Journal Review and Summary: Lipid Accumulation in Micro-Organisms

Introduction

It is imperative to have comprehension of the dynamics of lipid accumulation in micro-organisms. The knowledge will be vital in shedding light on how lipids produce renewable chemicals and fuels, as well as the assembly of biological membranes. Lipid accumulation has been an area of concern in the realm of microbiology because of various benefits that the body derives from the accumulation. In fact, there have been efforts to increase lipid accumulation through altering enzymes or fatty acids catabolism (Lemmer, Dohnalkova, Noguera, & Donohue, 2015).

Goal of the Research

The goal of the research is to analyze the molecular dynamics that regulate microbial lipid accumulation in purple bacteria. Purple bacteria have the ability to increase membrane content only when subjected to low oxygen conditions. The research investigates the process with the help of Rhodobacter sphaeroides, which can grow due to aerobic and anaerobic respiration. In addition, these bacteria can change according to various levels of oxygen, unlike other facultative bacteria. Under high O₂ tensions, for instance, Rhodobacter sphaeroides have their cell envelope resembling Gram-negative bacteria. Similarly, in situations with low O₂ tensions, Rhodobacter sphaeroides increases their surface for the assembly of photosynthetic apparatus. The surface increase is achieved through invaginations of an intracytoplasmic membrane.

Discussion of Experimental Approach and Justification

The experimental approach adopted in this research seeks to address whether an increment in membrane lipid abundance has a correlation with ICM assembly. Moreover, the nature of the correlation will be of paramount importance because the content of fatty acids in wild-type cells has a direct correlation with BChl levels. Additionally, even though a vast majority of individuals have acquainted themselves with systems that aid in regulation of pigment and protein components of photosynthetic membranes, there is little knowledge on the synthesis of phospholipids. In fact, phospholipids are primarily responsible for the formation of ICM bilayer. In addition, the experimental research design will be important in shedding light on the membrane that will be useful for ICM development as well as the precise mechanism that will be effective in an increase of phospholipid levels and fatty acids (Lemmer et al., 2015). The increase will be a retaliatory move that seeks to confront low levels of oxygen. Cells constituting ICM have a high phospholipid synthesis rate. The cells also have a greater proportion of lipids in cellular biomass as compared to cells under high O₂ tensions. Moreover, there is also an investigation as to whether Rhodobacter sphaeroides can increase their membrane production under low oxygen tensions while placed under a photosynthetic apparatus.

The experimental approach adopted in the research has been important because it aids in the identification of a regulatory method that would increase microbial lipid content (Lemmer et al., 2015). It is equally essential to note that the bacteria strains applied during the experiment were subjected to growth at a temperature of 300 ºC within a minimum medium that was succinate-based.

Results and the Author’s Hypothesis

The results of the experiment support the author’s hypothesis because it tests whether R. sphaeroides have high membrane lipid content in the environment with high O₂ levels as compared to low O₂ levels. In this respect, the results have been obtained by drawing a correlation between the membrane-integral ICM spectral levels and the membrane content. Appropriate drawing of the correlation was acquired by first having to quantify membrane lipid content as a function of O₂ tension.

The results also support the author’s hypothesis because it is apparent that lipids tend to stabilize the protein structure of a membrane. Moreover, the investigation is an important part of gaining a deeper insight into the mechanisms as well as regulation of membrane proteins (Lemmer et al., 2015). The results also aim to draw the relationship that exists between membrane lipid contents and SC levels. To get accurate and reliable results, it was necessary to take all the extracted BChl as a measure for SC assembly, fatty acids, and lipid phosphorous levels in the quest of making the lipid membrane content assessable.

The results also support the author’s argument by expressing measurements on a per-cell basis so as to gain insights in physiological changes that cells have undergone in the course of experimental conditions. The alterations can be attributed to the fact that other cellular components of biomass are not rigid because they are likely to change in biomass so long as light intensity and O₂ levels also keep varying. In this respect, the experimental design that has been adopted described accurately a succinct physiology of lipid accumulation only under the set experimental conditions. Additionally, the results also show that SC will be inherently absent in cultures that have high levels of O₂ (Lemmer et al., 2015). However, the SC will be present in anaerobic cultures that are subjected to either light or dark conditions.

In most cases, the cultures will have characteristic absorbance peaks ranging between 800 and 850 nm. The results also show that cells will be more likely to grow at the rate of 30% so long as the levels of O₂ are not detectable. Additionally, cells that are subjected to growth under anaerobic conditions will contain a measurable level of BChl (5-6 *10-18 mol/cell). The results would have been quite different if the research cells had been subjected to high O₂ levels. The high level, in this case, implies the level of about 30%. The results were congruent with the author’s hypothesis and thus can be attributed to the fact that the cells that were grown anaerobically contained fatty acids and lipid phosphorous levels that were three times higher as compared to cells grown under high O₂ tension. Therefore, the results are consistent with the increased membrane content that has a correlation with ICM formation (Lemmer et al., 2015).

Similarly, the types of fatty acids were the same under all the growth conditions that were tested in the experiment. The fatty acids were also similar to the composition of fatty acids that were observed in other studies pertaining to R. sphaeroides. In this case, the results can be attributed to lipids phosphorous and fatty acids having levels that tend to mirror each other. The experiment opted to use fatty acids levels as a method of assessing the membrane lipid content in the course of the experimental study. However, some aspects of the research design may be improved in the quest of increasing the accuracy of the research outcomes. For instance, the light intensity can vary under anaerobic conditions (Lemmer et al., 2015). The effect of changing light intensity will influence the lipid and pigment content so long as the light intensity varies in a consistent manner. The improvement will provide additional information on how the lipid and pigment content is affected by light.

Significance of the Paper to Medical Bacteriology/Mycology

The paper will make a contribution to the realm of medical bacteriology because the research tends to address the correlation between the membrane fatty acid content and levels of BChl in wild-type cells. The correlation is established under environmental conditions that aid in controlling ICM levels. The paper has thus been significant in the assembly of ICM as well as potential engineering of microbes in the production of chemicals and lipid biofuels. The engineering will be based on the fact that R. sphaeroids have a mechanism of increasing lipid content in retaliation to lower O₂ levels (Lemmer et al., 2015). In addition, there has been an upcoming trend regarding biodiesel as an attractive alternative because of the impact it poses for the environment. Moreover, the fuel is effective because it is made from renewable sources. In this respect, the concept of microbial development, as illustrated in the experiment, has been integral in medical bacteriology because it explains how bacteria can be manipulated to enhance their ability to accumulate oils. As a general rule in mycology, a vast majority of microorganisms, such as yeast, bacteria, algae, and fungi, have the ability to accumulate oils when exposed to specific conditions. Similarly, accumulation of lipid content has been attained by subjecting R. sphaeroides to certain conditions with varying levels of light intensity and oxygen.

Moreover, the contents of the paper are important and can be applied in the production of microbial oils. The latter are vital because they can be used in the production of biodiesel. The paper also gives an impetus for identification of new microorganisms that have lipid production capabilities in the quest of improving the efficiency of biodiesel production. Such microorganisms are referred to as microbial producers. When compared with other plant oils, it is apparent that microbial oils are advantageous in reference to their short lifecycle as well as climate and season. The paper has also been of paramount importance because the developed concept may utilize the microbial oils as an oil feedstock for the production of biodiesel. Even though there have been many works and experiments that pertain to oil production and microorganisms, the adopted research design seeks to address the contemporary procedure that is well applicable in medical bacteriology.

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