Aug 6 (Reuters) - The S&P 500 was muted at the open on Friday, as a strong increase in jobs in July sparked concerns of higher inflation at a time when the Delta variant of the coronavirus has cast a shadow over a broader economic rebound. The Dow Jones Industrial Average rose 13.2 points, or 0.04%, at the open to 35077.44. The S&P 500 was flat at 4429.07, while the Nasdaq Composite dropped 30.9 points, or 0.21%, to 14864.216 at the opening bell. (Reporting by Sruthi Shankar in Bengaluru) Our Standards: The Thomson Reuters Trust Principles.