Hyaluronic acid production by Klebsiella pneumoniae strain H15 (OP354286) under different fermentation conditions

BACKGROUND

Hyaluronic acid (HA) has gained significant attention due to its unique physical, chemical, and biological properties, making it widely used in various industries. This study aimed to screen bacterial isolates for HA production, characterize favorable fermentation conditions, and evaluate the inhibitory effect of bacterial HA on cancer cell lines.

RESULTS

A total of 108 bacterial isolates from diverse sources were screened for HA production using HPLC, turbidimetric, and carbazole determination methods. Among the HA-producing isolates, Klebsiella pneumoniae H15 isolated from an animal feces sample, was superior in HA production. The strain was characterized based on its morphological, cultural, and biochemical characteristics. Molecular identification using 16S rDNA sequencing and phylogenetic analysis confirmed its identity. Fermentation conditions, including pH, temperature, time, and agitation rate, were optimized to maximize HA production. The basal medium, comprising sucrose (7.0%) as carbon source and combined yeast extract with peptone (1.25% each) as nitrogen substrate, favored the highest HA production at pH 8.0, for 30 h, at 30 °C, under shaking at 180 rpm. The average maximized HA concentration reached 1.5 g L-1. Furthermore, bacterial HA exhibited a significant inhibitory effect on three cancer cell lines (MCF-7, HepG-2 and HCT), with the lowest concentration ranging from 0.98-3.91 µg mL-1.

CONCLUSIONS

K. pneumoniae H15, isolated from animal feces demonstrated promising potential for HA production. The most favorable fermentation conditions led to a high HA production. The inhibitory effect of bacterial HA on cancer cell lines highlights its potential therapeutic applications. These findings contribute to a broader understanding and utilization of HA in various industries and therapeutic applications.

Comparison of the fermentation and bacterial community in the colon of Hu sheep fed a low-grain, non-pelleted, or pelleted high-grain diet

Microbial fermentation in the hindgut is likely an important contributor to energy availability in ruminants, except for the rumen. This study aimed to investigate commensal bacteria in the colon influenced by diverse dietary niches. Fifteen male sheep were randomly allotted into three feeding groups: non-pelleted low-grain (CON, n = 5), non-pelleted high-grain (HG, n = 5), and pelleted high-grain (HP, n = 5) diets. The HG and HP groups had higher fermentation parameters than the CON group, especially acetate concentration (CON = 46.91; HG = 61.66; HP = 77.99). The HG diet altered the composition of commensal bacteria in the colon in comparison to the CON group, including the increase of genera related to acetate production (e.g., Acetitomaculum spp.), butyrate production (e.g., Coprococcus spp. and Subdoligranulum spp.), and starch degradation (e.g., Prevotella spp., Roseburia spp., and Oscillibacter spp.). The colon functional compendium had co-alteration with taxonomic changes that indicated non-pelleted HG diet caused a detrimental colonic niche. The HP diet specifically promoted the abundance of Ruminococcus, Olsenella, and Alloprevotella genera to achieve the highest acetate concentration and decreased the starch-degrader Roseburia spp. and Oscillibacter spp. in contrast to the HG group. Our results provide a systematic view of the microbial fermentation, community, and functional guilds in colonic digesta and mucosa in regard to using an HP diet to maintain colonic niche homeostasis under the adverse influence of the HG diet.Key Points• Non-pelleted and pelleted high-grain diets altered sheep colonic fermentation.• Non-pelleted and pelleted high-grain diets resulted in diverse microbial composition.• The pelleted method ameliorated microbial functions compared with the high-grain diet.

Pomegranate peel waste: a new substrate for citric acid production by Aspergillus niger in solid-state fermentation under non-aseptic conditions

Citric acid production from dried and non-dried pomegranate peel wastes by the fungus Aspergillus niger B60 in solid-state fermentation (SSF) under non-aseptic conditions was investigated. The maximum amount of citric acid (278.5 g/kg dry peel) was achieved using dried (at 45 °C for 48 h) pulverized pomegranate peels with moisture content 75% and initial pH 8.0, after 8 days of fermentation at 25 °C. Under the same fermentation conditions, a higher amount of citric acid (306.8 g/kg dry peel) was observed during SSF of non-dried peels as a substrate. The addition of methanol as an inducer at a concentration of 3% (w/w) into the dried and non-dried pomegranate peel wastes increased the amount of citric acid to 300.7 and 351.5 g/kg dry peel, respectively. The non-dried pomegranate peel waste in SSF under non-aseptic conditions is a cheap and useful substrate for the commercial production of citric acid with low energy cost. The utilization of inexpensive agro-industrial wastes through SSF can contribute to achieve industrially feasible and environmentally sustainable bio-production of citric acid.

