The Application of an On-Line Optical Sensor to Measure Biomass of a Filamentous Bioprocess

Monitoring of all critical process parameters in bioprocess engineering is essential. Sensors have been previously developed for specific parameters such as on-line temperature, pH or stirring control and data logging. However, biomass monitoring needs further development. All current non-invasive technology, such as Near Infra-Red, is limited on biomass measurement of animal and insect cells. Biomass monitoring of industrial bioprocesses of filamentous microorganisms still requires sample removal from the vessel, which could potentially compromise sterility. This study has focused on the application of a non-invasive optical sensor in the on-line monitoring of the biomass of the filamentous microorganism Streptomyces coelicolor A3 (2). Raw output data from the biomass monitor were directly compared to data from the sensors measuring dissolved oxygen levels and off gas evolution and the results successfully demonstrate that the optical sensor is sensitive in identifying different levels of biomass. Therefore, it is possible to use the simple output data to provide real time information on biomass levels of filamentous microorganisms, a very powerful tool in bioprocess engineering

Effect of a siderophore producer on animal cell apoptosis: a possible role as anti-cancer agent.

Iron plays an essential role in the proliferation of aggressive tumors therefore it represents an ideal target for cancer therapy. Cell free supernatants from a siderophore producing actinobacterium previously isolated from Thailand were tested against six human cancer cell lines including malignant melanoma A 375 (ATCC no.: CRL-1619), colorectal adenocarcinoma SW620 (ATCC no.: CCL-227), gastric carcinoma Katob III (ATCC no.: HTB-103), liver hepatoblastoma HepG2 (ATCC no.: HB-8065), breast carcinoma BT474 (ATCC no.: HTB-20) and Acute T cell leukemia Jurkat (ATCC no.: CRL-2063). Following treatment of cells with the bacterial culture supernatant the cell viability of A375 cells was dramatically decreased with cell survival of less than 34 % within 48 h. The rest of the cell lines were largely unaffected. Therefore it is suggested that the actinobacterium produced a cytotoxic compound responsible for the cell death by inducing apoptotic activity. We further speculate that this compound was desferioxamine E as the bacterium is known to produce this compound under the culture conditions used

Detection of pathogenic bacteria in aqueous media: Assessing the potential of real-time electromagnetic wave sensing

This paper reports on the capabilities of a novel electromagnetic wave sensing method to detect and identify the presence of various pathogenic bacteria in aqueous media. In particular, the change in the electromagnetic wave signal in microwave frequency range is used as an indicator of bacteria presence. The assessment was conducted by recording reflected signal spectra when the sensor was in contact with deionised water, Escherichia coli, sterile nutrient broth and Pseudomonas aeruginosa solutions. The distinct feature of the proposed system is that the detection is performed in real time, without the need for additional sample processing or chemicals. This bacteria detection method would be of benefit in a broad range of applications, ranging from water quality monitoring in wastewater treatment facilities to safety assurance in healthcare and food industry

A demonstration of athermal effects of continuous microwave irradiation on the growth and antibiotic sensitivity of Pseudomonas aeruginosa PAO1.

Stress, caused by exposure to microwaves (2.45GHz) at constant temperature (37± 0.5(o) C), alters the growth profile of Pseudomonas aeruginosa PAO1. In the absence of microwave treatment a simple, highly reproducible growth curve was observed over 24 hours or more. Microwave treatment caused no reduction in growth during the first 6 hours, but at a later stage (>12hours) the growth was markedly different to the controls. Secondary growth, typical of the presence of persisters clearly became apparent, as judged by both the dissolved oxygen and the cell density profiles. These treated cells showed distinct morphological changes, but on re-growth these cells reverted to normal. The Microwave Induced Persisters were subject to antibiotic challenge (tobramycin) and showed increased sensitivity when compared to the un-stressed planktonic cells. This is in marked contrast to antibiotic induced persisters which show increased resistance. This provides evidence for both a non-thermal effect of microwaves and a previously undescribed route to a novel form of antibiotic susceptible persister cells. This article is protected by copyright. All rights reserved

Tackling water pollution: real-time monitoring of residual Antimicrobials concentration in aquaculture with microwave spectroscopy

To prevent the improper use of antimicrobials in aquaculture and to assist the food safety law enforcement, this paper reports on a bespoke electromagnetic (EM) wave sensing method for real-time in situ monitoring of residual antimicrobials concentrations in water samples. The antimicrobials solutions were tested in bespoke microwave cavity. Transmitted and reflected power signals were analysed in GHz frequency range and these were dependent on both: the type of antimicrobials present in water and on their concentration

Nitro-Carba test, a novel and simple chromogenic phenotypic method for rapid screening of carbapeneamase-producing Enterobacteriaceae.

