Enterobacter Cancerogenus Research Articles

The Etiological and Antimicrobial Susceptibility Profiles of the Bacteria Obtained from Ovine Caseous Lymphadenitis Cases in the Çankırı Region, Türkiye.

Sheep caseous lymphadenitis (CLA) causes significant economic losses in the livestock sector by causing a loss in the quantity and quality of animal products and a loss in the breeding value of animals. Although the primary agent in CLA's etiology is Corynebacterium pseudotuberculosis, some other opportunistic microorganisms also play a role. Therefore, the control and treatment of CLA necessitates the identification of the relevant etiological agents. This study aimed to conduct an in vitro culture and molecular characterization (PCR analysis and 16S rRNA sequencing) of the bacteria involved in sheep CLA cases reported in the Çankırı province of Türkiye and determine the antibiotic susceptibility of the case isolates. In total, 82 (16.4%) of 500 sheep in five farms were diagnosed with CLA. Following the culture of the superficial abscesses samples, C. pseudotuberculosis was identified in 30 (36.59%) as a result of PCR, Pseudomonas spp. in 8 (9.76%), and Enterobacter cancerogenus in 1 (1.22%), as a result of 16S rRNA sequencing. These data revealed extensive heterogeneity among the Pseudomonas isolates, with hints of derivation from a common ancestry for some and phylogenetic similarity to isolates from Germany, Malaysia, and India. In contrast to the high susceptibility to cefoperazone and lincomycin, the high resistances of C. pseudotuberculosis and Pseudomonas spp. isolates to cephalothin, ceftiofur, cloxacillin, amoxicillin, and bacitracin were remarkable. Based on these findings, it was concluded that for an effective treatment and control of ovine CLA cases, there is a need to consider the possible involvement of opportunistic bacteria other than the primary causative agent, C. pseudotuberculosis. It also contributed to increasing the country-specific sequence data and establishing new taxa from a universal perspective.

Reference Genes for Expression Analyses by qRT-PCR in Enterobacter cancerogenus.

The Enterobacter cancerogenus strain EcHa1 was isolated from the dead larvae of Helicoverpa armigera, and has the potential for biocontrol of some Lepidoptera insects. In order to screen insecticidal-related genes by qRT-PCR, stable endogenous reference genes used for normalizing qRT-PCR data were selected and evaluated from 13 housekeeping genes (HKGs). The expression levels of the HKGs were determined using qRT-PCR under different experimental conditions, including two culture temperatures and three bacterial OD values. Five stability analysis methods (Ct, BestKeeper, NormFinder, geNorm, and RefFinder) were used to comprehensively rank the candidate genes. The results showed that the optimal reference genes varied under different experimental conditions. The combination of gyrA and gyrB was recommended as the best reference gene combination at 28 °C, while gyrA and rpoB was the best combination at 37 °C. When the OD values were 0.5, 1.0 and 2.0, the recommended reference gene combinations were ftsZ and gyrA, rpoB and gyrB, and gyrA and pyk, respectively. The most suitable reference genes were gyrA and gyrB under all experimental conditions. Using gyrA and gyrB as the reference genes for qRT-PCR, EcHa1 was found to invade all tissues of the H. armigera larvae, and expressed a candidate pathogenic factor Hcp at high levels in gut, Malpighian tubules, and epidermis tissues. This study not only establishes an accurate and reliable normalization for qRT-PCR in entomopathogenic bacteria but also lays a solid foundation for further study of functional genes in E. cancerogenus.

Revisiting host identification of bacteriophage Enc34: from biochemical to molecular.

Our correction reflects the evolving landscape of bacterial identification, where molecular methods have supplanted traditional biochemical tests. This case underscores the significance of revisiting past identifications, as seemingly known bacterial strains may yield unexpected discoveries, necessitating essential updates to the scientific record. Despite the host identity correction, our genome announcement retains importance as the first complete genome sequence of a Hafnia alvei bacteriophage.

