure 1.Port protector covering needleless access device.Methods F. oxysporon was grown on Sabouraud Dextrose (Sab Dex) agar. Two protocols were used: (1) aliquots of ~1 × 106 CFU were loaded to the surface of eight NAD’s and allowed to air dry, and (2) the surface of 20 NAD’s were contaminated via touching to a dense lawn of Fusarium on culture plates. Half of the NAD’s were decontaminated with a port protector for one minute; the other half had no decontamination step (along with positive/negative controls). NAD’s were then (1) placed whole in Sab Dex broth or (2) touched to a fresh Sab Dex agar plate, and growth observed for 7 days.ResultsIn all cases, NAD’s that had been decontaminated with the alcohol-impregnated port protector showed no growth after seven days in broth (Figure 2) or on plates (Figure 3). NAD’s lacking the decontamination step invariably showed abundant growth.Figure 2.Growth in broth after 7 days of decontaminated (+) vs. nondecontaminated (−) NAD’s, with appropriate controlsFigure 3.Growth on plates after 7 days of decontaminated (+) vs. nondecontaminated (−) NAD’s, with appropriate controls. Ten replicates performed.ConclusionUse of two different techniques demonstrates that a 70% isopropyl alcohol impregnated port protector achieves decontamination of F. oxysporon from the surface of needleless access devices.Disclosures All authors: No reported disclosures.

Deletion of oxyR in Legionella pneumophila causes growth defect on agar.

The intracellular pathogen Legionella pneumophila (Lp) is a strict aerobe, surviving and replicating in environments where it frequently encounters reactive oxygen species (ROS), such as the nutrient-poor water environment and its replicative niche inside host cells. In many proteobacteria, the LysR-type regulator OxyR controls the oxidative stress response; however, the importance of the OxyR homologue in Lp is still unclear. Therefore, we undertook the characterization of phenotypes associated with the deletion of oxyR in Lp. Contrary to the wild type, the oxyR deletion mutant exhibits a severe growth defect on charcoal - yeast extract (CYE) agar lacking α-ketoglutarate supplementation. Growth in AYE broth (CYE without agar and charcoal), in amoeba and in human cultured macrophages, and survival in water is unaffected by the deletion. Supplementing CYE agar with antioxidants that neutralize ROS or introducing the oxyR gene in trans rescues the observed growth defect. Moreover, the mutant grows as well as the wild type on CYE plates made with agarose instead of agar, suggesting that a compound present in the latter is responsible for the growth defect phenotype.

The Survival of Endophytic Bacteria Isolated from Jerusalem Artichoke In Drought Conditions

Four endophytic bacteria isolated from Jerusalem artichoke had the ability of plant growth promotion. These bacteria, isolate 3.13, 4.43, 5.2 and 5.18, were selected to study the promotion of plant growth in drought condition. Thus, survival of the bacteria under drought condition needed for the investigation. All four isolates showed the growth in Nutrient Broth (NB) containing 20% Polyethylene Glycol (PEG). Moreover, all four isolates were tested their survival in NB with 20% PEG and soil by incubating at 30, 35, 40 and 45â—¦C. Reasonable survival was observed in all isolates at 30 to 40â—¦C of both media. Furthermore, isolate 5.18 demonstrated the growth at 45â—¦C and maintained cell numbers at 4.19A—104 CFU/mL after 29 days and 1.30A—107 CFU/mL after 57 days in NB with 20% PEG and in the soil, respectively.

English

Pasteurella multocida causes fowl cholera (FC), a contagious bacterial disease of domestic and wild avian species. It is a Gram negative coccobacilli causing acute highly fatal septicemia with high morbidity and mortality rate. Control of fowl cholera is primarily performed by good management practice and vaccination in areas where disease is endemic. For a quality vaccine, high density growth of P. multocida along with its capsule and outer membrane protein (OMP) is necessary. In the present study, physiochemical factors (growth medium, temperature, pH, incubation time and stirring along with aeration affecting growth density) were evaluated. Growth density was determined by colony forming unit (CFU) and dry mass. Physiochemical factors used in maximum growth density (1.32×1012CFU or 9 mg/ml) of bacteria were between 35 to 40°C, 7.2 to 8.2 pH and 1000 rpm stirring, along with aeration during incubation of 24 h in Brain Heart infusion (BHI) broth. P. multocida showed maximum growth (1.32×1012 or 9 mg/ml) in BHI broth with continuous stirring and aeration (1000 rpm) at 38°C for 24 h. Thus, there was a positive co-relation between colony forming unit (CFU) and dry mass of bacteria. Key words: Brain heart infusion (BHI), aeration, agitation, fermentor, dry mass.