Sensitivity of Coriandrum sativum extract on bacterial pathogens isolated from digestive system of rabbits, and its role on in vitro cecal gas production and fermentation

The present context was aimed to investigate the antibacterial potency of aqueous extract of coriander (Coriandrum sativum L.) leaves against bacterial pathogens isolated from the organs associated with digestive system of rabbit. This study also evaluated the influence of varied doses of aqueous extract of C. sativum (AECS) leaves on in vitro gas production (GP), methane (CH₄) production, and some other pivotal fermentation parameters from caecal sample of rabbits. The pathogenic bacteria were isolated from mouth, caecum, and anus of rabbits, and further identified through morphological, biochemical, and molecular tools. The growth inhibitory characteristics of AECS against pathogens were determined using disc diffusion assay. Surprisingly, the result revealed lack of antibacterial potential at tested concentrations. Further, in order to demonstrate the in vitro GP and fermentation parameters in rabbits, four treatments comprising of 0, 0.6, 1.2, and 1.8 mL extract/g dry matter (DM) of AECS were used. Results showed no linear or quadratic effect (P > 0.05) on in vitro GP and CH₄ production after the supplementation of AECS in the feeding diet. However, the inclusion of AECS at the concentration of 1.8 mL/g DM exhibited the lowest asymptotic CH₄ production and initial delay prior to CH₄ production. Similarly, the addition of AECS at 1.8 mL/g DM concentration reduced asymptotic GP as well as CH₄ production, and improved fermentation parameters of rabbits when compared with the control and other tested doses. In a nutshell, the tested doses of AECS showed lack of antibacterial trait against the pathogenic bacteria isolated from mouth, caecum, and anus of rabbits. Besides, the AECS exhibited the unique potentiality of reducing GP and improving diversified fermentation parameters in rabbits, thereby suggesting its plausible role as an alternative to commercially available growth promoters in livestock industries.

Reprint of: Effect of fermentation parameters, elicitors and precursors on camptothecin production from the endophyte Fusarium solani

Volumetric productivity of camptothecin from the suspension culture of the endophyte Fusarium solani was enhanced up to ∼152 fold (from 0.19μgl(-1)d(-1) to 28.9μgl(-1)d(-1)) under optimized fermentation conditions including initial pH (6.0), temperature (32°C) and agitation speed (80rpm) with (5% (v/v)) ethanol as medium component. Among various elicitors and precursors studied, tryptamine (0.5mM) as precursor and bovine serum albumin (BSA) (0.075mM) as an elicitor added on day 6 of the cultivation period resulted in maximum enhancement of camptothecin concentration (up to 4.5 and 3.4-fold, respectively). These leads provide immense scope for further enhancement in camptothecin productivity at bioreactor level. The cytotoxicity analysis of the crude camptothecin extract from the fungal biomass revealed its high effectiveness against colon and mammary gland cancer cell lines.

Effect of fermentation parameters, elicitors and precursors on camptothecin production from the endophyte Fusarium solani

Volumetric productivity of camptothecin from the suspension culture of the endophyte Fusarium solani was enhanced up to ∼152 fold (from 0.19 μg l(-1) d(-1) to 28.9 μg l(-1) d(-1)) under optimized fermentation conditions including initial pH (6.0), temperature (32 °C) and agitation speed (80 rpm) with (5% (v/v)) ethanol as medium component. Among various elicitors and precursors studied, tryptamine (0.5 mM) as precursor and bovine serum albumin (BSA) (0.075 mM) as an elicitor added on day 6 of the cultivation period resulted in maximum enhancement of camptothecin concentration (up to 4.5 and 3.4-fold, respectively). These leads provide immense scope for further enhancement in camptothecin productivity at bioreactor level. The cytotoxicity analysis of the crude camptothecin extract from the fungal biomass revealed its high effectiveness against colon and mammary gland cancer cell lines.

Molecular characterisation and biomass and metabolite production of Lactobacillus reuteri LPB P01-001: A potential probiotic

Lactobacillus reuteri LPB P01–001 was isolated from the gastrointestinal tract of wild swine and was characterised by biochemical testing and sequencing of gene 16S rRNA. A simple and low-cost culture medium based on cane sugar (2.5% p/v) and yeast extract (1% p/v) was used in the production of this probiotic. The fermentative conditions were a) pH control at 6.5 and b) no pH control; both were set at 37°C in a 12 L slightly stirred tank bioreactor. Fermentation parameters such as the specific growth rate, productivity and yield of biomass, lactic and acetic acid levels were determined. L. reuteri LPB P01–001 behaves as an aciduric bacteria because it grows better in a low pH medium without pH control. However, the lactic acid production yield was practically half (9.22 g.L^-1) of that obtained under a constant pH of 6.5, which reached 30.5 g.L^-1 after 28 hours of fermentation. The acetic acid production was also higher under pH-controlled fermentation, reaching 10.09 g.L^-1after 28 hours of fermentation. These parameters may raise the interest of those committed to the efficient production of a probiotic agent for swine.

Optimization of fermentation parameters for production of ethanol from kinnow waste and banana peels by simultaneous saccharification and fermentation

A study was taken up to evaluate the role of some fermentation parameters like inoculum concentration, temperature, incubation period and agitation time on ethanol production from kinnow waste and banana peels by simultaneous saccharification and fermentation using cellulase and co-culture of Saccharomyces cerevisiae G and Pachysolen tannophilus MTCC 1077. Steam pretreated kinnow waste and banana peels were used as substrate for ethanol production in the ratio 4:6 (kinnow waste: banana peels). Temperature of 30°C, inoculum size of S. cerevisiae G 6% and (v/v) Pachysolen tannophilus MTCC 1077 4% (v/v), incubation period of 48 h and agitation for the first 24 h were found to be best for ethanol production using the combination of two wastes. The pretreated steam exploded biomass after enzymatic saccharification containing 63 gL(-1) reducing sugars was fermented with both hexose and pentose fermenting yeast strains under optimized conditions resulting in ethanol production, yield and fermentation efficiency of 26.84 gL(-1), 0.426 gg (-1) and 83.52 % respectively. This study could establish the effective utilization of kinnow waste and banana peels for bioethanol production using optimized fermentation parameters.