Vacuum distillation residue upgrading by an indigenous Bacillus cereus

Nutrient optimization for indigenous microbial consortia of a Bhagyam oil field: MEOR studies

The microbial enhanced oil recovery (MEOR) method is an eco-friendly and economical alternative technology. The technology involves a variety of uncertainties, and its success depends on controlling microbial growth and metabolism. This study is one of a kind that showed successful tertiary recovery of crude oil through indigenous microbial consortia. In this study, a medium was optimized to allow ideal microbial growth under reservoir conditions through RSM. Once the nutrient recipe was optimized, the microbial metabolites were estimated through gas chromatography. The maximum amount of methane gas (0.468 mM) was produced in the TERIW174 sample. The sequencing data set showed the presence of Methanothermobacter sp. and Petrotoga sp. In addition, these established consortia were analyzed for their toxicity, and they appeared to be safe for the environment. Furthermore, a core flood study showed efficient recovery that was ~25 and 34% in TERIW70 and TERIW174 samples, respectively. Thus, both the isolated consortia appeared to be suitable for the field trials.

Microbial diversity and activity of an aged soil contaminated by polycyclic aromatic hydrocarbons

In-depth understanding of indigenous microbial assemblages resulted from aged contamination by polycyclic aromatic hydrocarbons (PAHs) is of vital importance in successful in situ bioremediation treatments. Soil samples of three boreholes were collected at 12 different vertical depths. Overall, the dominating three-ring PAHs (76.2%) were closely related to distribution patterns of soil dehydrogenase activity, microbial cell numbers, and Shannon biodiversity index (H') of indigenous microorganisms. High-molecular-weight PAHs tend to yield more diverse communities. Results from 16S rRNA analysis indicated that possible functional groups of PAH degradation include three species in Bacillus cereus group, Bacillus sp. SA Ant14, Nocardioides sp., and Ralstonia pickettii. Principal component analysis indicates significant positive correlations between the content of high-molecular-weight PAHs and the distribution of Bacillus weihenstephanensis KBAB4 and Nocardioides sp. The species B. cereus 03BB102, Bacillus thuringiensis, B. weihenstephanensis KBAB4, and Nocardioides sp. were recognized as main PAH degraders and thus recommended to be utilized in further bioremediation applications. The vertical distribution characteristics of PAHs in soil profiles (1-12 m) and the internal relationship between the transport mechanisms of PAHs and the response of soil biological properties help further understand the microbial diversity and activity in an aged site.

Bioremediation of soil contaminated crude oil by Agaricomycetes

BACKGROUND

One of the most important environmental problems is the decontamination of petroleum hydrocarbons polluted soil, particularly in the oil-rich country. Bioremediation is the most effective way to remove these pollutants in the soil. Spent mushroom compost has great ability to decompose lignin-like pollution. The purpose of this study was the bioremediation of soil contaminated with crude oil by an Agaricomycetes.

METHODS

Soil sample amended with spent mushroom compost into 3%, 5% and 10% (w/w) with or without fertilizer. Ecotoxicity germination test was conducted with Lipidium sativa.

RESULTS

The amplified fragment (18 s rDNA) sequence of this mushroom confirmed that the strain belonged to Pleurotus ostreatus species with complete homology (100% identity). All tests experiment sets were effective at supporting the degradation of petroleum hydrocarbons contaminated soil after three months. Petroleum contaminated soil amended with Spent mushroom compost 10% and fertilizer removed 64.7% of total petroleum hydrocarbons compared control. The germination index (%) in ecotoxicity tests ranged from 60.4 to 93.8%.

CONCLUSIONS

This showed that the petroleum hydrocarbons contaminated soil amended with 10% Spent mushroom compost had higher bioremediation ability and reduced soil toxicity in less than three months.