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Cross-correlating analyses of mineral-associated microorganisms in an unsaturated packed bed flow-through column test; cell number, activity and EPS.

Abstract：

:In heap bioleaching and waste-rock dumps, complex microbial communities exist in the flowing and interstitial liquid phases and mineral surface-associated biofilms, often embedded in extracellular polymeric substances (EPS). Microbial activity in the interstitial phase and mineral ore surface facilitates mineral degradation, resulting in either metal recovery or acidic, metal -bearing drainage from sulfidic waste-rock. Determining microbial presence and activity through microorganisms leaving the heap or dump has severe limitations. Hence, increasingly the ore-bed is sampled to quantify and characterise this. Here, methods for cell detachment and quantification, microbial activity measurement on the mineral surface and evaluation of EPS, quantitatively and biochemically, were refined and validated to assess microbial presence, using mineral coated beads in continuous flow-through columns. Number of wash steps required were assessed over increasing colonisation times over 30 days. Microbial cells colonising the mineral surface, pre- and post-washing were visualised by scanning electron microscopy (SEM) and their activity quantified by isothermal microcalorimetry (IMC). Using IMC, detachment and enumeration of detached cells, we demonstrated that 6-8 washes provided a reliable estimation of mineral-associated microorganisms, with less than 10% of cells or microbial activity associated with the surface following treatment. This allowed consolidated refinement of the protocol using traditional detachment method, SEM and IMC to provide correlative data. Extraction of EPS in a complete flow-through system is reported for the first time and the biochemical composition was similar to those reported under batch bioleaching conditions.

journal_name

Res Microbiol

journal_title

Research in microbiology

authors

Makaula DX,Huddy RJ,Fagan-Endres MA,Harrison STL

doi

10.1016/j.resmic.2020.09.002

subject

Has Abstract

pub_date

2020-01-01 00:00:00

pages

222-229

issue

eissn

0923-2508

issn

1769-7123

pii

S0923-2508(20)30085-1

journal_volume

171

pub_type

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Cross-correlating analyses of mineral-associated microorganisms in an unsaturated packed bed flow-through column test; cell number, activity and EPS.