scholarly journals In Situ Determination of the Intracellular pH of Lactococcus lactis and Lactobacillus plantarum during Pressure Treatment

2002 ◽  
Vol 68 (9) ◽  
pp. 4399-4406 ◽  
Author(s):  
Adriana Molina-Gutierrez ◽  
Volker Stippl ◽  
Antonio Delgado ◽  
Michael G. Gänzle ◽  
Rudi F. Vogel
Keyword(s):  
Lactobacillus Plantarum ◽  
Lactococcus Lactis ◽  
Intracellular Ph ◽  
Ambient Pressure ◽  
Viable Cell ◽  
Pressure Treatment ◽  
Stress Reactions ◽  
Ph Homeostasis ◽  
Cell Counts ◽  
Internal Ph

ABSTRACT Hydrostatic pressure may affect the intracellular pH of microorganisms by (i) enhancing the dissociation of weak organic acids and (ii) increasing the permeability of the cytoplasmic membrane and inactivation of enzymes required for pH homeostasis. The internal pHs of Lactococcus lactis and Lactobacillus plantarum during and after pressure treatment at 200 and 300 MPa and at pH values ranging from 4.0 to 6.5 were determined. Pressure treatment at 200 MPa for up to 20 min did not reduce the viability of either strain at pH 6.5. Pressure treatment at pH 6.5 and 300 MPa reduced viable cell counts of Lactococcus lactis and Lactobacillus plantarum by 5 log after 20 and 120 min, respectively. Pressure inactivation was faster at pH 5 or 4. At ambient pressure, both strains maintained a transmembrane pH gradient of 1 pH unit at neutral pH and about 2 pH units at pH 4.0. During pressure treatment at 200 and 300 MPa, the internal pH of L. lactis was decreased to the value of the extracellular pH during compression. The same result was observed during treatment of Lactobacillus plantarum at 300 MPa. Lactobacillus plantarum was unable to restore the internal pH after a compression-decompression cycle at 300 MPa and pH 6.5. Lactococcus lactis lost the ability to restore its internal pH after 20 and 4 min of pressure treatment at 200 and 300 MPa, respectively. As a consequence, pressure-mediated stress reactions and cell death may be considered secondary effects promoted by pH and other environmental conditions.

scholarly journals Effects of Pressure-Induced Membrane Phase Transitions on Inactivation of HorA, an ATP-Dependent Multidrug Resistance Transporter, in Lactobacillus plantarum

2002 ◽  
Vol 68 (3) ◽  
pp. 1088-1095 ◽  
Author(s):  
H. M. Ulmer ◽  
H. Herberhold ◽  
S. Fahsel ◽  
M. G. Gänzle ◽  
R. Winter ◽  
...  
Keyword(s):  
Cell Death ◽  
Multidrug Resistance ◽  
Liquid Crystalline ◽  
Ambient Pressure ◽  
Viable Cell ◽  
Phase Region ◽  
Pressure Treatment ◽  
Cell Counts ◽  
Gel Phase ◽  
Multidrug Resistance Transporter

ABSTRACT The effects of pressure on cultures of Lactobacillus plantarum were characterized by determination of the viability and activity of HorA, an ATP-binding cassette multidrug resistance transporter. Changes in the membrane composition of L. plantarum induced by different growth temperatures were determined. Furthermore, the effect of the growth temperature of a culture on pressure inactivation at 200 MPa was determined. Cells were characterized by plate counts on selective and nonselective agar after pressure treatment, and HorA activity was measured by ethidium bromide efflux. Fourier transform-infrared spectroscopy and Laurdan fluorescence spectroscopy provided information about the thermodynamic phase state of the cytoplasmic membrane during pressure treatment. A pressure-temperature diagram for cell membranes was established. Cells grown at 37°C and pressure treated at 15°C lost >99% of HorA activity and viable cell counts within 36 and 120 min, respectively. The membranes of these cells were in the gel phase region at ambient pressure. In contrast, cells grown at 15°C and pressure treated at 37°C lost >99% of HorA activity and viable cell counts within 4 and 8 min, respectively. The membranes of these cells were in the liquid crystalline phase region at ambient pressure. The kinetic analysis of inactivation of L. plantarum provided further evidence that inactivation of HorA is a crucial step during pressure-induced cell death. Comparison of the biological findings and the membrane state during pressure treatment led to the conclusion that the inactivation of cells and membrane enzymes strongly depends on the thermodynamic properties of the membrane. Pressure treatment of cells with a liquid crystalline membrane at 0.1 MPa resulted in HorA inactivation and cell death more rapid than those of cells with a gel phase membrane at 0.1 MPa.

