Characterization Of Culturable Bacteria Research Articles

Health risk assessment and characterization of PM2.5 bound bioaerosols at the municipal solid waste landfill site of Nagpur, India

Landfill being the reservoir of organic waste, serves as the most important source in the generation and emission of bioaerosols in the environment, and these bioaerosols have a significant impact on the environment and public health. In India, there are limited studies on the characterization of culturable bacteria and fungi in the bioaerosols originating from landfills. Therefore, the present study aimed to quantify and identify the bioaerosols and study their characteristics at a landfill site in Nagpur, India. The study describes the seasonal variation of PM2.5, PM2.5-associated bacteria and fungi in the landfill air, their molecular identification, antibiotic resistance, pathogenicity, dispersion and health risk assessment during winter and pre-monsoon seasons at the landfill site and surrounding residential sites in upwind and downwind directions. The study showed PM2.5 concentration was highest in the winter season (265.56 μg/m3) followed by the pre-monsoon season (173.1 μg/m3) at the landfill site. The culturable bioaerosol level was also significantly higher in winter (11056 CFU/m3) in comparison to pre-monsoon season (2244 CFU/m3) at the landfill site. Upon isolating and characterizing the microorganisms in the bioaerosols, some of the bacterial isolates, like Bacillus, Staphylococcus gallinarum, and Streptomyces speibonae were found to be resistant to chloramphenicol, netillin, nitrofurantoin, streptomycin etc. About 30% of the bacterial isolates were found to show β-hemolytic virulence activity. This indicated the presence of multi-drug resistant and potentially pathogenic bacteria in the bioaerosols over the landfill. The health risk assessment in adults indicated that the workers at the landfill site were at risk of bacterial aerosol in the winter season (hazard quotient i.e., HQ>1). The impact of bioaerosols on children needs to be investigated in the further studies and regular monitoring of bioaerosols is suggested to avoid any morbidity. To the best of our knowledge, this is the first study on the characterization of microorganisms from the bioaerosols over an open landfill site in India.

Characterization of culturable bacteria from pulp and paper industry wastewater, with the potential for degradation of cellulose, starch, and lipids

The search for microbial enzymatic activities applied to wastewater treatment is an important task in environmental biotechnology. Microbial enzymes have been previously explored in hostile habitats. They are increasingly important in extreme habitats; biological wastewater from the pulp and paper mill industry can harbor microorganisms with valuable enzymatic capabilities that can improve the efficiency for the same process of depuration. This study was performed to characterize and evaluate cellulolytic, amylolytic, and lipolytic activities of bacteria isolated from a pulp and paper effluent. The enzymatic activities were evaluated by the formation of a clear halo around the colonies in defined substrate media. By the use of a sequence analysis of 16S rDNA libraries, isolates were identified. The 16S rDNA libraries belong to the Bacillus subtilis, B. megaterium, B. licheniformis, B. pumilus, B. thuringiensis, B. cereus, Chryseobacterium daecheongense, and Microbacterium sediminis (an alkali-tolerant bacteria which has only been isolated from deep-sea sediment). B. cereus was the best strain for cellulose and lipase activities; moreover, C. daecheongense was best for amylase activity. The present study shows that the aerated lagoons from the pulp and paper industry are a promising source of bacterial with different enzyme activities. This data is relevant for industrial applications.

Isolation and characterization of culturable bacteria from bulk soil samples and the rhizosphere of arid-adapted Tylosema esculentum (Burchell). A. Schreiber (Marama bean) in Namibia

Plant growth promoting (PGP) bacteria are microorganisms living in association with plants. PGP bacteria have various physiological activities that they perform which are beneficial to plants. For example, phosphate solubilisation, nitrogen fixation, phytostimulation and formation of siderophores. The aim of this investigation was to determine the diversity of PGP bacteria and to characterise them for possible promotion of plant growth from the rhizosphere of Tylosema esculentum , a nutritious arid adapted legume. For that purpose, in this study, bacteria were isolated from marama bean rhizosphere and bulk soil. The bacteria were screened for their ability to solubilise phosphates, for aminocyclopropane-1-carboxylate (ACC) deaminase activity, production of catalase, hydrogen cyanide, ammonia and protease activity. Efficiency of phosphate solubilising activity by bacteria was determined by phosphate solubilisation index. DNA was extracted from bacterial cultures and used to obtain 16S rDNA amplicons for bacterial molecular identification. A total of eight bacterial strains were isolated from the rhizosphere and 19 strains from bulk soil with potential plant growth promoting traits. The 27 bacterial isolates showed phosphate solubilising activity and five of the isolates had a solubilisation index of at least 6. A total of 23 isolates showed ACC deaminase activity. Hydrogen cyanide was produced by 16 isolates; 26 isolates had catalase activity, 23 isolates showed protease activity and all the isolates produced ammonia. The identified genera include Bacillus, Raoultella, Klebsiella, Acinetobacter, Arthrobacter, Kosakonia and Burkholderia . From this study, we conclude that there is a community of bacteria living in T. esculentum rhizosphere and proposed that in future these native bacterial strains can be used as biofertilisers for this arid agro-ecological area after verifying their suitability for inoculum development. Key words: Rhizobacteria, plant growth promoting bacteria, Kosakonia, Burkholderia. Abbreviation: PGP, Plant growth promoting.

