Rhizodegradation of Pyrene by a Non-pathogenic Klebsiella pneumoniae Isolate Applied With Tagetes erecta L. and Changes in the Rhizobacterial Community

Abstract

The non-clinical Klebsiella pneumoniae variants, isolated from different environments, are now well acknowledged for their role in plant-growth promotion and biodegradation of pollutants. In the present study, a non-clinical environmental isolate K. pneumoniae AWD5 is being described for rhizoremediation of pyrene, applied through the rhizosphere of an ornamental plant, Tagetes erecta L (marigold). The non-pathogenic nature of AWD5 was established using an in vivo mouse model experiment, where AWD5 was unable to cause lung infection in tested mice. Degradation of pyrene, in the presence of succinate as co-substrate, was observed to be 87.5% by AWD5, after 21 days of incubation in minimal (Bushnell–Hass) medium in vitro conditions. Consequently, the bacterial inoculation through the rhizosphere of T. erecta L. plants resulted in 68.61% degradation of pyrene, which was significantly higher than control soil. Inoculation of AWD5 also improved plant growth and exhibited an increase in root length (14.64%), dry root weight (80.56%), shoot length (3.26%), and dry shoot weight (45.35%) after 60 days of incubation. T. erecta L., an ornamental plant, was also found to be suitable for bioremediation of pyrene. The effect of AWD5 application, and rhizoremediation process, on rhizosphere bacterial diversity and community structure has been studied using the metagenomic analysis of the 16S (V3–V4) region of rRNA. 37 bacterial phyla constituted the core microbiome, which was dominated by Proteobacteria followed by Actinobacteria, Actinobacteria, and Planctomycetes for all the treatments. AWD5 inoculation enhanced the relative abundance of Firmicutes and Acidobacteria as compared with other treatments. Genus Kaistobacter and Verrucomicrobia were found to be an abundant indigenous population in pyrene-spiked soils. Bacterial richness and diversity were analyzed using the Shannon–Wiener (H) index. A lower diversity index was observed in pyrene-spiked soils. Canonical correspondence analysis (CCA) showed a possible linkage with plant growth attributes and available nitrogen content that influences diversity and abundance of the bacterial community.

Comparison of the petroleum removal efficiencies and plasmid profiles of clinical and environmental Klebsiella pneumoniae strains

“…Moreover, P. aeruginosa NCIM 5514 degraded 61.0% of crude oil during 60 days of incubation (Varjani and Upasani 2016). Rajkumari et al (2021) reported that a non-clinical environmental isolate K. pneumoniae AWD5 was achieved 87.5% of pyrene degradation in the presence of succinate as Fig. 1 The petroleum degradation and bacterial growth of Kp1, Kp2 and Kp RSKK 574 strains co-substrate within 21 days of incubation (Rajkumari et al 2021).…”

“…Rajkumari et al (2021) reported that a non-clinical environmental isolate K. pneumoniae AWD5 was achieved 87.5% of pyrene degradation in the presence of succinate as Fig. 1 The petroleum degradation and bacterial growth of Kp1, Kp2 and Kp RSKK 574 strains co-substrate within 21 days of incubation (Rajkumari et al 2021). It is known that various microorganisms can metabolize different groups of hydrocarbons as straight, branched, and cyclic alkanes and aromatics as a sole carbon source.…”

Association of Sequence types, Antimicrobial Resistance and Virulence Genes in India isolates of Klebsiella pneumoniae: A Comparative Genomics Study

“…However, 49 clinical strains were also not detected with these two major virulent genes (Figure 6). Rhizosphere soil AWD5 K. pneumoniae is avirulent in the lung infection mice model (Rajkumari et al, 2021). The AMR and virulence characteristics are overlapped in both clinical and environment.…”

Antibacterial Activity of Marigold Flower (Tagetes Erecta L.) Ethanol Extract Cream Against Staphylococcus Aureus

“…Previous research revealed that marigold flowers have antibacterial effects (Cahyaningrum et al, 2020), antimicrobial (Padalia and Chand, 2015), antimalarial , antihyperlipidemic (Kresnapati et al, 2021), and anti-inflammatory (Selvam et al, 2021). Flavonoid compounds have maximum inhibitory activity of K. pneumonia (Rajkumari et al, 2021). Marigold flower essential oil has antifungal activity and the maximum apoptotic rate of 90%, as seen from the HepG2 cell line at 82 and 122 g/ml (Safar et al, 2020).…”

“…The androgen dihydrotestosterone hormone causes excess oil production in the skin. This hormone can increase the size of the sebaceous glands, which has implications for sebum production in the skin (Cahyaningrum et al, 2020;Rajkumari et al, 2021). This situation makes it easier for acne causing bacteria to grow ideally (Puluh et al, 2019).…”