Intracellular pH homeostasis during cell-cycle progression and growth state transition in Schizosaccharomyces pombe

2001 ◽  
Vol 114 (16) ◽  
pp. 2929-2941 ◽  
Author(s):  
Jim Karagiannis ◽  
Paul G. Young
Keyword(s):  
Cell Cycle ◽  
Schizosaccharomyces Pombe ◽  
Intracellular Ph ◽  
Cell Cycle Progression ◽  
State Transition ◽  
Homeostatic Regulation ◽  
Ph Homeostasis ◽  
Vegetative Cells ◽  
Growth State ◽  
Internal Ph

Accurate measurement of intracellular pH in unperturbed cells is fraught with difficulty. Nevertheless, using a variety of methods, intracellular pH oscillations have been reported to play a regulatory role in the control of the cell cycle in several eukaryotic systems. Here, we examine pH homeostasis in Schizosaccharomyces pombe using a non-perturbing ratiometric pH sensitive GFP reporter. This method allows for accurate intracellular pH measurements in living, entirely undisturbed, logarithmically growing cells. In addition, the use of a flow cell allows internal pH to be monitored in real time during nutritional, or growth state transition. We can find no evidence for cell-cycle-related changes in intracellular pH. By contrast, all data are consistent with a very tight homeostatic regulation of intracellular pH near 7.3 at all points in the cell cycle. Interestingly, pH set point changes are associated with growth state. Spores, as well as vegetative cells starved of either nitrogen, or a carbon source, show a marked reduction in their internal pH compared with logarithmically growing vegetative cells. However, in both cases, homeostatic regulation is maintained.

scholarly journals Response of Listeria monocytogenes to Disinfection Stress at the Single-Cell and Population Levels as Monitored by Intracellular pH Measurements and Viable-Cell Counts

2009 ◽  
Vol 75 (13) ◽  
pp. 4550-4556 ◽  
Author(s):  
Vicky G. Kastbjerg ◽  
Dennis S. Nielsen ◽  
Nils Arneborg ◽  
Lone Gram
Keyword(s):  
Listeria Monocytogenes ◽  
Single Cell ◽  
Intracellular Ph ◽  
Bacterial Population ◽  
Single Cells ◽  
Viable Cell ◽  
Population Subdivision ◽  
Single Cell Level ◽  
Cell Level ◽  
Cell Counts

ABSTRACT Listeria monocytogenes has a remarkable ability to survive and persist in food production environments. The purpose of the present study was to determine if cells in a population of L. monocytogenes differ in sensitivity to disinfection agents as this could be a factor explaining persistence of the bacterium. In situ analyses of Listeria monocytogenes single cells were performed during exposure to different concentrations of the disinfectant Incimaxx DES to study a possible population subdivision. Bacterial survival was quantified with plate counting and disinfection stress at the single-cell level by measuring intracellular pH (pHi) over time by fluorescence ratio imaging microscopy. pHi values were initially 7 to 7.5 and decreased in both attached and planktonic L. monocytogenes cells during exposure to sublethal and lethal concentrations of Incimaxx DES. The response of the bacterial population was homogenous; hence, subpopulations were not detected. However, pregrowth with NaCl protected the planktonic bacterial cells during disinfection with Incimaxx (0.0015%) since pHi was higher (6 to 6.5) for the bacterial population pregrown with NaCl than for cells grown without NaCl (pHi 5 to 5.5) (P < 0.05). The protective effect of NaCl was reflected by viable-cell counts at a higher concentration of Incimaxx (0.0031%), where the salt-grown population survived better than the population grown without NaCl (P < 0.05). NaCl protected attached cells through drying but not during disinfection. This study indicates that a population of L. monocytogenes cells, whether planktonic or attached, is homogenous with respect to sensitivity to an acidic disinfectant studied on the single-cell level. Hence a major subpopulation more tolerant to disinfectants, and hence more persistent, does not appear to be present.

scholarly journals The Joint Effect of pH Gradient and Glucose Feeding on the Growth Kinetics of Lactococcus lactis CECT 539 in Glucose-Limited Fed-Batch Cultures