Molecular Characterisation of Gut Bacteria in Wista Rat After Green Tea Consumption

Green tea can influence the gut bacteria by either stimulating or hindering the growth of specific species. This experimental study was carried out in Rivers State, Nigeria to molecularly characterize gut bacteria in Wista rats after green tea consumption. Twenty-five (25) rats divided into five groups were used; each group had five (5) rats having an average weight range of 70g – 130g. After acclimatization of 2 weeks, groups (2, 3, 4 & 5) were feed with green tea extract based on standard method using oral gavage with rat feed pellet and water for seven (7) days and fourteen (14) days respectively based on their body weights and group 1 (control) was fed with rat feed pellet and water only for same duration and their weights recorded. Stool samples were collected aseptically by pulling from each group into sterile stool sample bottles and sent to the laboratory for immediate analysis. Conventional microbiological methods of culturing and molecular methods were utilized for identification of isolates, total heterotrophic plate count and antibiotic susceptibility were also done. The data from this study were analysed using SPSS version 23, to survey difference in gut bacterial count of wista rats after fed with green tea, rat weight across the study groups, and the values were expressed as mean ± SD at a 5% alpha level. The study reported a statistical difference in bacterial plate count at (P≤0.05) in Groups 2, 3, 4, and 5 after 14 Days of Acclimatization, after 7 days of Treatment and after further 14 Days of Treatment. Group 1 showed no statistical significance at P=0.212. Furthermore, there was significant difference in weight comparison at (P≤0.05) in rats contained in all groups after 7 days and after further 14 days of treatment, rats in group 1 showed weight gain. There was weight loss in all the treatment groups (2 ,3, 4, and 5). Antibiotic-resistant assay pattern of the isolates showed multiple drugs resistance to all the antibiotics used with Bacillus and Enterobacter being the most resistant isolates. The molecular characterization and identification of the isolates revealed close relatedness to Staphylococcus arlettae, Enterobacter cloacae, Enterobacter cancerogenus, Acinetobacter nosocomialis, Comamonas testosterone, Klebsiella veriicola, Bacillus thuringiensis, Bacillus pumilus and Bacillus cereus, it showed that the molecular technique proved to be more specific and accurate than the convectional technique in the identification and characterization of the isolates. Also, the gut bacterial count of the rats that were treated with the tea were significantly raised indicating that the tea has the potential to influence the abundance and diversity of gut bacteria. As seen in this study, molecular characterisation of gut bacteria identifies bacteria upto their specie level and they are influenced by diet.

Genomic features of a plant growth-promoting endophytic Enterobacter cancerogenus JY65 dominant in microbiota of halophyte Suaeda salsa

Genomic features of a plant growth-promoting endophytic Enterobacter cancerogenus JY65 dominant in microbiota of halophyte Suaeda salsa

Isolation and Characterization of Biosurfactant-producing Bacteria from Ternary Effluent within Maiduguri Metropolitan Council

Almost all surfactants currently in use are chemically derived from petroleum. However, the diversity of biosurfactants, environment friendly characteristics, the possibility of their production through fermentation and their potential applications in areas such as environmental protection, surface crude oil recovery, health care and food processing industries, has made its interest steadily increasing in recent years. This research is targeted towards the isolation of indigenous biosurfactant producing bacteria from the local tanneries in Maiduguri. Physico – chemical parameters such as temperature and pH of all samples were tested at the site of collection, while others such as Biochemical Oxygen Demand (BOD), Desolved Oxygen (DO) and Electrical Conductivity (EC) were tested ex – situ. Simple and selective microbiological media were used for the isolation. A total of ten (10) different bacterial isolates were obtained from the eighteen (18) samples tested. Identification of the isolates was achieved through morphological and Biochemical analysis. The isolates obtained included Providencia rettgeri, Salmonella enterica, Enterobacter cancerogenus, Leminorella richardii, Bacillus licheniformis, B. niacini, Paenibacillus residui, Proteus mirabilis, Lysinibacillus massiliensis and L. fusiformis. Of the ten (10) isolates obtained, only seven (7) were found positive for biosurfactant production. They incuded P. rettgeri, E. cancerogenus, L. richardii, B. niacini, P. residui, L. massiliensis and L. fusiformis, of which L. fusiformis showed the highest emulsification activity of 25% at 4cm emulsion height. The results suggest that the Majema tannery effluents harbour biosurfactant - producing bacteria. Thus, tannery effluents can be possibly remediated using the biosurfactants and bacteria producing the biosurfactants.

