Formation of trans Fatty Acids Is Not Involved in Growth-Linked Membrane Adaptation of Pseudomonas putida

Abstract

Fatty acid compositions in growing and resting cells of several strains of Pseudomonas putida (P8, NCTC 10936, and KT 2440) were studied, with a focus on alterations of the saturation degree, cis-trans isomerization, and cyclopropane formation. The fatty acid compositions of the strains were very similar under comparable growth conditions, but surprisingly, and contrary to earlier reports, trans fatty acids were not found in either exponentially growing cells or stationary-phase cells. During the transition from growth to the starvation state, cyclopropane fatty acids were preferentially formed, an increase in the saturation degree of fatty acids was observed, and larger amounts of hydroxy fatty acids were detected. A lowered saturation degree and concomitant higher membrane fluidity seemed to be optimal for substrate uptake and growth. The incubation of cells under nongrowth conditions rapidly led to the formation of trans fatty acids. We show that harvesting and sample preparation for analysis could provoke the enzyme-catalyzed formation of trans fatty acids. Freezethawing of resting cells and increased temperatures accelerated the formation of trans fatty acids. We demonstrate that cis-trans isomerization only occurred in cells that were subjected to an abrupt disturbance without having the possibility of adapting to the changed conditions by the de novo synthesis of fatty acids. The cis-trans isomerization reaction was in competition with the cis-to-cyclopropane fatty acid conversion. The potential for the formation of trans fatty acids depended on the cyclopropane content that was already present.The bacterial cytoplasmic membrane is an important target and/or receptor for stress factors. As a response to permanent physical and chemical changes in the cell environment, several protective mechanisms and metabolic adaptation reactions have evolved (10,52,56). At the level of membrane lipids and fatty acids, these processes are often referred to as homeoviscous adaptation (57). Cells control the fluidity of their membranes by altering the lipid composition to compensate for changes in fluidity induced by certain environmental factors, such as temperature or the presence of toxic, membrane-active compounds. In most cases, however, microorganisms are not able to compensate for externally induced fluidity changes with 100% efficacy (7,37,38). They can tolerate and maybe even need a wider range of different lipid compositions to establish homeostasis, especially during growth. Lipids can coexist in physically separated microdomains with more or less fluid-or gel-phase behavior, and membrane functions are locally influenced by many factors other than fluidity (20, 43). These are the reasons for attempts to enlarge the term homeoviscous adaptation (to maintain membrane fluidity) by use of the term homeophasic adaptation (to adjust membrane fluidity).At the level of lipid membrane composition, the predominant response of many bacteria to environmental perturbations is the alteration of lipid acyl chain structures by ...

Influence of α-tocopherol supplementation on trans-18:1 and conjugated linoleic acid profiles in beef from steers fed a barley-based diet

“…Martin and Jenkins (2002) and Pottier et al (2006), however, suggested that vitamin E might have inhibitory and stimulatory effects on the growth and function of bacteria that produce t10-and t11-18:1, respectively. Given that ruminal environmental stress is an important factor for the synthesis of trans fatty acids in the rumen (Hä rtig et al, 2005), vitamin E may in some way alleviate this stress, although it may not be through its typical role as an anti-oxidant, given the highly reduced environment of the rumen.…”

Mechanisms of Bifidobacteria Resistance to Lipolytic Enzymes of Staphylococcus Aureus

“…Изменение состава фосфолипидов является эволюционным ответом микроорганизмов на физические и химические изменения в окру-жающей среде, своеобразной адаптацией, ко-торая включается в период роста бактерий [8,9,10]. Однако механизмы гомеофазовой адап-тации у разных микроорганизмов отличаются.…”

“…Однако механизмы гомеофазовой адап-тации у разных микроорганизмов отличаются. Преобладающей реакцией многих бактерий на внешние воздействия является модификация ацильной цепи липидных структур за счет из-менения соотношения насыщенных и ненасы-щенных жирных кислот [2,10]. Также описа-ны механизмы сокращения или удлинения це-пи, изменения в соотношении разветвленных жирных кислот, рост-зависимое метилирова-ние или насыщение циклопропаном, а также цис-транс-изомеризационное преобразова-ние двойных связей (π -диастереометрия) [3,14].…”

“…На физические и хими-ческие воздействия микроорганизмы реагиру-ют определенными метаболическими реакци-ями и изменением состава мембранных фос-фолипидов [8,9]. Регулирование бактериями параметров текучести мембраны для поддер-жания собственного гомеостаза при воздей-ствии внешних факторов среды получило на-звание гомеофазовой адаптации [10]. Страте-гия модуляции жирнокислотного состава мем-браны лежит в основе выживания штаммов во внешней среде при воздействии дезинфициру-ющих и антисептических средств, мембран-ных токсинов, резких перепадов температуры и давления.…”

“…Страте-гия модуляции жирнокислотного состава мем-браны лежит в основе выживания штаммов во внешней среде при воздействии дезинфициру-ющих и антисептических средств, мембран-ных токсинов, резких перепадов температуры и давления. В связи с этим различные меха-низмы гомеофазовой адаптации активно изу-чаются для разработки превентивных мер по формированию госпитальных штаммов в эко-логической системе стационаров [10,11]. Су-щественный интерес представляют собой ис-следования модификации липидного состава цитоплазматической мембраны у бактерий, входящих в состав кишечного микросимбио-ценоза, так как разнообразие входящих в него микросимбионтов и их метаболитов формиру-ет особые экологические факторы и условия.…”