2019 ◽  
Vol 68 (2) ◽  
pp. 269-280
Author(s):  
MÓNICA COSTAS MALVIDO ◽  
ELISA ALONSO GONZÁLEZ ◽  
RICARDO J. BENDAÑA JÁCOME ◽  
NELSON PÉREZ GUERRA
Keyword(s):  
Lactococcus Lactis ◽  
Viable Cell ◽  
Product Formation ◽  
Ph Gradient ◽  
Feeding Strategies ◽  
Fed Batch ◽  
Batch Cultures ◽  
Cell Counts ◽  
First Time ◽  
Kinetics Of

Two glucose-limited realkalized fed-batch cultures of Lactococcus lactis CECT 539 were carried out in a diluted whey medium (DW) using two different feeding media. The cultures were fed a mixture of a 400 g/l concentrated lactose and a concentrated mussel processing waste (CMPW, 101.72 g glucose/l) medium (fermentation I) or a CMPW medium supplemented with glucose and KH2PO4 up to concentrations of 400 g glucose/l and 3.21 g total phosphorus/l, respectively (fermentation II). For an accurate description and a better understanding of the kinetics of both cultures, the growth and product formation by L. lactis CECT 539 were both modelled, for the first time, as a function of the amounts of glucose (G) added and the pH gradient (VpH) generated in every realkalization and feeding cycle, by using an empirical polynomial model. With this modeling procedure, the kinetics of biomass, viable cell counts, nisin, lactic acid, acetic acid and butane-2,3-diol production in both cultures were successfully described (R2 values > 0.970) and interpreted for the first time. In addition, the optimum VpH and G values for each product were accurately calculated in the two realkalized fed-batch cultures. This approach appears to be useful for designing feeding strategies to enhance the productions of biomass, bacteriocin, and metabolites by the nisin-producing strain in wastes from the food industry.

Effect of Cocultivation on Lactobacillus plantarum Strains Growth and Antagonistic Activity

2021 ◽  
Vol 83 (1) ◽  
pp. 12-20
Author(s):  
I.L. Garmasheva ◽  
◽  
O.M. Vasyliuk ◽  
L.T. Oleschenko ◽  
◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Lactobacillus Plantarum ◽  
Viable Cell ◽  
Antagonistic Activity ◽  
Fermented Foods ◽  
Cell Counts ◽  
Inhibition Zones ◽  
Mrs Medium ◽  
Mrs Broth ◽  
Vegetable Fermentation

The use of bacterial starters for the production of fermented foods has several advantages over traditional spontaneous fermentation, as it provides a rapid and controlled decrease of pH, improves the microbiological quality of the product, and prolongs the shelf-life. Fermented foods are typically produced using mixed cultures of lactic acid bacteria (LAB) due to the synergism between their constituent bacterial cultures. So, the compatibility of the LAB strains decides the efficacy of a multi-strain starter. The purpose of this study was to investigate the effect of the cocultivation of Lactobacillus plantarum strains on the growth, acidification, and antagonistic activity to determine suitable strain combinations for fermented vegetable production. Methods. The effect of cocultivation on growth characteristics of four L. plantarum strains was determined in MRS medium and cabbage-based medium with 2.5% NaCl. After 8 h of cultivation at 30°C and 37°C, the number of viable cells (CFU/ml) and the pH of the medium were determined. The antagonistic activity of monocultures of L. plantarum and their six compositions against opportunistic pathogenic microorganisms was determined by the method of delayed antagonism. Results. During growth in MRS broth at 30°C cocultivation of L. plantarum 47SM with L. plantarum 691T or L. plantarum 1047K strains led to enhanced rates of growth compared to the monocultures, suggesting some degree of symbiosis between these strains. Viable cell counts of L. plantarum 47SM, 1047K and 691T strains and ΔpH values of L. plantarum 952K, 1047K, and 691T strains were higher after 8 h growth in the cabbage-based medium at 30°C compared to MRS broth. Despite the intensive growth of L. plantarum monocultures in cabbage-based medium, a significant decrease of viable cell counts and ΔpH values during cocultivation at 30°C were found. Cocultivation did not affect the average size of the growth inhibition zones of most of the indicator strains used. However, growth inhibition zones of Shigella flexneri, Escherichia coli, and Proteus vulgaris decreased in some L. plantarum mixed cultures compared to monocultures. Thus, the growth inhibition zones of E. coli and S. flexneri by mixed culture L. plantarum 47 SM+1047K were significantly smaller compared to the growth inhibition zones of L. plantarum monocultures. Conclusions. Thus, based on the data obtained in present work, we can assume that some of these L. plantarum strains used in the work may be bactericinogenic. Although the four L. plantarum strains studied are compatible when cocultivated in a standard rich MRS medium, the results of cocultivation in a cabbage-based medium with 2.5% NaCl does not allow to recommend the use of these L. plantarum strains simultaneously in the starter for vegetable fermentation. Further investigation of bacteriocinogenic properties and mechanisms of growth inhibition under cocultivation in vegetable-like conditions are needed, which will allow combining of some of these L. plantarum strains with LAB strains of other species or genera to create multi-starters for vegetable fermentation.