CO2-mediated bloater defect can be induced by the uncontrolled growth of Enterobacteriaceae in cucumber fermentation.

Enterobacteriaceae are known to proliferate in cucumber juice, deriving energy from the fermentation of sugars to organic acids and ethanol, and theoretically generating carbon dioxide (CO2). We hypothesized that the CO2 produced by the indigenous Enterobacteriaceae in the early stage of cucumber fermentation accumulates in the fermenting fruits causing bloater defect. The ability of seven Enterobacteriaceae, indigenous to cucumber, to grow and produce CO2 in cucumber juice medium (CJM), a sterile model system for cucumber fermentation, was characterized. The induction of bloater defect in cucumber fermentation conducted with pasteurized and acidified fruits was also evaluated. The generation times of the seven Enterobacteriaceae in CJM ranged between 0.25 and 8.20 h and resulted in carbon dioxide (CO2) production to estimated amounts of 7.22-171.5 mM. Enterobacter cancerogenus and Enterobacter nimipressuralis were among the bacteria that produced the most and the least CO2 in CJM, respectively, at estimated mM concentrations of 171.58 ± 42.96 and 16.85 ± 6.53. Inoculation of E. cancerogenus and E. nimipressuralis in acidified and pasteurized cucumbers resulted in the production of 138 and 27 mM CO2, respectively. Such Enterobacteriaceae produced 2% hydrogen in the model cucumber fermentations. A bloater index of 25.4 and 17.4 was calculated from the cucumbers fermented by E. cancerogenus and E. nimipressuralis, respectively, whereas no defect was observed in the fruits collected from uninoculated control fermentation jars. It is concluded that the metabolic activity of the Enterobacteriaceae indigenous to cucumber can produce sufficient CO2 in cucumber fermentations to induce bloater defect.

Development of a biofilm-forming bacterial consortium and quorum sensing molecules for the degradation of lignin-containing organic pollutants

The presence of lignin along with other pollutants makes effluent more complex when it is discharged from Pulp and paper mills. The present study investigates the use of biofilm-forming bacteria isolated from pulp paper mill effluent contaminated sites (PPMECSs) for lignin degradation. Isolated biofilm-forming and lignin-degrading bacteria were identified as Bacillus subtilis, Enterobacter cancerogenus, and Bacillus licheniformis by 16S rRNA gene sequencing. Thin liquid chromatography (TLC) analysis showed that the consortium of bacteria produced acyl-homoserine lactone (AHL) as quorum sensing molecules and extracellular polymeric substances (EPS) that protect the bacterial consortium under unfavorable conditions. The potential consortium was able to reduce lignin (900 ppm) by 73% after 8 days of incubation in a minimal salt medium containing kraft lignin and glucose at pH 7.0 and 37 °C as compared to individual strains. The degradation by-products were identified as amides, alcohols, and acids. The major organic pollutants in the effluent were reduced after treatment of the constructed consortium, thus confirming active biotransformation and biodegradation of the lignin. Microscopic examination also indicated the presence of lignin induced biofilm formation. Hence, the constructed biofilm-forming bacterial consortia based on quorum sensing offered a sustainable and effective solution to treat lignin-containing complex pollutants.

Cross-Over Pathogenic Bacteria Detected in Infected Tomatoes (Solanum lycopersicum L.) and Peppers (Capsicum annuum L.) in Bulgaria.