Sinorhizobium meliloti Glutathione Reductase Is Required for both Redox Homeostasis and Symbiosis.

Glutathione (l-γ-glutamyl-l-cysteinylglycine) (GSH), one of the key antioxidants in Sinorhizobium meliloti, is required for the development of alfalfa (Medicago sativa) nitrogen-fixing nodules. Glutathione exists as either reduced glutathione (GSH) or oxidized glutathione (GSSG), and its content is regulated by two pathways in S. meliloti The first pathway is the de novo synthesis of glutathione from its constituent amino acids, namely, Glu, Cys, and Gly, catalyzed by γ-glutamylcysteine synthetase (GshA) and glutathione synthetase (GshB). The second pathway is the recycling of GSSG via glutathione reductase (GR). However, whether the S. meliloti GR functions similarly to GshA and GshB1 during symbiotic interactions with alfalfa remains unknown. In this study, a plasmid insertion mutation of the S. melilotigor gene, which encodes GR, was constructed, and the mutant exhibited delayed alfalfa nodulation, with 75% reduction in nitrogen-fixing capacity. The gor mutant demonstrated increased accumulation of GSSG and a decreased GSH/GSSG ratio in cells. The mutant also showed defective growth in rich broth and minimal broth and was more sensitive to the oxidants H2O2 and sodium nitroprusside. Interestingly, the expression of gshA, gshB1, katA, and katB was induced in the mutant. These findings reveal that the recycling of glutathione is important for S. meliloti to maintain redox homeostasis and to interact symbiotically with alfalfa.IMPORTANCE The antioxidant glutathione is regulated by its synthetase and reductase in cells. In the symbiotic bacterium S. meliloti, the de novo synthesis of glutathione is essential for alfalfa nodulation and nitrogen fixation. In this study, we observed that the recycling of glutathione from GSSG not only was required for redox homeostasis and oxidative stress protection in S. meliloti cells but also contributed to alfalfa nodule development and competition capacity. Our findings demonstrate that the recycling of glutathione plays a key role in nitrogen fixation symbiosis.

Profiling of Intra- and Extracellular Enzymes Involved in Fructification of the Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes).

Fruiting bodies of Ganoderma lucidum have been widely used as a source of potent nutraceutical products. However, the key proteins involved in fructifying G. lucidum, to our knowledge, have not yet been reported. We evaluated the protein profile of fruiting and nonfruiting G. lucidum strains at various developmental stages: mycelia, spawn running, pinning, and fruiting body. Four strains of G. lucidum (GL-I to GL-IV) were grown in both liquid medium (mushroom minimal medium broth) and bags of wheat straw, after which the biomass and fruiting bodies were harvested. Enzyme studies revealed enhanced intracellular and extracellular enzymatic activities during the spawn run stage compared with that during mycelial growth in broth. The esterase and peroxidase activities increased significantly during the pinning of the fruiting cultures, thus indicating their positive role in fructification. Fourier transform infrared spectroscopy of proteins at 3 stages of cultivation-spawn run, pin head formation, and fruiting-exhibited the presence of hydrophobic amino acids and an ordered protein structure in fruiting strains (GL-I and GL-II), indicating the presence of hydrophobin proteins and their role in mushroom fructification. However, basic and aromatic amino acids predominated in the nonfruiting strain GL-IV, and an unordered protein structure was present, which indicate the positive role of hydrophobic amino acids and hydrophobin proteins in mushroom fructification.

