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Microscale biosensor for measurement of volatile fatty acids in anoxic environments.

ABSTRACT: A microscale biosensor for acetate, propionate, isobutyrate, and lactate is described. The sensor is based on the bacterial respiration of low-molecular-weight, negatively charged species with a concomitant reduction of NO(-)(3) to N(2)O. A culture of denitrifying bacteria deficient in N(2)O reductase was immobilized in front of the tip of an electrochemical N(2)O microsensor. The bacteria were separated from the outside environment by an ion-permeable membrane and supplied with nutrients (except for electron donors) from a medium reservoir behind the N(2)O sensor. The signal of the sensor, which corresponded to the rate of N(2)O production, was proportional to the supply of the electron donor to the bacterial mass. The selectivity for volatile fatty acids compared to other organic compounds was increased by selectively enhancing the transport of negatively charged compounds into the sensor by electrophoretic migration (electrophoretic sensitivity control). The sensor was susceptible to interference from O(2), N(2)O, NO(2)(-), H(2)S, and NO(-)(3). Interference from NO(-)(3) was low and could be quantified and accounted for. The detection limit was equivalent to about 1 microM acetate, and the 90% response time was 30 to 90 s. The response of the sensor was not affected by changes in pH between 5.5 and 9 and was also unaffected by changes in salinity in the range of 2 to 32 per thousand. The functioning of the sensor over a temperature span of 7 to 30 degrees C was investigated. The concentration range for a linear response was increased five times by increasing the temperature from 7 to 19.5 degrees C. The life span of the biosensor varied between 1 and 3 weeks after manufacturing.

SUBMITTER: Meyer RL

PROVIDER: S-EPMC123769 | biostudies-literature | 2002 Mar

REPOSITORIES: biostudies-literature

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Microscale biosensor for measurement of volatile fatty acids in anoxic environments.

Meyer Rikke Louise RL Larsen Lars Hauer LH Revsbech Niels Peter NP

Applied and environmental microbiology 20020301 3

A microscale biosensor for acetate, propionate, isobutyrate, and lactate is described. The sensor is based on the bacterial respiration of low-molecular-weight, negatively charged species with a concomitant reduction of NO(-)(3) to N(2)O. A culture of denitrifying bacteria deficient in N(2)O reductase was immobilized in front of the tip of an electrochemical N(2)O microsensor. The bacteria were separated from the outside environment by an ion-permeable membrane and supplied with nutrients (excep ...[more]

PMID: 11872469

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Project description:Simple Summary Acheta domesticus (house cricket) flour is one of the most promising and sustainable sources of nutrients. It is rich in protein, minerals, fatty acids, amino acids, and vitamins and it has a low impact on the consumption of natural environmental resources. On the other side, fermentation with lactic acid bacteria represents a technological tool that can improve further the nutritional quality of flours. Therefore, the aim of the present research was to study the adaptability of the Lactobacillus plantarum strain on insect flour fermentation. Fatty acids, amino acids, minerals, and aroma volatile compounds were analyzed during 48 h of fermentation. Fermentation improved the nutritional quantity of the bioactive compounds, mainly after 24 h of fermentation, where they reached higher extended values. Overall, our findings indicate that insect flour is able to support the growth and development of the Lactobacillus plantarum strain, leading to an enriched insect flour sourdough that could be further used in the manufacturing of new products. Abstract Acheta domesticus (L.1758) has been recently accepted by the European Union as a novel food, being the third insect that has been approved for human consumption. Nowadays, researchers’ attention is focused on exploiting new protein sustainable sources, and, therefore, insect flour has gained more and more interest. Organic acids, fatty acids, amino acids, aroma volatile compounds, and minerals were analyzed through HPLC-RID (High-performance liquid chromatography), GC-MS (Gas chromatography-mass spectrometry), LC-MS (Liquid chromatography–mass spectrometry), ITEX/GC-MS and AAS (Atomic Absorption Spectrophotometry), respectively. Fermentation of the insect flour with Lactobacillus plantarum ATCC 8014 strain (Lp) leads to an increase in organic acids such as lactic, acetic, and oxalic, whilst citric acid decreases its value. SFA (saturated fatty acids) and MUFA (monosaturated fatty acids) groups were positively influenced by Lp fermentation; meanwhile, PUFA (polysaturated fatty acids) decreased during fermentation. A positive trend was observed for amino acids, aroma volatile content, and minerals enhancement during insect sourdough fermentation, mainly at 24 h of fermentation. Acheta domesticus (A. domesticus) sourdough fermentation represents a new tool that needs to be further exploited aiming to improve the nutritional qualities of the final products.

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Microscale biosensor for measurement of volatile fatty acids in anoxic environments.

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Microscale biosensor for measurement of volatile fatty acids in anoxic environments.

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