The ability of certain human pathogens to adapt to plants without losing their virulence toward people is a major concern today. Thus, the aim of the present work was the investigation of the presence of cross-over pathogenic bacteria in infected tomato and pepper plants. The objects of the study were 21 samples from seven different parts of the plants and three from tomato rhizosphere. In total, 26 strains were isolated, identified by MALDI-TOF, and phenotypically characterized. The PCR amplification of the rpoB gene was applied as an approach for the rapid detection of cross-over pathogens in plant samples. A great bacterial diversity was revealed from tomato samples as nine species were identified (Leclercia adecarboxylata, Pseudesherichia vulneris, Enterobacter cancerogenus, Enterobacter cloacae, Enterobacter bugandensis, Acinetobacter calcoaceticus, Pantoea agglomerans, Pantoea ananatis, and Pectobacterium carotovorum). Polymicrobial contaminations were observed in samples T2 (tomato flower) and T10 (tomato fruit). Five species were identified from pepper samples (P. agglomerans, L. adecarboxylata, Pseudomonas sp., Pseudomonas putida, and Enterococcus sp.). Antibiotic resistance patterns were assigned in accordance with EFSA recommendations. All isolates showed varying resistance to the tested antibiotics. The genetic basis for the phenotypic antibiotic resistance was not revealed. No genes for the virulence factors were found among the population. To our knowledge, this is the first overall investigation of tomato and pepper cross-over pathogenic bacterial populations in Bulgaria.

Characterisation of a Bacterium from Selat Tebrau and Screening of Microbial Genomes for Dehalogenases

Current study was to investigate the presence of dehalogenase in the isolated bacterium from Selat Tebrau that can grow on 2,2-dichloropropionic acid (2,2-DCP is an active compound in herbicide Dalapon®). Strain RN1, a Gram-negative and rod in shape was tentatively identified as Enterobacter cancerogenus based on basic biochemical and the 16S rRNA gene analyses. The calculated cells doubling time were 5.29 hours based on growth of the bacterium in liquid minimal media with 10, 20 and 30 mM of 2,2-DCP, respectively. However, no growth was observed at 40 mM 2,2-DCP liquid minimal medium due to increase in 2,2-DCP toxicity. It was hypothesized that, strain RN1 produced dehalogenase(s) which merits a further study of the genomic data of the same genus and species available in the database. A putative dehalogenase, designated as DehRN was located in the published data of Enterobacter cancerogenus. Pairwise of DehRN amino acids with known dehalogenase resulted in sequence identity of <20%, suggesting a new class of dehalogenase enzyme in the Enterobacter cancerogenus.Keywords: 2,2-DCP, dehalogenase, dichloropropionate, Enterobacter, haloalkanoic acid

Plant-associated microbiota as a source of antagonistic bacteria against the phytopathogen Erwinia amylovora.

Control of bacterial plant diseases is a major concern, as they affect economically important species and spread easily, such as the case of fire blight of rosaceous caused by Erwinia amylovora. In the search for alternatives to the use of agrochemicals and antibiotics, this work presents a screening of natural bacterial antagonists of this relevant and devastating phytopathogen. We recovered bacterial isolates from different plant tissues and geographical origins and then selected those with the strongest ability to reduce fire blight symptoms ex vivo and remarkable in vitro antagonistic activity against E. amylovora. None of them elicited a hypersensitivity reaction in tobacco leaves, most produced several hydrolytic enzymes and presented other biocontrol and/or plant growth-promoting activities, such as siderophore production and phosphate solubilization. These isolates, considered as biocontrol candidates, were identified by 16S rRNA sequencing as Pseudomonas rhizosphaerae, Curtobacterium flaccumfaciens, Enterobacter cancerogenus, Pseudomonas azotoformans, Rosenbergiella epipactidis and Serratia plymuthica. This is the first time that the last five bacterial species are reported to have biocontrol potential against E. amylovora.

Antibiotic Resistant Enterobacteriaceae in Milk Alternatives

The consumption of non-dairy milk is on the rise due to health benefits. Although there is increasing inclination towards milk alternatives (MA), there is limited data on antibiotic resistant bacteria in these substitutes. The aim of this study was to investigate antimicrobial resistance of bacteria isolated from MA. A total of 138 extracts from almonds (n = 63), cashew nuts (n = 36), and soybeans (n = 39) were analyzed for Enterobacteriaceae. The identification of the bacteria was based on biochemical and PCR methods. Antibiotic sensitivity was determined by using the Kirby-Bauer disk diffusion technique. Overall, 31% (43 of 138) of extracts were positive for Enterobacteriaceae. Ten bacterial species were identified, of which Enterobacter cloacae (42.7%) and Enterobacter cancerogenus (35.4%) were the most predominant species (p < 0.05). Antibiotic resistance was exhibited to vancomycin (88.3%), novobiocin (83.8%), erythromycin (81.1%), which was significantly higher (p < 0.05) than in tetracycline (59.5%), cefpodoxime (30.6%), and nalidixic acid (6.3%). There was no resistance displayed to kanamycin and imipenem. ERY-NOV-VAN-TET and ERY-NOV-CEP-VAN-TET were the most common resistant patterns displayed by Enterobacter cloacae. The findings of this study suggest that MAs, though considered healthy, may be a reservoir of multidrug resistant opportunist pathogens.

