Biodegradation of petroleum by bacteria isolated from fishes of Indian Ocean

In this study, oil degrading bacteria discovered from fish living near the oil ports at Karachi in Pakistan were characterized. The bacteria isolated from skin, gills, and gut in fish could consume crude oil as a source of carbon and energy. Total 36 isolates were tested using Nutrient Agar (NA) and MSA media with different crude oil concentrations (0.2%, 0.5%, 0.7%, 1%, 2%, and 5%) and 4 out of 36 isolates (two Gram positive and two Gram negative bacteria) were selected for further identification. 16S rRNA gene sequencing revealed that the isolates are related to Bacillus velezensis, Bacillus flexus, Pseudomonas brenneri and Pseudomonas azotoforman. Oil degrading potential of these bacteria was characterized by GC-MS analysis of degradation of oil components in crude oil as well as engine oil. We found that one (2, 6, 10, 14-Tetramethylpentadecane) out of 42 components in the crude oil was fully eliminated and the other oil components were reduced. In addition, 26 out of 42 oil components in the engine oil, were fully eliminated and the rest were amended. Taken together, these studies identify that B. velezensis, B. flexus, P. brenneri and P. azotoforman have high oil degrading potential, which may be useful for degradation of oil pollutants and other commercial applications.

Isolating and Characterizing Phosphorus Solubilizing Bacteria From Rhizospheres of Native Plants Grown in Calcareous Soils

Many soils including urban soils have high legacy soil phosphorus (P) due to repeated applications of P fertilizers, but a large portion legacy soil P is fixed by calcium in the calcareous soils. Phosphorus solubilizing bacteria (PSB) have the ability to transfer fixed (non-labile) soil P into bioavailable P. The aim of this study was to isolate P solubilizing bacteria from the rhizospheres of four local native plants [broomsedge bluestem (Andropogon virginicus), giant sword ferns (Nephrolepis biserrata), sawgrass (Cladium jamaicense), and sea ox-eye daisy (Borrichia frutescens)] grown in low bioavailable P calcareous soils and to determine their ability to solubilize P. A total of 44 strains of PSB were isolated with 15 of them being identified by sequencing the 16S rRNA genes as Bacillus flexus, Beijerinckia fluminensis, Enterobacter ludwigii, Enterobacter sp., and Pantoea cypripedii. After a 7-day incubation, these strains reduced pH to <4.27 and increased water-soluble P up to 588 mg L−1. Enterobacter ludwigii showed superior P solubilizing ability amount PSB isolated. Therefore, the isolated strains from the local native environment have the potential to thrive in local calcareous soils and possess strong ability to transform non-labile P into bioavailable forms for plants to uptake.

Molecular Characterisation and Plasmid Profiling of Hydrocarbon Utilizing Bacteria Isolates from Wetlands in Rivers State, Southern Nigeria

Wetlands can intercept runoff from surfaces prior to reaching open water and remove pollutants through physical, chemical, and biological processes thereby protecting and preserving the environment. Because of unsustainable oil exploration activities, most wetlands in Rivers State, Southern Nigeria have suffered severe petroleum-damaged ecosystems. This research was carried out to characterize and identify the hydrocarbon utilizing bacteria associated with crude oil polluted wetlands and to screen for the presence of plasmids that could confer resistance to antibiotics using both cultural and molecular methods. Soil samples were collected from three different wetlands across the state with hand auger at two depths of 0-15cm and 15-30cm twice monthly for three months. The presence of microbial activity was determined by the enumeration and isolation of total heterotrophic and hydrocarbon utilizing bacteria. Eight (8) most occuring hydrocarbon utilizing bacterial isolates were isolated and identified culturally and phenotypically from the 54 wetland soil samples. These bacteria isolates were confirmed to be Bacillus flexus, Bacillus subtilis, Lysinibacillus macroides, Staphylococcus aureus, Chryseobacterium aquifrigidense, Pseudomonas aeruginosa and Salmonella enterica molecularly via sequencing of the 16S rRNA gene. The most common bacteria isolated were Bacillus species, followed by Pseudomonas at a dilution of 106. Seven (7) out of the eight (8) isolates (except Salmoella enterica) showed the presence of the 25kb plasmids at various intensities.