scholarly journals Microencapsulation of Lactococcus lactis Gh1 with Gum Arabic and Synsepalum dulcificum via Spray Drying for Potential Inclusion in Functional Yogurt

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1422 ◽  
Author(s):  
Nurul Farhana Fazilah ◽  
Nurmelissa Hanani Hamidon ◽  
Arbakariya B. Ariff ◽  
Mohd Ezuan Khayat ◽  
Helmi Wasoh ◽  
...  
Keyword(s):  
Spray Drying ◽  
Lactococcus Lactis ◽  
Gum Arabic ◽  
Streptococcus Thermophilus ◽  
Viable Cell ◽  
Starter Cultures ◽  
Lactobacillus Delbrueckii ◽  
Bacterial Cells ◽  
Cell Counts

There has been an explosion of probiotic incorporated based product. However, many reports indicated that most of the probiotics have failed to survive in high quantity, which has limited their effectiveness in most functional foods. Thus, to overcome this problem, microencapsulation is considered to be a promising process. In this study, Lactococcus lactis Gh1 was encapsulated via spray-drying with gum Arabic together with Synsepalum dulcificum or commonly known as miracle fruit. It was observed that after spray-drying, high viability (~109 CFU/mL) powders containing L. lactis in combination with S. dulcificum were developed, which was then formulated into yogurt. The tolerance of encapsulated bacterial cells in simulated gastric juice at pH 1.5 was tested in an in-vitro model and the result showed that after 2 h, cell viability remained high at 1.11 × 106 CFU/mL. Incubation of encapsulated cells in the presence of 0.6% (w/v) bile salts showed it was able to survive (~104 CFU/mL) after 2 h. Microencapsulated L. lactis retained a higher viability, at ~107 CFU/mL, when incorporated into yogurt compared to non-microencapsulated cells ~105 CFU/mL. The fortification of microencapsulated and non-microencapsulated L. lactis in yogurts influenced the viable cell counts of yogurt starter cultures, Lactobacillus delbrueckii subs. bulgaricus and Streptococcus thermophilus.

scholarly journals Development of milk powder containing Lactobacillus plantarum NCIMB 8826 immobilized with prebiotic hi-maize starch and survival under simulated gastric and intestinal conditions

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Ronamae Bradford ◽  
Vondel Reyes ◽  
Franklin Bonilla ◽  
Federico Bueno ◽  
Bennett Dzandu ◽  
...  
Keyword(s):  
Lactobacillus Plantarum ◽  
Spray Drying ◽  
Immobilized Cells ◽  
Milk Powder ◽  
Viable Cell ◽  
Simulated Gastric Fluid ◽  
Maize Starch ◽  
Simulated Intestinal Fluid ◽  
Cell Counts ◽  
Free Cells

Abstract The objectives of this study were to develop a probiotic milk powder containing Lactobacillus plantarum NCIMB 8826 immobilized with prebiotic Hi-maize starch and to analyze cell viability after spray drying and exposure to simulated gastric and intestinal conditions. Milk powders containing free L. plantarum and cells immobilized with Hi-maize starch were assessed. Powders were evaluated during storage at 4 °C for 15 days. After spray drying, at 0 and 15 days of storage both treatments had over 8 log CFU/g of viable cells and there were higher viable counts found for immobilized cells compared to free cells after 120 min in simulated gastric fluid. At 15 days of storage, immobilized cells had higher viable counts than free cells after exposure to simulated intestinal fluid for 120 min. The combined probiotic and prebiotic milk powder had stable viable cell counts at refrigerated storage conditions and under simulated gastric and intestinal transit. Graphical abstract

scholarly journals Protective Effect of Sucrose and Sodium Chloride for Lactococcus lactis during Sublethal and Lethal High-Pressure Treatments