Characterization of culturable bacteria in larval cultures of the Chilean scallop Argopecten purpuratus

The early stages of culture of the Chilean scallop Argopecten purpuratus are affected by the mortality attributed to the presence of pathogenic bacteria. The purpose of this study was to characterize the culturable bacteria present in larval cultures of A. purpuratus in the presence and absence of antibiotic (Tetracycline). Bacterial counts on marine agar from water, algal, and larval samples from the culture units were carried out. These counts were performed every three days during 20 days of incubation. The bacterial strains isolated from count plates were identified by 16S rDNA gene sequence analysis. Additionally, the total bacterial counts from culture water were determined by epifluorescence microscopy. Culturable bacterial counts of water samples ranged from 8 × 103 to 3 × 104 CFU mL–1. These counts represent from 3% to 18% of the total bacterial counts. The culturable bacterial counts in larvae were between 3 × 107 and 3 × 108 CFU g–1 and were on average higher in the absence of antibiotic (P < 0.05). Microalgal bacterial counts ranged from 1 × 104 to 9 × 104 CFU mL–1. Of the 46 strains isolated and identified, 25 (54%) belonged to the Gammaproteobacteria, 11 (24%) to the Bacilli, 5 (11%) to the Actinobacteria, 4 (9%) to the Alphaproteobacteria, and 1 (2%) to the Flavobacteria. The most dominant genera in the water samples were Alteromonas, Brevibacterium, Bacillus, Microbacterium, and Marinobacter, while the most dominant genera in larvae were Pseudoalteromonas, Bacillus, Marinobacterium, Alteromonas, and Vibrio, from a total of 15 different bacterial genera identified. The survival of larvae decreased drastically during the 20 days of culture, showing no differences to antimicrobial treatments. The results indicate that there is a high diversity of culturable bacteria present in the larvae, and most are different from those found in the water and microalgae supplied as food.

Occurrence and characterization of culturable bacteria and fungi in metalworking environments

Modern metalworking fluids (MWFs) provide the breeding ground for microorganisms that could enter the ambient environment via aerosolization. This manuscript describes the occurrence, type, concentration and size distribution of bacteria and fungi in an MWF environment by sampling aerosols and MWF sumps. In this study, computer numerical control (CNC) thread-cutting and grinding processes at a socket-manufacturing plant were investigated. Cladosporium and Aspergillus were the dominant fungal isolates in this study. Peak fungal concentrations (797 CFU/m3) were observed during thread-cutting processes, and the most prevalent fungi were in the size range of 2.1–3.3 μm. Moreover, Exiguobacterium spp.,Micrococcus spp., and Staphylococcus capitis were the dominant bacterial isolates identified. The most prevalent bacteria were in 4.7–7.0 μm size range. This study indicates that the type of machine tools was not associated with MWF sump microbial concentrations. The total bacterial and fungal contamination in MWF sump samples reached levels of 105 CFU/ml. Pseudomonas spp. was the only bacterium identified in the MWF sumps, and Aspergillus, Penicillium, and yeast were the predominate fungi identified.

Isolation and characterization of culturable bacteria from tropical coastal waters

In this study we isolated and characterized some culturable bacteria from tropical coastal waters of Peninsular Malaysia. We obtained between 0.23 and 1.85 × 103 cfu mL–1 in the Zobell 2216E medium, and cultured 0.04% to 0.12% of total bacterial counts. Different bacterial strains were then selected by 16S rDNA RFLP using four restriction enzymes (DdeI, HhaI, RsaI, and Sau3AI), of which HhaI gave the most RFLP patterns. A total of 54 unique strains were obtained and these were identified by their 16S rDNA gene sequence. These bacterial strains could be divided into five classes: 38 strains of γ-Proteobacteria (61.1%); 3 strains of α-Proteobacteria (5.5%); 2 strains of the Cytophaga-Flavobacterium-Bacteroides group (3.7%); 3 strains of high GC, Gram-positive bacteria (5.5%); and 13 strains of low GC, Gram-positive bacteria (24.1%). These isolates have good potential for further biotechnological studies since about 56% of the isolates exhibited amylase activity, whereas 36% and 18% of the isolates had protease and lipase, respectively. Most (>70%) of the isolates also produced poly-ß-hydroxybutyrate.