Inoculation of endophytic bacteria improves nutritional and antioxidant profiles in hydroponic sweet pepper

Summary

This experimental study evaluated the capacity of 10 endophytic bacterial inocula to enhance nutritional and bioactive compound profiles in hydroponically grown sweet peppers, addressing the depletion of beneficial microbiota caused by routine disinfection practices. Plantibacter flavus-A and certain bacterial consortia significantly elevated thiamine levels (up to 57% above control) and enhanced polyphenol and flavonoid content, with corresponding improvements in antioxidant activity. The findings suggest that strain-specific and metabolite-specific effects operate, with SP5 (Paenibacillus taichungensis) and consortium SP9 identified as most promising for commercial hydroponic sweet pepper production.

Regional applicability

The study employed hydroponic systems, which are increasingly used in controlled-environment agriculture in the United Kingdom. The findings may be applicable to UK glasshouse horticulture, though the transferability of inocula efficacy would depend on local environmental conditions, water chemistry, and microbial ecology. The work demonstrates a potential route to nutrient enhancement in soilless systems, relevant to UK protected horticulture policy and practice.

Key measures

Thiamine (B1), riboflavin (B2), tocopherols (vitamin E), vitamin C redox couple, total polyphenols, hydroxycinnamic acid derivatives, total flavonoids, flavonols, antioxidant radical scavenging activity (ROO•, HO•, ABTS•+ assays)

Outcomes reported

The study assessed the effects of 10 different endophytic bacterial inocula on vitamin contents (thiamine, riboflavin, tocopherols, vitamin C), polyphenols, and antioxidant properties of sweet peppers grown hydroponically. Key findings included strain-dependent increases in thiamine concentration (up to 57% above control) and polyphenol content, with some consortia improving oxidative stress markers.

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