2004 ◽  
Vol 70 (4) ◽  
pp. 2013-2020 ◽  
Author(s):  
Adriana Molina-Höppner ◽  
Wolfgang Doster ◽  
Rudi F. Vogel ◽  
Michael G. Gänzle
Keyword(s):  
High Pressure ◽  
Protective Effect ◽  
Lactococcus Lactis ◽  
Multiple Drug Resistance ◽  
Compatible Solutes ◽  
Buffer System ◽  
Pressure Treatment ◽  
Transport Activity ◽  
Ph Homeostasis ◽  
Ionic Solutes

ABSTRACT The bactericidal effect of hydrostatic pressure is reduced when bacteria are suspended in media with high osmolarity. To elucidate mechanisms responsible for the baroprotective effect of ionic and nonionic solutes, Lactococcus lactis was treated with pressures ranging from 200 to 600 MPa in a low-osmolarity buffer or with buffer containing 0.5 M sucrose or 4 M NaCl. Pressure-treated cells were characterized in order to determine viability, the transmembrane difference in pH (ΔpH), and multiple-drug-resistance (MDR) transport activity. Furthermore, pressure effects on the intracellular pH and the fluidity of the membrane were determined during pressure treatment. In the presence of external sucrose and NaCl, high intracellular levels of sucrose and lactose, respectively, were accumulated by L. lactis; 4 M NaCl and, to a lesser extent, 0.5 M sucrose provided protection against pressure-induced cell death. The transmembrane ΔpH was reversibly dissipated during pressure treatment in any buffer system. Sucrose but not NaCl prevented the irreversible inactivation of enzymes involved in pH homeostasis and MDR transport activity. In the presence 0.5 M sucrose or 4 M NaCl, the fluidity of the cytoplasmic membrane was maintained even at low temperatures and high pressure. These results indicate that disaccharides protect microorganisms against pressure-induced inactivation of vital cellular components. The protective effect of ionic solutes relies on the intracellular accumulation of compatible solutes as a response to the osmotic stress. Thus, ionic solutes provide only asymmetric protection, and baroprotection with ionic solutes requires higher concentrations of the osmolytes than of disaccharides.

scholarly journals Karakteristik Minuman Laktat Sari Buah Durian Lay (Durio kutejensis) yang Disuplementasi dengan Kultur Lactobacillus selama Penyimpanan pada Suhu Rendah (Characteristic of Durian Lay (Durio kutejensis) Lactic Beverage Supplemented with Lactobacillus culture during cold storage)

2017 ◽  
Vol 36 (4) ◽  
pp. 424
Author(s):  
Neti Yuliana ◽  
Tintan Noviyeziana ◽  
Sutikno Sutikno
Keyword(s):  
Lactic Acid ◽  
Lactobacillus Plantarum ◽  
Cold Storage ◽  
Sugar Content ◽  
Storage Period ◽  
Viable Cell ◽  
Total Soluble Solid ◽  
Cell Counts ◽  
Sensory Score ◽  
Soluble Solid

