The Microflora Within the Tissue of Fruits and Vegetables^a

Abstract

SUMMARY Bacteria occur within normal, sound fresh fruit tissues. They are mostly gram‐negative motile rods, representatives of the Pseudomonadaceae and the Enterobacteriaceae. Lactic‐acid‐forming bacteria are found on the surface of crops. In different crops and in different varieties, bacteria may appear abundantly in one field and rarely in others. They are found more frequently in low‐growing vegetables than in tree borne fruits. In cucumbers the bacteria are more often in the tissue close to the periphery and less often in the central core. In tomatoes their frequency is highest close to the stem‐scar and the central core of the fruit, decreasing toward the fruit periphery. It appears that the bacteria can enter the living plant tissue by different pathways and may persist there as harmless commensals. When the vegetables are brined, the bacteria multiply in the tissue as well as in the brine. Lactobacilli penetrate gined tomatoes primarily through the stem‐scar and multiply more rapidly in the fruit than in the brine. During fermentation of tomatoes and cucumbers the Enterobacteriaceae are mostly Suppressed by the lactic‐acid‐forming bacteria. However, if the latter are excluded by surface disinfection of the fruits, the Enterobacteria continue to multiply, causing internal bloaters, an increase in pH, and, ultimately, putrefaction.

Survival of Salmonellae on and in Tomato Plants from the Time of Inoculation at Flowering and Early Stages of Fruit Development through Fruit Ripening

“…Additionally, in the secondary xylem, the axial and ray parenchyma store nutrients and water (7) which sustain viability of plants and, possibly, promote survival of human pathogenic bacteria. The presence of epiphytal flora within tissue of fruits and vegetables through various pathways was reported by Samish et al (27). By examining eight internal locations of tomatoes, they observed that bacteria are unevenly distributed in the fruit, and entry may be from the stem scar tissue through the core and into the endocarp.…”

“…This study suggested that some epiphytal flora might reach internal tissue of tomatoes through natural apertures because of their small size and motility. It may be that bacteria enter fruit tissue more readily in the early stages of fruit development, at a time when various channels are not yet covered by corky or waxy materials (27). Broken trichomes on young fruits represent another site of entry of microorganisms.…”

Endophytic bacterial communities in the periderm of potato tubers and their potential to improve resistance to soil‐borne plant pathogens

“…Endophytic bacteria have been isolated within the tissues of healthy tomato (Solanum lycopersicum) (Samish et al, 1963) and potato (Solanum tuberosum) plants ( De Boer & Copeman, 1974;Sanford, 1948). Subsequently, many studies have demonstrated a relationship between endophyte bacteria and fungal pathogenesis in plants.…”

Evidence of Association of Salmonellae with Tomato Plants Grown Hydroponically in Inoculated Nutrient Solution

“…The inner tissue of sound produce is generally considered to be sterile. However, endophytic bacteria are known to reside in a wide range of plant tissues (7,16,28), including those consumed as raw vegetables (11,12,19,23,25,27,31). Samish et al (23) studied 10 fruits and vegetables and found that bacteria, mostly members of two families, the Pseudomonadaceae and the Enterobacteriaceae, were present in sound, raw cucumber and tomato fruits.…”