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Lacticaseibacillus rhamnosus CRL1505 can be used in functional products as a probiotic powder (dried live cells) or as a postbiotic intracellular extract containing inorganic polyphosphate as a functional biopolymer. Thus, the aim of this work was to optimize the production of Lr-CRL1505 depending on the target of the functional product (probiotic or postbiotic). For this purpose, the effect of culture parameters (pH, growth phase) on cell viability, heat tolerance and polyphosphate accumulation by Lacticaseibacillus rhamnosus CRL1505 was evaluated. Fermentations at free pH produced less biomass (0.6 log units) than at controlled pH while the growth phase affected both polyphosphate accumulation and cell heat tolerance. Exponential phase cultures showed 4-15 times greater survival rate against heat shock and 49-62% increased polyphosphate level, compared with the stationary phase. Results obtained allowed setting the appropriate culture conditions for the production of this strain according to its potential application, i.e., as live probiotic cells in powder form or postbiotic. In the first case, running fermentations at pH 5.5 and harvesting the cells at the exponential phase are the best conditions for obtaining a high live biomass yield capable of overcoming heat stress. Whereas the postbiotic formulations production requires fermentations at free pH and harvesting the cells in exponential phase to increase the intracellular polyphosphate level as a first step., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

The term postbiotics has acquired great interest in recent years. Numerous studies have shown a potential beneficial effect of its use in many inflammatory pathologies. However, it has not been much explored in ocular inflammatory diseases. The aims of this study were to develop and characterise an ophthalmic formulation with a postbiotic of Lactiplantibacillus plantarum CRL 759, and to evaluate its anti-inflammatory actions on murine macrophage stimulated with lipopolysaccharides (LPS) in vitro . First, we evaluated the ability of L. plantarum CRL 759 to generate a supernatant with anti-inflammatory property using different buffers. Then, we studied the stability at different temperatures and storage times of the generated postbiotic. In vitro assays showed that incubation of L. plantarum CRL 759 in modified phosphate buffer according to Sorensen (called POF-759), generated a supernatant that significantly reduced the production of interleukin-6, tumour necrosis factor-α, and nitric oxide by RAW 264.7 cells stimulated with LPS. Furthermore, POF-759 maintained its anti-inflammatory activity at room temperature, 4 and -20 °C, up to 30 days of storage. From the studies reported here, a postbiotic product with anti-inflammatory properties and optimal characteristics for the formulation of eye drops was obtained.

In previous in vitro studies, an inorganic additive (MCM 3 ) showed a thermo-protective effect on the cell viability of Lacticaseibacillus rhamnosus CRL1505 (Lr-CRL1505). In this work, cultures of this probiotic strain were spray dried at lab scale using two carriers: maltodextrin (powder MA) and maltodextrin plus MCM 3 (powder MA/MCM 3 ). The cell survival was higher in powder MA/MCM 3 (72.8%) than in powder MA (42.8%). Different rehydration media, including the additive MCM 3 , and two temperatures (37 °C and 45 °C) were evaluated. The best results were obtained in cells rehydrated at 37 °C in MCM 3 . During the storage of the powders, the highest cell counts were observed in the MA/MCM 3 powder. Our results demonstrated that the presence of MCM 3 in the carrier and in reconstitution media benefits the spray drying process and the recovery of dehydrated cells. Thus, the use of this additive of inorganic nature and low cost represents a promising technological alternative., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

In this work, the thermotolerance of Lactobacillus rhamnosus CRL1505, an immunobiotic strain, was studied as a way to improve the tolerance of the strain to industrial processes involving heat stress. The strain displayed a high intrinsic thermotolerance (55°C, 20 min); however, after 5 min at 60°C in phosphate buffer a two log units decrease in cell viability was observed. Different heat shock media were tested to improve the cell survival. Best results were obtained in the mediumcontaining inorganic salts (KH2PO4, Na2HPO4, MnSO4, and MgSO4) likely as using 10% skim milk. Flow cytometry analysis evinced 25.0% live cells and a large number of injured cells (59.7%) in the inorganic salts medium after heat stress. The morphological changes caused by temperature were visualized by transmission electronic microscopy (TEM). In addition, TEM observations revealed the presence of polyphosphate (polyP) granules in the cells under no-stress conditions. A DAPI-based fluorescence technique, adjusted to Gram-positive bacteria for the first time, was used to determine intracellular polyP levels. Results obtained suggest that the high initial polyP content in L. rhamnosus CRL 1505 together with the presence of inorganic salts in the heat shock medium improve the tolerance of the cells to heat shock. To our knowledge, this is the first report giving evidence of the relationship between polyP and inorganic salts in thermotolerance of lactic acid bacteria.

Aims: To evaluate the efficacy of a novel microencapsulation procedure using whey protein and pectin to improve the survival rate of Lactobacillus rhamnosus CRL 1505 to low pH and bile., Methods and Results: Lactobacillus rhamnosus CRL 1505 was encapsulated by ionotropic gelation using pectin (PE) and pectin-whey protein (PE-WP). Both types of beads (MC(PE/WP) and MC(PE-WP/WP)) were covered with a layer of whey protein by complex coacervation. The noncapsulated lactobacilli were not sensitive to bile salts but to acid. Both microparticles protected Lact. rhamnosus CRL 1505 at pH 2.0, but only MC(PE/WP) was effective at pH 1.2., Conclusions: The combination of ionotropic gelation and complex coacervation techniques is efficient to obtain microcapsules of pectin covered with whey proteins. The MC(PE/WP) beads were more stable than the MC(PE-WP/WP) beads in simulated gastric conditions, thus offering better protection to Lact. rhamnosus CRL 1505 at low pH., Significance and Impact of the Study: Pectin beads with a whey protein layer (MC(PE/WP)) could be used as probiotic carrier in functional foods of low pH (e.g. apple juice), thus protecting Lact. rhamnosus CRL 1505 against the stressful conditions of the gastric tract., (© No claim to Argentinean Government works. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.)