Detection of Quorum Sensing Signal Molecules, Particularly N-Acyl Homoserine Lactones, 2-Alky-4-Quinolones, and Diketopiperazines, in Gram-Negative Bacteria Isolated From Insect Vector of Leishmaniasis

Gram-negative bacteria are known to use a quorum sensing system to facilitate and stimulate cell to cell communication, mediatedviaregulation of specific genes. This system is further involved in the modulation of cell density and metabolic and physiological processes that putatively either affect the survival of insect vectors or the establishment of pathogens transmitted by them. The process of quorum sensing generally involves N-acyl homoserine lactones and 2-alkyl-4-quinolones signaling molecules. The present study aimed to detect and identify quorum sensing signaling molecules of AHLs and AHQs type that are secreted by intestinal bacteria, and link their production to their extracellular milieu and intracellular content. Isolates for assessment were obtained from the intestinal tract ofPintomyia evansi(Leishmaniainsect vector). AHLs and AHQs molecules were detected using chromatography (TLC) assays, with the aid of specific and sensitive biosensors. For identity confirmation, ultra-high-performance liquid chromatography coupled with mass spectrometry was used. TLC assays detected quorum sensing molecules (QSM) in the supernatant of the bacterial isolates and intracellular content. Interestingly,Pseudomonas otitidis,Enterobacter aerogenes,Enterobacter cloacae, andPantoea ananatisisolates showed a migration pattern similar to the synthetic molecule 3-oxo-C6-HSL (OHHL), which was used as a control.Enterobacter cancerogenussecreted C6-HSL, a related molecules to N-hexanoyl homoserine lactone (HHL), whileAcinetobacter gyllenbergiiexhibited a migration pattern similar to 2-heptyl-4-quinolone (HHQ) molecules. In comparison to this, 3-oxo-C12-HSL (OdDHL) type molecules were produced byLysobacter soli,Pseudomonas putida,A. gyllenbergii,Acinetobacter calcoaceticus, andPseudomonas aeruginosa, whileEnterobacter cloacaeproduced molecules similar to 2-heptyl-3-hydroxy-4-quinolone (PQS). ForPseudomonas putida,Enterobacter aerogenes,P. ananatis, andPseudomonas otitidisextracts, peak chromatograms with distinct retention times and areas, consistent with the molecules described in case of TLC, were obtained using HPLC. Importantly,P. ananatisproduced a greater variety of high QSM concentration, and thus served as a reference for confirmation and identification by UHPLC-MRM-MS/MS. The molecules that were identified included N-hexanoyl-L-homoserine lactone [HHL, C10H18NO3, (M + H)], N-(3-oxohexanoyl)-L-homoserine lactone [OHHL, C10H16NO4, (M + H)], N-(3-oxododecanoyl)-L-homoserine lactone [OdDHL, C16H28NO4, (M + H)], and 2-heptyl-3-hydroxy-4(1H)-quinolone [PQS, C16H22NO2, (M + H)]. Besides this, the detection of diketopiperazines, namely L-Pro-L-Tyr and ΔAla-L-Val cyclopeptides was reported forP. ananatis.These molecules might be potentially associated with the regulation of QSM system, and might represent another small molecule-mediated bacterial sensing system. This study presents the first report regarding the detection and identification of QSM and diketopiperazines in the gut sand fly bacteria. The possible effect of QSM on the establishment ofLeishmaniamust be explored to determine its role in the modulation of intestinal microbiome and the life cycle ofPi. evansi.

