Biocatalytic Desulfurization Capabilities of a Mixed Culture during Non-Destructive Utilization of Recalcitrant Organosulfur Compounds

Abstract

We investigated the biodesulfurization potential of a mixed culture AK6 enriched from petroleum hydrocarbons-polluted soil with dibenzothiophene (DBT) as a sulfur source. In addition to DBT, AK6 utilized the following compounds as sulfur sources: 4-methyldibenzothiophene (4-MDBT), benzothiophene (BT), and 4,6- dimethyldibenzothiophene (4,6-DM-DBT). None of these compounds supported the growth of AK6 as the sole carbon and sulfur source. AK6 could not grow on dibenzylsulfide (DBS) as a sulfur source. The AK6 community structure changed according to the provided sulfur source. The major DGGE bands represented members of the genera Sphingobacterium, Klebsiella, Pseudomonas, Stenotrophomonas, Arthrobacter, Mycobacterium, and Rhodococcus. Sphingobacterium sp. and Pseudomonas sp. were abundant across all cultures utilizing any of the tested thiophenic S-compounds. Mycobacterium/Rhodococcus spp. were restricted to the 4-MDBT culture. The 4-MDBT culture had the highest species richness and diversity. Biodesulfurization of DBT by resting cells of AK6 produced 2-hydroxybiphenyl (2-HBP) in addition to trace amounts of phenylacetate. AK6 transformed DBT to 2-hydroxybiphenyl with a specific activity of 9 ± 0.6 μM 2-HBP g dry cell weight−1 h−1. PCR confirmed the presence in the AK6 community of the sulfur-specific (4S) pathway genes dszB and dszC. Mixed cultures hold a better potential than axenic ones for the development of a biodesulfurization technology.

Desulfurization of Dibenzothiophene by Pseudomonas fluorescens (UCP 1514) Leading to the Production of Biphenyl

“…Among the numerous biodesulfurization cultures isolated, there are several that possess an extended 4S pathway such that 2-HPB is not the end product of DBT desulfurization, and instead 2-methoxybiphenyl (2-MBP) [38][39][40], biphenyl [41], or 2,2-dihydroxybiphenyl [42] are produced. The toxicity of 2-MBP is reported to be only slightly less than 2-HBP [43], but this study examined the inhibition of DBT biodesulfurization by externally added 2-MBP or 2-HBP and did not address the intracellular accumulation of 2-HBP [44].…”

Diesel-born organosulfur compounds stimulate community re-structuring in a diesel-biodesulfurizing consortium

“…To elucidate the DBT biodesulfurization pathway, DNA from the MG1 consortium was used to detect the 4S pathway genes (dszAbC) using gene specific primers [ 17 , 28 , 29 ]. For the detection of the biodesulfurization intermediates, the MG1 consortium was grown in CDM with glucose (10 mM) and DBT (0.1 mM) as described earlier (in triplicates) and samples (25 mL) were withdrawn at the beginning of the experiment and then after 24, 48, and 72 h. The culture samples were centrifuged (10,000 rpm, 10 min, 4 °C) to remove cells and the cell–free supernatants were extracted with one volume of GC-grade ethyl acetate.…”

“…Despite more than 30 years of research and development, biodesulfurization has not been applied at an industrial scale yet mainly due to the low catalytic efficiency of the available biodesulfurizing bacteria [ 4 , [14] , [15] , [16] ]. Most of the previous research has focused on axenic cultures of biodesulfurizing bacteria [ [17] , [18] , [19] ]. On the contrary, much less efforts have been invested to exploit the advantageous lifestyle of bacterial consortia that could potentially promote the biodesulfurization activity through various microbial interactions [ 20 , 21 ].…”

“…In an early study, it was reported that the biodesulfurization activity of a consortium consisting of the biodesulfurizing Rhodococcus rhodochrous IGTS8 (later identified as R. erythropolis IGTS8) and the non-biodesulfurizing Enterobacter cloacae was higher than that of the biodesulfurizing strain IGTS8 alone [ 22 ]. Recently, a biodesulfurizing mixed culture was enriched from a hydrocarbon–polluted soil and consisted mainly of species belonging to Sphingomonas , Klebsiella , Mycobacterium , Rhodococcus , Stenotrophomonas , Sphingobacterium , Pseudomonas , and Arthrobacter [ 17 ]. A commercial bacterial consortium consisting of Alcaligenes faecalis , Acinetobacter sp., Bacillus sp., Komagataeibacter hansenii , Oceanobacillus iheyensis , Ochrobactrum anthropic , Paenibacillus lautus and Providencia rettgeri was used for the biodesulfurization of heavy gas oil and achieved 71.8 % biodesulfurization rate after 6 h of treatment [ 23 ].…”

Avaliação da remoção adsortiva do tiofeno de uma gasolina modelo utilizando ZSM-35 impregnada com molibdênio

“…Sendo assim, a viabilidade técnica de processos alternativos e/ou complementares à HDS é uma crescente no meio científico, sendo que os principais processos alternativos e/ou complementares de dessulfurização estudados visam a aplicação de processos biotecnológicos [9][10][11], utilização de processos oxidativos [12][13][14], e a aplicação de processos adsortivos utilizando diferentes materiais adsorventes [2,5,15]. A dessulfurização adsortiva recebe destaque por ser um dos métodos que utiliza condições operacionais de temperatura e pressão mais brandas [6].…”