Extract from the fermented soybean product Natto inhibits Vibrio biofilm formation and reduces shrimp mortality from Vibrio harveyi infection

Many bacteria, including Vibrio pathogens of shrimp, need to colonize and/or form biofilms in hosts or the environment to cause disease. Thus, one possible control strategy for shrimp Vibriosis is biofilm inhibition. With this objective, an extract from the Japanese fermented soybean product, Natto was tested with the luminescent shrimp pathogen Vibrio harveyi (VH) for its ability to inhibit or degrade biofilm and to interfere with cell growth in broth. Natto is a traditional fermentation product of Bacillus subtilis var Natto (BSN1). Using 96 well microtiter plates coated with 0.4% chitosan, we found that biofilm formation by VH was inhibited, while growth in parallel broth cultures was not. When an extract from Natto prepared using BSN1 was mixed with feed for the whiteleg shrimp Penaeus vannamei before immersion challenge with V. harveyi at 106 cfu/ml, survival was significantly higher (p≤0.05) than for control shrimp given feed without these additives. Further work done to test whether d-amino acids were involved in biofilm formation as previously reported for B. subtilis, Staphylococus aureus and Pseudomonas aeruginosa gave negative results. In conclusion, we discovered that Natto extract can inhibit Vibrio biofilm formation and that it or BSN1 alone added to shrimp feed can significantly reduce shrimp mortality in immersion challenges with pathogenic VH. This shows some promise for possible application against Vibriosis in shrimp since Natto is generally regarded as safe (GRAS) for human consumption.

UTILIZATION OF WHEY AS A CHEAP SUBSTRATE FOR THE OPTIMIZATION OF LIPASE PRODUCTION BY Bacillus subtilis B10 ISOLATED FROM DAIRY INDUSTRY

Whey, a by-product of the dairy industry, acts as a prime source of environmental pollution due to its high organic load. Its utilization as a substrate for lipase production is an attractive option in facing the challenge associated with whey disposal. However, there are only very few studies that have reported the production of lipase using whey. In this study, 43 bacterial strains were isolated from dairy industry soil sample, of which, 26 were found to produce lipase. Since whey contains lactose as the sole carbon source, the ability of the isolates to utilize this sugar was tested and two of the isolates B3 and B10 were positive for growth in phenol red lactose broth. When they were cultured by submerged fermentation and their lipase activities quantified, strain B10 displayed 0.79U/ml of activity. In order to improve the production of lipase, one-factor-at-a-time method was used to study the impacts of oil inducers, nitrogen sources, mineral salts and whey concentration on the process. Statistical optimization was performed using the Box-Behnken design of Response Surface Methodology (RSM). From this design, 75% whey, 4% (v/v) sunflower oil, 0.625% (w/v) beef extract and 0.2% (w/v) CaCl2 were inferred to be the optimal conditions that resulted in a maximum lipase activity of 0.954U/ml. Analysis of variance indicated statistical significance of the model. Lipase being an industrially sought-after enzyme owing to its unique properties, this cost-effective route to its production from a waste substrate holds paramount environmental and economic significance.

Halotolerant aminopeptidase M29 from Mesorhizobium SEMIA 3007 with biotechnological potential and its impact on biofilm synthesis

The aminopeptidase gene from Mesorhizobium SEMIA3007 was cloned and overexpressed in Escherichia coli. The enzyme called MesoAmp exhibited optimum activity at pH 8.5 and 45 °C and was strongly activated by Co2+ and Mn2+. Under these reaction conditions, the enzyme displayed Km and kcat values of 0.2364 ± 0.018 mM and 712.1 ± 88.12 s−1, respectively. Additionally, the enzyme showed remarkable stability in organic solvents and was active at high concentrations of NaCl, suggesting that the enzyme might be suitable for use in biotechnology. MesoAmp is responsible for 40% of the organism’s aminopeptidase activity. However, the enzyme’s absence does not affect bacterial growth in synthetic broth, although it interfered with biofilm synthesis and osmoregulation. To the best of our knowledge, this report describes the first detailed characterization of aminopeptidase from Mesorhizobium and suggests its importance in biofilm formation and osmotic stress tolerance. In summary, this work lays the foundation for potential biotechnological applications and/or the development of environmentally friendly technologies and describes the first solvent- and halo-tolerant aminopeptidases identified from the Mesorhizobium genus and its importance in bacterial metabolism.