Characterization of an exopolysaccharide produced by Enterobacter sp. YU16-RN5 and its potential to alleviate cadmium induced cytotoxicity in vitro.

Natural biopolymers have gained remarkable attention for bioremediation particularly in heavy metal removal and oil degradation due to their non-toxic nature and lack of secondary pollution. The exopolysaccharides (EPS) produced by the bacteria have become an important class of biopolymers that are employed in bioremediation. The bacteria isolated from the rhizospheric soil have higher metal tolerance and their EPS are effective in biosorption of heavy metals. Here, we report the characterization of an EPS (EPS-RN5) isolated from the root nodule-associated bacteria, Enterobacter cancerogenus strain YU16-RN5 and its heavy metal biosorption abilities. The bacteria isolated from the West coast of India was cultured in yeast extract mannitol (YEM) medium for EPS extraction and to study the production kinetics on a temporal scale. The biochemical composition, rheological properties and thermostability of EPS-RN5 was characterized by standard methods. The biosorption potential of EPS-RN5 against the selected heavy metals was analyzed by employing the inductively coupled plasma atomic emission spectroscopy (ICP-AES) technique. Further, cell culture experiments were used to test the role of EPS-RN5 in reducing the cytotoxicity exerted by the heavy metals in vitro using a human embryonic kidney cell line (HEK 293T). The bacteria showed good growth in YEM media and the maximum EPS yield was 1800mg/L at 96h. The molecular weight of EPS-RN5 was 0.7 × 106Da and it contained 61.5% total sugars and 14.5% proteins. The monosaccharide composition of the EPS included glucose, sorbose and galactose in the ratio 0.25:0.07:1.0. The EPS-RN5 showed high thermal stability with a degradation temperature of 273°C. Rheological analysis revealed the non-Newtonian behavior, with pseudoplastic characteristics. The EPS-RN5 efficiently absorbed cadmium and other heavy metals such as mercury, strontium, copper, arsenic, and uranium. In vitro studies revealed significant protective effect against the cadmium-induced cytotoxicity in HEK 293T cells. These results indicate the potential applications of EPS-RN5.

Bacteriological Evaluation of Non-Regulated Herbal Remedies Sold in Port Harcourt, Nigeria

An essential mandate of food and drug regulatory agencies is to ensure that products offered for public consumption are free from such level of microbial contamination as to endanger the health of consumers. A number of herbal remedies offered to the public were found not to be regulated as evidenced by the absence of regulation numbers on the labels. Thus, this study sought to determine the level of bacterial contamination of packaged, labeled, non-regulated herbal remedies sold in Port Harcourt. Seventy two samples of twelve different locally produced, liquid, packaged, labeled, orally administered, non-regulated herbal remedies were purchased randomly from retail outlets within Port Harcourt metropolis. They were assessed for total heterotrophic bacterial counts (THBC) and total coliform counts (TCC). One hundred and sixty four bacterial strains obtained were characterized and identified by standard techniques employing Gram staining and biochemical methods. The mean THBC was 3.77±0.77 Log10cfu/ml ranging from 3.20±0.99 to 4.37±0.91Log10cfu/ml. The mean TCC was 3.17±1.02 Log10cfu/ml; with the range between 2.32±1.81 and 3.98±0.47 Log10cfu/ml. All 164 bacterial isolates belong to eleven genera, and 22 species namely Staphylococcus aureus (59;36.0%), Enterobacter cloacae (13; 7.9%), Enterobacter pyrinus (10; 6.1%), Klebsiella pneumoniae (10; 6.1%), Pseudomonas aeruginosa (10; 6.1%), Bacillus subtilis, (8; 4.9%) Enterobacter aerogenes (7;4.3%), Serratia rubidaea (7;4.3%), Proteus (Cosenza) myxofaciens (6;3.7%), Staphylococcus epidimidis (6;3.7%) Serratia marcescens (4;2.4%) Bacillus cereus (3;1.8%), Citrobacter rodentium (3;1.8%), Enterobacter hormaechei, (3;1.8%) Klebsiella oxytoca, (3;1.8%) Proteus mirabilis (3;1.8%). Hafnia alvei (2;1.2%), Salmonella pullorum (2;1.2%), Streptococcus pyogenes (2;1.2%) Enterobacter cancerogenus (1; 0.6%) Salmonella enterica (1; 0.6%), Salmonella typhi (1; 0.6%). Given that these products were processed, packaged, labeled and offered for sale to the public without regulatory numbers, it is suggested that regulatory agencies should ensure that all such products are brought within the ambits of the regulatory laws.