ISOLATION OF CELLULOLYTIC BACTERIA FROM SOIL AND VALORIZATION OF DIFFERENT LIGNOCELLULOSIC WASTES FOR CELLULASE PRODUCTION BY SUBMERGED FERMENTATION

Cellulases are known to convert cellulose into monomeric or dimeric structures, hence playing an important role in bioethanol production, along with their applications in textile and paper industries. This study was directed towards the isolation and screening of cellulase producing bacteria from different soil samples on CMC (carboxymethyl cellulose) agar plates, followed by Gram’s iodine staining. Six strains showed clear zones of hydrolysis on CMC agar plates. Isolates were identified as Bacillus megaterium, Pseudomonas stutzeri, Bacillus aerius, Bacillus paralichniformis, Bacillus flexus, and Bacillus wiedmanni by 16S rRNA gene sequencing. These strains were cultivated by submerged fermentation for cellulase production using various lignocellulosic wastes, such as corn cob, rice husk, wheat straw, seed pods of Bombax ceiba and eucalyptus leaves. Results showed that Pseudomonas stutzeri is the best cellulase producer among these strains. It offered the highest cellulase activity of 170.9±4.1 (IU/mL/min) in media containing eucalyptus leaves after 24 h of incubation at 37 °C, followed by Bacillus paralichniformis, Bacillus wiedmanni, Bacillus flexus, Bacillus aerius and Bacillus megaterium. These bacterial strains and lignocellulosic wastes could be potentially used for industrial exploitation, particularly in biofuels and textiles.

Expression, biochemical and structural characterization of high-specific-activity β-amylase from Bacillus aryabhattai GEL-09 for application in starch hydrolysis

Background β-amylase (EC 3.2.1.2) is an exo-enzyme that shows high specificity for cleaving the α-1,4-glucosidic linkage of starch from the non-reducing end, thereby liberating maltose. In this study, we heterologously expressed and characterized a novel β-amylase from Bacillus aryabhattai. Results The amino acid-sequence alignment showed that the enzyme shared the highest sequence identity with β-amylase from Bacillus flexus (80.73%) followed by Bacillus cereus (71.38%). Structural comparison revealed the existence of an additional starch-binding domain (SBD) at the C-terminus of B. aryabhattai β-amylase, which is notably different from plant β-amylases. The recombinant enzyme purified 4.7-fold to homogeneity, with a molecular weight of ~ 57.6 kDa and maximal activity at pH 6.5 and 50 °C. Notably, the enzyme exhibited the highest specific activity (3798.9 U/mg) among reported mesothermal microbial β-amylases and the highest specificity for soluble starch, followed by corn starch. Kinetic analysis showed that the Km and kcat values were 9.9 mg/mL and 116961.1 s− 1, respectively. The optimal reaction conditions to produce maltose from starch resulted in a maximal yield of 87.0%. Moreover, molecular docking suggested that B. aryabhattai β-amylase could efficiently recognize and hydrolyze maltotetraose substrate. Conclusions These results suggested that B. aryabhattai β-amylase could be a potential candidate for use in the industrial production of maltose from starch.

Sustainable Repairing and Improvement of Concrete Properties Using Bacterial Consortium Isolated From Egypt

The small cracks in concrete constructions are inevitable due to deterioration during their service life throughout different load combination factors. In this study, we aimed to isolate, identify, and construct a bacterial consortium able to heal small cracks of concrete and enhance the different properties of concrete. Six isolates of bacillus, endospore-forming bacteria were isolated. There are only three isolates out of the six coded as NW-1, MK and NW-9 were showed the ability to produce urease enzyme and able to grow at 60°C with optimum growth at a temperature of 40°C. These isolates were survived in high pH, where isolate NW-1 was tolerated pH up to 11 with optimum growth at 10 while the isolates NW-9 and MK showed growth at pH 12 with an ideal growth at 10. CaCO3 production was observed by the three bacterial isolates whether in pure or mixed cultures (bacterial consortium) but the consortium consisting of MK and NW-9 was significantly the highest in productivity among them. Therefore, these two isolates were identified using 16s as Bacillus flexus MK-FYT-3 and Bacillus haynesii MK-NW-9 and deposited to GenBank under accession numbers MN965692 and MN965693 respectively. The effect of bacteria on some properties of concrete was studied, and the results showed that the compressive and tensile strengths of bio-concrete specimens were significantly increased by 31.29, 29 % after 7 days and 36.3, 39 % after 28 days of curing compared to control specimens. The results of permeability indicated that the bio-concrete specimens significantly showed less permeability than the control specimens by 21.1, 23.1% after 7 and 28 of curing, respectively. To determine the concrete density, Ultrasonic Pulse Velocity (UPV) test was performed, and the bio-concrete specimens gave higher values ​​than control specimens by 26 and 20% after curing for 7 and 28 days, respectively. Also, surface healing of concrete was observed visually, the bio-concrete showed white precipitates around and inside the cracks after 7 days, which led to almost complete sealing of concrete after 28 days of curing, while the control samples were showed only very slight deposits on the surface and away from the cracks. The micro-analysis of concrete samples using SEM and XRD were done. It was found that the bio-concrete specimens showed crystalline precipitate with different shapes under SEM, while no such deposits appeared in the control specimens. On the other hand, the XRD profile was explained the characteristic peaks of calcium carbonate in both the bio-concrete and the control specimens, but the peak intensity was higher in the bio-concrete than the control specimens. This reflects the effectiveness of bacterial consortium in repairing and preventing the concrete cracks from spreading in addition to improving the various properties of concrete leading to increasing its life and sustainability.