Mlečnokislinska fermentacija japonskega (Fallopia japonica) in češkega dresnika (Fallopia bohemica) z namenom izdelave organskega gnojila

Malec, Luka (author), Jamnik, Polona (mentor), Cvejić, Rozalija (comentor)

Japonski in češki dresnik predstavljata velike izzive pri vzdrževanju urbanih zelenih površin zaradi invazivne in hitre rasti ter omejene učinkovitosti mehanskih, kemičnih ali bioloških metod odstranitve. Odstranjena biomasa, bogata z dušikom predstavlja neizkoriščen vir hranil, ki se ga lahko pretvori v organska gnojila s pomočjo mlečnokislinske fermentacije. V tej raziskavi smo preučevali biotransformacijo odpadnega materiala dresnika tekom fermentacije z uporabo L. plantarum, silažnega dodatka ter kompostnega dodatka EM Bokashi. Spremljali smo potek fermentacije preko meritev bakterijske rasti in spremembe pH ter določali produkcijo bakterijskih metabolitov z uporabo HPLC in LC – MS/MS. Posušeno biomaso dresnika smo rehidrirali, inokulirali z različnimi kulturami ter nato homogeniziranega fermentirali v anaerobnem okolju pri 37 ℃. Mlečnokislinska fermentacija je potekla pri dodatku vseh kultur. Prišlo je do razlik v hitrosti bakterijske rasti in acidifikacije substrata, kjer se je dodatek Bokashi izkazal kot najmanj učinkovit. Proizvodnja mlečne kisline je bila v skladu s pričakovanji in primerljiva z literaturo (2,53 ± 0,56 mg/g pri fermentaciji z L. plantarum, 1,75 ± 0,05 mg/g pri fermentaciji s silažnim dodatkom, 0,18 ± 0,15 mg/g pri fermentaciji z Bokashi), produkcija ocetne kisline pa minimalna. Koncentracija prostih aminokislin se je tekom fermentacije zmanjšala, podobno kot koncentracija celokupnih biogenih aminov. Kljub celokupnemu zmanjšanju vsebnosti biogenih aminov se je koncentracija nekaterih tekom fermentacije povečala, kar nakazuje na dekarboksilazno aktivnost uporabljenih starter kultur. Koncentracija GABA v fermentirani biomasi je bila po fermentaciji prav tako manjša, z izjemo fermentacije z L. plantarum, kjer ni bilo razlike. Celokupno, rezultati kažejo na uspešno fermentacijo dresnika. Nizke koncentracije nekaterih metabolitov kažejo na potrebo po dodatnih raziskavah in optimizaciji procesa fermentacije.

• Language: Slovenian
• Keywords: japonski dresnik, fermentacija, gnojila
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Year: 2024
• PID: 20.500.12556/RUL-163064
• COBISS.SI-ID: 210716419
• Publication date in RUL: 02.10.2024

Secondary language

• Language: English
• Title: Lactic acid fermentation of Japanese (Fallopia japonica) and Czech gorse (Fallopia bohemica) for the purpose of producing organic fertilizer

Abstract

Japanese and Czech knotweed pose major challenges in the maintenance of urban green spaces due to their invasive and rapid growth and the limited efficacy of mechanical, chemical or biological removal methods. The removed biomass, rich in nitrogen, represents an unused source of nutrients that can be converted into organic fertilizers with the help of lactic acid fermentation. In this research, we studied the biotransformation of the waste material of the knotweed during fermentation using L. plantarum, silage additive and EM Bokashi compost additive. We monitored the course of the fermentation by measuring bacterial growth and pH changes, and determined the production of bacterial metabolites using HPLC and LC – MS/MS. The dried biomass of knotweed was rehydrated, inoculated with different cultures and then homogenized and fermented in an anaerobic environment at 37 ℃. Lactic acid fermentation occurred with the addition of each culture, but there were differences in the rate of bacterial growth and substrate acidification, where the addition of Bokashi proved to be the least effective. Lactic acid production was in line with expectations and comparable to the literature (2.53 ± 0.56 mg/g for fermentation with L. plantarum, 1.75 ± 0.05 mg/g for fermentation with a silage additive, 0.18 ± 0.15 mg/g for fermentation with Bokashi) whereas acetic acid production was minimal. The concentration of free amino acids decreased during fermentation, similar to the concentration of total biogenic amines. Despite the overall decrease in the content of biogenic amines, the concentration of some increased during fermentation, which indicates decarboxylase activity of used starter cultures. GABA concentration decreased as well during fermentation, with the exeption of fermentation with L. plantarum where there was no change in concentration. Overall, the results indicate a successful fermentation of knotweed, however the unexpected and low concentrations of some metabolites indicate the need for further research and optimization of the fermentation process.

• Keywords: japanese knotweed, fermentation, fertilizers