Endophytic Bacteria in Banana In Vitro Cultures: Molecular Identification, Antibiotic Susceptibility, and Plant Survival

Abstract

Microbial contamination is a common problem that causes significant losses in plant micropropagation systems. The present study reports on the identification and control of bacterial contaminants in banana in vitro cultures. Twelve isolates belonging to Bacillus pumilus (S2), Bacillus subtilis (R2 and M4), Geobacillus stearothermophilus (S1, S3, S4, P2, M3 and R3) and Paenibacillus spp. (P1, R1 and M2) were identified by sequencing of 16S rRNA, gyrA or gyrB genes. Antibiotic susceptibility testing was performed with the disk diffusion method on bacterial isolates using 36 antimicrobial agents. Some antibiotics, notably Ticarcillin, Penicillin, Ampicillin, Cefazolin and Imipenem, had a broader range of bactericidal activity than others did. When contaminated axillary shoot cultures of banana were treated with 100 or 200 mg·L−1 of ticarcillin, ampicillin or penicillin the bacteria were eliminated, but a reduction in shoot multiplication and growth was observed. These findings contribute to minimizing the losses in the commercial micropropagation of banana.

Biotechnological interventions in banana: current knowledge and future prospects

“…Besides, bavistin (0.1%) and 70% (v/v) ethanol also act as a powerful sterilizing agent for banana explants ( Bhutani et al., 2021 ; Prakasha et al., 2019 ; Yadav et al., 2021 ). In addition, some antibiotics such as penicillin, ampicillin, and ticarcillin have also been used to curb bacterial contaminants in banana tissue cultures ( El-Banna et al., 2021 ). Liquid cultures containing rifampicin for up to 30 days were able to inhibit the growth of Gram-positive bacteria in banana shoot tips with no effect on plant growth ( Van Den Houwe and Swennen, 1999 ).…”

Managing Lethal Browning and Microbial Contamination in Musa spp. Tissue Culture: Synthesis and Perspectives

“…Meanwhile, contamination is caused by phyllospheric, rhizospheric, and endophytic microorganisms that reside on, in, and inside the plants [14,15]. When the contamination of explants is not properly treated, it can cause a decrease in the regenerative ability, reduction in callus growth, and inhibition of adventitious shoot growth [15][16][17].…”

“…Meanwhile, contamination is caused by phyllospheric, rhizospheric, and endophytic microorganisms that reside on, in, and inside the plants [14,15]. When the contamination of explants is not properly treated, it can cause a decrease in the regenerative ability, reduction in callus growth, and inhibition of adventitious shoot growth [15][16][17]. The presence of microbial contaminants also leads to an increase in plant mortality, variation in growth (reduction in shooting proliferation and rooting), tissue necrosis, and even explant death [18].…”

Effect of Plant Preservative MixtureTM on Endophytic Bacteria Eradication from In Vitro-Grown Apple Shoots

“…Avoiding microbial contamination of plant tissue cultures is critical to successful micropropagation [ 11 ]. Despite extensive surface sterilization and the use of best practices for culture maintenance, the contamination of plant tissue may be a persistent problem during micropropagation [ 12 , 13 , 14 ]. This source of contamination is known as endophytes, which are of particular concern because they can survive surface sterilization [ 14 ].…”

“…Endophyte contamination causes culture losses and directly affects the efficiency of micropropagation protocols [ 13 ]. These microorganisms live within plant tissues and may not be visible until after several rounds of subculture and/or after the cultures have undergone some stress [ 12 , 13 , 14 , 15 ]. For example, many plant species have shown that bacterial infection may not always became apparent at the early initial stage of tissue culture; however, after an extended culture duration or any other stresses, such as a long period without subculture, bacterial haze can appear around the base of cultures that initially appeared to be clean and can therefore pose a significant problem for the propagation and distribution of in vitro plants.…”