Influence of roadside pollution on the phylloplane microbial community of Alnus nepalensis (Betulaceae)

Abstract

Abstract:The North Eastern region of India is undergoing industrial development at a faster rate than expected. Roads form the main system of transportation and communication owing to the hilly topography of the region. Automobiles discharge a number of gaseous and trace metal contaminants. Human activities like stone grinding, road construction and sand milling also increase the atmospheric dust and heavy metal contaminant level. These contaminants get settled on leaf surfaces at roadsides and enter in contact with phylloplane microorganisms. This study compares microorganisms on leaf surfaces of alder (Alnus nepalensis (Betulaceae)) on roadside and non-roadside environments. Two sites dominated by alder were selected. One at a busy road intersection on the National Highway no. 44 in Shillong with high traffic density (8 000-9 000 heavy vehicles/day), taken as the polluted site and the other one in a forest approximately 500 m away from the roadside considered as the unpolluted site. Analysis of phylloplane microorganisms, lead, zinc, copper, cadmium and sulphur was carried out from leaves. The bacterial population was higher at the unpolluted site. Bacterial population showed a significant negative correlation with lead, zinc, copper, cadmium and sulphur. Similarly, fungal population was higher at the unpolluted site. A total of 29 fungal species were isolated from the phylloplane of A. nepalensis (polluted site 16 species; unpolluted site 28 species). Some fungal forms like Mortierella sp., Fusarium oxysporum and Aureobasidium pollulans were dominant in the polluted site. Numbers of phylloplane fungi and bacteria were significantly reduced in the polluted site. The correlation coefficient indicated a detrimental effect of metals like lead, zinc, copper, cadmium and sulphur on the microbial community of leaf surfaces. The specificity of certain fungi to the unpolluted site may be attributed to their sensitivity to pollution. The predominance of Aureobasidium pollulans, Fusarium oxysporum and Mortierella sp. in the polluted site may be due to their resistance to pollutants in roadside conditions. Rev. Biol. Trop. 56 (3): 1521-1529. Epub 2008 September 30.

Responses of Phyllosphere Microbial Population of Some Common Road Trees In Relation To Dust Deposition – A Case Study in Kolkata, India

“…Presence of different vehicular exhausting metals was greater in the roadside site in compare to the non-roadside site (Fig 4).The fluctuation of CFU of bacteria and fungi clearly showed a negatively significant correlation with the variation in labels of Pb, Zn, Cd and Cu in polluted site but in non-roadside sampling site elevated count of microbial populations wasfound, which was not significant between those trace metals and samples collected from the sampling site of Rajarhat (S 2 ).Dust deposition on the phylloplane of the three plants left a damaging effect on the microbial community of the phyllosphere shown by the coefficient correlation data analysis - Table 2‖. These findings were supported by Joshi [21]. That study reflected decrease of bacteria and fungi with increase of pollution at roadside site.…”

“…Five mature leaves samples were collected from P 1 , P 2 and P 3 at the two sites in sterilised zipper bags and transported for microbial assay in between twenty-four hours to laboratory. Microbial analysis by isolation of micro-fungi and bacteria was done by serial dilution method as described by Joshi [21]. One gram of leaf sample was weighed and taken in a 250-ml conical flask containing 100 ml of sterilised distilled water.…”

“…However, in case of fungi, total count may be higher sometimes near the roadside for the low pH concentration [20].A Study in North Eastern region of India revealed that the number of fungal and bacterial significantly decreased with the increasing amount of roadside pollution level in Alnusnepalensisand Pinuskesiya. Microbes are generally negatively correlated with different metal like Zinc, Lead Copper, Cadmium and Sulfur [21].The growth of bacteria, filamentous fungi and yeast on the leaf surface of trees like mango [22] are also affected by different chemical sprays.…”

Diversity of pectinolytic molds on major indian mango cultivars

“…Extensive studies have been conducted on the diversity of epiphytic microbes on annuals or perennials with deciduous leaves (De Jager et al 2001, Joshi 2008) and the long-lasting leaves of evergreen trees such as mangoes (De Jager et al 2001). Recently, Jha et al (2010) showed that the mango fruit surface supports a varied climax community.…”

Phyllosphere Bacterial Population of Woody Species in Subtropical Forest at Shivapuri-Nagarjun National Park, Nepal Himalaya

“…There is great variability in bacterial communities even within the same species in tree canopies of Tropical Atlantic Forest [10]. Recent investigations emphasize the negative effects of air pollutants on the phyllosphere microbial community [11]. A typical feature of epiphytic bacterial population is the high variability in space and time.…”