Prevalence of enterotoxin genes and antibacterial susceptibility pattern of pathogenic bacteria isolated from traditionally preserved fish products of Sikkim, India

Suka ko maacha, sidra and sukuti are traditionally preserved fish products of Sikkim in India. The present study was aimed to assess the microbiological quality of traditionally preserved fish products by identifying the potential pathogenic bacteria, detecting the enterotoxins, and screening the antibiotic susceptibility patterns. The pH and moisture contents of fish products were 6.5–7.1 and 7.2–15.0%, respectively. The microbial load of aerobic bacteria was 105 to 107 cfu/g, Staphylococcus count was 105 to 106 cfu/g, Bacillus count was 104 to 106 cfu/g and total coliform count was 105 to 107 cfu/g, respectively. Based on the 16S rRNA gene sequence analysis, bacterial species isolated from traditionally preserved fish products were Bacillus cereus, Salmonella enterica, Staphylococcus sciuri, Staphylococcus aureus, Staphylococcus edaphicus, Staphylococcus nepalensis, Staphylococcus vitulinus, Enterobacter hormaechei, Enterobacter cloacae, Klebsiella pneumonia, Escherichia coli, Escherichia fergusonii, Providencia vermicola, Providencia stuartii, Providencia rettgeri, Enterobacter cancerogenus, Acinetobacter radioresistens and Pseudomonas plecoglossicida. The ELISA tests detected enterotoxins produced by Bacillus cereus and Staphylococcus in few samples. Bacillus cereus and Staphylococcus enterotoxin genes were detected in few samples by PCR method. More than 90% of antibiotic sensitivity pattern was shown towards gentamicin, norfloxacin, streptomycin, ciprofloxacin, tobramycin, and trimethoprim. The highest rate of resistant pattern was observed towards amoxicillin-clavulanate (53%) followed by nitrofurantoin (45%), ampicillin (37%), aztreonam (30%), and cefoxitin (26%).

Sea foam-associated pathogenic bacteria along the west coast of India.

Anthropogenic activities release effluents containing nutrients and pathogenic bacteria that change the characteristics of coastal ecosystems. An important type of marine pollution which has occurred in 3 different states in India during 2019 is sea foam. Sea foam was found on Hole beach, Goa (Lat: 15.404° N, Long: 73.787° E), where nutrients (NO3- = 137 μM and organic nitrogen = 121 μM) from a garbage dumpyard are released directly via streams/gutters to coastal waters. This resulted in a bloom of the diatom Thalassiosira pseudonana, associated with high concentration of total organic carbon and fucoxanthin. Decay of this bloom along with strong agitation due to rocks and wave action resulted in sea foam. We isolated foam-associated bacteria and identified pathogenic bacteria including Enterobacter cancerogenus through 16S rRNA gene sequencing. Such foam-associated pathogenic bacteria, could be antibiotic resistant, and may have adverse effects on human health. This can also hamper the tourism industry of a small state like Goa that relies heavily on tourism.

Bacteriophages Infecting Gram-Negative Bacteria in a Commercial Cucumber Fermentation