OBJECTIVES: The present study developed Nitro-Carba Test (NCT), a rapid and simple chromogenic method for screening of Carbapenemase-producing Enterobacteriaceae (CPE). METHODS: The NCT was validated with a total of 31 carbapenemase-producing isolates (9 KPCs, 11 MBLs and 11 OXA-48s) and with 56 non-carbapenemase-producing strains. The assay relies on the hydrolysis of nitrocefin in the presence of carbapenems. The carbapenemases were extracted with lysis buffer prior to addition to wells with and without imipenem (IPM), meropenem (MEM) and ertapenem (ETP). Following the addition of nitrocefin, a change in colour from yellow to red, indicating carbapenemase production, was observed within 20min. The susceptibility profiles of each bacterial strain were also investigated. RESULTS: A NCT detected all 31 CPEs within a timeframe of only 10seconds to 12min. All carbapenemase producers hydrolyzed nitrocefin in all wells. No colour change in the wells with carbapenems was observed in non-carbapenemase producers. The sensitivity for all three carbapenems was 100%, while specificity of IPM, MEM and ETP were 64.29%, 91.07% and 100%, respectively. IPM, MEM and ETP against all carbapenemase-producing strains had MIC values ranging from 0.5 to ≥256μg/mL, 0.25 to ≥256μg/mL and 1 to ≥256μg/mL, respectively. OXA-48-producing isolates showed lower MIC values compared with producers of MBL and KPC. CONCLUSION: This assay is a promising method detecting CPE rapidly. The NCT is a simple and reliable method, capable of detecting CPE in even carbapenem-susceptible strains

Monitoring Use Of Antibiotics In Aquaculture

In the aquaculture industry around the world antibiotics are used for fish disease prevention and treatment. High residual levels of those antibiotics may contaminate natural water resources as well as soil, aquatic animals and plants. Their overuse in human and animal populations can lead to the development of resistant microbial strains, posing a dire threat to global health. Use of antibiotics in aquaculture and its impact on the environment is a growing concern amongst scientists, yet quantifying the amount of use and how much is being disseminated into the environment is very difficult. As with the use of antibiotics in food production more generally, there is a need for better data. To prevent the improper use of antibiotics in aquaculture and to assist the food safety law enforcement, this paper reports on assessing the feasibility of a bespoke electromagnetic wave sensing method for real-time in situ monitoring of residual antibiotic concentrations in water samples. For the first time the antibiotics solutions were tested in contact with planar sensor with interdigitated electrode pattern on a number of substrates, including Rogers®, FR4 and flexible polyimide substrates. Specifically, this paper communicates the experimental results of using bespoke microwave planar type sensors for the determination of Quinolones, in particular Enrofloxacin (ENR) and Norfloxacin (NOR) antibiotic concentrations. Reflected power signals were analysed in GHz frequency range and these were dependent on both: the type of antibiotic present in water and on its concentration

Persister cells: formation, resuscitation and combative therapies.

Persister cells, or superfits, have been strongly implicated in the recalcitrance and recurrence of chronic bacterial infection through the dormant (metabolically reduced) phenotype they display and the tolerance to antimicrobial agents this dormancy grants them. The complex biochemical events that lead to the formation of persister cells are not completely understood, though much research has linked the degradation of type II toxin/antitoxin systems and reduced cellular ATP levels to the rise in stress response molecules (where (p)ppGpp is of particular interest), which induce this dormant state. The equally complex mechanism of resuscitation is initiated by the cells' ability to sense nutrient availability via chemotaxis systems. Levels of secondary messenger proteins (i.e., cAMP) within the cell are reduced to allow the resuscitation of ribosomes, by ribosomal resuscitation factor HflX, to reinstate protein synthesis and, therefore, growth to re-populate. Techniques of superfit eradication utilise one, or more, of three approaches (i) direct killing, (ii) re-sensitising persister cells to conventional antimicrobials, or (iii) prevention of persister formation though few laboratory findings have been translated to clinical practice. This work will outline current findings in the field with a critical approach, where possible