No abstract

The present study aimed to isolate the high-efficiency petrol metabolizing thermophilic bacteria from petrol contaminated soil samples. Isolation was carried out through enrichment culture, serial dilution and pour plate methods using the petrol supplemented minimal salt media. The isolated bacteria were analyzed to document growth behavior, petrol removal efficiencies, antibiotic resistance profile, and biochemical characteristics. The 16S rRNA based phylogenetic analysis helped to reveal the identity of isolated bacterial species and construct the phylogenetic trees. Total nine bacteria were isolated, out of which three (IUBP2, IUBP3, IUBP5) were identified as Brevibacillus formosus, one (IUBP1) was found similar to Brevibacillus agri, four (IUBP7, IUBP8, IUBP13, and IUBP14) shared homology with Burkholderia lata, and one (IUBP15) with Burkholderia pyrrocinia. All the isolates were fast growing and exhibited considerable petrol degradation potential. The highest petrol removal efficiency (69.5% ± 13.44/6 days) was recorded for the strain IUBP15 at a petrol concentration of 0.1% (v/v). All bacteria studied (100%) were positive for esculinase and phosphatase. Many strains exhibited positive responses for arginine dehydrolase (22%), β-naphthylamidase (11%), β-D-glucosaminide (33%), mannitol (55%), sorbitol (66%) and inulin (88%) fermentation test. While all were sensitive to the antibiotics, some of them were found resistant against chloramphenicol and oxacillin. The remarkable biochemical characteristics and considerable petrol removal potential (40–70%) highlights utilization of the bacteria isolated for petrol bioremediation, mineralization of organophosphates, dairy and food industry, and also as biofertilizers and biocontrol agents.

No abstract

16The focus of present study was to isolate and characterize bacteria which can be 17 effectively used for toluene, a highly recalcitrant pollutant, bioremediation. For isolation 18 of bacteria from the tannery effluents selective enrichment and serial dilution methods 19 were employed. The isolated bacteria were subjected to growth curve analysis, estimation 20 of toluene removal efficiencies, biochemical tests, antibiotic sensitivity assays and 21 molecular characterization based upon 16S rRNA gene. The rRNA genes sequences were 22 analyzed through BLAST to determine similarity index of isolates with bacterial database 23 sequences. To trace the evolutionary history, phylogenetic trees were constructed using 24 MEGA version 7. Total twenty toluene metabolizing bacteria (4)(5)(6)(7)(8)(9)(10)(11)(12) 16, 19, 21, 25 23-26, 28 and 30) were isolated and characterized. Their rRNA gene sequences have 26 been submitted to Genbank. Fifteen of the twenty isolates showed homology to 27 2 Brevibacillus agri strain NBRC 15538, four found similar to Bacillus paralicheniformis 28 strain KJ-16 and one homologous to Burkholderia lata strain 383. All bacterial isolates 29 were resistant to chloramphenicol but sensitive to teicoplanin and linezolid. However, 30 few (i. e.; IUBT9 and 26) were sensitive to oxacillin. Biochemical characterization 31 indicated all bacteria positive for alkaline phosphatases (100%). While many were found 32 positive for p-nitrophenyl N-acetyl β, D-glucosaminidase (35%), hydroxyproline β-33 naphthylaminopeptidase (15%), esculinase (65%), mannitol (75%), sorbitol (95%) and 34 inulin (90%) fermentation. Biochemical profile suggests the use of isolated bacteria for 35 future exploitation in several fields like bioremediation of toluene, ethanol production, 36 biomass hydrolysis, biosensors, biofertilizers, as a marker for milk pasteurization in dairy 37 industries and evaluation of soil quality. 38 Importance 39Toluene is a highly toxic environmental pollutant. We have isolated bacteria which can 40 be effectively used for the removal of toluene from environmental resources. Moreover, 41 these bacteria are capable to produce many valuable enzymes which can be used in many 42 industrial processes for the production of a wide range of products. Further study may 43 help to exploit these bacterial for the benefit of humanity. 44 45 Key words: toluene metabolizing bacteria, bioremediation, toluene removal efficiency, 46 Brevibacillus agri, Bacillus paralicheniformis, Burkholderia lata, rRNA profiling 47 48 49Toluene (methylbenzene) is an omnipresent pollutant and is a cause of concern due to its 50 resistance to chemical, photolytic and biological degradation, lipophilic nature, 51 bioaccumulation, long-range transport and wide range adverse effects on environment, 52 wild life, biota and human health (1). Being lipophilic, it gets accumulated in lipid bilayer 53 of cell membrane and alters the structure of living cells (2). Toluene is a man-made 54 hydrocarbon and its major sources in urban air e...

During present study, four naphthalene‐ metabolizing bacteria were isolated from tanneries effluents through enrichment on naphthalene as sole carbon source in minimal salt medium. The bacteria were analyzed to document growth pattern, naphthalene removal efficiency, biochemical and molecular characteristics, antibiotic sensitivity, and metabolic profile. The 16S ribosomal RNA gene sequences were compared through BLAST (basic local alignment search tool) similarity search tool and three isolates were found homologous to Brevibacillus agri strain NBRC 15538 and one similar to Burkholderia lata strain 383. The naphthalene removal efficiencies ranged from 1.16 ± 0.056 mg/h (IUBN1) to 1.379 ± 0.021 mg/h (IUBN26). All isolates were positive for p‐nitrophenyl phosphate (PO4), esculin, and inulin fermentation tests. Majority were positive for glucosaminidase (IUBN3, 17, and 26) and a few for mannitol and sorbitol fermentation (IUBN1). Identification of metabolites through gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry analysis allowed tracing pathways associated with naphthalene degradation. Intermediates such as cis‐dihydrodiolnaphthalene, 2‐hydroxychromene‐2‐carboxylate, 6‐hydroxyhexanoic acid, acetyl‐CoA confirmed that the present study bacteria can metabolize naphthalene through a pathway which differs from the pathways reported in earlier known bacteria. Due to fast growth rates, high naphthalene removal potentials, and multiple degradation pathways, these bacteria can be exploited for bioremediation of naphthalene.