Cucumber fermentations are one of the most important vegetable fermentations in the United States. The fermentation is usually driven by lactic acid bacteria (LAB) indigenous to fresh cucumbers. But LAB are greatly outnumbered by many Gram-negative bacteria on fresh cucumbers, which may influence the growth of LAB and the incidence of bloater defect (hollow cavities formed inside fermented cucumbers) leading to serious economic loss to the pickle industry. Rapid elimination of Gram-negative bacteria is crucial to the dominance of LAB and the reduction of bloater defect in the fermentation. Various factors can affect the viability of Gram-negative bacteria in cucumber fermentation. Bacteriophages (phages) may be one of such factors. This study explored the abundance, diversity, and functional role of phages infecting Gram-negative bacteria in a commercial cucumber fermentation. Cover brine samples were taken from a commercial fermentation tank over a 30-day period. On day 1 and day 3 of the fermentation, 39 Gram-negative bacteria and 26 independent phages were isolated. Nearly 67% of Gram-negative bacterial isolates were susceptible to phage infection. Phage hosts include Enterobacter, Citrobacter, Escherichia, Pantoea, Serratia, Leclercia, Providencia, and Pseudomonas species. About 88% of the isolated phages infected the members in the family Enterobacteriaceae and 58% of phages infected Enterobacter species. Eight phages with unique host ranges were characterized. These phages belong to the Myoviridae, Siphoviridae, or Podoviridae family and showed distinct protein profiles and DNA fingerprints. The infectivity of a phage against Enterobacter cancerogenus was evaluated in cucumber juice as a model system. The phage infection at the multiplicity of infection 1 or 100 resulted in a 5-log reduction in cell concentration within 3 h and rapidly eliminated its host. This study revealed the abundance and variety of phages infecting Gram-negative bacteria, particularly Enterobacteriaceae, in the commercial cucumber fermentation, suggesting that phages may play an important role in the elimination of Gram-negative bacteria, thereby facilitating the dominance of LAB and minimizing bloater defect. To our knowledge, this is the first report on the ecology of phages infecting Gram-negative bacteria in commercial cucumber fermentations.

Isolation of Lignin-Degrading Bacteria from Different Sources and Testing of Their Ligninolytic Activities

Nine lignin-degrading bacteria were isolated from petroleum-contaminated soil and animal manure samples and characterized by 16S rRNA sequence analysis. Three isolates were identified as Enterobacter cancerogenus, two as Enterobacter ludwigii, one as Citrobacter sedlakii, one as Citrobacter farmeri, one as Klebsiella pneumoniae, and one as Citrobacter murliniae. These bacteria used ligno sulphate as the sole carbon source but did not utilize kraft lignin (KL) as the sole source of carbon and energy. For this reason, basic nutrients, such as 1.0% glucose (w/v) and 0.5% peptone (w/v), were used as additional carbon and nitrogen sources to stimulate bacterial growth for KL decolorization. Under these conditions, the isolates L1, L2, L3, L4, PT21, PT22, PT41, G1, and C1 degraded kraft lignin by 37 %, 14 %, 20%, 43%, 48%, 51%, 28%, 60%, and %99, respectively. The decolorization of Remazol Brilliant Blue R (RBBR) by the isolates was analyzed. The isolates were decolorized at 20-90 % of RBBR, respectively.

Siderophore production by bacteria isolated from mangrove sediments: A microcosm study

Mangroves are one of the most productive ecosystems worldwide covering up to 75% of the coastline in the tropics and subtropics. They support a highly diverse community (marine and terrestrial) and serves as reservoirs of nutrients for coastal and shelf waters. Bacterial diversity in mangroves includes heterotrophs, autotrophs (nitrogen fixation) and pathogens (phytopathogens, marine, and human). All these bacterial groups require sequestration of bioavailable iron, which is largely done by the production of siderophores. In this study, microcosm experiments were conducted to test the effect of incubation conditions (temperature, iron concentration, pH, and carbon source) on growth and siderophore production in four mangrove sediment bacterial isolates- Escherichia vulneris, Enterobacter cancerogenus, Pantoea agglomerans, and Enterobacter bugandensis. Our study showed that all isolates produce more siderophores (30 to 60%) at low iron concentrations (10 nM to 1 μM) during lag-phase and early log-phase of growth. Low temperature suppressed bacterial growth without significantly altering the siderophore production, whereas low pH suppressed both growth and siderophore production in these isolates. Although all isolates could produce siderophores when using different carbon sources, glucose served as an ideal carbon source. The observed changes in growth and siderophore production may be attributed to species-specific physiological traits, changes in bioavailability of iron and/or combination of both. Our results suggest that in a changing global environment, warming of the surrounding waters may not reduce the siderophore production and hence, they will be essential in sustaining bacterial activity in sediments.