Characterization and Biolubricant Performance of <i>Marinobacter alanticus</i> Lipid Extract

Renewable and sustainable materials to replace petroleum-based lubricants are increasingly sought in tribology and energy applications. In this study, Marinobacter atlanticus cultures were harvested and cells extracted for intracellular lipids for subsequent combined chemical and tribological evaluation. Mass spectrometry revealed that the extract was dominated by the wax ester palmityl palmitoleate, confirming a high-molecular-weight ester profile favorable for boundary lubrication. Differential scanning calorimetry and thermogravimetric analysis indicated a glass transition at 0°C, a melting endotherm at 40°C, and an onset of thermal degradation near 220°C, providing a workable thermal window for moderate-temperature applications. Pin-on-disk tribometry of the neat extract yielded an average friction coefficient of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:mover><mml:mi>μ</mml:mi> <mml:mo>¯</mml:mo></mml:mover> <mml:mo>=</mml:mo> <mml:mn>0.117</mml:mn> <mml:mspace></mml:mspace> <mml:mrow><mml:mo>(</mml:mo> <mml:mrow><mml:mo>±</mml:mo> <mml:mn>0.02</mml:mn></mml:mrow> <mml:mo>)</mml:mo></mml:mrow> </mml:mrow> <mml:annotation>$\bar{\mu } = 0.117\ ( { \pm 0.02} )$</mml:annotation></mml:semantics> </mml:math> and an average specific wear rate of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:mover><mml:mi>K</mml:mi> <mml:mo>¯</mml:mo></mml:mover> <mml:mo>=</mml:mo> <mml:mn>1.1</mml:mn> <mml:mo>×</mml:mo> <mml:msup><mml:mn>10</mml:mn> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>8</mml:mn></mml:mrow> </mml:msup> <mml:mrow><mml:mo>(</mml:mo> <mml:mrow><mml:mo>±</mml:mo> <mml:mn>2.9</mml:mn> <mml:mo>×</mml:mo> <mml:msup><mml:mn>10</mml:mn> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>9</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:mo>)</mml:mo></mml:mrow> <mml:mi>m</mml:mi> <mml:msup><mml:mi>m</mml:mi> <mml:mn>2</mml:mn></mml:msup> <mml:msup><mml:mi>N</mml:mi> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$\bar{K} = 1.1 \times {{10}^{ - 8}}( { \pm 2.9 \times {{{10}}^{ - 9}}} ){\mathrm{m}}{{{\mathrm{m}}}^2}{{N}^{ - 1}}$</mml:annotation></mml:semantics> </mml:math> , values that compare favorably with conventional plant oils. Additionally, the bacterial lipid was blended into both poly-α-olefin (PAO) and polyol ester (POE) base stocks at several additive weight percentages. Low-level additions (<5 wt.%) further reduced friction relative to the neat bacterial extract and wear rate relative to the neat PAO, while the bacterial extract did not solubilize well into the POE. Collectively, the data demonstrate that lipids from M. atlanticus constitute a promising renewable drop-in additive or standalone biolubricant for industrial formulations, advancing the transition toward sustainable tribological materials.