The objective of this study was to characterize the durian lay juices supplemented by Lactic Acid Bacteria (LAB)  culture during cold storage. The LAB cultures consisted of Lactobacillus plantarum FNCC-0265, Lactobacillus acidophillus FNCC-0051 and combination of these LABs. After being inoculated with a 24 h – old culture starters, durian lay juice was incubated at 37 °C for 2 hours and kept at 4 °C for 0, 1, 2, 3 and 4 weeks. Changes in pH, total lactic acid, and sugar content, viable cell counts of LAB, total soluble solid, viability of LAB, and sensory characteristic during fermentation were measured. The results revealed that pH decreased from 4.79 to 4.20; sugar content reduced from 4.52 to 0.75 %; total soluble solid reduced from 8.93 to 7.97 °Bx, and sensory score reduced from 3.71 (like) to 3.40 (moderate like); while  the total lactic acid increased from 0.33 to 0.69 %; viable cell counts of LAB increased from 8.86  to 9.14 log CFU/ml; and % viability of LAB decreased from 100 to 95.90, during storage. Combination of Lactobacillus plantarum FNCC-0265 and Lactobacillus acidophillus FNCC-0051 cultures at two weeks cold storage period was the best treatment, based on the sensory and viable cell counts of LAB. The characteristics of this durian lay juice probiotic were pH 4.46, total lactic acid 0.59 %, sugar content 2.13 %, viable cell counts of LAB 9.33 log CFU/mL, total soluble solid 9.60 °Bx, and carbohydrate 45,05 %. This durian lay juice contained oxalate (107.56 mg/L), malic (527.895 mg/L), lactic (4381.49 mg/L) and citric (351.245 mg/L) acid.ABSTRAKTujuan penelitian ini adalah mengkaji karakteristik minuman laktat sari durian lay yang disuplementasi dengan kultur bakteri asam laktat (BAL) selama penyimpanan pada suhu rendah. Kultur BAL terdiri dari Lactobacillus plantarum FNCC-0265, Lactobacillus acidophillus FNCC-0051, dan campuran keduanya.  Sari buah durian lay diinokulasi dengan kultur berumur 24 jam lalu diinkubasi pada suhu 37 °C selama 2 jam dan kemudian disimpan selama 0, 1, 2, 3, dan 4 minggu. Perubahan pH, total asam, gula, total sel BAL. Total padatan terlarut, viabilitas BAL, dan sensori selama penyimpanan dingin diukur. Hasil penelitian menunjukkan bahwa terjadi perubahan pH dari 4,79 ke 4,20; kandungan gula dari 4,52 ke 0,75%; total padatan terlarut dari 8,93 ke 7.97 °Bx, viabilitas BAL dari 100 % menjadi 95,90 %,  dan skor sensori dari 3,71 suka ke 3,40 (agak suka); sementara pada total asam terjadi peningkatan dari 0,33 ke 0,69 %; dan sel hidup BAL meningkat dari 8,86 menjadi 9,14 log CFU/mL. Berdasarkan parameter sensori, perlakuan kultur campuran Lactobacillus plantarum FNCC-0265 dan Lactobacillus acidophillus FNCC-0051 yang disimpan selama 2 minggu merupakan perlakuan terbaik. Sari buah durian lay ini mempunyai karakteristik sebagai berikut: pH 4,45, total asam laktat 0,83 %, gula 2,20%, sel hidup BAL 9,33 log CFU/mL, total padatan terlarut  9,16 °Bx, dan karbohidrat 35,04 %. Asam organik yang terkandung pada jus durian lay ini adalah asam oksalat (108 mg/L), malat (528 mg/L), laktat (4382 mg/L) dan sitrat (351 mg/L).

scholarly journals 1250. Novel Boronic Acid Transition State Analogs (BATSI) with in vitro inhibitory activity against class A, B and C β-lactamases

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S643-S643
Author(s):  
Maria F Mojica ◽  
Christopher Bethel ◽  
Emilia Caselli ◽  
Magdalena A Taracila ◽  
Fabio Prati ◽  
...  
Keyword(s):  
Active Site ◽  
Inhibitory Activity ◽  
Covalent Bond ◽  
Thiol Group ◽  
Viable Cell ◽  
Free Thiol ◽  
Transition State Analogs ◽  
Cell Counts ◽  
Free Thiol Group

Abstract Background Catalytic mechanisms of serine β-lactamases (SBL; classes A, C and D) and metallo-β-lactamases (MBLs) have directed divergent strategies towards inhibitor design. SBL inhibitors act as high affinity substrates that -as in BATSIs- form a reversible, dative covalent bond with the conserved active site Ser. MBL inhibitors bind the active-site Zn2+ ions and displace the nucleophilic OH-. Herein, we explore the efficacy of a series of BATSI compounds with a free-thiol group at inhibiting both SBL and MBL. Methods Exploratory compounds were synthesized using stereoselective homologation of (+) pinandiol boronates to introduce the amino group on the boron-bearing carbon atom, which was subsequently acylated with mercaptopropanoic acid. Representative SBL (KPC-2, ADC-7, PDC-3 and OXA-23) and MBL (IMP-1, NDM-1 and VIM-2) were purified and used for the kinetic characterization of the BATSIs. In vitro activity was evaluated by a modified time-kill curve assay, using SBL and MBL-producing strains. Results Kinetic assays revealed that IC50 values ranged from 1.3 µM to &gt;100 µM for this series. The best compound, s08033, demonstrated inhibitory activity against KPC-2, VIM-2, ADC-7 and PDC-3, with IC50 in the low μM range. Reduction of at least 1.5 log10-fold of viable cell counts upon exposure to sub-lethal concentrations of antibiotics (AB) + s08033, compared to the cells exposed to AB alone, demonstrated the microbiological activity of this novel compound against SBL- and MBL-producing E. coli (Table 1). Table 1 Conclusion Addition of a free-thiol group to the BATSI scaffold increases the range of these compounds resulting in a broad-spectrum inhibitor toward clinically important carbapenemases and cephalosporinases. Disclosures Robert A. Bonomo, MD, Entasis, Merck, Venatorx (Research Grant or Support)

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