Determination of the prevalence of viral aetiology of diarrhea in children less than 5 years of age in Baghdad province

Determination the prevalence of viral, parasitic and bacterial etiology of gastroenteritis in children less than 5 years of age with diarrhea in various hospitals of Baghdad province. A total of 250 stool samples were collected from various hospitals of Baghdad province .Samples were investigated for bacterial and parasitic enteropathogens using microscopic examination. Bacterial culture of stool samples was done in different culture media including MacConkey, XLD, DCA, TCBS and campylobacter media, TCBS and selenite F broth and bacterial growth was examined by analytical profile index (Api20E) system , commercial antisera and colonies characteristics. Enzyme immunoassays were used to identify Group A rotavirus ,Astrovirus and enteric adenovirus Out of 250, 106 children (42.4%) were diagnosed as viral infection of which Rotavirus was found in the majority of cases 91 (36.4%), Adenovirus was detected in 15(6%) patients. bacterial causes were 63 (25.2%) of which 36 (14.4%) were Escherichia coli (ETEC), 12 (4.8%) were Shigella flexneri , 6(2.4%) were Campylobacter jejunii and 9(3.6) were Salmonella enteritidis . Entamoeba histolytica 22 (8.8%) and Giardia lamblia 22 (8.8%) were the most frequent parasite which isolated from all diarrheal stool specimens. Also from total of 250 samples, 40 samples (16%) were dysenteric stool specimens (bloody diarrhea) and the most common pathogens isolated from dysenteric stool specimens were E.histolytica 22(8.8%), Shigella flexneri 12(4.8%) and Campylobacter jejunii 6 (2.4%). The current study revealed a high prevalence of rotavirus as most common cause of diarrhoea in children less than 5 years of age.

An analogous wood barrel theory to explain the occurrence of hormesis: A case study of sulfonamides and erythromycin on Escherichia coli growth.

Hormesis has aroused much attention during the past two decades and may have great implications on many fields, including toxicology and risk assessment. However, the observation of hormesis remains challenged under laboratory conditions. To determine favorable conditions under which to observe hormesis, we investigated the hormetic responses of Escherichia coli (E. coli) upon exposure of different concentrations of sulfonamides and erythromycin at different time points and in different culture media: Luria-Bertani (LB) broth and Mueller Hinton (MH) broth. Our results reveal that the antibiotics, both individually and combined, produce hormetic effects on E. coli growth in MH broth at the stationary phase, with the maximum stimulatory response increasing with time. However, in LB broth, the hormetic response was not observed, which can be explained by an analogous “wood barrel theory”. Our study suggests that the culture medium and time should be taken into consideration in hormetic studies, and compound mixtures should also receive more attention for their potential to induce hormesis.

Assessment of probiotic characteristics of lactic acid bacteria isolated from fermented yak milk products of Sikkim, India: Chhurpi, Shyow, and Khachu

ABSTRACTThe present study documents the probiotic attributes of indigenous lactic acid bacteria (LAB) isolated from local fermented Yak milk products namely Chhurpi, Shyow and Khachu prepared in the northern and eastern region of Sikkim in the Himalayas. Samples were collected aseptically and a total of 170 LAB was isolated and screened for putative probiotic properties like hypocholesteromic effect, acid tolerance, bile tolerance, bile salt hydrolase (BSH) activity and cell surface hydrophobicity. It was observed that 70 LAB isolates showed cholesterol lowering activity, out of which 35 isolates were selected that showed 50% and less cholesterol reducing effect in vitro. Acid tolerance test revealed good tolerance of 12 isolates at pH 2.5 and pH 2.0 for up to 2 hours. The tolerance to 0.5% and 1% of three bile salts acid revealed more growth in MRS broth containing taurocholic acid with the isolates revealing good BSH activity leading to bile acid deconjugation. The cell surface hydrophobicity ranged from 20–95%. Furthermore, 16S rRNA gene sequencing revealed Lactobacillus plantarum YD5S and YD9S, L. pentosus YD8S, L. paraplantarum YD11S, Enterococcus lactis YHC20 and E. faecium YY1 as the best isolates with technological properties. The isolates may serve as potential probiotic candidates with potential for hypocholesteromic benefits in the future.