The Plant Pathogenic Bacterium Streptomyces scabies Degrades the Aromatic Components of Potato Periderm via the β-Ketoadipate Pathway

Abstract

The outer potato periderm layer consists of dead suberized cells. Suberin, a protective biopolymer, is made of a polyaliphatic portion covalently linked to polyaromatic moieties. Evidence accumulates that Streptomyces scabies, the main causal agent of potato common scab, can degrade the suberin aliphatic part but its ability to degrade the aromatic portion has not been documented. This polyaromatic portion is mainly composed of cinnamic acids. In this study, two cinnamates (trans-ferulic or p-coumaric acids) were added to the culture medium of S. scabies strains EF-35 and 87.22. HPLC quantification revealed that both strains efficiently utilized these compounds. A proteomic study coupled with gene expression analysis led to the identification of putative catabolic pathways for cinnamates. Catabolism of both compounds appeared to occur via the β-ketoadipate pathway. Gene SCAB_15301, encoding for a putative vanillate monooxygenase, was partly deleted from S. scabies strain 87.22 genome. The mutant retained its ability to catabolize trans-ferulic acid into vanillate but lost its ability to further degrade the latter compound. When the wild-type mutant and complemented strains were grown in the presence of suberin-enriched potato periderm, accumulation of vanillic acid was observed only in the mutant culture medium. This work presents evidence that S. scabies can degrade not only the aliphatic part of suberin but also the constituents of suberin aromatic portion. This may provide ecological and pathological advantages to S. scabies as a saprophyte and pathogen.

Identification of antagonistic Streptomyces strains isolated from Algerian Saharan soils and their plant growth promoting properties

“…Currently, crop-destroying fungi cause yield losses of about 20% worldwide, with an additional 10% loss postharvest (Fisher et al 2018). In addition to fungal diseases, there are those engendered by bacteria, such as common scab, which is characterized by dark lesions that develop especially on tubers, and the main causal agent is Streptomyces scabiei (Khalil et al 2019). Hence, the utilization of beneficial microorganisms as biological control agents is considered an environmental friendly alternative to combat crop diseases and pesticide resistance.…”

Genomic and physiological traits provide insights into ecological niche adaptations of mangrove endophytic Streptomyces parvulus VCCM 22513

“…It was in agreement with previous studies demonstrating that Streptomyces spp. were able to utilize benzaldehyde, catechol, phenylacetic acid, protocatechuic acid, and even polycyclic aromatic hydrocarbons as growth substrates (Khalil et al 2019). Using genome-wide comparison, the complete pathways for degradation of aromatic compounds including protocatechuate, gentisate, 4-hydroxyphenylpyruvate, cinnamate, 3-phenylpropionate, and styrene were only identified in S. parvulus genomes including VCCM 22513 and JCM 4068 T .…”

“…Bacterial growth was monitored after 16 days of incubation at 30 °C. For aromatic compound degradation experiments, the strain VCCM 22513 was inoculated in CM basal medium (l-asparagine 0.5 g; K 2 HPO 4 0.5 g; MgSO 4 •7H 2 O 0.2 g; FeSO 4 •7H 2 O 0.01 g; casein hydrolysate 0.05 g; pH 7.0 per liter) supplemented with gentisate (60 μM), cinnamate (80 μM), styrene (80 μM), or protocatechuate (60 μM) (Khalil et al 2019). The CM basal medium without aromatic compounds was used as a negative control.…”

Pectobacterium carotovorum: agente fitopatógeno causante de la pudrición blanda en la papa (Solanum tuberosum)

“…Otra enfermedad de origen bacteriano es la costra de la papa, causada por S. cabies, enfermedad muy común en el cultivo y que, al contrario de Ralstonia sp., es una de las más inocuas en lo que hace referencia a la repercusión económica, porque causa efectos cosméticos en la cosecha, afectando la calidad pero no el rendimiento ni la conservación de los cultivos (Beaulieu et al, 2019;Dees & Wanner, 2012). Finalmente, la pudrición blanda causada por P. carotovorum, objeto de esta revisión, es una de las enfermedades más relevantes en la afectación del tubérculo, en la etapa de poscosecha, generando grandes pérdidas económicas.…”